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Int. J. Product Lifecycle Management, Vol. 8, No. 3, 2015

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Data requirements and assessment of technologies enabling a product passport within products exposed to harsh environments: a case study of a high pressure nozzle guide vane César Portillo-Barco Research and Development, MARS-Wrigley, Santa Catarina, Nuevo León, CP 66358, Mexico Email: [email protected]

Fiona Charnley* Cranfield Centre for Competitive Creative Design (C4D), Cranfield University, Cranfield Rd, Cranfield, Bedfordshire, MK43 0AL, UK Email: [email protected] *Corresponding author Abstract: The circular economy production model challenges the limitations of the current linear economic model of production. An improved product lifecycle management (PLM) system, such as in a product passport, can support the circular model. In order for such a system to be robust and reliable, knowledge needs to be created from raw data acquired by sensors in a product through its life. Nevertheless, data acquisition can be challenging or even impossible in harsh environments. Through a case study of a high pressure nozzle guide vane (HPNGV) in a jet engine (a product exposed to harsh environments), this paper aims to define what are the data requirements supporting use cases within a product passport and explore and propose novel applications of sensing technologies acquiring data in hostile environments. A systematic analysis of required data sets of an HPNGV supporting an enhanced knowledge was carried out. Furthermore, a state-of-the-art review in sensing technologies surrounding those sets of data was conducted; those technologies were then assessed, leading to recommendations for feasible and novel applications, which would facilitate a proof-of-concept-stage. Finally, the methodology framework presented is recommended for use with products with similar limitations. Keywords: sensors; harsh environments; product passport; nozzle guide vane; NGV; improved product lifecycle management; circular economy. Reference to this paper should be made as follows: Portillo-Barco, C. and Charnley, F. (2015) ‘Data requirements and assessment of technologies enabling a product passport within products exposed to harsh environments: a case study of a high pressure nozzle guide vane’, Int. J. Product Lifecycle Management, Vol. 8, No. 3, pp.253–282.

Copyright © 2015 Inderscience Enterprises Ltd.

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C. Portillo-Barco and F. Charnley Biographical notes: César Portillo-Barco is currently the Packaging Development and Innovation Manager at MARS-Wrigley. He has a Chemical Engineering Background and holds an MSc in Global Product Development and Management from Cranfield University. His research interests focus on the innovation through collaboration and its application for improved product lifecycle management and sustainability. He has collaborated with a diverse group of organisations and universities, including the leadership of product development projects for the construction, food and packaging sectors. Fiona Charnley is a Lecturer in Sustainable Product and Service Design and Design Program Director within the Centre for Competitive Creative Design (C4D) at the Cranfield University. Her research interests surround the development and implementation of whole system design approaches for the transition towards a more circular and resilient economy. She has led multiple research projects in collaboration with organisations of varying sizes and across industrial sectors resulting in significant advances in transformational and closed-loop models of design and manufacture.

1

Introduction

Per recent analysis, the top 22 minerals and metals reservoirs in the world are going to be exhausted within the next 10 to 50 years (Diederen, 2010). In addition, there is a stricter control on the substances that are being used within products driven by tighter regulations (European Parliament and Council, 2006). Furthermore, pressure given by the economy performance in recent years demands higher efficiencies while improving reliability of assets. Under this scenario, there is an increasing concern between organisations regarding how product lifecycle management (PLM) can be enhanced, thus having better performance, enable regeneration, mitigate supply risk and avoid negative impacts to the environment. The current linear production model of material extraction, goods production and disposal at the end of life is no longer providing an answer for those concerns. The circular economy production model attempts to tackle this problem as it recognises the finite nature of resources and calls for a regenerative design. One of the main changes proposed by this model is to approach product design in a more holistic way, targeting zero waste by means of a closed-loop flow of materials through maintenance, reuse, remanufacture and recycling (The Ellen MacArthur Foundation, 2012). Such a change will require a seamless integration among current product lifecycle stages and systems (Kiritsis, 2011; Cassina et al., 2009), such as design, supply, maintenance and end of life, and a thorough knowledge of the product during its life. The potential of this integration under a single system has been identified by a number of authors and portrays a very promising future (PROMISE Consortium, 2012)

1.1 Systems supporting a circular model Fathi and Holland (2009) proposed a knowledge-based feedback integration to improve product innovation. They also recognise the limitations of product use information sharing between stakeholders. They proposed a transition to a product-service system in order to overcome such obstacle. On the other hand, while the concept is not new,

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different sectors, such as academia, regulation entities and enterprises have been pushing an improved PLM, in the form of a product passport as a way to increase efficiency in resource management, which would support a circular model (European Commission, 2013; The Ellen MacArthur Foundation, 2014). In the same context, the product passport concept has been defined by the European Commission as “a set of information about components and materials that a product contains, and how they can be disassembled and recycled at the end of the product’s useful life”. This will serve as the definition for the purpose of this paper.

1.2 Sensors and knowledge Regardless of the concepts proposed above, such a system would rely on the knowledge obtained from product information. Information is obtained by analysing data, such as data collected through the product use. For the system to be robust, the data needs to be accurate and real-time. An effective way to achieve this is by sensor integration into the product. Sensors, as part of information technology, can support tracking and product status by the use of enhanced analytics. While this could be thought as a straightforward process, sensor integration into products can have various limitations such as cost, connectivity, product main function interference and survival in hostile conditions.

1.3 Sensing in harsh environments Sensing and data acquisition in harsh environments has received a significant amount of attention within different industries (Leo et al., 2012). Périsse et al. (2013) stress the importance of measuring internal conditions, such as structure integrity inside a nuclear reactor, whilst Knudsen et al. (2003) state that oil well sensors (for perforations in the oil and gas industry) have to survive very harsh conditions. Piovesan et al. (2012) presented the challenges of non-destructive inspection methods of the oil and gas production lines installed in deep-water. In addition, Knappe et al. (2013) recognised the importance of measurements inside a diesel engine to generate and validate predictive models. The importance of measuring conditions such as temperature and strain in harsh environments to assist better design of components and enhance effectiveness of predictive systems for jet engines has been highlighted (Ghoshal et al., 2012; Hatcher et al., 2014). Moreover, Pulliam et al. (2001), Feist et al. (2013) and Hatcher et al. (2014) stressed the need of such measurements for performance optimisation and control of new propulsion systems, key contributors for an improved PLM.

1.4 Research questions For conditions such as temperature, currently developed sensing technologies present limitations in harsh environments. In the event of integration of systems, such as in a product passport, products exposed to those environments will be constrained by limitations in technology and therefore not able to be incorporated into further analysis for an improved PLM. In this respect, two approaches have been identified in order to overcome such challenges. They are: 1

the development of current technologies with novel materials resisting harsh conditions (Yang, 2013)

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C. Portillo-Barco and F. Charnley indirect measurements (Fu et al., 2014).

