Mechanism Study Of MHD Acceleration And Experimental System Design

MHD technology is a combination of classical fluid mechanics andelectrodynamics of the new technology. The use of plasma for active flow control iswidely used in the aerospace research. Conductive fluid can be used for generatingpower or accelerating in a magnetic field. However, in the process of flight or groundtest, the generation of uniform plasma with a condition of strong magnetic field andthe influence of the MHD and flow field coupling effect is concerned. For theapplications of propulsion system, there are many key technologies.For major infrastructure issues raised above, the paper funded by Li Mingengine plant "×××" project, studies of key technologies for MHD acceleration havebeen carried out. The MHD acceleration system applied to turbine engine ground testhas been designed and set up. Particularity of flow field for MHD channel has beenstudied. An experimental study of atmospheric discharge mechanism under strongelectromagnetic, flow field environment has been launched. Provided technicalsupport for the project. The main contents and conclusions are as follows:1) With turbine engines for the application object, the design of MHD systemparameters has been carried out.There is a critical electric field Ecrfor MHD channel makes the flow smoothlythrough the channels in Mach1without choking. While the air flow with a greaterelectric field than the critical electric field in the channel will be stable in a certainstate of supersonic flow. When the electric field in the channel is less than the criticalelectric field a choking occurs. Three modes of the channel have been given. Theselection of electromagnetic field, load in MHD channel have been analyzed intheory. At the same time the irreversibility of model transformation path has beenverified. Boundary and back pressure resistance properties of MHD channel havebeen found. Analyze of the particularity for MHD channel provides a theoreticalbasis for the design of MHD acceleration system.2) Experimental research for key technologies of MHD systemSecondly, comparing validation experiments of the designed schemes of variousplasma generator have been carried out. The discharge characteristics of nanosecondpulse discharge under atmospheric pressure conditions and the selection ofnanosecond pulse power parameters have been analyzed. The required scheme ofplasma generator for MHD acceleration system has been detrermined. The influenceof the magnetic field, flow and the nanosecond pulse power parameters on the discharge has been studied. Pointed out that the flow makes the breakdown voltageincreases at the same time also transforms the discharge mode from filaments todiffuse. And also found that a certain frequency of nanosecond pulse power canincrease discharge current, but at a certain frequency and inhibit the dischargecurrent in a magnetic field. These specialities lay the foundation in MHDacceleration test. Since the pulse radiation power during the experiment stronginfluence on the electronic components is very serious, experimental results obtainedare not very satisfactory, needs to be improved in the subsequent course of the study.3) Design and implementation of MHD acceleration ground test system.According to the experiment and numerical simulation, MHD system has beendesigned. Two options have been designed for gas generator. And ultimately selectedbased on the use of ignition gas generator turbine engine ignition program. With themixing section, shunt and nozzle, the flow of air reaches flow parameters requiredMHD acceleration system for turbine engine ground test has been designed,including high enthalpy gas generator, plasma generator and validation test system ofdischarge mechanism, electromagnetic field excitation system and implementation ofthe accelerating system. Iprovement program has been poposed, if the effect is notideal.