Evaluation of Combustion Noise Scaling Laws by an Optical Technique

An investigation which was conducted to verify the existence of a one-to-one correspondence between the acoustic and optical emissions from open premixed turbulent flames is described. The sound pressure and the time derivative of the emission intensity of light radiation have been compared using a) direct time traces, b) a cross-correlation technique, and c) spectral analysis. Further substantiation to the existence of the correlation has been provided by evaluating combustion noise scaling laws using optical measurements. These laws have been compared with existing scaling laws obtained from sound pressure measurements. Important conclusions regarding the origin of combustion noise have been drawn from these results.