Theory Modeling And Control Research Of Big Vacuum Chamber's Pumping And Recovering

For the operator's safety,the machine's safety and the normal work of the equipment,vacuum simulation experiment is indispensable to an aerospace instrument and aircraft in military aerospace.In this experiment,it is demanded to simulate the pressure changes when the aircraft launch and reverse back in the large container on the ground.Certainly the aircraft may also stay in a certain height for a time in the process of launching and returning.To simulate this processes,we need to pump and recover the large vacuum container.When the aircraft is launching we pump,or we need to recover.In order to achieve this purpose,the computing of pumping and recovering is a must.Existing computing model are some simplified treatments of some equations about vacuum calculation and the results of this model compared with the actual is bigger error.This article adopts the method of numerical calculation to establish a new mathematical computing and controlling model of the large container's pumping and recovering processes.This paper preliminary step by step completes the study of the following:(1)Pipeline pressure distribution of the vacuum system is derived;(2)Equivalent hypothesis method in the processing of valve is proposed;(3)Pumping and recovering mathematics model of three kinds of flow in simple vacuum system without valve is proposed.(4)Pumping and recovering mathematics model of three kinds of flow in simple vacuum system with valve is proposed.(5)Valve opening computing theory model for three kinds of flow pattern with a given pumping and recovering time in simple vacuum system is proposed.The theory is the base of controlling of processes of pumping and recovering.(6)The computing model's feasibility,its scope of application,the remainder of pipe diameter,valve opening effective mediation range and the place of valve on pipeline are analyzed.Results indicate that,the theory models that are proposed in the paper is feasible and the calculation accuracy is better.Analysis shows that viscous flow and viscous-molecular flow are the remainder of pipe diameter but molecular flow not.Analysis also shows that the valve control effect not obvious in viscous-molecular flow and the place of valve on pipeline influence on the processes of pumping and recovering in three kinds of flow.