Detonation Research for Propulsion Applications

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Detonation Research for Propulsion Applications

Detonation Research for Propulsion Applications

Sponsored by ONR MURI “Multidisciplinary Study of Pulse Detonation Engines” PSU/CIT/Princeton Team

J. E. Shepherd, E. Schultz, J. Austin, T. Chao, E. Wintenberger, P. Hung

Graduate Aeronautical LaboratoriesCalifornia Institute of Technology

Pasadena, CA 91125 USA

Midyear Review, San Jose, CA, February 10-11, 2000

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Activities at CaltechActivities at Caltech

• Cellular structure characterization

• Initiation

• Diffraction

• Structural and thermal response

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Cellular StructureCellular Structure

• Purpose: characterize detonations in JP-5, JP-8, JP-10 fuels (measurement

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CIT 288-mm Detonation TubeCIT 288-mm Detonation Tube

Tube modifcations:

1. Redesigned using FEM2. Stronger flange-tube connections3. Thicker flanges4. Double number of fasteners5. Heating system a) 8 zones of control b) 10 kW total power6. Higher temperature seals

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Detonation initiationDetonation initiation

• DDT time scale analysis

• Ideal vs real performance with DDT

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DDT ScalingDDT Scaling

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0

2

4

6

8

10

12

0 100 200 300 400

time

pre

ssu

re

end wall

exit

Ideal PDE ImpulseIdeal PDE Impulse

Computation by H. Hornungusing Amrita (AMR)q/RT1 = 40, = 1.2Taylor-Zeldovich IC

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DiffractionDiffraction

• Test series with H2, C2H4, C3H8 fuels– Ar, He, N2, CO2 dilution.– Model development

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Structural responseStructural response

• Response of tube to detonation loading

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CIT PresentationsCIT Presentations

• Structural response (Joe Shepherd)

• Diffraction (Eric Schultz)

• DDT and ideal performance (Jo Austin)

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Progress to DateProgress to Date

• 288-mm tube modifications started– mechanical changes done

• Diffraction study in 38-mm tube done– kinetics validation, model development

• Preliminary DDT time scale study

• Impulse, P(t) measurements initiated

• 2D transient FEM studies

2/10/00 California Institute of TechnologyGraduate Aeronautical Laboratories

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Structural Response of Detonation Tubes

Structural Response of Detonation Tubes

J. E. Shepherd, T. Chao, P. Hung - GALCIT

2/10/00 California Institute of TechnologyGraduate Aeronautical Laboratories

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GoalsGoals

• Modeling of thermo-elastic response of tubes to detonation loading

• 3D FEM computations with imposed detonation or shock loading

• Develop design criteria

• Experiments to examine failure mechanisms and thresholds

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Flexural Wave ExcitationFlexural Wave Excitation

• Traveling loads (shock or detonation) excite flexural waves in tubes

• Resonance associated with waves traveling at flexural wave speed

• Deformations can be up to 4X static equivalent

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Flexural Wave ExcitationFlexural Wave Excitation

1.5 mm thick steel tube, 25 mm 0.5 m longCritical velocity 927 m/s, shock speed 950 m/s2D Axi-symmetric explicit FEM

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Loading by Flexural WavesLoading by Flexural Waves

Experiments in Caltech 288-mm detonation tube

Amplification factor

U (m/s)

Measured strain (hoop)

t (ms)0 2 4 6 8

10-4

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Future DirectionsFuture Directions

• More realistic tube configuration

• Use gas dynamic simulations to provide boundary conditions

• Investigation of stress concentrations

• Coupling to thermal effects

• Comparison with measurements in model tubes

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ID Task Name

1 Cellular Structure Measurements

2 Modify detonation tube

3 Mechanical design

4 Machining

5 Thermal design

6 Thermal system procurement

7 Installation and checkout

8 Setup tube

9 Hot tests with HC gases

10 Liquid fuel handling system

11 Hot tests with vaporized liquid fuels

12 Operation with liquid fuels

13 Tests with liquid fuels

8/9

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Schedule ISchedule I

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ID Task Name

15 Detonation Initiation

16 Set up PLIF system

17 Preliminary measurements

18 Analysis of DDT times

19 Design new test section

20 Preliminary experiments

21 Detailed Experiments

22 Detonation Diffraction

23 Experiments in 38-mm tube

24 Model development

25 Documentation

26 Design initiation system for 1200-l vessel

27 Procure initiator system

28 Measure critical diameters with O2-N2 mixes

5/1

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Schedule IISchedule II

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ID Task Name

29 Tube Structural and Thermal Response

30 Develop thermo-elastic model

31 Heat transfer, strain rate measurements

32 Validation of model

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Schedule IIISchedule III