Nevertheless, an analysis of available technologies and how they could be used to support the acquisition of current unknown data is scarce in literature. Furthermore, while many authors have highlighted the importance of sensing in harsh environments assisting improved design, predictive maintenance and performance, their main focus is in one particular technology at a time. Given these limitations, two main research questions arise: 1

What are the data requirements, which need fulfilment so a product exposed to a harsh environment can be incorporated into an improved PLM (such as in a product passport)?

2

What technologies are available and how could they be used to overcome the challenges of sensing in harsh environments?

As a result, for a product exposed to harsh environments, this paper aims to define data requirements within the context of a product passport, explore novel applications of sensing technologies and make recommendations for implementation. In order to achieve this aim, this paper initially deploys and reviews data requirements of a product passport, confirming the importance of sensing operational and environmental conditions in a broader PLM context. Then, a case study of a high pressure nozzle guide vane (HPNGV) in a jet engine is presented comprising the following stages: •

A detailed failure mode and effect analysis (FMEA) of a HPNGV is conducted and conditions to be monitored are identified.

•

A state-of-the-art review in sensing technologies monitoring such conditions is carried out.

•

An assessment of feasible technologies, gaps in current technologies and novel applications are highlighted.

•

Recommendations supporting the implementation of a product passport proof-of-concept in harsh environments are proposed.

2

Methodology

The research approach used in this study was inductive as in its majority, qualitative data is being analysed to generate a conclusion (Robson, 2011). This paper followed four rigorous stages of systematic research: scoping, definition of a gap of opportunity, implementation and validation. Overall, the study included 13 expert interviews, four site visits and 12 stakeholder meetings. A schematic representation of the research methodology used is depicted in Figure 1. In the first three stages, data collection methods and analysis tools were used. The validation was a continuous process with a final assessment of results. More details are provided in the following sections.

Data requirements and assessment of technologies Figure 1

257

Research methodology used (see online version for colours)

2.1 Data collection methods Unstructured interviews were used in the early exploratory stages of the research, to identify the data requirements of a product passport. In particular, these initial unstructured interviews created a snowball sampling effect (Perks, 2010) in where interviewees referred to additional experts. Then, semi-structured interviews were developed and conducted with these experts as to maintain flexibility while keeping the focus on the needs and limitations affecting the sector. Semi-structured interviews are best when interviewing experts because they are normally selected deliberately (Muskat et al., 2012). In addition, unstructured and semi-structured interviews were preferred over questionnaires as they offer the flexibility of modifying the line of enquiry (Robson, 2011). The experts interviewed in this research were prominent professionals in the information technology and aerospace industries, covering data acquisition, business processes, maintenance and design as well as recognised academics and researchers in the fields of integrated vehicle health monitoring (IVHM), micro fabrication (MF), thermography (TG) and thermo barrier coatings (TBCs). With the exception of one person, all the interviews were conducted through site visits. Site visits were very useful as it was possible to meet face-to-face with the interviewee and allowed observing, taking notes and accessing documentation and equipment samples for a better understanding of the industry of interest and what is important for them. In parallel with the data collection, an extensive literature review was carried out, which included more than 60 journal papers surrounding condition monitoring in harsh environments.

2.2 Data analysis and evaluation Several methods for data analysis were used, depending on the needs of the research stage. TRIZ function analysis (Gadd, 2011) was used in the product passport requirement definition (scoping phase) as it reveals all the components in a system, its functions and its interactions. Furthermore, content analysis (Muskat et al., 2012) was the primary method used to interpret the data collected during the literature review and interviews.

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During the core part of the research (gap of opportunity and implementation), FMEA played an important role as both a data collection and analysis tool. FMEA is widely known in the aerospace industry (Moubray, 1997) and in this research context provided an excellent definition of the research direction. This was possible as it is meant to describe the function of an object/device/system and analyse all the ways in which it could potentially fail and the effects surrounding those failures (Griffin and Somermeyer, 2007). This, which also served as a key data collection method, allowed the determination of the conditions behind the promotion of HPNGV failures for a further exploration of their measurements in a very thorough manner. Nevertheless, obtaining the best results depended on the collaboration of experts from different areas, such as design, operation and maintenance. Once the targeted conditions were identified, a quality function deployment (QFD) matrix was adapted for data analysis and sensor design requirements identification. QFD helps to ensure the design targets are related with the expressed customer requirements (collected during the data collection) in a product (Sarkis and Liles, 1995; Liu, 2000). As the ultimate goal is to deploy sensors in such a harsh environment, the best way was to define targets based on customer requirements as if a sensor surviving in the HPNGV harsh environment was to be designed. Then, in a second QFD matrix, it was possible to systematically assess the technologies found for each condition against the design targets. For a more accurate evaluation of those technologies, within the QFD matrix, the design targets were categorised in ‘must have’ and ‘nice to have’ requirement targets as in the Kano model (Chen and Chuang, 2008). Normally, there should be three types of requirements (revealed requirements, expected requirements and exciting requirements), however, in order to minimise complexity of the evaluation, only two categories were used as suggested in the TRIZ ideal outcome audit (Gadd, 2011). Each requirement was then assigned a weight value. Three was used for ‘must have’ and one was used for ‘nice to have’ requirements. This way, asymmetry was assured. On the other hand, each technology was scored against each requirement. The score used here was also different in order to assure the failure to comply with a ‘nice to have’ requirement would not negatively affect the selection of a technology. Further details on these criteria can be found in the results section.

2.3 Validation Weekly stakeholder meetings, which included experts from the concerned areas, allowed continuous validation of the research process. The same process was followed during the validation of the results. These meetings occurred regularly in the form of conference calls with duration of 45 minutes. As mentioned, the total number of meetings was 12 and during those, the need to contact additional experts was addressed as part of the mentioned snowball sampling effect.

3

Product passport requirements

Given the previous work done surrounding the concept of a product passport by different authors, such as those stated by the PROMISE Consortium (2012), several potential benefits and use cases were identified. For the purpose of this piece of research, there was a need to narrow down the use cases to a minimum in order to conceive a potential proof-

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of-concept stage. During a site visit, it was possible to identify several uses cases in where three of them were potential candidates for the project partners. Those were hazardous and critical materials management, end of life regeneration and predictive performance and maintenance. In order to have a clearer view of how such a system would work, there was a need to define the data requirements of it. TRIZ function analysis was used as it provides a simple understanding of how benefits could be reached through functions. Once functions were defined, it was feasible to identify the data requirements needed to fulfil each function. After the data requirements were deployed, they were reorganised by use case. From 48 system requirements identified, six of them were found in direct relation with sensing technologies. In this manner, the impact of the sensing and data acquisition over the use cases was more apparent and ensured the relation between the focus of the research and the product passport concept. Table 1 shows a summarised version. Table 1

Relationship between product passport key use cases, requirements and potential sensing technologies applications

Use case Hazardous and critical materials

End of life regeneration

Predictive performance and maintenance

System requirements

Potential sensing technologies application

Track the material and product through different reuses. Materials could become hazard and critical in the future. Mitigate issues with legislation changes.

