Text operators for PDF

Proceedings of the National Conference on Innovative Trends in Mechanical and Aerospace Engineering (ITMAE-2014)

MAE 136

Pulse Detonation Propulsion System - PEC Chandigarh Experience Subhash Chander, Research Scholar and T K Jindal, Associate Professor

Abstract-- Pulse detonation technology has the potential to revolutionise both in-atmosphere and space flight. Having an engine capable of running efficiently at Mach 5 will not only allow for faster, more efficient intercontinental travel, but will also change the way spacecrafts are launched. It has got huge potential for missile, aircraft and many other applications. It has got many merits including simple design, small form factor, low cost of operations. Noise, DDT, vibrations and safety are still key impediments in the field, which are being addressed worldwide. The present paper discusses about the basics and applications of Pulse detonation engine, challenges faced and their remedial follow-ups by PECChandigarh team [1]. Index Terms-- Pulse detonation engine (PDE), deflagration, detonation, Deflagration to detonation (DDT), DAQ, Schelkin spiral, Fire Control System (FCS), Rocket, Aerospace, Missile propulsion I. NOMENCLATURE C2H2 DAQ DDT FCS Fig. O2 M PDE PV φ

Acetylene Data Acquisition System Deflagration to detonation Fire Control System Figure Oxygen Mach No. Pulse Detonation Engine Pressure Volume Equivalence ratio

years. Key issues for further development include fast and efficient mixing of the fuel and oxidizer, the prevention of auto-ignition, and integration with an inlet and nozzle. The main differences between the PDE and the conventional internal combustion engine is that in the PDE the combustion chamber is open and no moving parts are used to compress the mixture before ignition and no shaft work is extracted [3]. Instead, the compression is an integral part of the detonation, and two of the main advantages of the PDE are the efficiency and simplicity which can be explained by the fact that the combustion occurs in detonative mode [4]. The efficiency of the cycle can be explained by the high level of pre compression due to the strong shock wave in the detonation. Also, the simplicity of the device is a result of the fact that the shock wave responsible for this compression is an integral part of the detonation. PDE is similar to both the pulse-jet and the ram jet engine as no moving part is present in these engines. But in those two cases the mechanism behind the precompression is completely different. For the pulse-jet the precompression is a result of momentum effects of the gases, and is a part of the resonance effects of the engine. In the ramjet, pre-compression is obtained through the ram effects as the air is decelerated from supersonic to low subsonic. The major drawback with this concept is that the engine is ineffective for speeds lower than around M = 2. The pulse detonation engine works on Humphrey cycle whereas gas turbines work on Brayton cycle. The cycles are as shown in the figure 1. The Humphrey cycle gives more area under the PV curve, thus making it more efficient engine as compared to Gas turbine Engines [5]. The frontal area in case of pulse detonation engine will be very small thereby reducing drag to a large extent.

II. INTRODUCTION

III. APPLICATIONS OF PULSE DETONATION ENGINES

A pulse detonation engine, or "PDE", is a type of propulsion system that uses detonation waves to combust the fuel and oxidizer mixture. The engine is pulsed because the mixture must be renewed in the combustion chamber between each detonation wave initiated by an ignition source. Theoretically, a PDE can operate from subsonic up to a hypersonic flight speed having thermodynamic efficiency higher than other designs like turbojets and turbofans, because a detonation wave rapidly compresses the mixture and adds heat at constant volume[2]. Consequently, moving parts like compressor spools are not necessarily required in the engine, which could significantly reduce overall weight and cost. PDEs have been considered for propulsion for over 70

Pulse detonation engine, although presently, in the development stage, is having potential in following applications:

SVIT, Vasad

A. Pulse Detonation Applications The applications of pure PDEs are primarily military, as they are light, easy to manufacture, and have higher performance around Mach 1 than current engine technologies (Marshall Space Flight Center). This makes them an ideal form of propulsion for missiles, unmanned vehicles, and other small-scale applications (NASA Glenn Research Center). The decrease in efficiency of PDEs at higher Mach numbers, the noise generated by them, and the advantages of using them in a

ISBN: 978-81-923462-8-1

185


hybrid combination, means that pure PDEs will likely not be used often for large-scale applications (Marshall Space Flight Center).

