Theoretical Design and Numerical Study of Multistage Ejector Pump

A five-stage ejector pump was designed for high altitude test bed. The pneumatic function method was used to carry out the design. The first two stages have tow ejectors working in parallel and the other three stages have one ejector. Condensers were used between stages to remove water vapor which is chosen as the driving gas. CFD method was used to predict the properties of each stage of ejector. The overall performance of the five-stage ejector pump was obtained by analyzing the properties of each stage of the pump. The results show that with the increase of inlet pressure the mass pumping speed of each stage ejector increases and the ejection coefficient increases, too. The volume pumping speed increases as the inlet pressure increases, and decreases after reaching a certain pressure. The obtained ejector pump met the service requirements, which means that the pneumatic function method is effective in ejector design.