Method for Eliminating Aerodynamic Lift Vibration of Rigid Rotor Helicopters Based on the Novel Sine-trim Model
Method for Eliminating Aerodynamic Lift Vibration of Rigid Rotor Helicopters Based on the Novel Sine-trim Model
复制标题
基于新型正弦配平模型的刚性旋翼直升机气动升力振动消除方法
DOI：
10.1016/j.ast.2019.105655
复制
发表时间：
2020
影响因子：
5.6
通讯作者：
吕维梁
中科院分区：
文献类型：
--
作者：
吕维梁
根据电机工程中交流电压的相量叠加原理，提出了一种消除刚性旋翼直升机气动升力振动的新方法-正弦调整法。基于自由尾迹方法，结合内外配平模块，提出了一种先进桨叶概念旋翼气动分析模型。内倾模块通过调整各方位角的桨距，将刚性偏置旋翼的升力分布曲线转化为近似正弦曲线。提出了一种加速算法，大大提高了内倾计算效率。外配平模块选取下旋翼的幅值作为预置配平值，通过修改上、下旋翼的升力正弦曲线参数，对直升机整体力和力矩进行可靠有效的配平。在正弦配平中，上下旋翼具有相似的正弦升力分布参数，其相位和振幅呈现正相反的关系。计算结果表明，对刚性旋翼进行正弦调整后，无论飞行速度、桨叶数、旋翼转速等飞行和工作条件如何变化，都可以消除刚性旋翼的总气动升力振动。最优桨距控制分布是多个高次谐波输入的综合叠加，可在所有方位角得到。对于相同的升力偏置，在正弦修整之后，与传统的前进叶片概念转子相比，有效升阻比可能具有较小程度的损失。
A novel methodology called sine-trim is proposed from the phasor superposition principle for AC voltages in electrical engineering to eliminate the aerodynamic lift vibration of rigid rotor helicopters. An advancing blade concept rotor aerodynamic analysis model is presented on the basis of free-wake method associated with the inner- and outer-trim modules. The inner-trim module transforms the blade lift distribution curve of a rigid lift-offset rotor into a similar sinusoidal one by adjusting the blade pitch in each azimuth. An acceleration algorithm that could greatly improve the inner-trim calculation efficiency is provided. The outer-trim module selects the amplitude of the lower rotor as the preset trim value, and it is reliable and effective in trimming the overall forces and moments of the helicopter by modifying the lift sinusoid curve parameters of the upper and lower rotors. In the sine-trim, the upper and lower rotors have similar sinusoidal lift distribution parameters, and their phases and amplitudes exhibit a direct inverse relationship. Calculation results show that after being sine-trimmed, the total aerodynamic lift vibration of the rigid rotors could be eliminated regardless of the change in flight and operating conditions, such as flight speed, number of blades, and rotor rotational speed. The optimal blade pitch control distribution, which is a comprehensive superposition of many higher harmonic inputs, is obtained in all azimuths. For the same lift-offset, after sine-trimming, the effective lift-to-drag ratio may have a small degree of loss compared with the conventional advancing blade concept rotor.