Numerical Simulation of Air Vortex Interaction With Porous Screen

In this paper, numerical analysis of a two-dimensional vortex ring impinging through porous screen surface is investigated. The vortex ring is generated by a piston-cylinder assembly. The objective is to study the flow behavior of vortex ring when passing through porous screen and especially to obtain the values which are difficult to achieve in experiment method, such as kinetic energy and vorticity. A variety of parameters are set to be control groups, including porosity of porous screen (ϕ = 0.3, 0.6 and 0.8), Reynolds number of vortex ring (Re = 700 – 3000), piston diameter (D = 20mm, 34mm and 50mm) and gap between piston and porous screen (L = 50mm, 100mm and 150mm). The following results are acquired: (1) Porosity plays an important role on the vortex ring structure and flow behavior, (2) Reynolds number have notable influence on the vorticity evolution of vortex ring in the situation of low porosity, (3) Larger piston dimension results in slower progress of vortex ring transmission and sharper reduction of vortex ring kinetic energy, and (4) The gap length has significant effect on kinetic energy of vortex ring only in the situation of low porosity.