含不同桨尖的无轴承旋翼直升机气动机械稳定性

Aeromechanical stability of bearingless rotor helicopter with different blade tip shapes

直升机旋翼桨尖形状可以有效提高旋翼气动性能,但可能会降低旋翼气弹稳定性.这方面的研究包括不同桨尖形状的旋翼气动性能、孤立旋翼气弹稳定性、无铰式旋翼直升机气动机械稳定性.不同桨尖形状的无轴承旋翼直升机的气动机械稳定性研究还未见到报道.研究了含不同桨尖无轴承旋翼直升机的气动机械稳定性,基于哈密顿原理和中等变形梁理论,并通过桨尖形状引起的非线性位移协调条件,建立了含不同桨尖形状的无轴承旋翼/机体耦合系统的气动机械动力学模型.计算的ITR无轴承旋翼直升机地面共振和空中共振的稳定性与实验结果一致,证明了建立的气动机械动力学模型的准确性。计算了桨尖前掠、后掠、上反、下反、尖削和形状组合对无轴承旋翼直升机地面共振和空中共振稳定性的影响,计算结果表明,桨尖形状能有效改变无轴承旋翼直升机的气动机械稳定性.

The blade tip shapes of helicopter rotor can improve the aerodynamic performance of rotor effectively, but may re-duce the aeroelastic stability of rotor. The studies in this area include the aerodynamic performance of rotor, the aeroelastic sta-bility of isolated rotor, and the aeromechanical stability of hingeless rotor with different blade tip shapes. The aeromechanical stability of bearingless rotor helicopter with different blade tip shapes has not been reported, and has been systemically investi-gated in this paper. Based on the Hamilton's principle and the moderate deflection beam theory, and through the nonlinear dis-placement compatibility conditions caused by the blade tip shapes, the aeromechanical dynamic model of bearingless rotor/fuselage coupled system with various blade tip shapes has been established.The calculated stability of ground resonance and air res-onance of the ITR bearingless rotor helicopter are consistent with the experimental results,verifying the aeromechanical dy-namic model established in this paper. The effects of blade tip sweep-forward,sweep-backward,anhedral, droop, taper and tip combination on the ground resonance and air resonance of bearingless rotor helicopter are calculated. The results indicate that the blade tip shapes can effectively change the aeromechanical stability of bearingless rotor helicopter.