Figure 1: Comparison of Humphrey and Brayton Cycle

B. Hybrid Pulse Detonation Applications

Figure 2: A PDE Hybrid Turbofan

Pulse detonation engines are well-suited for combination with turbofan and turbojet engines. This hybrid combination can be applied not only to produce faster aircraft, but also to make them more efficient and environmentally friendly. In a conventional turbofan engine, air travels into and around the combustion chamber. The air travelling around the chamber mixes with the exhaust from the combustion chamber to provide the thrust [7]. In a hybrid pulse detonation engine, the bypass air enters pulse detonation tubes that surround the standard combustion chamber as shown in the figure 2. The tubes are then cyclically detonated; one detonates while the others fill with air or are primed with fuel. This combination promises to require simpler engine mechanisms and yield higher thrust with lower fuel consumption (NASA Glenn Research Center; General Electric). Hybrid pulse detonation engines will allow commercial aircraft to be faster, more efficient, and more environmentally friendly. NASA is projecting that the intercity travel time will reduce significantly. In addition, they suggest that NOx emissions may decrease by up to 80% (NASA Glenn Research Center). SVIT, Vasad

Similarly, hybrid PDEs can also be used in military applications. A large number of modern fighter jets employ afterburner-equipped low-bypass turbofan or turbojet engines. Although this process is an effective solution, it is not a fuel efficient solution. Hybrid PDEs will deliver the same thrust with less fuel consumption. Missile application of PDE is also giving encouraging results. C.Pulse Detonation Rocket Engines (PDREs) Similar to PDEs, PDREs produce thrust by cyclically detonating propellants within a detonation chamber and exhausting the combustion products through a nozzle. However, unlike PDEs PDREs must carry all of the oxidizer necessary to complete their specific missions onboard, and PDREs may have vacuum start and restart requirements for many applications [8]. PDREs will incorporate propellant storage, feed, and injection system components; one or more detonation chambers ignition systems, detonation chamber/ nozzle interface hardware, nozzles, and engine control system components. Similar to PDEs, numerous PDRE configurations may evolve depending upon engineering design solutions adopted to overcome technical challenges [9]. Once propellants are injected into PDRE detonation chambers, the fast-acting propellant injection valves close to seal the detonation chamber and detonation is initiated. The detonation wave passes through the detonation chamber at supersonic velocities, igniting the propellants and elevating the upstream pressure to several times (6-12 times) that of the initial fill pressure. Like conventional, steady combustion rocket engines, PRDEs require pressurization of the detonation chamber to obtain high performance. However, due to the high pressure ratios associated with detonation combustion, PDRE detonation chamber fill pressures are much lower than chamber pressures associated with conventional rocket engines. PDREs can employ a variety of thermodynamic cycles to power turbo pumps, such as gas generator, staged combustion, or expander cycles, or incorporate pressurized feed systems. PDRE operating pressures may be on the order of 100-200 psia, as compared to several hundred psia for conventional open cycle engines and several thousand psia for conventional closed cycle engines. The multiple-chamber PDRE concept shown in Figure 2 is provided by Pratt & Whitney Aero sciences. This concept includes six detonation chambers coupled to a common feed system and nozzle assembly. Operationally, the detonation chambers are fired in a phased manner allowing the feed system and manifolds to operate in a steady state manner. All of the detonation chamber combustion products are exhausted through the single common nozzle. Other PDRE configurations are possible. PDRE designs and configurations are influenced by specific mission requirements and engineering solutions adopted to address fundamental technical and operability issues. Proposed new PEC multitube & multicycle configuration is shown in figure 3 [9].

ISBN: 978-81-923462-8-1

186


IV. SPACE FLIGHT APPLICATIONS While air breathing pulse detonation engines would not be able to operate in space, they may be used to reduce the cost and complexity of launching spacecraft. As PDEs do not require heavy and expensive pumps, they offer a viable alternative to current rocket engines. The decreased weight, along with better fuel consumption, would significantly reduce the cost of launching spacecraft. Using pulse detonation in combination with other propulsion sources could potentially decrease the cost of launching payloads into space. V. DESIGN OF PULSE DETONATION FOR PEC EXPERIMENTAL SETUP This section provides information specific to the equipment and techniques used to complete the experimentation performed in support of this work (figure 4). All testing associated with this project occurred in the Aerospace Engineering Department of PEC University of Technology, Chandigarh [1]. An engine capable of burning both Acetylene/oxygen and Acetylene/air mixture was required to complete the desired research. A PDE designed and used for previous experimentation was used as the baseline engine for this project [10]. Prior to initial experimentation, numerous modifications were made to the engine and test cell to improve on the previous design and enable switching between fuel types with minimum impact. New fuel supply systems were constructed, a thrust stand was incorporated to measure axial thrust data, and new data acquisition software created for high-speed data capture.

