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旋翼桨-涡干扰(BVI)噪声是旋翼气动噪声抑制的主要对象之一。其中,高阶谐波控制(HHC)是一种较为有效的噪声主动抑制方法。为探究HHC方法的降噪效果、降噪机理及参数影响规律,基于嵌套网格生成方法,采用可压雷诺Navier-Stokes方程对流场进行求解,建立了适合于模拟旋翼桨-涡干扰流场的计算流体力学(CFD)数值方法。在流场CFD分析的基础上,采用FW-H(Ffowcs Williams-Hawking)方程预测桨-涡干扰状态下的旋翼噪声,通过对施加高阶谐波控制后的BO-105模型旋翼BVI噪声进行算例验证,得到了一套可以应用于高阶谐波控制下旋翼BVI噪声估算的CFD/FW-H方法。通过对不同HHC方案的数值模拟,发现在直升机斜下降状态下,施加高阶谐波控制后的旋翼BVI噪声能够降低多达4~7dB。进一步,细致分析了HHC方案的控制频率、输入相位以及输入幅值3个参数对旋翼BVI噪声抑制效果的影响,得到了相关参数的影响规律。并且,基于输入幅值对HHC降噪效果的影响规律,对高阶谐波控制方法的降噪机理做出了进一步的说明。
Rotor blade-vortex interference (BVI) noise is one of the main targets of rotor aerodynamic noise suppression. Among them, higher order harmonic control (HHC) is a more effective method of active noise suppression. In order to explore the noise reduction effect, noise reduction mechanism and parameter influence law of HHC method, based on the nested grid generation method, the flow field is solved by the compressible Reynolds Navier-Stokes equation, Field computational fluid dynamics (CFD) numerical method. Based on the CFD analysis of the flow field, the FW-H (Ffowcs Williams-Hawking) equation is used to predict the rotor noise in the propeller-vortex interference condition. By calculating the BVI noise of the BO-105 rotor model with high-order harmonic control, For example, a set of CFD / FW-H method which can be applied to rotor BVI noise estimation under higher order harmonic control is obtained. Through the numerical simulation of different HHC schemes, it is found that the rotor BVI noise can be reduced by up to 4 ~ 7dB after the high-order harmonic control is applied under the helicopter ramp-down condition. Further, the influence of HHC scheme’s control frequency, input phase and input amplitude on the noise suppression effect of BVI rotor are carefully analyzed, and the influence law of relevant parameters is obtained. And based on the influence of input amplitude on the noise reduction effect of HHC, the noise reduction mechanism of high-order harmonic control method is further described.