Optimization of static vanes in a supersonic separator for gas purification

•The swirling flow is strengthened in the diverging part of the Laval nozzle.•Gas expansion and swirling flow are mutual opposed effect for supersonic separators.•Swirl angle ranging from 45° to 60° is recommended for gas supersonic purification.•Vane height should be 0.125-0.3 times of the radius of the nozzle entrance.•The 8 to 16 vanes are reasonable to obtain good expansion and separation performance.

In the present work, a set of static vanes are employed as the swirling flow generator in the supersonic separator for gas purification application. The computational fluid dynamics modeling is developed to optimize the vane structures. The numerical results show that the swirling flow is strengthened in the diverging part of the Laval nozzle due to the decreasing radius of the inner body along the flow direction. The expansion characteristic and swirling separation performance are opposing for the supersonic separator. It means that strengthening the swirling flow is bound to weaken expansion effect, and vice versa. The swirl angle, height and number of the static vane are optimized using the numerical model taking into consideration the balance between the expansion characteristic and swirling separation performance. The optimization results indicate that 45°-60° swirl angle, 0.125-0.3 dimensionless height and 8-16 vanes are reasonable for gas purification using the supersonic separator.