Research On Simulation And Performance Optimization For Electromagnetic Railgun

Electromagnetic railgun (EMRG), as a new concept kinetic energy weaponusing electromagnetic launch technology to accelerate projectile, is an importantarmament having the advantages of high muzzle velocity, long range and easycontrol of energy release and can be widely used in future military fields. Thelauncher works in strict, complicated and dangerous conditions of high voltage,large current and heavy load. So, the simulation and performance optimization ofEMRG is an important research content in development and application stage.Through the deep analysis of the EMRG characteristic, this dissertation focuses onsimulation data analysis, steady current waveform realization, performanceoptimization under the steady current waveform and quick solution of dischargesequence of pulsed power modules before launch. The main researches are given asfollows：(1) The mathematical model of EMRG and its components are established.According to EMRG characteristic and constructional trail, EMRG is divided intothree main components including power, rail and armature-projectile. Consideringthe physics effects of each part during launch, the model of these components areestablished by modular modeling method. According to the interaction among thethree components, the whole EMRG model is established by integrating everycomponent model together as the foundation for the subsequent simulation, analysisand optimization work.(2) Aiming at the non-stationary and multiple stages characteristics of theoutput of electromagnetic railgun, a consistency analysis method for simulation databased on improved grey relational analysis theory is proposed and is proved tosatisfy four grey relational axioms. An improved grey relational grade model forconsistency analysis is constructed in terms of the shape and distances of series.Considering the condition that work process of actual system usually consists ofmultiple stages and work status in every stage has different impact on the finalresults, the comprehensive relational grade is defined and is used to test theconsistency of the whole simulation data. Then, aiming at the need for consistencyanalysis for simulation data in frequency domain, and combining with the characterthat prior knowledge is not required in wavelet multi-scale analysis, non-stationarydata is converted to stationary data by which the consistency analysis is performedin frequency domain based on maximum entropy spectral estimation methodcomprehensively. Finally, a consistency analysis method combing time domain withfrequency domain for simulation data based on D-S evidence theory is proposed by the two kind of consistency analysis results, which can analyze the consistency ofsimulation data. The following example is given to illustrate the effectiveness of themethod.(3) In view of the requirement for stable discharging current during launch, amulti-stages design strategy of discharge sequence (MSDSDS) is proposed.According to the discharging characteristics of the pulsed power modules withdischarge sequence in a certain manner, launch process is divided into multiplestages. In each stage, the deviations between maximum peak value of local currentand the expected value is limited to the minimum value through the dischargesequence design for the purpose of the realization for the steady current. Introducingthe deviations information into influencing updating process of velocity, a particleswarm optimizer with dynamically adjusting inertia weight (DPSO) is proposed forthe discharge sequence design, which increases the efficiency for optimizationprocess in every stage by controlling the velocity of the particle swarm. TheMSDSDS and DPSO is an effective method to the realization of the steady currentduring launch. The following example is given to illustrate the effectiveness of themethod.(4) Aiming at performance optimization of the EMRG under allowed condition,a performance optimization method based on metamodel is proposed. Uniformexperimental design is applied to gain the simulation experiment scheme for theselected design variable. In each scheme, the discharge sequence is designed toobtain the steady current by the MSDSDS and DPSO. Using the data fromsimulation experiment based on uniform experimental scheme, the performancemetamodel is constructed under the condition of steady current. The metamodel withcharacter of simple structure and little computation demand is convenient quickly tosolve the performance optimization problem for EMRG under the condition ofsteady launch. The following example is given to illustrate the effectiveness of themethod.(5) For the fast response of the EMRG in future battlefield, a quick solution ofthe discharge sequence using before launch is proposed. The velocity is classified asmaximal velocity and interval velocity, which is the velocity between the twoadjacent maximal velocities. A table concerning the relationships between maximalvelocity and discharge sequence with various number pulsed power modules, as wellas a metamodel about the interval velocity and the discharge sequence areestablished. According to the expected muzzle velocity, the discharge sequence ofpulsed power modules are quickly obtained using the relationship between muzzlevelocity and discharge sequence of pulsed power modules. The solution can beobtained quickly by this method. And the validity of the method is demonstrated bysimulation. (6) Considerable algorithms, methods, and strategies are required in theinvestigation of EMRG by simulation technology. An integrated electromagneticrailgun simulation system (IEMRGSS) is designed and established for convenientinvestigation of the EMRG. The two modes, alone operation and networkdistribution, can be chosen in terms of different research objectives. Simulationanalysis, optimization, and demonstration for the EMRG can be performed using theIEMRGSS presented in this dissertation. The dissertation will support theinvestigation of EMRG and has comprehensive applicability, which is easy to extendand update to a new version.According to the problems in simulation and performance optimization for theEMRG, a series of relavant algorithms, methods, and strategies are proposed and anintegrated simulation system for the EMRG is developed in this dissertation. Theinvestigation can significantly support analysis, design, operation, anddemonstration of the electromagnetic railgun, and is with important academic andapplied values.