椭球对称面层流边界层计算

LAMINAR BOUNDARY LAYER CALCULATION IN THE SYMMETRY-PLANE OF A PROLATE SPHEROID

本文计算了椭球对称面上的定常流层流边界层和突然起动后非定常层流边界层的流动,椭球的厚度比为0.25,来流迎角为6°、30°、45°和50°。进行了定常流步长对计算精度影响的数值实验,选取了合理的计算步长,发现在迎角47°时出现边缘分离;进行了非定常流空间初值误差对计算结果影响的数值实验,证实这种影响是暂时和局部的,因而可用局部相似的方法处理前端奇点;还给出了表面摩擦力系数和边界层位移厚度的计算结果。

Steady and impulsively-started unsteady laminar boundary layer flows along the symmetry-plane of a prolate spheroid with ratio of 0.25 are calculated at incidence angles of 6°, 30°, 45°and 50°respectively Numerical experiments about the effect of steps on the steady calculation are carried out and appropriate steps selected. It is found that marginal separation occurs near the nose at an incidence of 47°. Numerical experiments on the effects of spatial initial profiles on the unsteady calculation are also carried out and it is confirmed that the effect of the errors of spatial initial profiles are temporal and local, and that the nose singularity can be treated by the method of local similarity. Results of calculated skin friction and displacement thickness are given.