轻型火箭发射噪声场的分布特性

为了解小火箭发射噪声特性及其在喷口外围的声压场分布规律，针对燃气射流产生噪声问题进行了实验研究和数值计算。讨论了超声速射流噪声的3个主要成分(湍流混合噪声、啸音和宽带激波相关噪声)及相关特点，指出它们产生的根本原因是湍流射流的速度扰动。通过分析不同实验测点的射流噪声声压级峰值，得到了燃气射流噪声在轴向和径向上的分布规律，即随着离喷口距离的增大，轴向噪声的衰减程度大于径向。在实验基础上，利用大涡模拟与FW-H(Ffowcs Williams-Hawkings)声学比拟相结合的方法对燃气射流噪声的声学特性进行计算。结果表明，此方法获得的计算结果与实验结果吻合较好，可为进一步研究射流噪声控制提供参考。

Distribution characteristics of rocket launching noise field

To investigate the characteristics of rocket launching noise and the acoustic distribution around the nozzle, the gas jet noise was studied experimentally and numerically. Three main components (turbulent mixing noise, screech tone and broadband shock noise radiation) and respective features of supersonic jet noise were explored, which revealed that the speed disturbance of the turbulent jet is the principal factor influencing noise radiation. The sound pressure level peaks of the jet noise at different test points were analyzed, and the distribution rule of the jet noise was got in the axial and radial directions. The investigated results show that with increasing the distance from the nozzle exit, the attenuation of noise in the axial direction is higher than that in the radical direction. Based on the experiments, the sound pressure level peaks of the supersonic jet noise were calculated by large eddy simulation and Ffowcs Williams-Hawkings acoustic analogy. The calculated results are in agreement with the experimental ones, which can provide reference for further study of controlling jet noise.