X

Product location.

X

Track the product through different reuses. Mitigate issues with legislation changes.

X

Sensing of environmental and operational conditions.

X

Live data and product location transmission. Updates allow knowing how and where the product is.

X

Connectivity between different products and equipment across the fleet.

X

Auto calibration of sensing technology.

X

Sensing technology needs able to be friendly with old devices.

X

However, in order to focus the efforts of this piece of research, one use case, predictive performance and maintenance, was identified as key for the project partners.

4

Case study: a HPNGV in a jet engine

Within the aerospace industry, there is an increasing need for better prediction of maintenance and performance. Thus, maximum utilisation and minimum waste is achieved. Per earlier discussion, all of these require knowledge constructed from raw data, which today is only partially possible by monitoring cooler sections of the engine or by shop visits, which is ineffective and expensive compared with a potential in-flight

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sensing scenario. A case study of a nozzle guide vane (NGV) in the high-pressure section of a jet engine was undertaken, as their performance is a constant matter of research given their important role in the propulsion generation.

4.1 High pressure nozzle guide vanes NGV’s are static pieces of highly valuable metal alloys mounted into a disc inside a jet engine. Their main function is to direct and deliver the gas flow in the correct direction, at the right velocity into the next stages in the engine turbine. A turbine in a jet engine comprises low and high-pressure sections. The high-pressure section starts just after the combustion chamber. The first point of contact of the combustion gases is the turbine high-pressure disc containing NGV’s (see Figures 2, 3 and 4). The section closest to the exhaust is the low-pressure section. As the high-pressure section has the most hostile environment in the entire engine, the measurement of conditions is challenging, something confirmed by the interviewees. Even though there could be up to 25 different sensors in an engine (Rolls-Royce, 2014), they do not include measurement of conditions in a HPNGV. As an additional input from some interviewees, if those measurements were possible, i.e., trailing edge wear, HPNGV’s and overall engine improved PLM would be achieved through the prediction of the health, performance and servicing. Compared with the low-pressure turbine NGV’s, HPNGV’s have a more detailed design. Such design includes complex holes and baffles for cooling, as well as high valuable alloys designed for fatigue. In the majority of the cases, HPNGV’s would include a TBC (see Figure 4). Figure 2

Schematic representation of a jet engine with the NGV discs highlighted (see online version for colours)

Source: Adapted from Nomenclaturo (2014)

Data requirements and assessment of technologies Figure 3

261

Schematic representation of a turbine NGV disc and NGV detail

Source: Adapted from Transportation Safety Board of Canada (2015) Figure 4

High-pressure NGV (see online version for colours)

Source: Adapted from Wikipedia (2014)

4.2 Failure modes and sensing needs In order to have a holistic understanding of what happens to an HPNGV and its sensing needs, an FMEA was conducted in partnership with two sector professionals. The FMEA is presented in Table 2. From this analysis, main causes of failure and their characterisation were identified. This allowed the determination of condition monitoring needs. Further information in regards of current industry standard sensing capabilities was determined with the aforementioned professionals. In addition, it was possible to derive that variation in gas speed in the turbine could be inferred with existing or additional pressure sensors in the exhaust section. The above information made it possible for the focus definition of the research. The details are shown in the Table 3.

Poor application of coating Foreign object damage (FOD) Abrasive contamination in air (e.g., sand) High sulphur fuel Poor air quality Operation near volcanos Microstructural defect in material

Corrosion

Relative movement between NGV platforms and shroud

Upstream component failure

Upstream component failure

Abrasive wear

Changes in thermal profile

Foreign object damage (FOD)

Ingestion

Contact between similar metals in high temperature environment

Adhesive wear

Incorrect temperature profile

Pressure rumble from combustor (High frequency vibrations)

High cycle fatigue

Creep

Thermal fatigue: expansion and contraction difference between different parts of the engine during an operation cycle (different materials, different masses)

Low cycle fatigue

Distortion: Leading to lower efficiency or possibly vane blockage (which can then even lead to the surfaces of the vane separating)

Changes in temperature profile: leading to burning and/or cracking

Loss of material in platform, leading to loss of strength in platform, leading to distortion and lower efficiency

Pitting of surfaces: Loss in efficiency

Loss of cooling efficiency: See other entries regarding increases to operating temperature (e.g., burnback)

Gas speed/vane integrity

Temperature

Movement/vane integrity

Gas speed/vane integrity

Temperature/vane integrity

Temperature Temperature

Distortion of blades: reduction in cooling efficiency, resulting in further damage such as burnback (burning of the trailing edges)

Temperature/material inspection

Distortion of blades: Affects efficiency

Distortion of blades: reduction in cooling efficiency, resulting in further damage such as burnback (burning of the trailing edges)

Airflow/material inspeciton

Air/fuel quality/temperature

Suflidation: Can corrode internal baffles leading to lower vane cooling

Distortion of blades: Affects efficiency

Coating thickness/integrity

Cracking: Damage to cooling pathways resulting in further damage such as burnback (burning of the trailing edges) Spalling of coating: leads to loss of thermal barrier coating and thermal damage (e.g., burnback)

Temperature/vibration Temperature/vibration

Cracking: parts of vanes come loose and FOD downstream components

Temperature/vibration Temperature/vibration

Cause characterization (condition to be monitored)

Cracking: Damage to cooling pathways resulting in further damage such as burnback (burning of the trailing edges)

Effect Cracking: parts of vanes come loose and FOD downstream components

Secondary function: Cause

Set the pressure balance between the turbine sections

Function:

Table 2

Failure mode

Direct the airflow in the correct direction and velocity into the High

Pressure turbine

Main

High pressure nozzle guide vane (HPNGV)

262 C. Portillo-Barco and F. Charnley

FMEA of a typical HPNGV

Data requirements and assessment of technologies Table 3

263

Current industry standard sensing capabilities of interest of a HPNGV

High pressure turbine section/NGV Condition

Current industry standard sensing capabilities Yes

Comments

No

Temperature

X

Temperature is only measured in the Intermediate or low pressure section.

Vibration

X

Vibration is not currently measured.

Integrity/wear

X

Integrity or wear is not currently measured.

Movement

X

Movement is not currently measured.

Gas speed*

X

Air speed is not currently measured directly in the HP section. This could be implied by pressure differentials information in the exhaust section.

Sulphur*

X

There is not current sensor for sulphur oxides in the exhaust nor in the amount of sulphur in the fuel. Fuel check is conducted at supplier audits/contracts against industry standards.

