超临界正癸烷同轴剪切喷注热声振荡数值模拟

以液体火箭发动机同轴剪切喷嘴燃烧室作为研究对象，对超临界压力下低温正癸烷向高温正癸烷喷注过程中，由于高温正癸烷被快速冷却导致密度剧烈变化进而引发的热声振荡现象进行数值模拟。研究了出口压力、高温正癸烷流动速度与温度、低温正癸烷喷注速度与温度对热声波振幅与频率的影响。结果表明：当高温正癸烷被快速冷却时，其自身体积快速收缩，同时由于附近高温正癸烷的惯性导致压力先增大后减小，快速交替变化，从而产生热声波在高温正癸烷中传播。热声波振幅与频率的大小主要由高温正癸烷在不同压力与温度下的热物性决定。热声波的频率随着高温正癸烷声速增大而增大；热声波的振幅由高温正癸烷的相对压力系数与温度变化率共同决定。

Numerical simulation of thermoacoustic oscillations during n-decane shear-coaxial injection processes at supercritical pressure

The thermoacoustic oscillations induced by the dramatic change of fluid density resulted from rapid temperature variations during the shear-coaxial injection process at supercritical pressure is numerically simulated. The effects of outlet pressure, high-temperature n-decane flow rate and inlet temperature, low-temperature n-decane injection rate and inlet temperature on the oscillation amplitude and frequency are investigated. The results show that the high-temperature n-decane shrinks drastically in volume when cooled rapidly, and the pressure increases first and then decreases rapidly due to the inertial of surrounding high-temperature n-decane, thus generating thermoacoustic oscillations. The amplitude and frequency of thermoacoustic waves are mainly determined by the thermophysical properties of high-temperature n-decane at different pressures and temperatures: the frequency of thermoacoustic waves increases with the increase of the sound speed of high-temperature n-decane; the amplitude of thermoacoustic waves is determined by the relative pressure coefficient of the high-temperature n-decane and the rate of temperature change.