An Experimental and Computational Study of a Swirl-Stabilized Premixed Flame

Abstract

An unconfined strongly swirled flow is investigated for different Reynolds numbers using particle image velocimetry (PIV) and Large Eddy Simulation (LES) with a Thickened Flame (TF) model. Both reacting and non-reacting flow results are presented. In the LES-TF approach, the flame front is resolved on the computational grid through artificial thickening and the individual species transport equations are directly solved with the reaction rates specified using Arrhenius chemistry. Good agreement is found when comparing predictions with the experimental data for the non-reacting cases studied. For the reacting flows, the mean axial velocity profiles are in good agreement with measurements at lower Re; at high Re, the computations show a more compact and attached flame whereas experimental observations show a slightly lifted flame. Tangential velocity predictions consistently show the peak at the flame front location while measurements show greater radial spreading of the tangential momentum. The predicted RMS fluctuations exhibit a double-peak profile with one peak in the burnt and the other in the unburnt region. The measured and predicted heat release distributions are in qualitative agreement with each other and exhibit the highest values along the inner edge of the shear layer. The precessing vortex core (PVC) is clearly observed in both the non-reacting and reacting cases. However, it appears more axially-elongated for the reacting cases.