Air quality*

X

Intake air quality is not currently measured.

Preinspection for integrity*

X

It is assumed that the parts are inspected for integrity, coating adhesion, etc.

Note: *This variable does not need to be inspected in the HP section.

4.3 State-of-the-art review for sensors in operational and harsh environments Typical conditions inside jet engines include temperatures of 1,500°C or more, high centrifugal forces and high abrasion (Feist et al., 2013; Yang, 2013; Gregory et al., 2002; Tougas and Gregory, 2013; Pulliam et al., 2001). Under these conditions, a traditional contact sensor, such as a thermocouple will not survive (Chang et al., 2014; Saunders, 2007; Patrick, 2000; Allison et al., 1997). On the other hand, non-contact measurement methods could require significant invasion. These are the main reasons why there is no current direct condition monitoring in a HPNGV. Consequently, information about the maintenance and operation of these parts is either gathered in shop visits or implied by indirect measurements conducted in other sections of the engine, leading to conservative operation margins (Feist et al., 2013). Per industry experts, the above combined with data about the engine operational environment, would enable enhanced analytics for even better engine components health and performance predictions, thus improving the overall PLM.

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Table 4

State-of-the-art review for the operational and environmental conditions of a HPNGV

Technology

Conditions monitored 1

2

3

4

5

6

7

Based on information from the authors

Metallic thermocouples

X

Tougas and Gregory (2013), Gregory et al. (2002), Gregory and You (2005), Saunders (2007)

Colorimetric pyrometry

X

Chang et al. (2014)

Phosphor thermometry

X

X

Infrared (IR) pyrometry and imaging

X

X

X

Baleine (2014)

Piezoelectric thermocouples (ceramic)

X

X

X

Tougas and Gregory (2013), Gregory et al. (2002), Gregory and You (2005)

Acoustic thermometry

X

Allison et al. (1997), Patrick (2000), Knappe et al. (2013), Feist et al. (2013)

Périsse et al. (2013), De Podesta (2014)

Dye penetrant

X

Magnetic particle

X

Gamauf (2009)

eddy current

X

Gamauf (2009), Reimche et al. (2013), Chana et al. (2013)

X-ray

X

Ewert et al. (2012)

Ultrasound

X

Piovesan et al. (2012), McLay and Verkooijen (2012), Kresic and Ironside (2005), Beuker et al. (2005)

X-ray fluorescence

X

Doering et al. (2004), Lomax (2011)

X

Astarita and Carlomagno (2013), Qingju et al. (2013), Genest et al. (2013)

Beamforming and acoustic holography (mixed acoustics)

X

Fu et al. (2014)

Structured light illumination

X

Summa (2014), Frankowski and Hainich (2011), Hassebrook et al. (2007), Wang et al. (2009a)

White light interferometry

X

Ullrich and Ernst (2012), Conroy (2010)

Laser vibrometry

X

Termography

Accelerometer

X

Calcagno and Marmigi (1999), Gamauf (2009)

X

Giuliani et al. (2007), Altunlu et al. (2014), Schwitzke et al. (2013)

X

Wroblewski and Grabill (2001)

Microwave Light probes

X X

Woike et al. (2013, 2014) Jones (1996), Maekawa et al. (2014)

Data requirements and assessment of technologies Table 4

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State-of-the-art review for the operational and environmental conditions of a HPNGV (continued)

Technology Extrinsic fabry/perot interferometry and fibre Bragg grating (FBG)

Conditions monitored 1

2

X

3

4

5

6

7

X

Based on information from the authors Pulliam et al. (2001), Wild (2013), Knudsen et al. (2003)

Electric capacitive

X

Wang et al. (2009b), Reuder et al. (2009), Smit et al. (2008), Karion et al. (2013)

Near infrared off/axis integrated cavity output spectroscopy

X

Berman et al. (2012)

Cavity ring down spectroscopy

X

Karion et al. (2013)

Tuneable laser diode absorption spectroscopy

X

WMO (2008), SpectraSensors (2014)

Fourier transform infrared spectrometry (FTIR). Exhaust gases

X

X

X

Corporan et al. (2007), Fleig et al. (2012), Bhagwan et al. (2014), Heland and Schäfer (1998), Marran et al. (2001), Voitsekhovskaya et al. (2013), Murray et al. (2008), Smith et al. (2008)

Fourier transform infrared spectrometry (FTIR). Weather Hazards

X

X

X

Corporan et al. (2007), Fleig et al. (2012), Bhagwan et al. (2014), Heland and Schäfer (1998), Marran et al. (2001), Voitsekhovskaya et al. (2013), Murray et al. (2008), Smith et al. (2008)

Solid state ionics

X

Mulmi et al. (2014)

4.3.1 Technology for condition monitoring The data collected including the identified technologies and their relation with the condition of interest is summarised in Table 4, in where conditions monitored by each technology are marked. The conditions are: 1

temperature

2

integrity and wear

3

vibration

4

movement (displacement)

5

sulphur

6

humidity

7

weather hazards (volcanic ashes and icing conditions).

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Figure 5

Full adapted QFD for assessment of technologies versus design targets and requirements (see online version for colours)

Design Requirements

Method

A

B

C

Top Row: Requirement weight - Bottom Rows: requirement fulfilment per each technology Total "Must have" "Nice to have" Score

Technology

Conditions to be monitored 1

2

3

4

3

3

3

3

3

1

1

Non- Structured Light Contact Illuminaon

-3

-3

-3

-1

-1

0

0

-33.00

X

Non- White light Contact interferometry

-3

-3

-3

-1

-1

0

0

-33.00

X

NonLaser Vibrometry Contact

-1

-1

-1

-1

-1

1

0

-14.00

X

X

X

X

X

X

X

X

X

5

6

7

X

0

0

0

0

-1

1

0

-2.00

-1

-1

-1

0

-1

0

0

-12.00

NonLight Probes Contact

-3

-3

-3

-3

-1

0

0

-39.00

Extrinsic Fabry-Perot Interferometry and Contact Fiber Bragg Grang (FBG)

-1

-1

-1

0

-1

1

0

-11.00

Contact Electric capacive

0

0

0

0

0

0

0

0.00

X

Near Infrared Off-Axis NonIntegrated Cavity Contact Output Spectroscopy

0

0

0

0

0

0

0

0.00

X

Non- Cavity Ring Down Contact Spectroscopy

0

0

0

0

0

0

0

0.00

X

Tuneable Laser Diode NonAbsorpon Contact Spectroscopy

0

0

0

0

0

0

0

0.00

X

0

0

-3

-1

0

1

0

-11.00

X

X

X

0

0

-1

-1

0

1

0

-5.00

X

X

X

0

-3

-1

-1

-1

0

0

-18.00

X

b

c

d

e

f

Contact Solid State Ionics Design targets Category

a

Environment

Space

Based on information from the Authors Summa (2014); Frankowski and Hainich (2011); Hassebrook et al . (2007); Wang et al. (2009) Ullrich and Ernst (2012); Conroy (2010)

Giuliani et al. (2007); Altunlu et al. (2014); Schwitzke et Feasible and can be used in Combustor with the novelty of the al. (2013) movement. Nevertheless, there is no single device development for this technology and several devices need to be assembled. Accelerometers can be used to indirectly detect combustor Wroblewski and Grabill (2001) rumble without the need of in-situ sensors. They can use exisng sensors in the engine and just increased analycs. Novel for integrity and vibraon as their current focus is for p Woike et al . (2013, 2014) clearance. A new sensor would need to be developed for vibraon and integrity near the HP secon. It seems that light probes are not well accepted in jet engines and Jones (1996); Maekawa et al. (2014) only one test was conducted in the fan stage. They can be bought off-the-shelf.

