Effect of dilution air on the scalar flowfield at combustor sector exit

Abstract

Spontaneous Raman diagnostics are applied to the exit plane of a full-scale 10-cup double-annular research combustor sector to obtain the mean and rms of temperature and mole fractions of major species for comparison with predictions of the code CONCERT-3D for the same geometry and operating conditions. CONCERT-3D has been developed and used extensively in the past and represents a fully elliptic three-dimensional computational fluid dynamics code to predict flowfields in practical full-scale combustors. The theory/data comparison is encouraging. The mean and rms temperature profiles and mean profiles of the major species are predicted quite well by the model. Dilution air is shown to have a significant impact on the mean and rms temperature profiles at the sector exit. The mean temperature profile is forced inbound by the outer dilution air, whereas the inner dilution air forces the temperature profile to be center-peaked with lower peak values. The rms turbulence fluctuation levels are generally increased by the dilution air. The effect on profiles of major species is similar. CONCERT-3D predicts these trends well. Overall, larger values of rms fluctuations are measured than predicted by the model. Possible reasons for these and other differences are discussed.