Figure 4 Conceptual Pulse detonation engine

A. Pulse Detonation Engine Details A single tube, “valveless” PDE was constructed by the investigating team conducting thesis research. The engine consisted of a combustion tube, fuel injector system, and ignition system. Since the initial design, modifications made by current research team to fuel injector scheme, flow choke sizing, fuel / air inlet geometry, spiral dimensions and mounting technique, tube diameter, and combustion chamber volume have been implemented to facilitate performance improvements throughout continuous design process. Specific engine parameters and systems used during experimentation in support of this research are discussed below and photograph of the test rig is included in figure 4. B. Fuel Injection/Air Delivery The fuel injection/air delivery system was designed to provide control of the stoichiometry of the fuel/air mixture supplied to the combustor. Supply air delivery incorporated a valveless design in that a constant flow of supply air was provided to the engine. Control of the fuel mixture was achieved by varying the pressure of injected fuel. Fuel pressure changes altered the mass flow rate ratio of fuel to supply air, which is defined as the equivalence ratio (φ). The mathematical expression for equivalence ratio is given by:

Where

is the mass ratio of fuel to air for the experimental

mixture and

is the mass ratio of fuel to air for the

stoichiometric mixture. Performance varied with changing equivalence (φ) ratio. C. Oxygen/Air Delivery Supply air was delivered from O2 cylinder at varying mass flow rates w.r.t. the pressure in the pipe line controlled by the valves in line. The supply was controlled by solenoid valve operated through Labview software. Figure 3: Conceptual Multitube Pulse Detonation Engine

SVIT, Vasad

ISBN: 978-81-923462-8-1

187


K. Engine/Thrust Stand Interface D. Acetylene Injection Thrust stand means the test rig fabricated that will support An independent injector system was constructed to supply Acetylene from cylinder into the combustion chamber. the entire engine on it. The thrust stand is 12 feet long, 3 feet Electrically-controlled high frequency Techno make solenoid wide, 4 feet high in dimensions, with another 1.5 feet curved valve injector was joined by a common feed manifold and cowl covering over it, to prevent any mishaps to the people mounted to the fuel arm downstream of the flow chokes. The working nearby the structure. gaseous fuel mixed with supply air prior to entry into the L. Thrust Stand combustion chamber. As in all systems including thrust stand, which contain mass and elasticity, the thrust stand was assumed to be capable of E. Ignition System The ignition system consists of a 24 V DC Condenser and free vibration, as well as forced vibration at the excitation spark plug arrangement. The control for the spark plug ignition frequency which PDE testing would occur. Vibration analysis is with the control circuit only. The VI control gives an option identifies the primary physical characteristics which govern to ignite the spark plug after the gas has been released into the system response as mass, damping and stiffness. In the presence of light (assumed here) or no damping, the system system for the required amount of time. The oxygen inlet and the acetylene inlet are near the spark will vibrate very near the natural frequency. plug itself, which enables us to start the combustion, by M. Channel Calibration / Voltage – to - Thrust Conversion: imparting a high voltage spark to the gases. The first phase of the process consisted of calibration of the individual channels which transfer load cell data to the data F. Combustion Tube The combustion tube is a hollow steel pipe (Grade 304) collection system and convert voltage data to force units. with an internal diameter of 48 mm and external diameter of Small imperfections in cable manufacturing, varying length of 60 mm, providing us a thickness of 6 mm which is strong supply cable per channel, and other factors lead to small enough to withstand the detonation pressures generated inside variances during the data transmission process which must be the tube. The combustion tubes are of various sizes, 20 cm, 40 normalized to eliminate constant sources of bias error. This cm, 80 cm and 100 cm. These various sizes enable us to get process was completed in conjunction with manufacturer any size tube for our experiment in the steps of 20 cm with a representatives, with no load on the thrust stand and support pins installed. The first step was to install a load cell simulator minimum length of 70 cm. in place of actual load cells, and apply excitation voltages at known excitation ranges. G. Primary Structure The primary structure comprises of the combustion tubes lying on the middle support bar. The combustion tubes are VI. TEST CELL/ PDE CONTROL encapsulated in a curved wedge fitted on a slider, to reduce The engine and support equipment in test cell was friction to the least amount possible. The fully loaded system controlled by a National Instruments (NI) VI software program with 3.5 m tube length has a friction of 17 N. installed on a personal computer (PC) in the control room with H. Load Cell The load cells (Max Load Make) fitted in the structure are high capacity load cells with a maximum value of 500 kgf. The loads cells are fitted on the one extreme point of the structure on the axis of the tube, which allows us to measure the thrust produced on the system [11].