X

NonMicrowave Contact

Fourier Transform NonInfrared Spectrometry Contact (FTIR). Exhaust gases Fourier Transform Non- Infrared Spectrometry Contact (FTIR). Weather Hazards

Comments Measures integrity of a surface. For shop only, it is affected by radiaon of combuson. Measures integrity of a surface. For shop only, it is affected by radiaon of combuson. There is a current patent from Luhansa.

Contact Accelerometer

X

Level of readiness

There are current MEMS developed to measure temperature and Pulliam et al . (2001); Wild (2013); Knudsen et al . (2003) vibraon, the challenge is the harsh environment. SiC and Saphire are proposed. FBGsensors are commercially available. Yang Wang et al. (2009); Reuder et al . (2009); Smit et These sensors are commercially available and have been tested al. (2008); Karion et al . (2013) for calibraon issues for measurement of air humidity. There is an instrument currently developed by NASA for Berman et al . (2012) measurements of Greenhouse effect gases including H2O. Los Gatos Research are leaders on this. There are instruments developed by Picarro using this technique Karion et al . (2013) for airborne applicaons measuring the Greenhouse gases, such as water vapor. Can be use to measure humidity. For Humidity measurements, These sensors are already in use by WMO (2008); SpectraSensors (2014) Luhansa and UPS and are already off-the-shelf for humidity measurements. Corporan et al. (2007); Fleig et al . (2012); Bhagwan et This technology can be used to analyse gases such as SO2 and al . (2014); Heland and Schäfer (1998); Marran et al . SO3, however, it is sll not mature as SO3 is difficult to track due (2001); Voitsekhovskaya et al . (2013); Murray et al . to its chemical instability This technology can be used to detect weather hazards. However, Corporan et al. (2007); Fleig et al . (2012); Bhagwan et al . (2014); Heland and Schäfer (1998); Marran et al . these sensors are currently developed for ground-based and (2001); Voitsekhovskaya et al . (2013); Murray et al . Forward-Looking of threats aboard an aircra is sll under (2008); Smith et al. (2008) development. Non-matured yet. First tests conducted only for SO2 and CO2 in Mulmi et al . (2014) 2014.

g Energy

Design requirements A The sensor must measure reliably in the operaonal environment B The technology has to be able to acquire data without minimum invasion C The technology should keep the energy consumpon at minimum

Desgin targets a The sensor must resist the operaonal temperature (1,260°C minimum per recommendaon from Ghoshal et al., 2012 b The sensor must resist the operaonal forces and abrasive environment c The sensor reading dri must be insignificant under the typical operaonal condions d The sensor must be able to fit into current plane/engine structure without major invasion e The data acquired must be transmied into the current infrastructure f The sensor should be able to monitor more than one condion g The sensor uses the exisng resources to harvest energy

For the evaluation of such technologies, customer requirements for a sensor were deployed and sensor design requirements and targets were proposed using an adapted QFD, which is represented in Figure 5. According to the work in Ghoshal et al. (2012) these should be: •

survivability at specified temperature

•

long-term durability

•

adequate sensitivity at high temperature zones

•

maintain adequate adhesive bonding to the structures

•

data acquisition hardware needs to survive high temperatures

•

not prone to electromagnetic interferences and extreme temperature changes.

The proposed targets also took into account the input from a respected expert in the topic within the US Army Research Laboratory. As part of an interview with this expert, it was stated that particular sensors would need to be fully tested in a real engine. Nevertheless, in order to reach such level of maturity, some lab rig test would be needed first.

4.3.2 Energy harvesting While energy harvesting was one of the sensor design targets pursued in state-of-the-art review, besides piezoelectric materials, none of the identified technologies included energy harvesting capabilities. In addition, while piezoelectric materials have a

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mechanical energy harvesting nature, they need to be specifically developed for that purpose in order to be effective. There are recent advances in energy harvesting technologies for structural health monitoring (SHM) presented by Davidson and Mo (2014). Those methods include ambient and wind vibrations, rotational energy, thermal energy and solar power. It could be said that vibration energy harvesting is matured, as they are commercially available. One other technology, which has promising future in the aerospace industry, is the thermoelectric generation (TEG). Tests have already been conducted for naval and space applications (Jovanovic et al., 2006; Hi-Z Technology, 2014). A combination of these methods is something to consider, as they would supply the energy needed for in-flight health monitoring systems.

4.3.3 Electronics supporting sensors in harsh environments Yang (2013) proposed a device, which includes a thermal-sprayed contact thermocouple attached to a turbine blade. The thermocouple is then connected to a silicon-carbide (SiC) wireless electronic device, which can serve as data acquisition and digital identifier. This device would be mounted in one of the sides of the mounting section of the blade. Tests conducted revealed it can hold up to 450°C versus latest electronics 200°C limit. A depiction of this device is shown in Figure 6. The above is coincident with recent reflections shared in the International Instrumentation Symposium 2013 (Behbahani et al., 2013) where it was shown that silicon-on-insulator (SOI) instrumentation holds up to 250°C and SiC components can hold up to 500°C. While the temperature in that section of a blade or HPNGV would not be expected to be in the range of 1,500°C, the operation of such miniaturised electronics will be limited to areas in where that section operates below 500°C. In addition, further tests in particular engines will be required to determine its full feasibility. During the mentioned symposium, it was also stated that one of the biggest challenges is the fact that the operation temperature of engines is moving in the opposite direction (higher temperatures) to the efforts of putting more instrumentation into the engine. More instrumentation would provide intelligence to enable analogue-to-digital conversion. One approach to tackle this is to put the instrumentation (full authority digital engine control, FADEC) as far from the heat sources as possible. The problem with such approach is the large wiring harness. This can bring interference, noise and risk of fire. Another path proposed is to move the FADEC into a more centralised location, with the challenge of bulky and heavy forced cooling systems. The solution proposed then is to increase the robustness of the electronics and packaging. Some requirements for such instrumentation on cost and working temperature are proposed. Nevertheless, as there is no off-the-shelf solution thus far, the recommendations from the group conducting the research were to work in collaboration within the interested parties to develop reliable and low cost robust instrumentation. In the meantime, the FADEC units will progress limited to cooler areas of the engine.

