Flow design for advanced engineering solutions

1 Dr.-Ing. Roland Schmehl

Faculty of Aerospace Engineering TU-Delft, 31. August 2009

Flow design for advanced engineering solutions

2 Dr.-Ing. Roland Schmehl

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Introduction & motivation – Technological challenges of kite power systems

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Flow design cases – – – – –

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Case 1: Low-emission combustion Case 2: Droplet deformation and breakup Case 3: Rocket engine ignition Case 4: ECLSS condensate buffer Case 5: Airbag deployment

Future perspectives

Outline

3 Dr.-Ing. Roland Schmehl

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Aerodynamics, structural deformation and stability – – – – –

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Introduction Technological challenges of kite power systems I

Exterior flow characteristics (attached, separated, unsteady, ...) Interaction with flexible (pressurized) kite structure Buckling of inflated elements Response to off-design loading Aerodynamic interaction of kites (e.g. from trailing vorteces)

Materials – Minimum weight & maximum strength – System life span

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Kite system control – Control algorithms – Optimization

4 Introduction

Dr.-Ing. Roland Schmehl

Technological challenges of kite power systems II

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Operation – Start-up and shut-down of kite power system – Safety analysis

5 Case 1: Low-emission combustion

Dr.-Ing. Roland Schmehl

Experimental Lean-Premix-Prevaporize combustor

Institute for Thermal Turbomachines o. Prof. Dr.-Ing. Sigmar Wittig University of Karlsruhe

6 Dr.-Ing. Roland Schmehl

Low-emission combustion Experimental analysis

Installation in high-pressure high-temperature test rig for PDPA & laser lightsheet spray analysis Institute for Thermal Turbomachines o. Prof. Dr.-Ing. Sigmar Wittig University of Karlsruhe

7 Low-emission combustion

Dr.-Ing. Roland Schmehl

Combustor working principle & design objective

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Design objective: – Optimal mixing and evaporation of injected fuel in premix zone – Reduce number of droplets in reaction zone (= reduced NOx emissions)

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Technology: – Air-assisted pressure-swirl atomization – Swirl-stabilized flame

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Difficulty – Flame extinction & flash-back – Complex two-phase flow physics – Challenge for measurement

and simulation Institute for Thermal Turbomachines o. Prof. Dr.-Ing. Sigmar Wittig University of Karlsruhe

8 Dr.-Ing. Roland Schmehl

Low-emission combustion CFD analysis

– Contour-fitted multi-block mesh for single- and twophase flow analyses using inhouse code METIS-Ladrop

– Spray analysis indicating different types of secondary droplet breakup – Model framework available in ANSYS-CFX and OpenFOAM Institute for Thermal Turbomachines o. Prof. Dr.-Ing. Sigmar Wittig University of Karlsruhe

9 Dr.-Ing. Roland Schmehl

Case 2: Droplet deformation & breakup Aerodynamic breakup phenomena

Bag breakup

Multimode breakup Increasing relative velocity Shear breakup

Institute for Thermal Turbomachines o. Prof. Dr.-Ing. Sigmar Wittig University of Karlsruhe

10 Dr.-Ing. Roland Schmehl

Droplet deformation & breakup Classification of numerical techniques

Institute for Thermal Turbomachines o. Prof. Dr.-Ing. Sigmar Wittig University of Karlsruhe

11 Dr.-Ing. Roland Schmehl

Droplet deformation & breakup Deformation under aerodynamic shock load

Normal mode analysis: water droplet in horizontal shock tube flow

Institute for Thermal Turbomachines o. Prof. Dr.-Ing. Sigmar Wittig University of Karlsruhe

12 Dr.-Ing. Roland Schmehl

Droplet deformation & breakup Droplets falling into a horizontal free jet

Institute for Thermal Turbomachines o. Prof. Dr.-Ing. Sigmar Wittig University of Karlsruhe

13 Case 3: Rocket engine ignition

Dr.-Ing. Roland Schmehl

Storable propellant upper-stage engine of Ariane 5

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Hypergolic propellants MMH/N2O4

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Multiple re-ignition in vacuum Regenerative cooling by MMH Multiple point injection Engine dry mass: 1.2 t Total propellant usage: 10 tons Vacuum thrust: 3 tons Tank pressure: 1.8 MPa Chamber pressure: 1.1 Mpa Chamber temperature: 3000 K

Propulsion and Aerothermodynamics Division European Space Agency

Image source: EADS Astrium-ST

14 Rocket engine ignition

Dr.-Ing. Roland Schmehl

Ariane 5 flight 142 anomaly in 2001

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Observed anomaly: – Pressure peak and subsequent high-frequency combustion instability – Combustion chamber overheats and chamber cooling lines are punctuated – Propellant loss results in lower orbit of payload (ARTEMIS)

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Objective: – Identify possible reasons for pressure peak using CFD & available data from parallel experimental investigations at ONERA and DLR

Propulsion and Aerothermodynamics Division European Space Agency

15 Rocket engine ignition

Dr.-Ing. Roland Schmehl

Possible causes addressed in failure analysis

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Propellant thermodynamics? Flow dynamics (is pre-flow phase long enough, ...)? Combustion chemistry (pre-ignition reaction products, nitric acid, ...)? Pre-ignition accumulation of propellant (spray deposition, ...)? Dynamic coupling of internal hydraulic circuits and supply lines? Pressure dependence of atomization (pressure-swirl type atomizers)?

