Research On The Synergetic Characteristics Of Metal-based Particles And Microwave Discharge Plasma

With the continuous expansion of the working height boundary of the air-breathing combined power flight vehicle,the speed range of the flight vehicle gradually crosses from subsonic speed to hypersonic speed.The large-span aerodynamic parameters in extreme environments will cause the engine to deviate from normal operating conditions,resulting in lower combustion performance and lower propulsion power,which poses a technical challenge to the stable operation of the engine in a wide range of working conditions.Combining the principle of microwave-assisted combustion,the principle of synergy between metal-based particles and microwave and the operation law of the combined engine,a coordinated combustion regulation with local energy enhancement is proposed,which provides a referenceable technical approach for ensuring the normal and stable operation of the engine under wide-range operation.This paper is oriented to the technical requirements for the regulation of the combustion heat release area in the engine combustion chamber.From the perspective of exploring the influence of various factors on the microwave action part of the synergy and the microwave action process,simulation and experimental research on the synergistic characteristics of metal-based particles and microwave discharge plasma are carried out:Firstly,through the theoretical analysis of electromagnetic and combustion,the synergistic effect is divided into two ways:heating metal based particles by microwave to promote the combustion of multi-point area,electric field distortion caused by metal based particles to promote the formation of microwave discharge plasma on the surface of metal base to improve the combustion efficiency,The experimental platform of synergy characteristics was designed and built.Secondly,the simulation was carried out for the main factors of the synergistic effect between metal based particles and microwave discharge plasma,and the simulation model of the structure device was established.The results show that the structure can provide enough background field strength for microwave dielectric absorption.The main influencing factors are selected through the results,and the phenomenon of selective absorption of particle size to microwave excitation with different frequencies is revealed.Thirdly,facing the instability of particle flow in the real aerodynamic environment,the simulation of variable parameters and variable particle distribution is carried out,and different random distribution models of particles are established.The results show that the flow changes have some influence on the regional field strength.At the same time,the simulation results of variable microwave frequency under the particle motion model verify again that the particle size has selective absorption for different frequencies of microwave excitation,and the highest field strength of the best matching combination is 650 kV/m.Then,the particles of different sizes are classified into three categories according to the simulated field strength distribution:low field strength size;High field strength size;Frequency selection size to provide reference for the parameter selection of particle size in subsequent experiments.Finally,experiments on the dielectric absorption properties of microwave energy and the variable parameter properties of synergistic effect were carried out.The results show that the power of microwave excitation and the type of atmospheric gas have no effect on the overall change trend of synergistic effect.Compared with Al₂O₃ and SiC,Fe₃O₄ has superiority in microwave energy absorption in terms of metal-based particles.From the results of particle size and frequency matching,the heating effect of the optimal matching is 574%higher than that of the worst matching,and the net power absorption intensity is increased by 45.8%in the experiment of discharge characteristics,and the discharge brightness of the synergistic effect is also greatly increased,and through the analysis of the existing data,two groups of superiority matching combinations are given:70?m-2475 MHz;40?m-2425 MHz.The two sets of advantage matching can correspond to the simulation results.Therefore,it is believed that the most critical variable for synergy is the degree of matching between particle size and microwave excitation frequency,which provides a data reference for the formulation of combustion-supporting strategies and subsequent research.