Calculation Of Vacuum Pumping Process In Space Environment Simulator

Space technology is put forward higher requirements,to the accelerated pace of space exploration.Space environment simulator is main equipment to protect the spacecraft,which including launch,safety operation,the return process,the vacuum environment is an important part in the ground simulation.In order to have a more in-depth understanding of the pumping process,needs more efficient,and to provide a theoretical basis,the vacuum space environment simulator pumping process was studied.A space environment simulator in the pre vacuum stage of the actual pumping process has been found that pump process of the 100Pa?10Pa took longer time,a serious impact on the pre vacuum pumping efficiency.To explore its causes,pressure drop curve and theoretical roots-screw vacuum pump pumping speed curve theory are simulated.By comparing with the actual measured pressure drop curve and the pumping speed curve,the factors that affect the efficiency of the vacuum pumping are analyzed and the corresponding solutions are put forward.A new research method of pre vacuum phase,CFX ANSYS software is put forward,and its feasibility is proved.ZJL-600 gas cooled roots pump is one of the main vacuum system for a space simulator,working independently in the pressure range of latm?40kPa,when the pressure reaches 40kPa-lOkPa,working with slide valve pump,after that as a mechanical booster pump with screw pump together to complete the pumping.In order to study air pumping process better,with a double gas cooled roots pump as the research object,the study on its performance is particularly importantthe,thermodynamic study on pump internal transport of gas.The process is divided into four stages of suction,injection,compression and exhaust,and the characteristics and mechanism of each process are discussed.The application of the knowledge of thermodynamics,the quantitative analysis of each process,obtains the gas volume,quality,pressure,temperature,internal energy,enthalpy,entropy and thermodynamic parameters of the time-dependent equations,ZJL-600 is calculated.Calculation of thermodynamic process for the design and application of double gas cooled roots pump has guiding significance.The cold dark environment equirements of heat sink for the entire space simulator provides a heat sealed,but the heat sink heat sealing and molecular flow required for pumping process of air permeability,which are incompatible.Calculation of the gas flow in the space environment simulator,we must first calculate the transmission probability of the heat sink in the molecular flow.The transmission probability is calculated from the gas permeability of the heat sink,using the TPMC method,the MolFlow+ software is used to calculate the transmission probability of the typical structure heat sink.The influence of key structure parameters on the heat sink transmission probability is discussed.It is proved that the "non complete transmission plane" is used to simulate the air exhaust process instead of the heat sink,which provides the basis for the study of the pumping process of the space environment simulator.In the high vacuum stage,the method of judging the high vacuum state of the space environment simulator is introduced.The transport process of the gas in the simulator is simplified,based on the steady state assumption and the uniform assumption.Based on the simplified model,the surface of the stars,the inner surface of the heat sink,the outer surface of the heat sink,and the inner surface of the tank body were theoretical analysis and simulate.By the theoretical analysis and the surface flow coupling relationship,the gas pressure of each surface is calculated,and the theoretical analysis results are provided to support the theoretical analysis.