  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. Also the predicted RMS fluctuations exhibit a
double-peak profile with one peak in the burnt and the other in the un-burnt
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 and the oscillations in the PVC are
damped with reactions.
