The code validation process is used to evaluate and verify the performance of newly-developed computational fluid dynamics (CFD) code packages that employ finite-rate chemical kinetics. Such comprehensive codes are used for designing and predicting the performance of modern combustors such as those used in aircraft gas turbine engines. The code validation process is critical to the development of new low-emissions combustors for tomorrow’s advanced aircraft engines. In support of this code validation process, we have made significant progress by providing the first quantitative single-shot multi-scalar data from a turbulent elevated-pressure (5 atm), swirl-stabilized, lean direct injection (LDI) type research burner operating on CH4-air using a spatially-resolved pulsed-laser spontaneous Raman diagnostic technique. The Raman diagnostics apparatus and data analysis that we present here were developed over the past 6 years at Glenn Research Center [refs. 1–5]. The single-shot capable Raman scattering system described here uses a pulse-stretched Nd:YAG laser for excitation, and a fiber-optically coupled electro-mechanically-gated high optical throughput Raman spectrograph fitted with a back-illuminated CCD sensor array. From the Raman scattering data, we produce spatially-mapped probability density functions (PDF’s) of the instantaneous temperature, determined using a newly developed low-resolution effective rotational bandwidth (ERB) technique [ref. 1]. The measured 3-scalar (triplet) correlations, between temperature, CH4, and O2 concentrations, as well as their PDF’s, also provide a high-level of detail into the nature and extent of the turbulent mixing process and its impact on chemical reactions in a realistic gas turbine injector flame at elevated pressures. The multi-scalar triplet data set presented here provides a good validation case for CFD combustion codes to simulate by providing both average and statistical values for the 3 measured scalars.
© 2008 Optical Society of AmericaPDF Article
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