1 / 34

Thermal characterisation of an ethanol flashing jet using differential infrared thermography

Eucass 2011, St Petersburg. Thermal characterisation of an ethanol flashing jet using differential infrared thermography.

gail-porter
Télécharger la présentation

Thermal characterisation of an ethanol flashing jet using differential infrared thermography

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Eucass 2011, St Petersburg Thermal characterisation of an ethanol flashing jet using differential infraredthermography H. Kamoun, G. Lamanna, B. WeigandInstitute of Aerospace Thermodynamics, Universität Stuttgart 70569 Stuttgart Germany J. SteelantESTEC-ESA, 2200 AG Noordwijk, The Netherlands

  2. Contents • Motivation & Objectives • Differential Infrared Thermography • Experimental Setup • Uncertainty analysis • Results • Summary

  3. Contents • Motivation & Objectives • Differential Infrared Thermography • Experimental Setup • Uncertainty analysis • Results • Summary

  4. Motivation & Objectives • Flashing: Sudden exposure of a superheated pressurized liquid to a low pressure environment  Fast phase transition • Relevant in many technical application • Accidental release of flammable and toxic pressure-liquefied gases in nuclear and chemical industry. • Benefit in propulsion system  enhanced atomisation P Liquid Pinj Vapor Psat(Tinj) Rp P∞ ΔT Tsat(P∞) Tinj T

  5. Motivation & Objectives • Flash-atomisation/vaporisation model  Temperature data for validation • Non-intrusive methods are needed • New method  Differential Infrared Thermography (DIT)

  6. Contents • Motivation & Objectives • Differential Infrared Thermography • Experimental Setup • Uncertainty analysis • Results • Summary

  7. Differential Infrared Thermography • Problem: • Spray emissivity: ε unknown • For a liquid or a gas ε = f (T, λ, density) DIT

  8. Differential Thermography - TBack = 286 K TBack = 366 K Liquid: ethanol, Tinj = 389K, pam = 0.2bar, pinj = 10bar

  9. Contents • Motivation & Objectives • Differential Infrared Thermography • Experimental Setup • Uncertainty analysis • Results • Summary

  10. Experimental Setup High-pressure liquid supply system Liquid tank Vacuum chamber Vacuum Pump Optical setup

  11. Experimental Setup • Heated modified diesel injector with D=150 μm andL/D= 6.6 • Short injection and transient times → Constant backpressure • Constant injection conditions (i.e. pressure & temperature) • Reproducible test conditions Courtesy of Bosch GmbH

  12. Experimental Setup Heated background 303 K<TBack <389 K Cooled background 280 K<TBack <290 K

  13. Differential Infrared Thermography

  14. IR Kamera • Resolution: 640x512 pixel • Detector: InSb • Detector cooling: Stirling Cooler • Spectral range: 1.5 - 5µm • Integrationmode: Snapshot • Calibration range: 5°C – 300°C FLIR Orion SC7000 Series

  15. Contents • Motivation & Objectives • Differential Infrared Thermography • Experimental Setup • Uncertainty analysis • Results • Summary

  16. Uncertainty analysis • The choice of the background temperatures • If Ispray < IBackground1,2and for the spray dilute region (εspray<<1) A calculation of the spray temperature is impossible Key point: the selection of the background temperature should enhance the contrast between spray and surroundings

  17. Uncertainty analysis • The sensitivity to measurement errors in e.g. the temperature recorded by the infrared camera TCam1 • For a given TsprayandTback1,2 ,the temperature recorded by the camera and the spray temperature error can be computed as a function of εspray

  18. Uncertainty analysis Liquid: ethanol, Tinj = 389K, pam = 0.2bar, pinj = 10bar The best results are obtained when the spray temperature distribution is intermediate between the two background values

  19. Uncertainty analysis Tback1=337K, Tback1=366 K Max error: 25K Tback1=286 K, Tback1=366 K Max error: 4K

  20. Uncertainty analysis (Outlook) • Influence of multiple scattering inside the spray: • Neglecting infrared scattering may lead to an overestimation of the emitted spray radiation • Further investigation are needed to evaluate this effect on the temperature results • Comparison of the temperature results with Global Rainbow Thermometry data to validate the assumption made here.

  21. Contents • Motivation & Objectives • Differential Infrared Thermography • Experimental Setup • Uncertainty analysis • Results • Summary

  22. Results (Validation) • the window does not affect the temperature results • good agreement with the temperature measured by the thermocouples • Despite the good agreement a validation of the DIT can be accomplished only upon • comparison with other non-intrusive thermographic technique (e.g. GRT) • estimation of infrared scattering from a cloud of finely atomised droplets. Liquid: ethanol, Tinj = 403K, pam = 1 bar, pinj = 10bar

  23. Results r x Example of flash a atomising spray. Liquid: Ethanol, Tinj = 389 K, pam = 0.2 bar, p inj = 10 bar • Near the nozzle exit: narrow temperature profile • Downstream: flatter temperature profile • Rapidly decay of the temperature downstream the nozzle

  24. Results (Axial Profile) Liquid: ethanol, Tinj = 342 K, pinj = 10bar • Superheating Rp↑ → Cooling rate ↑

  25. Contents • Motivation & Objectives • Differential Infrared Thermography • Experimental Setup • Uncertainty analysis • Results • Summary

  26. Summary and Outlook • The potential of the differential infrared thermography (DIT) for the characterisation of the temperature evolution in am flashing jet has been explored • Experiments were carried out under vacuum condition employing ethanol as test fluid. • The best results are obtained when the spray temperature is intermediate between the two background values • The temperature showed a decay along the spray centreline • With increasing superheat level, the cooling rate increases • Results with a good agreement with the thermocouple measurement. Outlook • further investigation are needed to evaluate the effect of radiative, infrared scattering on the temperature measurement

  27. Thank You

  28. Backup

  29. Experimental Setup • Requirements: • Reproducible test conditions • P∞: from 0.02 bar to 0.4 bar • T∞=20°C • Tinj: from 35 °C to 140°C • Pinj= 10 bar • Good Vacuum (P∞=390 Pa) • Possibility to vary independently injection pressure and temperature • Problem: • Maintaining a constant backpressure • Solution: • Fast response injection

  30. Injector • Requirements: • Short injection and transient times → Constant backpressure • Constant injection conditions (i.e. pressure & temperature) • Reproducible test conditions  heated, modified diesel injector Courtesy of Bosch GmbH

  31. Results (Axial Profile) Liquid: ethanol, pam = 0.1 bar, pinj = 10bar

  32. Results (Axial Profile) Liquid: ethanol, Tinj = 389 K, pinj = 10bar

  33. Vacuum Chamber • Watercooling→ topreventtemperaturegradients in thetestchamber • Chambertemperaturecontrolledthrough 3 thermocouples

More Related