用于直升机舱内降噪的主减周期撑杆研究

Research on gearbox periodic strut for helicopter cabin noise reduction

主减速器齿轮啮合产生的中高频谐波振动是直升机舱内噪声的主要来源之一,通过抑制该振动向机体的传递可达到舱内降噪的目的。基于金属/橡胶周期结构,提出了一种适用于直升机舱内降噪的串/并联复合型主减周期撑杆,不仅具有宽频减振特性,而且能够满足直升机对撑杆的强度和刚度要求。为指导这种周期撑杆的设计,首先采用谱单元法建立了复合型主减周期撑杆的动力学模型,进一步建立了该周期撑杆的刚度和强度分析模型;在此基础上,分析得到了该周期结构的主要设计参数对减振特性、刚度及强度的影响规律;最后,以某轻型直升机为背景机设计了复合型主减周期撑杆,对其减振特性、刚度及强度特性进行了仿真研究,结果表明：所提出的设计方案可满足该直升机对主减撑杆的刚度和强度要求,且撑杆两端位移传递率在500~2 000Hz频率范围内的最大振动衰减超过60dB,验证了本文所提出复合型周期撑杆方案的可行性。

High-frequency harmonic vibration generated by meshing gear pairs is a significant source of helicopter cabin noise, which can be controlled by suppressing the vibration transferred to the fuselage. A series/parallel complex gearbox periodic strut for helicopter interior noise reduction is brought forward in this paper. The periodic strut exhibits good ability of broadband vibration attenuation, and can satisfy the intensity and stiffness required by the helicopter. A dynamical model Is established based on spectral finite element method. The stiffness and intensity analysis models are then developed based on experiential formula. The effects of the main design parameters are obtained. A complex gearbox periodic strut is designed for a certain light helicopter. The simulation results show that the complex gearbox periodic strut proposed can meet the required intensity and stiffness. In addition, the maximum displacement transmissibility from one side to the other side of the strut exceeds 60 dB in the frequency range from 500 to 2 000 Hz, verifying the feasibility of the strut.