Research On Theoretical Model Design And Performance Optimization Of Air Ejector

Nuclear power generation is the most widely used form of new energy applications.The safety problem of nuclear power plants has always been the focus of attention.The peripheral air ejectors of the nuclear power plant are installed near the main control room.When a nuclear power plant leaks,the air ejector draws the radioactive gas in the main control room,and then it is filtered and purified to the main control room for the normal operation of the equipment and human breathing.The air ejector plays a key role in it.The ejector has the characteristics of simple geometry structure,no internal moving parts,reliable operation and low cost,but it is very limited in practical applications because the ejection coefficient and work efficiency of the ejector are relatively low.Therefore,how to improve the ejection coefficient of ejectors and design the structure of ejectors reasonably are the key to promote the application and development of ejectors.In order to meet the engineering requirements,a combination of the theoretical analysis of the specific technical requirements and experimental verification of the prototype supporting equipment was developed.A nuclear ejector with a large ejector coefficient and high back pressure was developed.A series of studies were conducted in this paper:(1)On the basis of the constant pressure mixing theory,the one-dimensional mathematical model of the ejector is designed and calculated by the gas dynamic function method.The expression of ejector's ejection coefficient and the expression of some structural parameters of the ejector are deduced.(2)According to the requirements of the nuclear power plant,a 1:1 designed and and built experimental bench,and selection of matching gas supply devices,pipeline valves,instrumentation and control equipment,etc.After the construction of the experimental system was completed,strength check and withstand pressure tests were conducted.The experimental data was used to calculate the ejection coefficient of the air ejector and analyze the air ejector performance and efficiency.(3)Apply Solid Works software to create a three-dimensional model of the air ejector and introduce it into Flow Simulation for three-dimensional numerical simulation.Under certain operating conditions,the distribution of velocity fields and pressure fields inside the air ejector was obtained and analyzed.At the same time,the ejection coefficient of the ejector was calculated by changing the state parameters ofthe fluid(such as the pressure of the fluid),the geometric parameters of the air ejector(such as the nozzle distance and the shape of the nozzle throat)and connection method,and the influence of the parameters on the performance of the air ejector is analyzed,and then the results are compared with the results of the experiment and a consistent conclusion was reached.