The effect of variable motive pressures on the performance and shock waves in a supersonic steam ejector with non-equilibrium condensing

Complex flow phenomena and performance are not fully understood in supersonic steam ejectors as the neglect of the non-equilibrium condensation in many simulation studies. In this paper, a non-equilibrium condensation model including real physical properties was combined with the SST k-omega turbulence model to investigate the effects of variable motive pressures on the shock waves, non-equilibrium condensation, and ejector performance. The essential connection between the performance and shock waves was revealed from the mechanism perspective. The results show that when the shock wave intensity is the lowest and the shock wave number is the least whereas the second choking forms, the motive pressure is optimal. The closer the shock wave is to the second choking starting position near the diffuser entrance, the closer the discharge pressure is to the critical one. When the motive pressure increases, a dramatic increase in velocity dominates the increase in the mass flow rate of suction steam in the single choking mode; the over-expanded primary shock train region significantly squeezes the suction steam flow region and dominates the decrease in the mass flow rate of suction steam in the double choking mode; the intensity of the non-equilibrium condensing and shock waves increases, the pseudo-shock region expands, and the condensation shock wave position moves upstream by 1.2% while aerodynamic shock waves move downstream by 25.9%.

Automated summary

This paper investigates the effects of variable motive pressures on the shock waves, non-equilibrium condensation, and ejector performance in supersonic steam ejectors. The results reveal the essential connection between the performance and shock waves. It is found that the motive pressure is optimal when the shock wave intensity is the lowest and the shock wave number is the least, and the position of the condensation shock wave moves upstream by 1.2%.