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针对旋翼桨-涡干扰(BVI)现象的复杂特征,建立了一个耦合欧拉-拉格朗日数值方法用于干扰过程中脉冲气动载荷的计算。该方法将旋翼流场计算域分为两部分:在桨叶附近区域,通过求解Navier-Stokes方程来模拟流场中旋翼桨尖涡的形成;在尾迹输运区,采用自由尾迹模型表示尾迹涡的运动及其影响。噪声的计算采用基于声学类比法的FWH方程。应用上述方法以AH-1/OLS旋翼为研究对象,分析了桨盘迎角、前进比和拉力系数3个飞行参数对BVI噪声特性的影响。计算结果表明:BVI噪声具有很强指向性,受桨盘上多处干扰的共同作用,噪声可能向直升机前下方多个方向传播;通过调整下降角度和前飞速度,增大平行干扰的垂直干扰距离,可有效地规避强BVI的出现;拉力系数变化会引起传播方向的改变,而对干扰噪声的强度影响不大。
Aiming at the complex characteristics of rotor blade vortex-vortex disturbance (BVI), a coupled Eulerian-Lagrangian numerical method is established for the calculation of pulsed aerodynamic loads during disturbance. This method divides the computational domain of the rotor flow field into two parts: the Navier-Stokes equations are used to simulate the formation of rotor blade vortices in the flow field in the vicinity of the blade; in the wake transport area, the wake vortex The movement and its impact. The noise is calculated using the FWH equation based on acoustic analogies. The AH-1 / OLS rotors are used as the research object to analyze the influence of the three flight parameters of the angle of attack, the forward ratio and the pull coefficient on the noise characteristics of BVI. The calculated results show that the BVI noise has a strong directivity and is influenced by multiple disturbances on the propeller disk. The noise may propagate in multiple directions before and under the helicopter. By adjusting the descent angle and the forward flying speed, the vertical interference of parallel interference is increased Distance, can effectively avoid the emergence of strong BVI; pull coefficient changes will cause changes in the direction of propagation, while the interference noise intensity has little effect.