科研之友
微信
新浪微博
Facebook
分享链接
摘要
The flow past amicroramp immersed in a supersonic turbulent boundary layer is studied bymeans of numerical simulations with the implicit large-eddy simulation technique and experiments conducted with tomographic particle image velocimetry. The experimental data are mostly used to verify the validity of the numerical results by ample comparisons on the time-averaged velocity, turbulent statistics, and vortex intensity. Although some discrepancies are observed on the intensity of the upwash motion generated by the streamwise vortex pair, the rates of the recovery of momentum deficit and the decay of streamwise vortex pair intensity are found in good agreement. The instantaneous flow organization is inspected, making use of the flow realizations available from implicit large-eddy simulation. The flow behind the microramp exhibits significant large-scale unsteady fluctuations. Notably, the quasi-conical shear layer enclosing the wake is strongly undulated under the action of Kelvin-Helmholtz (K-H) vortices. The resulted vortices induce localized high-speed arches in the outer region and a deceleration within the wake associated with ejection of low-momentumfluid. Because of the presence of the K-H vortex, the streamwise vortex filaments exhibit downward and outward motions. The further evolution of vortical structures within the wake features the development of K-H vortices from arch shape to full ring in the far wake, under the effects of the streamwise vortices, which induce an inward motion of the vortex legs and eventually connect the vortex at the bottom.
- 出版日期2014-7
