基于主动后缘小翼控制的旋翼厚度噪声试验

基于声压相消原理,提出了一种基于主动后缘小翼控制的旋翼厚度噪声降噪方法。基于Ffowcs Williams-Hawkings(FW-H)方法给出了后缘小翼主动控制条件下旋翼气动噪声的计算公式;进行了试验总体方案设计,在全消声室开展了噪声主动抑制的开环试验(扫频、扫相和扫幅),并与数值计算结果进行了对比,验证了计算方法及试验的有效性;分析了后缘小翼偏转参数(幅度、频率、初始相位)对旋翼厚度噪声降噪的影响规律;分析了观测距离对厚度噪声降噪的影响。试验结果表明:不同频率的偏转规律均有一个最优的初始控制相位,合适的偏转规律相位能有效降低桨盘平面内观测点的厚度噪声2～3 dB。

Experiment on thickness noise of rotor based on control of active trailing edge

An on-blade control technique to reduce thickness noise was developed based on the principle of sound field cancellation. A high-accuracy method for calculation of helicopter rotor aerodynamic noise was established based on the Ffowcs Williams-Hawkings (FW-H) equations with the control of active trailing edge. The overall experimental scheme was designed and the open-loop experiment of active noise control was carried out in a fully anechoic chamber, and the experiment data were compared with theoretical calculation to verify the validity of the method and experiments results. The parameter influences of the amplitude, frequency and initial phase of the trailing edge deflection on the thickness noise reduction of the rotor were analyzed. The influences of the observation distance on the cancellation of rotor thickness noise were then deeply assessed. The experimental results demonstrated that there was an optimal phase at each frequency to minimize the noise at the observations, and it varied with different frequencies; the reasonable trailing edge control law can effectively reduce the thickness noise of the observation points in the plane of the rotor up to 2-3 dB.