共轴刚性旋翼气动干扰数值计算方法

建立了一个适用于共轴刚性旋翼气动特性分析的数值模拟方法。该方法采用任意拉格朗日欧拉方法(Arbitrary Lagrange Euler,ALE)描述的可压缩Navier-Stokes(N-S)方程求解流场,采用低数值耗散的Roe格式进行空间离散;使用多重嵌套网格方法以模拟双旋翼的运动。针对共轴刚性旋翼配平,引入"差量修正"策略解决了传统配平中雅克比矩阵计算复杂的问题。首先,对Harrington-2共轴双旋翼的悬停气动性能进行了计算,然后,对某2 m直径共轴双旋翼的悬停及前飞状态进行了计算,并与试验值进行了对比。结果表明:在典型状态下拉力系数的计算结果与试验值误差在3%以内,扭矩系数的计算结果与试验值误差基本在5%以内;所采用的数值计算方法对旋翼涡尾迹特征具有较高的捕捉精度,可以有效模拟共轴刚性旋翼悬停和小速度前飞下的复杂流场及其细节特征。

Numerical Method of Coaxial Rigid Rotor Aerodynamic Interaction

A numerical method is developed to predict the aerodynamic characteristics of rigid coaxial rotor. The method uses the compressible Navier-Stokes (N-S) equation described by arbitrary Lagrange Euler (ALE) to solve the flow field. A low numerical dissipative Roe format for spatial dispersion is adopted. Multiple overset grid method is used to simulate the motion of the coaxial rotor. A delta trim method is implemented to simplify the calculation of Jacobin matrix for rigid coaxial rotor trim. First, the aerodynamic performance of the Harrington-2 coaxial rotor in hover is calculated. Then, the hover and forward flight states of a 2 m diameter coaxial rotor are calculated and compared with the experimental values. The results show that, the error of the calculation result and the test value is less than 3% under the typical state, and the error of the torque coefficient is less than 5%. The numerical method has a high capture precision for the vortex wake characteristics of the rigid coaxial rotor, and can effectively simulate the detailed characteristics of the complex flow fluid in hover and the low-speed forward flight states.