Separation efficiency theoretical model of swirl-vane separator based on bidirectional vortex

•A bidirectional vortex is established of swirl vane separator.•Improved prediction accuracy of separation efficiency with new method.•The effects of inlet velocity, droplet diameter, swirl vane angle and hub diameter have been discussed. Swirl vane separator is a vital component to separate liquid water from gas to provide high quality steam to turbines in liquid water reactors. The gas rotating flow in the riser of a swirl vane separator is a bidirectional vortex. Its tangential velocity is similar with Rankine vortex. Its axial velocity is bidirectional. The gas bidirectional vortex is solved by constructing a Bragg-Hawthorne equation for the stream function. The gas flow velocity predicted by new method agrees quite well with CFD. The maximum velocity differences in axial direction are 6.2%. Based on this model, the droplet trajectory is obtained and a new separation efficiency model has been developed. The average difference between experiment results and the predicted separation efficiency is reduced from 14.7% to 3.1%. Moreover, parametric analysis using new model has been carried out to discuss the effect of inlet velocity, droplet diameter, swirl vane angle and hub diameter.