变转速模型旋翼挥舞摆振低阶载荷试验研究

Experimental investigation of flapwise and lagwise lower harmonic loads of a variable speed model rotor

为研究变转速旋翼挥舞和摆振方向低阶载荷,以无铰式复合材料模型旋翼为研究对象,通过试验研究,探讨了旋翼桨叶根部挥舞和摆振零阶及前3阶载荷随旋翼转速、前飞速度和旋翼拉力的变化关系。试验结果表明,在相同的配平条件(前飞速度、旋翼拉力、俯仰力矩及滚转力矩)下,降低旋翼转速有利于减小模型旋翼摆振零阶载荷,明显降低旋翼需用功率,进而提升直升机性能。当旋翼转速较低时,随着旋翼转速的降低,挥舞前3阶载荷幅值均较大。旋翼转速较低时,摆振弯矩前3阶也较大。当旋翼工作于摆振1阶共振转速附近时,旋翼挥舞前2阶和摆振前2阶载荷突增较为明显,挥舞3阶和摆振3阶变化相对较小,其中以摆振1阶载荷变化最为明显,需特别注意旋翼工作于共振转速附近时的载荷问题。

To investigate the characteristics of the flapwise and lagwise lower harmonic loads of variable speed rotors,a composite hingeless model rotor is tested in a wind tunnel.The zero and first three harmonic flapwise and lagwise root bending moments with the rotor speed,forward speed and rotor thrust are investigated.The test results indicate that reducing the speed of the model rotor can decrease the zero harmonic lagwise root bending moment,which means the reduction of the rotor power and the performance improvement of the rotor.At lower rotor speed,the first three flapwise harmonic loads increase with decreasing rotor speed.At lower rotor speeds,the first three lagwise loads are substantially large.When the rotor speed working near the first lagwise resonance rotor speed,the first two flapwise and lagwise loads are substantially large,and the variation of the third flapwise and lagwise loads are substantially small.Attention should be paid to the distinctly large first harmonic lagwise load,which can cause severe dynamic loads problems.