共轴刚性旋翼的悬停气动性能和流场干扰

建立了一种基于RANS (雷诺平均Navier Stokes)方程的共轴刚性旋翼悬停流场数值模拟方法。使用旋翼亚声速和跨声速悬停实验结果,验证了该方法的准确性。对刚性旋翼XH 59A流场模拟表明:气动特性与飞行实验结果比较吻合,共轴旋翼特性优于同实度单旋翼,具备更高的悬停效率。对比半实度单旋翼气动性能,受下旋翼对流动的抽吸影响,上旋翼性能略有下降；下旋翼性能下降更甚,主要是因为处于上旋翼下洗流中,其有效迎角减小。数值方法获得该旋翼最高悬停效率为67%,总距角为14°,14°。对比研究表明,共轴刚性旋翼较常规共轴旋翼极间距小,悬停性能更高。 

Aerodynamic performance and flow interaction of the coaxial rigid rotor in hover

A numerical method based on RANS(Reynolds averaged Navier Stokes) equations was developed to predict the aerodynamic performance of coaxial rigid rotor in hover. Validation of the method was carried out on the hovering tests for the subsonic and transonic flows. The simulation of rigid rotor XH 59A in hover showed that CFD prediction of rotor performance agreeed with the flight test data. Compared with single rotor of the same solidity, coaxial rigid rotor had better performance, along with bigger figure of merit. The performance of the upper rotor decreased less than that of the lower rotor. Reasons were related to the suction effect of the lower rotor on the flow and its location in the downwash flow field of the upper rotor, resulting in the decrease of its effect angle attack. Numerical method indicated that the optimum figure of merit for XH 59A was 67%, when the collective pitch angle for both rotors was 14°. Compared with traditional coaxial rotor, the interstage distance of rigid rotor was smaller, leading to a better aerodynamic performance.