火 箭 发 动 机 燃 烧 室 中 燃 烧 噪 声 的 计 算 模 型

Combustion noise is generally divided into direct noise and indirect noise. The model of direct and indirect noises caused by unstable heat release in combustors with throat congestion is derived in time and frequency domain，respectively. The dissipation of entropy waves and attenuation of acoustic waves are considered. A combustor with unstable heat release is simplified as a straight tube heated by an electric heat source for theoretical calculation. Compared with the experimental results，the prediction error of the direct noise is smaller than 4%，and the trend of pressure disturbance is basically the same. Based on this model，the effects of pipe length and temperature disturbance on noise intensity are analyzed. The results show that the shorter pipe length causes larger intensity of direct and indirect noises，and the longer pipe length results in clearer separation between these two noises. The intensity of the direct noise and indirect noise increases linearly with the temperature disturbance，and the growth rate and intensity of the direct noise are twice that of the indirect noise without dissipation.