I. Pressure Sensors: Pressure sensors of MEAS make are used to measure pressure of the gas detonated inside the pulse tube. it is used at four locations inside tube. J. Data Collection Hardware The data collection hardware comprises 4 pressure sensors (MEAS make), 3 thermocouples, 3 load cells (Maxload Make) each connected to the DAQ individually through the required circuit. SVIT, Vasad

terminations. The PC was linked to a NI PXI-1000B controller in the test cell through an internet connection to the PXI IP address. The program controlled engine operation by managing engine supply gas operation via ball valves located in the test cell. A BNC pulse generator also located in the control room controlled timing of trigger signals sent to both the fuel injectors and TPI via electrical relays located within the test cell. Also located within the control room were 24 VDC and 220 VAC master power switches, and an emergency shutoff button. The emergency shutoff button was provided as a safety feature and would disable test cell #2 by closing all supply gas ball valves and interrupt fuel injection and ignition trigger signals. VII. DATA ACQUISITION Data acquisition was controlled via the PC in the control room. The PC was linked to the SCXI-1000B controller mounted on the wall in the test cell, which in turn was linked to three NI data acquisition devices (DAQ) located on the engine stand. The PXI-6031E was 8channel, 16 bit card which

ISBN: 978-81-923462-8-1

188


collected operational parameters such as various engine temperatures and pressures, and supply gas pressures, at a rate of 10 kHz. A data file path designated on the control program directed data in the form of an excel spreadsheet to a selected location. These data streams were used to calibrate the stand prior to the commencement of testing, and record thrust data during engine operation. A second file path designated on the control panel directed thrust data in the form of an excel spreadsheet to a selected location. Additionally, thrust data was streamed to the control program GUI for real-time monitoring.

Instruments advises to use double buffer scheme in simultaneous mode. The same was tried; however, the problem was isolated to NI card onboard memory. The problem is being diagnosed with the replacement of large memory realtime card. After resolving all challenges, the PDE was fired successfully to acquire data for onward analysis [14]. The multiple level PAeroSim code was developed to analyse the results obtained from firing [15]. PDE Simulation (Pr.)

VIII. THE CHALLENGES FACED AND THEIR REMEDIAL MANAGEMENT:

p1 Bar p2 Bar p3 Bar p4 Bar

25

During the design of test rig and firing of system, a large no. of problems had cropped [12]. All these issues were addressed as follows:

20

15

10

5

0

6

Fig. 5 Initial output (red) & after shielding (blue)

6.1

6.2

6.3

6.4

6.5

6.6

time in sec.

Fig. 6 plot of pressure sensor with data clipping

A. Noise in all channels There was a huge noise in output of DAQ resulting in signal getting attenuated. So, proper grounding, shielding and crimping was initiated to resolve the issue. The figure 5 shows the level of improvement in the signal. B. Signal loss There was a signal loss observed during testing due long cables. It was in tune of mV while travelling a distance of 35 m. This defect was confirmed through Digital multimeter readings at sensor and DAQ end. This was more than 10%, when signals were small, making it further worse. Since distance was required for safety clearances, so it can’t be addressed through that route. So, problem was redressed by changing the data cable to low loss cables of resistance 0.01Ω/m with MIL connectors [13].

IX. CONCLUSIONS The pulse detonation engines have many advantages over the other engines for propulsive purposes and can be more reliable when developed fully. The results obtained by PEC after successfully addressing the issues surfaced during test runs are highly encouraging. The main concern is the production of the shocks and noise including the frequency of operation and the control of the temperature in the tube [16]. However there have been many excellent demonstrations of the engine all over the world. Pulse detonation engine is being seen as promising next generation propulsion system which will give aerospace vehicles clean configuration.

C. Sampling Frequency Problem During the PDE firing, many occasions, large portion of data was clipped due faulty double buffering schemes used for data acquiring. So, the DAQ sampling frequency was increased to > 1MS/s and problem got resolved.

Figure 7 Live firing captures with high speed camera

D. Data Loss: During firing of PDE, it was observed that there was loss of data as shown in figure 6 due memory buffer size. National SVIT, Vasad

ISBN: 978-81-923462-8-1

189


[16] Subhash Chander, TK Jindal, “Emerging trends in Aerospace Propulsion” in “Seminar on Emerging Trends in Aerospace Engg.” By The Aeronautical Society of India, Mar., 2014 (under review).

