Sound Generation by Turbulent Non-premixed Flames

Abstract

The sound spectrum from a turbulent non-premixed flame as measured in the far field is predicted. A closed form description for the sound spectrum is derived assuming infinitely fast chemistry. The sound spectrum can then be described in terms of the ID turbulent spectrum of the mixture fraction at the flame front. The input values for this turbulent spectrum are derived from a steady state CFD flame calculation. The predictions from the sound spectrum model are compared widi experiments performed in an acoustically one-dimensional combustion chamber. The comparison between measurements and prediction is good for flames in which the mixed-is-burnt approach is valid. For flames, whose burning velocity is limited by chemical kinetics the measured spectrum shows a steeper fall off than the spectrum from the predictions