剪切层形态对开式空腔气动噪声的抑制

摘要

如何抑制开式空腔内的气动噪声是航空研究领域的一个研究热点。采用非线性扰动方程和基于雷诺平均 NS 方程的湍流人工重构方法对空腔标模进行数值模拟，通过与风洞试验数据的对比，验证了该计算方法的可靠性。基于此，在空腔前缘上方采用不同几何形状的栅板措施，以此来改变空腔前缘的剪切层形态，对比分析其对空腔湍动能、速度型、声源、声压级分布及压力脉动频谱特性的影响，分析可得：仅改变剪切层的方向和强度并不能降低空腔中的声源强度，还需通过改变剪切层的稳定性来影响空腔中声源的分布及强弱，这样才能有效降低流激振荡效果。研究结果表明：采用被动控制措施改变剪切层形态能有效抑制空腔中的气动噪声，其具备一定的工程应用价值。%The suppresion of aerodynamic noise in open cavities is an important problem in aeronautical applications.The acoustic field of a standard cavity model was simulated by using the non-linear disturbance equations and synthetic reconstruction of turbulence based on the RANS equation.The reliability of the method was validated by comparing its result with the experimental data.Based on this,the impact of passive control measures of baffles on cavity turbulent kinetic energy,velocity profile,sound source distribution,pulsating pressure distribution and spectrum characters were analyzed.The analysis indicates that,the strength of the sound source cannot be reduced only by altering the direction or intensity of the shear layer.In order to reduce the flow oscillation effect,the maintaining of the stability of shear layer is also required to influence the distribution and strength of turbulent kinetic energy and sound source.The results show that the passive control measures can effectively decrease the cavity aerodynamic noise.