全叉树直角网格民机低速气动特性数值分析

由于几何外形的复杂性,民机低速气动特性的数值分析成为CFD技术中的难点之一.文章基于直角网格,采用分区面搭接技术,对存在剪刀叉不连续面的民机低速构型进行了绕流流场数值模拟.利用全叉树数据结构,根据当地物面曲率的变化,有选择地完成网格自适应加密,可减少网格数量,提高计算效率.基于中心有限体积方法和双时间推进算法,对民机起飞和着陆构型的绕流流场进行了Euler方程数值模拟,分析了应用八叉树和全叉树数据结构时的区别,计算结果与实验数据的对比,说明所述方法的正确性.

Numerically Analyzing More Efficiently High-Lift Aerodynamics of Transport Aircraft with Omni-Tree Cartesian Grids

Aim.Refs.1,2 and 3 are recent developments dealing with transport aircraft high-lift aerodynamics.Different from them,we use omni-tree Cartesian grids to achieve higher efficiency.In this paper,the computation of complex flow field using the adaptive Cartesian grid method and the cell-center finite volume method is carried out and compared with wind-tunnel experiments.We mainly use the onmi-tree data structure and the face-to-face algorithm.The onmi-tree structure allows the Cartesian grid to be adapted in an arbitrary manner and offers the potential of dramatic reduction of total number of cells to achieve a given level of solution accuracy.The face-to-face algorithm is established to precisely conduct the information exchange of flow fields on the interfaces among different zones.We solve the Euler equations using the cell-centered finite volume method and the dual-time step-length scheme.The above algorithm and methods have been verified with two test cases involving respectively a takeoff configuration and a landing one.Some computation results,given in Figs.3 and 4,show preliminarily that the grid generation and the flow field calculation are accurate; other computation results,presented in Tables 1 and 2,indicate preliminarily that the total number of cells are dramatically reduced with the accuracy almost unaffected.Thus we conclude preliminarily that our algorithm and methods are more efficient for solving the flow field of the complex high-lift configuration.