一种适合于旋翼前飞非定常流场计算的新型运动嵌套网格方法

针对旋翼流场计算中关键的运动嵌套网格技术,提出了一个新的网格单元关系快速判断方法。该方法通过计算特殊网格点在背景网格上的位置来建立桨叶网格在背景网格中所占据范围的关系,并用于嵌套网格洞单元的识别,又进一步将该方法推广用于Inverse Map的建立,在此基础上,建立了一套用于前飞流场计算的运动嵌套方法。通过多种前飞旋翼测试算例,分别评估了背景网格、桨叶网格尺寸改变对计算时间的影响,同时验证了该方法的可靠性,结果表明构建网格嵌套关系所用时间随桨叶网格和背景网格尺寸的变化幅度较小,且具有良好的鲁棒性,能够满足旋翼前飞状态计算的需要。最后,在基于前飞非定常N-S/Euler流场求解器中,采用该方法模拟了UH-60A和7A旋翼悬停/前飞状态的气动特性,通过计算时间的对比体现出该方法的高效性,并且流场计算结果与试验数据对比表明该方法可以有效地用于旋翼前飞非定常流场的计算。

A new moving-embedded grid method for numerical simulation of unsteady flow-field of the helicopter rotor in forward flight

Aiming at the key moving-embedded grid approach for predicting the flowfield of helicopter rotor,a new highly efficient method for judging the grid cell relationship has been presented.In this method,the occupied relationship of blade grids among the background grids has been established by calculating the position of special blade grid points among the back-ground grid system,and the method can be used to identify the hole cell among the moving-embedded grid system.Further,the method was extended to establish Inverse Map.Based on the present method,a moving-embedded grid technique has been developed for predicting the flowfield of rotor in forward flight.The effects of background grid and blade grid size on efficiency and reliability have been evaluated respectively by conducting many kinds of rotor test cases in forward flight.Test results showed that the consuming time in constructing the embedded-grid relationship increased slowly with the variable blade grid and background grid size,and it was demonstrated that the present method can satisfy the need for predicting the rotor flowfield in forward flight with good robustness.Finally,the aerodynamic characteristics of the UH-60A rotor in hovering flight and 7A rotor in forward flight have been simulated by the present method with unsteady N-S/Euler solver.By the comparisons of the consuming time by using different hole-cutting approaches and calculated results with experimental data,it was demonstrated that the method can be effective to simulate the unsteady rotor flowfield in forward flight with high-efficiency.