Investigation on the role of drainage structure in preventing the mass accumulation induced by shock/boundary-layer interactions in supersonic separators

Abstract

The occurrence of shock wave in nozzle and the blockage of fluid at the so called "second throat" are closely related to the drainage structure of supersonic separator, which result from the thickening of the boundary layer owing to the interaction between boundary layer and shock waves. Two types of drainage structures are proposed to solve the above problems and promote the separation performance for gas purification. The CFD modeling is used to optimize and evaluate the different drainage structures. The results show that the cylindrical drainage and the cascade drainage can efficiently alleviate or remove the mass accumulation at the "second throat". The cascade drainage with reflux channel and oblique openings is superior to other drainage structures, due to the low flow velocity and high centrifugal acceleration in the drainage section. The flow velocity and temperature in the cascade drainage chamber with reflux channel are opposing for separation performance of the supersonic separator. It means that high flow rate in cascade drainage section will lead to lower temperature, but increase the number of droplets carried by airflow, and vice versa.