交叉旋翼悬停气动性能和流场干扰

Aerodynamic Performance and Flow Interaction of the Intermeshing Rotors in Hover

针对交叉旋翼复杂的气动干扰问题,建立了一种适合于交叉旋翼气动分析的数值模拟方法.该方法采用三维非定常Reynolds平均Navier-Stokes(RANS)方程来求解流场,使用动态嵌套网格方法模拟旋翼运动.使用共轴旋翼悬停实验结果验证了该方法的准确性.利用该方法模拟了交叉旋翼在不同状态下的流场,计算了拉力和悬停效率,并与单旋翼、共轴旋翼计算结果进行对比分析,结果显示交叉旋翼流场存在较强的涡-涡和桨-涡干扰,旋翼桨尖涡在90°/270°附近相交;交叉旋翼的拉力系数及悬停效率随旋翼中心间距增大而增大,随交叉角变化较小;在相同总距角下,交叉旋翼悬停效率高于单旋翼和共轴双旋翼3%~8%.

Aiming at the complex aerodynamic interference problem of intermeshing rotors,a numerical simulation method was established suitable for aerodynamic analysis of the intermeshing rotors.The method solved the three-dimensional unsteady Reynolds Average Navier-Stokes(RANS)equations to simulate the flow field,and used the moving embedded grids to simulate the rotor motion.The hovering experiment results of coaxial rotors verified the accuracy of the method.The method was used to simulate the flow field of intermeshing rotors in different states,and calculate the thrust coefficient and hover efficiency.The results were compared with those of single rotors and coaxial rotors.The results show that there are strong vortex-vortex and propeller-vortex interactions in the intermeshing-rotor flow field.The tip vortices of the rotor blades are intersected near 90°/270°.The thrust coefficient and hovering efficiency of the intermeshing rotor increase with the increase of the rotor center spacing,and the change is small with the intersection angle.The hovering efficiency of the intermeshing rotors is 3%to 8%higher than that of single rotors and coaxial rotors at the same collective pitch.