Dynamic length research on the pulsating mixing of rotary pressure exchanger

The rotary pressure exchanger has been simulated by a two-dimension unsteady numerical model. The effects of inlet velocity, Strouhal number and pulsating amplitude on the motion of vortex and mixing characteristic in the duct have been studied. The results show that the forming of mixing zone is mostly caused by the periodic vortex shedding. The vortex strength is stronger, the mixing is evident. The bigger Strouhal number and the small pulsating amplitude increase the vortex strength, while the rising of the Strouhal number enlarges the size effect, and the mixing is little influenced. There is an optimal Strouhal number for a constant rotor. Moreover, the larger the pulsating amplitude is, the more stability the mixing zone will be, so the optimal Strouhal number will decline.