Aerodynamic Drag Reduction And Optimization Of Mira Model Based On Plasma

Due to the rapid development of the domestic economy,the speed of automobiles on highways generally exceeds 100km/h.In this environment,the energy crisis has become a problem that must be paid attention to in the development of science and technology,and highways have the greatest impact on automobile fuel economy.One of the factors is the aerodynamic drag coefficient.Based on this,this paper uses the standard Mira model as the research object to study the mechanism of plasma active aerodynamic drag reduction.Based on the analysis of the flow field,it explores the effect of plasma by applying plasma with different excitation voltages at the gas flow separation.The role and effect of pneumatic rent reduction,and the use of intelligent optimization algorithms to find the best voltage applied to the plasma at each position.The specific research content of this article is divided into the following five parts:1.Carry out CFD simulation of plasma,use a phenomenological model proposed by Shyy et al.to directly set the volume force of the plasma,and use it as a momentum source term into the aerodynamic control equation for calculation.Simulate the physiology model and verify the accuracy of the simulation results.2.Perform CFD simulation on the standard Mira model,chamfer the sharp edges on the basis of fully retaining the details,and establish a 1/4 scaled Mira model at the same time,and complete the grid division of the flow field and the simulation calculation of the basic model.3.Analyze the flow field characteristics of the calculation results of the basic Mira model.Through the analysis results,find the specific position where the plasma is applied,and study the influence of plasma at different positions and different voltages on aerodynamic drag,and at the same time under different wind speeds.Study the effect of plasma on the aerodynamic characteristics of Mira model.4.apply plasma to the Mira model in a combination of multiple positions,and according to the analysis results,find the interaction effect between each position,and determine the design variables and design goals of the experimental design.After determining the variable range,use the optimal Latin hypercube to select sample points,fit all sample points and calculation results to the Kriging response surface model,and finally analyze the accuracy of the approximate model based on the crossover error and the coefficient of determination R-square,and The multi-island genetic algorithm is used to search for the voltage at each position when the aerodynamic resistance is minimum.5.By comparing the results before and after optimization,and performing error verification and comparative analysis,the error is only 0.04%.At the same time,data mining is performed on the sample points to explore the positions and laws that have the greatest influence on the aerodynamic drag coefficient among the four positions A,B,C,and D.Finally,through data mining of sample points and corresponding results,and comparative analysis of optimization results,the following conclusions are drawn:(1)The aerodynamic drag coefficient of the original model is 0.2969,and the aerodynamic drag coefficient of the model after optimizing the applied voltage at each position is 0.2802,which reduces the resistance by 5.62%.(2)Among the four variables in this study,the aerodynamic drag coefficient is the most sensitive to the excitation voltage applied at A,with an impact level of 57%,followed by the excitation voltage applied at B,with an impact level of 32%.(3)When plasma is applied to each position separately,the two positions A and D have a drag reduction effect when applying a reduced voltage,and as the voltage increases,the effect will gradually decrease,and continuing to increase the voltage will even increase the resistance..The excitation voltage applied at C is not sensitive to the aerodynamic drag coefficient,and the excitation voltage applied at B will increase the aerodynamic drag coefficient.(4)As the excitation voltage of the plasma exciter gradually increases,its control effect on the fluid will become stronger and stronger,but the pneumatic drag reduction effect and the intensity of the excitation voltage are not completely linear,and there is a relationship between various positions interaction.