直升机双层平尾构型气动特性分析

Analysis of aerodynamic characteristics of helicopter biplane tailplane

为分析双层平尾气动特性,采用CFD方法建立了直升机平尾计算模型,获得了低速前飞和机身大迎角状态不同构型平尾的气动特性,分析了单层和双层平尾构型的气动特性和流场特点,研究了双层平尾对低速前飞状态和大迎角状态的纵向静稳定性改善作用机理。结果表明:双层平尾构型通过抑制旋翼/平尾干扰改善低速前飞状态下的直升机俯仰力矩突增问题,前进比为0.05时,双层平尾俯仰力矩比单层平尾减小56.8%;双层平尾的失速迎角和最大俯仰力矩增大,从而增强直升机大迎角状态的纵向静稳定性,迎角20°时,双层平尾俯仰力矩比单层平尾增大60.1%。

To analyze the aerodynamic characteristics of helicopter biplane tailplane,computational models for helicopter biplane tailplane and monoplane tailplane were established via CFD.The aerodynamic characteristics of different configurations of tailplanes at low speed forward flight and high angle of attack was obtained.The aerodynamic characteristics and flow characteristics of biplane/monoplane tailplane were analyzed.The mechanism of biplane tailplane to improve the longitudinal static stability at low speed forward flight and high angle of attack was investigated.The results show that the biplane tailplane can improve the helicopter pitch moment surge at low speed forward flight by restraining the rotor/tailplane interference,comparing with the monplane tailplane,the pitch moment of the biplane tailplane was reduced by about 56.8%at an advance ratio of 0.05.The stall angle of attack and maximum pitch moment of the biplane tailplane were larger,which can enhance the helicopter longitudinal static stability at high angle of attack,comparing with the monplane tailplane,the pitch moment of the biplane tailplane increased by about 60.1%at an attack angle of 20°.