飞机着陆过程中非定常地面效应数值模拟方法

针对飞机着陆过程的大位移运动,提出适于多块结构动网格生成的改进谢别德-无限插值混合方法,改进谢别德方法准确计算各网格块的边界网格变形,无限插值方法快速计算内部网格点变形,结合局部重构保证动态网格的合理分布.混合方法有效解决了单一无限插值法存在的动网格交错问题.进而将二维非定常地面效应N-S方程计算方法发展至三维情形,应用于带增升装置的翼身组合体着陆过程中非定常地面效应计算分析.结果表明:模型的升力系数随离地高度的减小而减小,非定常和准定常计算方法的结果存在一定差异,而考虑了非定常效应的算法更为准确.

Numerical Simulation of Landing Aircraft in Unsteady Ground Effect

For the aircraft′s large displacement during landing , a dynamic mesh algorithm with local remeshing technique based on modified Shepard Interpolation and Transfinite Interpolation ( TFI ) method has been proposed to preserve the grid quality:modified Shepard Interpolation to get the grid deformation on block edges and TFI employed to efficiently calculate the deformation of internal nodes of each block . The dynamic grid method overcomes poor grid quality of TFI .Furthermore,the Navier-Stokes equations in Arbitrary Lagrangian-Eulerian( ALE) frame have been solved to simulate the unsteady flows around the wing-body configuration close to the ground .As the aircraft approaches the ground ,the unsteady ground effect has been investigated .Computations indicate that there is a certain difference between the unsteady results with the quasi-steady(add the equivalent attack angle to aircraft′s attack angle)ones,and the un-steady results are more accurate.