火箭发动机燃气射流驱动液柱降噪实验

为了研究单兵火箭燃气射流噪声抑制的方法,设计了液体水柱放置在尾管中,采用高速摄影系统观察了高温高压燃气驱动液体水柱在大气环境中的扩散过程,并对气液混合物射流噪声声压进行了测量,对比了有无液体水柱两种状态下射流的测试结果.实验结果表明,在尾管中放置液体水柱后,由于气液之间的相互作用,改变了燃气射流流场结构以及降低了射流特征参数.通过与无液体水柱的燃气射流对比,发现有液体水柱时整个测点区域的噪声声压级峰值均有较大幅度的降低,且地面对声波的反射也减弱,噪声声压级峰值随着测点偏离射流中心轴线角度的增大而逐渐减小.因此,放置液体水柱后起到了明显的降噪效果,在偏离角为45°位置声压级峰值降低了6.4dB,验证了此方案的可行性. 

Experiment on jet noise reduction with a liquid column driven by rocket engine gas jet

In order to investigate the effective method of individual rocket burned gas jet noise reduction, a designed liquid column was placed in the tail tube. The dispersion processes of high-temperature high-pressure combustion-gas driving the liquid column in the air was observed by using a high-speed photographic system, and gas-liquid mixture jet noise was also measured; the test results of jet were compared under two conditions of no-water-column and water-column. The experimental results show that then liquid column was put in the tail tube, the jet flow structure was changed and the jet flow parameters were decreased due to the interaction of gas jet with water. It is concluded that the sound pressure level peak is reduced to some extent in whole test points region with the liquid column, compared with the result of no liquid column gas jet; and the impact of the ground on the acoustic wave is weakened. With the increasing angle of the measuring points deviating from the jet central axis, the sound pressure level peak decreases. So the liquid column plays an important role in suppressing noise, the peak sound pressure level decreases by 6.4dB at the angle of 45°, validating the feasibility of noise reducing scheme.