Propulsion and Aerothermodynamics Division European Space Agency

16 Rocket engine ignition

Dr.-Ing. Roland Schmehl

CFD analysis of oxidizer preflow phase

Propulsion and Aerothermodynamics Division European Space Agency

17 Rocket engine ignition

Dr.-Ing. Roland Schmehl

Effect of droplet size distribution on flow temperature

Propulsion and Aerothermodynamics Division European Space Agency

18 Dr.-Ing. Roland Schmehl

Rocket engine ignition Oxidizer preflow dynamics

Isosurfaces of liquid volume concentration vc=1%

Propulsion and Aerothermodynamics Division European Space Agency

19 Dr.-Ing. Roland Schmehl

Case 4: ECLSS condensate buffer Flow design optimization

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Purpose: – Preconditions two-phase flow entering flow separator in Environmental Control and Life Support System (ECLSS) of European Columbus module for ISS

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Objective: – Flow design optimization to minimize carry-over of liquid

Original design Propulsion and Aerothermodynamics Division European Space Agency

Improved design with anti-sloshing insets

20 ECLSS condensate buffer

Dr.-Ing. Roland Schmehl

Condensate buffer with low liquid phase loading

Propulsion and Aerothermodynamics Division European Space Agency

21 ECLSS condensate buffer

Dr.-Ing. Roland Schmehl

Condensate buffer with high liquid phase loading

Propulsion and Aerothermodynamics Division European Space Agency

22 Dr.-Ing. Roland Schmehl

ECLSS condensate buffer

Condensate buffer single-phase flow Large Eddy Simulation

Propulsion and Aerothermodynamics Division European Space Agency

23 Dr.-Ing. Roland Schmehl

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Case 5: Airbag deployment

Design objectives – Develop and validate final shape of deployed airbag for In-Position scenarios – Develop and validate shape evolution and interaction with dummy for Out-OfPosition (OOP) scenarios – Support continuous exploration of new airbag concepts and shapes driven by increasingly stringent occupant safety regulations

Simulation TNO Automotive Savety Solutions

Test

24 Dr.-Ing. Roland Schmehl

Airbag deployment In-Position dummy-airbag interaction

MADYMO MB/FE/UP simulation: first airbag deploys (~10 ms), then dummy impacts airbag TNO Automotive Savety Solutions

25 Dr.-Ing. Roland Schmehl

Airbag deployment Challenges of OOP modeling

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Folds or stacks of folded fabric → Affects modeling time & stability

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Tethers → Require high quality models

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Fluid-structure interaction (FSI) → Affects energy transfer to dummy

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Inflator characteristics → First milliseconds are decisive

TNO Automotive Savety Solutions

26 Dr.-Ing. Roland Schmehl

Airbag deployment Chest impact (OOP) on 3YR dummy I

TNO Automotive Savety Solutions

27 Dr.-Ing. Roland Schmehl

Airbag deployment Chest impact (OOP) on 3YR dummy II

TNO Automotive Savety Solutions

28 Dr.-Ing. Roland Schmehl

Airbag deployment Oscillating square-shaped piston

TNO Automotive Savety Solutions

29 Dr.-Ing. Roland Schmehl

Airbag deployment Curtain airbag demonstrator

TNO Automotive Savety Solutions

30 Airbag deployment

Dr.-Ing. Roland Schmehl

Prototype aviation safety device – – – –

TNO Automotive Savety Solutions

MADYMO simulation FE model of tube fabric CFD model of internal flow Ambient exterior

31 Future perspectives

Dr.-Ing. Roland Schmehl

Simulation approach for kite aerodynamics

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Used for support of system design and detail analyses

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Kite simulation toolbox based on MB dynamics (Adams solver) – Currently developed by ir. Jeroen Breukels

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FE / UP / CFD simulation using coupling – – – –

Membrane and foam structure represented by Finite-Element (FE) model Inflated chambers represented by Uniform-Pressure (UP) model Exterior flow field represented by CFD model Fluid-Structure algorithms to couple these models

→ Can be done using state-of-the-art airbag deployment solvers (e.g. MADYMO, LSDyna, …), if necessary in combination with dedicated aerodynamics solver (e.g. Fluent, …).

32 Dr.-Ing. Roland Schmehl

Future perspectives Design parameters of kite power system

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Boundary conditions – Flow properties: wind velocity, steadiness, turbulence level, ...

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System level design – – – –

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Transformation mechanism Bridle & line assembly Flight trajectories of kites Kite control system

Component level design – – – – – –

Kite type & design Kite aerodynamics Kite materials Tethers and lines materials Ground station ...

Lei-, Foil- & Bow-kites

33 Dr.-Ing. Roland Schmehl

Faculty of Aerospace Engineering TU-Delft, 31. August 2009

Flow design for advanced engineering solutions

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