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直升机小速度平飞和斜下降飞行时会产生严重的桨-涡干扰(BVI)噪声。基于修正Beddoes尾迹/桨叶动力学耦合方法和Farassat 1A公式,建立了一个新的能够计入高阶谐波控制(HHC)影响的旋翼桨-涡干扰气动载荷和噪声计算模型。在该模型中,高阶谐波控制引起的桨尖涡附加位移通过对高阶入流进行时间积分推导得出,而单一阶次的谐波输入引起的各阶谐波响应通过传递函数来确定,传递函数则由桨叶的动力学特性计算。首先对HARTⅡ旋翼斜下降飞行状态的桨-涡干扰气动载荷进行了计算模拟,验证了所建立方法的可靠性。然后,着重研究了在典型的三阶谐波桨根激励下,不同输入相位对HARTⅡ旋翼桨-涡干扰气动载荷和噪声特性的影响。结果表明:桨叶的动力学特性尤其是扭转特性对高阶谐波控制效果影响显著,且高阶谐波输入的相位选择对桨-涡干扰噪声的控制至关重要,若控制相位选择不当,反而会增大旋翼噪声。
Serious paddle-vortex interference (BVI) noise is generated when helicopters fly at low speeds and when they fly downhill. Based on the modified Beddoes wake / blade dynamics coupling method and the Farassat 1A formula, a new aerodynamic load and noise calculation model of rotor blade-vortex disturbance that can account for the influence of higher order harmonic control (HHC) is established. In this model, the additional displacement of tip vortex caused by higher-order harmonic control is deduced by time integration of higher-order inflow, and the harmonic response of each order caused by single-order harmonic input is determined by the transfer function. The transfer function is calculated from the dynamics of the blade. The aerodynamic loads of the propeller-vortex interference rotor with the rotor flying downhill are simulated and the reliability of the proposed method is verified. Then, the influence of different input phases on the aerodynamic loads and noise characteristics of HARTⅡ rotor-blade vortex disturbance under typical third-order harmonic root excitation is studied. The results show that the dynamics of the blades, especially the torsional characteristics, have a significant influence on the control effect of higher order harmonics, and the phase selection of higher order harmonic input is crucial to the control of propeller-vortex interference noise. If the control phase is not properly selected, But will increase the rotor noise.