REFERENCES

[1] TK Jindal, YS Chauhan, “Development of Pulse Detonation Rig”, A Report on sponsored research by TBRL, June, 2012. [2] G.D. Roy, S.M. Frolov, A.A. Borisov, D.W. Netzer, “Pulse detonation propulsion: challenges, current status, and future perspective”, Progress in Energy and Combustion Science 30 (2004), www.sciencedirect.com [3] Pulse Detonation Engine Technology: An Overview by Matthew Lam, Daniel Tillie, Timothy Leaver, Brian McFadden. [4] TK Jindal, "Pulse Detonation Engine - A Next Gen Propulsion", International Journal of Modern Engineering Research (IJMER) Vol.2, Issue.6, Nov-Dec. 2012 #ISSN: 2249-6645. [5] W.H. Heiser, D.T. Pratt, “Thermodynamic Cycle Analysis of Pulse Detonation Engines,” Journal of Propulsion and Power, Vol. 18, No. 5, 2002. [6] C.M Brophy, R. K. Hanson, “Fuel Distribution Effects on Pulse Detonation Engine Operation and Performance,” Journal of Propulsion and Power, Vol. 22, No. 6, 2006. [7] T. Bussing, J. Hinkey and L. Kaye, Adroit Systems, Inc., "Pulse Detonation Engine Preliminary Design Considerations," 30th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Indianapolis, IN (2729 June 1994). [8]

Francois Falempin, Dominique Bouchaud, Bernard Forrat, Daniel Desbordes, EmericDaniau, "Pulsed Detonation Engine Possible Application to Low Cost Tactical Missile and to Space launcher", AIAA-2001 - 3815, 37th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Salt Lake City, Utah, July 2001.

[9] Subhash Chander, TK Jindal, “Performance Enhancement Techniques by Application of Pulse Detonation Engine based Secondary Propulsion System for Surface to Air Missile”, Ph. D. State of the Art Report, PEC university of Technology, Chandigarh, Dec., 2013. [10] Subhash Chander, Dr. TK Jindal, “Design of Automated Fire Control System for C2H2/O2 Pulse Detonation Rig”, International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering, Vol. 2, Issue 2, Feburary 2013 http://www.ijareeie.com/volume-2-issue-2 # ISSN: 2278-8875.

BIOGRAPHY Subhash Chander is currently Ph. D. Scholar in PEC University of Technology, Chandigarh & Scientist ‘F’ in TBRL, Chandigarh, INDIA. He has 24+ years of research experience in Missile System Engg., Modelling & Simulation including Aerospace interests. He has guided 6 M.E students and 4 MCA Students. He has published 20+ papers in related area and has authored 100 + reports in relevant areas. He is the Life member of Institution of Engineers (India), Systems Society of India, The Aeronautical Society of India and High Energy Materials Society of India. He has also participated in many national and International conferences and seminars by presenting research work. He is currently perusing Ph. D. from PEC University of Technology, Chandigarh also. Dr. Tejinder Kumar Jindal is a Associate Professor in Aerospace Engineering Department, PEC University of Technology, Chandigarh is having 24 year+ experience in Aerospace and allied teaching & Research. He has guided 11 M.E students and 5 PhD Students. His research areas include Pulse Detonation, Solar Energy, Cryogenics and Wind energy. He has published 25+ papers in related area. He is the member of Institution of Engineers (India), Life member Indian Cryogenics Council, Life Member Aeronautical Society of India and Life member Solar Energy Society of India. He has participated in many national and International conferences and seminars.

[11] D. Mahaboob Valli, TK Jindal, “Thrust Measurement of Single Tube Valveless Pulse Detonation Engine,” International Journal of Scientific and Engineering Research (IJSER), Volume 4, Issue 3, ISSN 2229-5518. http://www.ijser.org/ online Research PaperViewer.aspx?Thrust-Measurement-of-Single-Tube-Valve-less-Pulse-Detonation-Engine.pdf , March 2013. [12] Subhash Chander, TK Jindal, “Integration Challenges in Design and Development of Pulse Detonation Test Rig” International Journal of Advance Research in Electrical, Electronics and Instrumentation Engineering, Volume 1, Issue 4, October 2012. [13] TK Jindal, "Effect of 24 V Control Pulse on the Data Acquired in a Pulse Detonation Engine Test", International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering, Vol. 1, Issue 4, October 2012, ISSN: 2278 – 8875. [14] T K Jindal, “Single Cycle Pulse Detonation Engine Testing”, International Journal of Mechanical Engineering, ISSN 2051-3232, Vol.40, Issue.10, Oct, 2012. [15] Subhash Chander, D Mahaboob Valli, TK Jindal, "Multiple Option Levels Based Full Function PEC Aero Simulation (PAeroSim) Development for Pulse Detonation Engines & Systems", Symposium on Applied Aerodynamics and Design of Aerospace Vehicle (SAROD 2013), November, 2013, Hyderabad, India. SVIT, Vasad

ISBN: 978-81-923462-8-1

190

Text operators for PDF

Text operators for PDF

Suggest Documents