Performance Study On The Rotating Shaft Adjustable Ejector

The static ejector is a kind of device,which can recovere low pressure gas by the jet effect of high pressure gas.There is momentum,heat and mass transfer between the fluids inside the ejector.The structure of the ejector generally includes nozzle,suction section,mixing chamber and diffuser chamber.The structure is simple and effective,and the processing cost is low.It is widely used in chemical production,aircraft industry,aerospace engineering,freshwater purification engineering,nuclear power plant applications and other engineering areas.However,the geometric structure of the traditional static ejector is not adjustable.The equipment can not work normally especially when the design conditions are deviated.So,how to improve the adaptability of ejectors to different conditions and improve the efficiency of ejectors has become the development direction of static ejectors in recent years.The rotating shaft adjustable ejector is designed in this paper.The internal flow field and the regulating performance of the rotating shaft ejector are studied by means of numerical method and experimental analysis.The main research contents are as follows.a.In a certain range,the increase of compression ratio P_M/P_L will not affect the ejection rate of the injector,which is called the choking state of the injector,and the choking state is a stable state of the ejector.Further improvement of P_M/P_L will destroy the choking state of ejector and cause the ejection rate of ejector to decrease rapidly.It is found that the increase of the expansion ratio P_H/P_L can help the injector to enter the choked state,but if the P_H/P_L is too high,it will cause the ejector ejection rate to decrease,and the best working point is found at the critical point when the ejector’s working state enters the choked state.b.It is found that when the ejector is in the non-choked state,the bigger throat opening H_kr of the adjustable ejector can promote the ejector into the choking state.When the ejector is in the choked state,the decrease of H_kr can reduce the mass flow rate of high pressure fluid Q_h,and control the free flow section area of the free flow beam at the outlet of the ejector nozzle,so that the ejector is in the critical point of the choking state and increases the ejection rate of the ejector under the same working condition.c.Compared with the adjustable cone ejector which is common,it is found that the operation parameters have similar characteristics to the ejectors.In terms of regulating performance,it is found that the rotating shaft type adjustable ejector can not only control the high pressure flow Q_h,but also have the ability to adjust the flow section area of the free flow beam and maintain the ratio of the throat to the outlet of the nozzle,which is a big advantage than the adjustable cone ejector which can only adjust the throat area of the jet nozzle.