关键词: 凹壁面切向射流, 大涡模拟, 尾流, 旋涡, 功率谱

Abstract: Large eddy simulation was used to simulate the influence of spherical particles near the wall on fluid flow characteristics under the action of tangential jets on the concave-wall. The simulated wake vortex results were in good agreement with the experimental tracer image. The vortex structure and its evolution process of particle wake with particle diameter dp=4 mm and radius of curvature of concave wall R=200 mm were studied. The changes of velocity, vorticity, and streamline around the particle were investigated at Reynolds number Re=700~10 000. The results showed that the vorticity in the influence area of particles increased, the peak value of vorticity always appeared on the upstream surface of particles, and the recirculation zone behind the particles shrank significantly with the increase of Reynolds number. When Re=700, there was only one wake vortex behind the particle along the concave wall jet spanwise. When Re≥2000, there were two wake vortices behind particles along the concave wall jet spanwise, and the tangential velocity and vorticity of the fluid fluctuated periodically. The particle lift and resistance were monitored. There was the vortex shedding frequency at Strouhal number St=0.000 854 when Re=2000, and the peak value of the lift power spectrum occurred at St=0.001 52. The frequency peak corresponding to the boundary layer and wake instability was not found in the drag power spectrum when Re=10 000, and the peak of the lift power spectrum occurred at St=0.008 74. The particle wake had a great influence on the flow field. The analysis of the particle wake characteristics in the tangential jet on the concave wall was an in-depth study of the liquid-solid two phase separation mechanism. It provided the theory for the characteristics of single particle wake vortex in the process of heterogeneous separation of the tangential jet from concave wall.

Key words: concave-wall jet, large eddy simulation, wake, vortex, power spectrum