Improvement of drainage structure and numerical investigation of droplets trajectories and separation efficiency for supersonic separators

Abstract As a new type of separation device, supersonic separator has received more and more attention in many areas. However, the interaction between boundary layer and shock wave in supersonic section results in the reverse pressure gradient and makes the boundary layer thicken, which form a so-called "second throat" that reduces the actual flow area and causes the fluid to be chocked. A novel cylinder drainage structure with larger drainage area was developed. When shock wave occurs, the high pressure will make more fluid enter into the openings on cylinder drainage structure, which is equivalent to increase the flow capacity. Therefore, the shock wave is weakened and the total pressure loss is reduced. Moreover, the prediction model of discrete phase coupling verified by experiments was adopted in order to predict the trajectory of droplets and separation efficiency for supersonic separator. The results show that with the increase of droplet size, the separation efficiency increases gradually and the particle diameter of 2 - 4 µm is sensitive to the separation. The droplets trajectory is more clear and regular in the nozzle with reflux channel and cylindrical drainage structure.