268 Figure 6

C. Portillo-Barco and F. Charnley Miniaturised electronic device in a turbine blade (see online version for colours)

Source: Yang (2013)

4.3.4 Sensor health Once a sensing technology reaches the maturity level to survive harsh environments, calibration protocols would be a next step. In this respect, Yan and Goebel (2003) proposed a system to use existing sensors to validate the sensor performance. This could be achieved by using existing hardware and software in the engine FADEC. These would allow assessing the health of the sensors and then providing more accurate information to the operator/maintainer. It is also suggested to cross check sensor health with sensors from different variables and data acquisition methods such as contact and non-contact. This will need development of in-flight analytics and intelligence. Nevertheless, it will help to assess the sensing system health and avoid unnecessary actions. This is achievable with existing sensors in cooler areas of the engine and eventually harsh environments could be incorporated.

4.4 Results The identified technologies were assessed using an adapted QFD against the established design targets and their design importance (Figure 5). Design importance was given by assigning a weight factor to each target. In this case, for the ‘must have’ targets, a value of three was used versus the value of one assigned to the ‘nice to have’. This asymmetry assured the ‘must have’ targets were given the most relevance. Then, each technology was given a score per each target reflecting its capability of target fulfilment. Because not all the targets were having the same weight (‘must have’ vs. ‘nice to have’), there was a need to score them differently in order to make sure the lack of a ‘nice to have’ target would not negatively impact the technology evaluation. Afterwards, each score was then multiplied by each target weight factor in order to obtain a total score, as in the following formulae:

Data requirements and assessment of technologies

269

n

Total _ Score =

∑(w ⋅v ) i

i

i =1

in where, w

design target weight factor

v

technology score per design target.

For the first five requirements (‘must have requirements’), the weight factor was ‘3’. For the last two requirements (‘nice to have’ requirements), the weight factor was ‘1’. Details on the different scales used for the different design targets are presented in Table 5. The total score was then placed in an adjacent column and it was used for the final assessment. The reason for the selection of a negative scale for the ‘must have’ requirements was based on the assumption that an off-the-shelf technology would be in a neutral position if complying with the expected requirements. Then if in addition, it complied with a ‘nice to have’ requirement, the score would have an impact above ‘zero’. Based on the assessed data, the scores were grouped in ranges and colour codes as an attempt to visually identify the level of feasibility and to provide a meaning to the score. See Figure 7. Table 5

Design target weighting factors Criteria for technology assessment

Design target ‘Must have’

‘Nice to have’

Score

Meaning

0

YES or not applicable

–1

Requires development

–3

NO

1

YES or not applicable

0

NO

After the feasibility scale was identified, then each technology was coloured and dashed for easy identification in Figure 5 (adapted QFD table). In addition, the QFD table also served as a workspace to capture current applications, find gaps, identify novel applications for different conditions and finally to collect findings and references utilised during the research. Based on the QFD and in the scale and definitions in Figure 7, a feasible technologies table was then constructed in order to extract the technologies that were more promising. A condensed version is available in Figure 8. Figure 7

Technology assessment scale (see online version for colours)

Scale N/A N/A -45.00 to -20.00 -19.99 to -10.00 -9.99 to -5.00 -4.99 to 0

Colour Code Current Applicaon X Novel applicaon X Non-Feasible (Red)

Meaning

Requires Major Development (Orange) Feasible with more Development (Yellow) Off-the-shelf/slight modificaons needed (Green)

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Figure 8

Method

Feasible sensing technologies in the HPNGV environment (see online version for colours) Technology

Top Row: Requirement weight - Bottom Rows: requirement fulfilment per each technology

Conditions to be monitored

3

3

3

3

3

1

1

Total Score

1

2

Non-Contact Phosphor Thermometry

0

-1

0

0

-1

1

0

-5.00

X

X

Non-Contact Eddy current

0

-1

0

0

-1

1

0

-5.00

X

3

4

5

6

7

Level of readiness

Based in information from Authors

Allison et al . (1997); Patrick (2000); Knappe et al . (2013); Feist et al . (2013) X

Gamauf (2009); Reimche et al. (2013); Chana et al. (2013)

X

X

Contact

Accelerometer

0

0

0

0

-1

1

0

-2.00

Contact

Electric capacive

0

0

0

0

0

0

0

0.00

X

Wang et al. (2009); Reuder et al . (2009); Smit et al. (2008); Karion et al . (2013)

Near Infrared Off-Axis Non-Contact Integrated Cavity Output Spectroscopy

0

0

0

0

0

0

0

0.00

X

Berman et al . (2012)

Non-Contact Cavity Ring Down Spectroscopy

0

0

0

0

0

0

0

0.00

X

Karion et al . (2013)

0

0

0

0

0

0

0

0.00

X

WMO (2008); SpectraSensors (2012)

Fourier Transform Infrared Non-Contact Spectrometry (FTIR). Weather Hazards

0

0

-1

-1

0

1

0

-5.00

Design targets

a

b

c

d

e

f

Non-Contact

Tuneable Laser Diode Absorpon Spectroscopy

Category

Environment

Space

Wroblewski and Grabill (2001)

X

X

X

Corporan et al. (2007); Fleig et al . (2012); Bhagwan et al . (2014); Heland and Schäfer (1998); Marran et al . (2001); Voitsekhovskaya et al . (2013); Murray et al . (2008)

g Energy

4.5 Analysis of results Once the more promising technologies were identified, there is a need to analyse how and which of them could be used effectively in the short term in order to support improved PLM implementation. Unfortunately, it was not possible to find off-the-shelf or even feasible technologies for every condition identified as key for monitoring the health and performance of a HPNGV. Nevertheless, in an attempt to recommend options supporting the implementation of improved PLM, the following technologies are discussed.

4.5.1 Temperature, vibration and integrity For the direct temperature and integrity monitoring of the HPNGV, phosphor thermometry is an option that has high potential. This is because TBC’s can easily be developed for phosphorescence without extra cost, and the fact that the technology is already being used in industrial applications, such as steel furnaces and power generation. Moreover, ground-based jet engine trials were recently conducted with success (Feist et al., 2013). Per insights from an interview with experts on TBC’s development, this technology has demonstrated its feasibility and it appears as if it will only need investment and commitment from a manufacturer thus it can fit into commercial flights. On the other hand, and of high relevance, as the coating is worn out with normal use, it would interfere with the real temperature measurement. Nevertheless, disruptions of temperature measurements and images from the HPNGV can be further compared with standards and be interpreted as HPNGV wearing and coating detachment. Moreover, limitations on typical optical probes can be overcome by using transpiration purged optical probes as proposed by VanOsdol et al. (2007).

