倾转旋翼/机翼连续过渡状态气动性能仿真分析

Numerical analysis of tiltrotor/wing aerodynamic characteristics in continuous conversion mode

基于重叠网格,构建适用于连续倾转过渡状态模拟的数值计算框架.针对无人机中的2个重要部件——旋翼和机翼,模拟旋翼/机翼系统从固定翼模式倾转至直升机模式的过渡状态.采用雷诺平均方程,比较不同前进比下的气动性能变化,分析侧风风速对过渡状态的气动性能影响.结果表明,机翼升阻力系数随着倾转角的增大而减小,变化程度随着前进比的增大而减小;旋翼拉力随着倾转角的增大而增大,变化程度随着前进比的增大而增大.当来流存在侧风情况时,机翼升阻力系数减小,在倾转角到65°后侧风风速较小时的机翼性能有一定提升.旋翼的拉力系数大小受侧风影响不大,但振荡幅度会因此增大.

A numerical simulation framework was established,which was suitable for simulations of the continuous conversion mode of the tiltrotor based on the overset mesh method.The transition of a rotor/wing system from fixed-wing mode to helicopter mode was simulated for two important components in unmanned aerial vehicles,the rotor and the wing.Reynolds-averaged Navier-Stokes equations were used to analyze the variations of aerodynamic characteristics in different advance ratios and the effects of crosswind velocity on aerodynamic characteristics in conversion mode.Results show that the lift and drag coefficients of the wing decrease with the increase of the tilt angle,and the variation decreases with the increase of the advance ratio.The rotor thrust increases with the increase of the tilt angle,and the variation increases with the increase of the advance ratio.When there is crosswind in the incoming flow,the lift and drag coefficients of the wing decrease.The performance of the wing in low crosswind velocity is improved after the tilt angle reaches 65°.The magnitude of the thrust coefficient of the rotor is not significantly affected by crosswind,but the oscillation amplitude increases as a result.