Generation of Combustion Noise

An analytical description is presented for the generation of noise in burning fuel‐air mixtures. Fluctuating pressure (noise) is shown to result when the heat release rate of the mixture passing through the reaction zone is variable with time. Experimental evidence in support of this view is presented and referenced from the literatures of acoustics and combustion. Several illustrative examples from common experience are pointed out. Premixed and diffusion flames of gas and liquid fuels are considered, and the role of flame and mixture turbulence in causing a varying heat release rate and noise is noted. The possibility appears to exist for substantially reducing the noise output of large combustion systems (jet engine, for example) by more effective control of the flame configuration and stability.