Effect of Velocity Fluctuation in an Unburnt Mixture Flow on Combustion Noise.

Abstract

A study was carried out to determine the relationship between sound pressure generated by open premixed flames and the velocity fluctuations in an unburnt mixture flow at a cylindrical single-port burner. The velocity fluctuations were measured at the burner port. The turbulent energy flux Ek. using the measured velocity fluctuations, was defined as an index of the velocity fluctuations. It was found that sound pressure generated by turbulent premixed flames on the burner can be determined by the turbulent energy flux Ek at the burner port, and that it is proportional to Ek*. The maximum sound pressure was generated by turbulent flames having an air ratio between 0.8 and 0.9. The effect of the laminar burning velocity on sound pressure was also investigated by changing the laminar burning velocity. It was found that the higher the laminar burning velocity of the mixture, the more sound pressure was generated from the turbulent flame for the same turbulent energy flux Ek.