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针对直升机旋翼液压阻尼器的力-速度非线性特性以及阻尼器与桨叶的变距、挥舞、摆振运动存在几何耦合的特点,提出了一种预估液压阻尼器飞行动载荷的计算模型。针对直升机悬停、巡航、大速度、定常转弯这几种典型的飞行状态,计算得到了液压阻尼器轴向速度和动载荷随桨叶方位角的变化曲线,分析了阻尼器特性对其飞行载荷的影响。结果表明:在四种典型的定常飞行条件下,阻尼器的轴向速度幅值均大大超过了其定压活门的开启速度,实际阻尼器的飞行动载荷幅值比设计值高38.1%~49.5%。这是由实际飞行中定压活门弹簧的预压缩量增加,使定压活门的开启压力提高所导致的。此种情况会对旋翼系统的结构强度和疲劳寿命带来不利影响,为降低其动载荷,需要改进定压活门弹簧预紧机构的设计,使其力-速度特性满足设计指标。
In view of the nonlinear characteristics of the force-speed of the hydraulic damper of helicopter rotors and the geometric coupling between the damper and the blade pitch, swinging and shimmy motion, a computational model for predicting the dynamic load of the hydraulic damper is proposed. According to the helicopter hovering, cruising, high speed, constant turning these typical flight conditions, calculated the axial velocity of the hydraulic damper and the dynamic load with the blade azimuth curve, the analysis of the damper characteristics of its flight load Impact. The results show that under four typical conditions of constant flight, the amplitude of the axial velocity of the damper greatly exceeds the opening speed of the constant pressure valve, and the actual dynamic load amplitude of the damper is 38.1% ~ 49.5 higher than the designed value %. This is caused by the fact that the pre-compression of the constant-pressure valve spring increases during the actual flight, resulting in an increase in the cracking pressure of the constant-pressure valve. This situation will adversely affect the structural strength and fatigue life of the rotor system. In order to reduce the dynamic load, the design of a constant-pressure valve spring preload mechanism needs to be improved to meet the force-speed characteristics of the design.