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Accelerometers are identified as another promising possibility. This is due to the fact that current can be used to detect combustor rumble and screech. As is known by the industry experts, these sources of vibration severely affect the integrity of the HPNGV’s. One of the main advantages of this technology is that is an indirect way to measure the vibration caused by the combustor; thus, they do not have to be in the high temperature environment. Nevertheless, additional in-flight analytics would need to be developed in order to identify the different vibrations, filter noise and develop a prediction of failure. This also may result in the need to install additional accelerometers through the engine, thus require additional investment. As identified in the literature, recent successful tests were conducted with Eddy current (EC) sensors in harsh environments (Chana et al., 2013). While the intended application was to measure tip clearance between the rotating blades and case, EC is a matured technology for integrity measurement. Thus, given the success of such tests, EC is proposed as a way to directly measure the integrity of the HPNGV.

4.5.2 Operational environment and sulphur In terms of operational environment of a jet engine, there are several factors that can affect its performance, such as relative humidity, temperature, pressure and weather threats such as, volcanic ashes and turbulence. Intake air temperature and pressure is already monitored in jet engines (Rolls-Royce, 2014), therefore, there is no need to explore such factors. On the other hand, the two main factors identified in the literature were air humidity and weather threats. The following technologies, while not suitable for direct engine installation, are off-the-shelf technologies that are increasingly being adapted by airlines in their fleets to measure relative humidity. Such technologies are: capacitive sensors and tuneable laser diode absorption spectroscopy. The main driver of the development of these technologies was the detection of weather hazards such as, icing conditions and storms. Until recently, these threats were only predicted by performing twice-a-day measurements of weather balloons in limited geographical locations. These sensors now enable airlines to have real-time weather information and avoid unnecessary delays and flight cancellations. In regards to weather hazards, Fourier transform infrared spectroscopy (FTIR) is a viable option. It appears as if in the short term it can be applied for forward-looking of weather threats in-flight devices. This would enhance the ability of crews to avoid hazards. The use of this technology is one of the main pushes from the Next Generation Air Transport System (NextGen), which is to be fully implemented in the next few years. If engine manufacturers were able to access that information, in addition to the current geographical position services (GPS) included in the aircraft avionics system, it could potentially assist in a better determination of real-time flight paths. These would be critical in the health prediction of an engine and its components and moreover, be compared with performance of other engines in the fleet.

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FTIR can also be used to measure the emissions of a jet engine, such as sulphur oxides (SOx). This information can be obtained at the airport level and generate a history of levels of emissions, which can be later on analysed and determine the health status and ‘age’ of the engine.

4.5.3 Energy harvesting Piezoelectric materials are good candidates for vibration energy harvesting. In fact, they are commercially available. In addition, thermo-electric generators (TEG) are another proven commercial option available which, in its end, harvest energy from waste heat. These two technologies can be tailored to a particular jet engine and combined if needed. In such a case, it would be possible to take advantage of the current wasted vibration and heat energy waste and as a result help sustain the current engine sensor network and FADEC. Thus far, real-time condition monitoring could be supported by at least two technologies (accelerometers and tuneable laser diode absorption spectroscopy), which are feasible to be applied in a potential immediate pilot test scenario. This would imply minor modifications to current aircraft/engine structures as found in the literature. On the other end, FTIR and EC sensors are options to keep a close eye on, as it promised to be further developed in the very near future. Finally, energy-harvesting technologies, such as TEG and piezoelectric harvesters are proven options. It is then recommended to further assess the trade-offs of them for implementation, as they seem to promise a feasible way to sustain the energy needs of an increasing sensing presence.

4.5.4 Novel applications Several novel applications were identified and assigned a level of feasibility. They are presented in Figure 9.

4.5.4.1 Movement (displacement) Infrared pyrometry (IP), as found in literature, has multiple applications. Based on the findings, it is then suggested that this technology, as well as laser vibrometry (LV), if implemented in a jet engine, could be used to measure the movement of HPNGV’s through comparison of position standards. Even though acoustic thermometry has low feasibility, given its working principles, could be used to measure displacement of objects. An option to avoid the limitations of acoustic thermometry is the combination of beamforming and acoustic holography. While the potential use of this technology is the integrity of a structure in a less hostile environment, it also has the potential of measuring displacement. Light probes are an off-the-shelf technology that has applications in cooler sections of a jet engine. While it has been used to measure tip clearance, the signal recovered by these sensors can also be interpreted as displacement. Fibre Bragg grating (FBG) sensors on their end, are capable of measuring several variables such as temperature and vibration. Based on its principles and the possibilities of MF, it is then suggested its use in displacement measurements. Nevertheless, this technology is not currently ready for harsh environments, although it could be used in cooler areas.

Data requirements and assessment of technologies Figure 9

273

Novel applications of current technologies (see online version for colours)

4.5.4.2 Integrity, wear and vibration On its end, microwave is currently being used for tip clearance, however, if appropriately developed, could also be used to measure integrity and vibration in a high-pressure section of a jet engine. On the other hand and as discussed earlier, EC sensors are a promising option for harsh environments. Because of its working principles, its application for displacement and vibration measurements is foreseen. It is then recommended to keep close attention to its development for its further application in the high-pressure section of a turbine.

4.5.5 Findings As a reflection of the results, it can be said that there is a significant amount of work conducted, in order to push the development of direct contact methods, such as thermometry and high temperature electronics. However, as assessed in this paper, it is still far from satisfying the demanding needs of components, such as the HPNGV. To add to this already complex scenario, there is a general consensus between engine manufacturers about increasing the operational temperatures in order to improve efficiency and reduce emissions. While research about the direct contact methods and electronics continues, their progress pace will not be adequate for a short term scenario,

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which is needed to better support PLM, such as in the proposed by the circular economy production model. The overall findings will be presented in the discussion section.

5

Discussion and recommendations

During the case study, almost 30 technologies were identified. These were then scored and evaluated in order to visualise their benefits, potential applications and feasibility in the HPNGV environment. The findings revealed that condition monitoring in harsh environment, regardless of the sector, is still a challenge and material for further research. Nonetheless, this exercise should serve as a point of reference enabling an outlook of progress made so far in the different sensing technologies for use in harsh environments. This research work should also serve as a glance of the possibilities and areas of opportunities of such applications. Additionally, the contents presented here, enable further analysis for application of the researched technologies in the broader field and in other areas.

