三维可压缩非定常流的壁面分离判据及其分离线附近的流动形态

Separation on fixed surface for three dimensional compressible unsteady flows

通过引入依赖于密度的物面法向速度变换wr=-1ρh1h∫2z0h1h2ρtdz,描述物理速度空间(ua,va,wa=u,v,w+wr)具有无滑移壁面条件的三维可压缩非定常连续方程可转换成变换速度空间(u,v,w)内具有无滑移条件定常连续方程。因此,采用定常壁面分离的分析方法和结论,再通过变换和研究wr的贡献,给出了三维可压缩非定常壁面分离的判则以及分离线附近的流动形态。研究指出,二维和三维情况下,都出现伴有壁外附着的壁面分离情况。数值模拟证实了理论和结论。

Through introducing a transformation for the density related velocity component wr=-ρh1h2^-1∫0^zh1h2Эt^-Эρdz on the direction normal to wall, the continuous equation of three dimensional un-steady compressible flow in physical space （ua ,va ,Wa^U,V,W＋Wr） with no-slip wall condition can be trans- formed to an equation for the steady flow in the transformed velocity space （u,v,w） with no-slip wall. Then, using the same analysing method and corresponding result of the steady flow separation, the criteria for the compressible unsteady flow can be obtained after considering the contribution of wr. It is found that there is a case that flow separates on wall and reattaches off wall in both two dimensional and three dimensional flow. The analysing results have been proved by numerical simulation.