基于动态非结构重叠网格法的直升机前飞非定常流场数值模拟研究

 发展了非结构重叠网格技术，提出适合于直升机旋翼运动的动态非结构重叠网格算法，该算法使得在采用非结构重叠网格模拟直升机流场时实现程序自动处理网格，不需任何人工干预。流动控制方程采用非定常可压缩Euler方程，空间离散采用Jameson有限体积法，时间推进采用双时间步长法，为加速收敛，在双时间步长内循环迭代中采用预处理技术。为验证本发展的预处理解算器以及动态非结构重叠网格的算法的可信性和有效性，开展一系列的数值实验，模拟了不同速度范围的NACA0012翼型绕流,Caradonna旋翼悬停和前飞流场以及Robin直升机机身-旋翼组合的前飞非定常流场，结果表明采用本文算法得到的结果是可信的，网格处理是自动高效的，可以应用于直升机全机流场模拟，为直升机设计提供可信指导数据。

Numerical Simulation Research of Unsteady Flow Field Around Helicopter in Forward Flight on Dynamic Overset Unstructured Grids

A new dynamic overset unstructured grids method is developed to simulate the unsteady flow field a-round helicopter.The developed neighbor-to-neighbor searching algorithm based on the advancing front method is used for donor searching.Unsteady Euler equations are solved on overset unstructured grids by an explicit dual time-stepping,Jameson finite volume method.Preconditioning method applied to inner iteration of the dual-time stepping is used to accelerate the solution of the governing equation.Many cases(flow past NA-CA0012 airfoil,Caradonna rotor in hover and forward flight,and Robin helicopter with four blades in forward flight)are considered to validate the method presented in the paper.All numerical results show that the developed dynamic overset unstructured grids method is very efficient for the simulation of helicopter flow field and the results are reliable.