高精度差分格式在机翼分离流计算中的应用

Application of high-order difference scheme to wing separation flow calculations

用一个模型方程分析了边界层方程的数值稳定性 ,指出稳定性问题会随计算雷诺数减小而变得严重 ,因而对较低的Re数 ,计算分离边界层流动采用高阶精度差分格式十分必要。本文同时给出用四阶精度差分格式求解在流动分离情况下边界层方程的技术方法 ;对一个大展弦比后掠翼在攻角等于 1 4°时计算了机翼上表面的分离线 ,并与文献上公布的用别的测算方法测出结果做了比较 。

The numerical stability of boundary layer equations is analyzed by using a model equation. It is shown that the instability will become a serious problem with decreasing Reynolds number. So it's necessary to use high-order difference scheme for calculating separated boundary layer flow with fairly low Reynolds number. The techniques of using four-order difference scheme for solving boundary layer equations with separation conditions are also presented in the paper. The separation lines on the upper surface of a swept wing with large aspect ratio under angle of attack equal to 14° are calculated. The computation result is compared with that has published in the reference with other prediction method, and all in all, both results are agreed fairly well.