射流对空腔噪声抑制效果研究

Suppression effect of jet flow on aerodynamic noise of cavity

高速空腔流动的流场结构非常复杂,在一定条件下存在严重的压力、速度等脉动,诱发强烈的噪声,声压级可达到170dB,对腔内的导弹及其自身结构安全构成很大的威胁。应用基于两方程剪切应力(SST)的尺度自适应(SAS)分离流模型的CFD技术和气动声学频域理论(FW-H积分方程),模拟了射流对二维M219空腔(长深比L/D=5)内气动噪声变化情况,研究了空腔流动特性、流场结构及发声机理。在此基础上,首先对比分析了不同射流位置对空腔噪声的抑制情况,以此确定一个工程上可实现的射流位置;然后,对比分析了不同射流状态(不同的射流流量、温度)对空腔噪声的抑制情况。由此可知,跨音速(Ma=0.85)条件下,采用不同的射流状态对空腔噪声具有不同的抑制效果,其中随着射流量及射流温度的增大,噪声抑制效果更加明显。

The structure of cavity flow field with high Mach number is very complex,in which pressure and velocity pulsate seriously, leading a fierce noise about almost 170 dB. The noise is posing a great threaten to the safety of the missile in the cavity and the structure of the cavity. This paper simulates the changes of the aeroacoustics in the M219 cavity（length to high aspect ratio L/D=-5） in which the jet flow from the engine is used and make a study on the flow characteristic, flow field structure and the sound mechanism in the cavity by applying the Scale-Adaptive Simulation（SAS） model developing from two equation SST turbulent model and aerodynamic acoustic frequency theory （FW-H integration formulation）. On the basis of this, the situation of jet flow which can be realized in the engineering is determined after comparing and analyzing the suppression effect on the cavity noise of the different jet situation. Then the suppression effect on the cavity noise of different jet state is compared and analyzed （different jet flow quality,temperature）. The conclusion can be drawn that in transonic condition,the different jet condition has a different suppression effect on the the cavity noise. With the increasing of the jet flow quality and jet temperature , the noise suppression effect is more obvious.