5.1 Recommendations for future research and application of sensing technologies in harsh environments and jet engine operational environment In the case study section, a group of technologies surrounding an HPNGV were assessed and analysed in an attempt to recommend the most feasible ones for a potential improved PLM system proof-of-concept in the form of a product passport. However, it is important to reflect about the findings and the general status of the areas of research regardless of its current feasibility. Based on the results of the case study, it is then recommended to look for the miniaturisation of indirect methods presented in this document. The argument behind this is that even if a material for direct contact sensing is developed, it will always be exposed to unpredicted abrasion from the environment and peaks of pressure from the combustor. These factors would affect the reliability of readings and would require frequent calibration and maintenance compared with indirect methods. The above proposal would increase the chances of data acquisition in the HPNGV environment, which would eventually support the implementation of the envisioned proof-of-concept scenario. In terms of operational environment, the fact that the NextGen is something to be implemented globally in the next few years provides the leverage on the use of FTIR for operational environment data acquisition.

5.2 Recommendations on collaboration between stakeholders for a successful implementation of sensing technologies Challenges on condition monitoring in harsh environments and proposals to overcome them in the particular HPNGV case study have already been discussed. Nevertheless, these proposals would be limited to a proof-of-concept scenario. It is foreseen that firm progress on the matter will only be possible through collaboration between the aerospace stakeholders, including engine and aircraft manufacturers, universities, sensor companies, research entities and authorities. Challenges for them are common and by joining efforts, those challenges could be promptly overcome, for the benefit and competitiveness of the

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sector. This would also enable them to better afford the even stricter regulations to come and develop a more robust management of resources, supporting a circular model.

5.3 Recommendations for application of identified technologies outside harsh environments As discussed before, with the exception of a couple of cases, current technologies face several limitations for condition monitoring in harsh environments. Nevertheless, advantage of the current exercise should be taken in order to explore other potential applications of such technologies in different environments and even different sectors. For example, many of the technologies reviewed here, could be easily applied to assist in the health prediction of several engine components in cooler sections of the engine. In addition, novel applications can be further explored. A concrete example could be the gas turbines in a thermoelectric power generation plant. Such type of equipment shares many similarities with jet engines and has the advantage of being ground-based.

5.4 Reflection on the potential benefits within the wider PLM and product passport context Section 3 of this paper presents use cases and requirements of a product passport, prioritising predictive performance and maintenance as the focus of the research. However, departing from this research focus results, a further reflection on the potential benefits into a wider PLM context is necessary. In this regard, it is important to acknowledge that the lack of data is an obstacle for a better management of a product or component through its life. Assuming that it was possible to acquire data in harsh environments, that data can be further analysed and turned into information. Subsequently, that information can be compared and combined with previous knowledge from the business, resulting in better predictions for the product. Those predictions would support procurement decisions on the component such as maintenance, potential reuses across other engines, remanufacturing options and finally, recycling. On the other hand, through the creation of advanced analytics, data acquired would allow the predictive performance to be achieved. This includes a more realistic definition of the product use and useful life, the reporting of current product health and in general of any enhanced product analytics. Such an analysis would serve as a critical input for improved product and component design, including specific operational environment scenarios. Hazardous and critical materials management use case can also benefit from the sensing technologies in discussion. As the NGV’s are made from critical materials, such as nickel alloys, using enhanced knowledge based on new data acquired, better sourcing strategies can be deployed, mitigating risk and supporting closed-loop material cycles. Similarly, it would be applicable for components having current or potential hazardous materials. While it can be foreseen that the above examples would help push boundaries of current PLM approaches, such as in a product passport, it is important to highlight that in order to apply the outcomes from this research into the aforementioned examples in the benefit of a wider PLM scenario, further research is required. This can be done through

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the development of a specific proof-of-concept scenario, which would require a define architecture and enhanced analytics.

5.5 Limitations of research During this research, there were some limitations that are relevant to recognise. In the state-of-the-art review conducted, there is a lot of focus on implementing direct contact methods versus non-contact ones, especially thermometry. Perhaps, this fact is due to the high relevance of the temperature measurements. However, there are other sensing needs such as vibration and integrity that need more attention. It is then reflected that there is a need for further research on technologies applicable in that respect. Another difficulty was the limited access to the failure information of the component in discussion during the data collection section. This was due to commercial information sensitiveness and confidentiality. It is believed by the authors that thorough access to such information would have provided even more valuable information to the research partners. Nonetheless, it is believed that this piece of research still fulfils the expectations stated earlier. Lastly, another relevant challenge was the difficult nature for approaching the topic in discussion in the context of the HPNGV. The sensing topic can be very vast, as many technologies exist. Thus, an effective way to approach it in a short time was needed. While the methodology used in the case study can be challenged, it appears as the combination of FMEA and QFD assures the robustness of this research as it goes to specific change in condition that cause the failures. While the methodology followed seemed effective, it is important to recognise the need from experts input through interviews, as well as some technical background from the researchers, thus, data interpretation was legitimate. In addition, although it would require further validation, it is still recommended for future researchers in similar situations to apply the methodology framework presented in this document.

6

Conclusions

In this paper, essential data requirements of a product passport were deployed. Through a case study of a HPNGV, the focus of the research was defined; sensing technologies for condition monitoring in the harsh environment as well as in the operational environment surrounding a jet engine. A state-of-the-art review in those technologies was then conducted. Opportunities were identified and recommendations for implementation within a product passport proof-of-concept were proposed. This piece of research impacts the field of sensing technologies in harsh environments and reflects how could it contribute to a wider PLM context. The contribution to knowledge of this paper is made through a state-of-the-art review and a systematic analysis of findings and sensing requirements of a HPNGV in the case study section. Then, a gap of opportunity in sensing technologies for harsh environments was identified and the novel applications, future research requirements and recommendations for implementation in the context of a product passport were reflected. The above provides fulfilment of the aim and answers the research questions:

Data requirements and assessment of technologies 1

What are the data requirements, which need fulfilment so a product exposed to a harsh environment can be incorporated into an improved PLM (such in a product passport)?

2

What technologies are available and how could they be used to overcome the challenges of sensing in harsh environments?

277

This was achieved as it identified novel applications and proposed feasible scenarios for the eventual short-term implementation of a proof-of-concept of the specified use case in a product passport. Finally, a framework for definition of sensing needs and assessment of available technologies against particular requirements for products under similar conditions is proposed. In this sense, this paper pushes the boundaries of current PLM approaches for products exposed to harsh environments. This paves the way for further assets to be incorporated into a product passport scenario assuring sensing needs are analysed holistically, possibilities are evaluated and developed, and an accelerated transition towards a more holistic PLM supporting a circular model is then enabled.

Acknowledgements The authors would like to thank project partners from Rolls-Royce, Cisco and Granta Design who supported this research. In addition, the authors would like to acknowledge the Mexican Science and Technology Council (CONACYT) for sponsoring one of the authors.

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