Analysis And Collaborative Optimization Of Aerodynamic Noise And Resistance Of Rearview Mirror Of A Vehicle

At present,energy conservation and emission reduction have become one of the key concerns of the automobile industry.The direct way to improve fuel economy while satisfying the power performance is to reduce the driving resistance of the automobile.At the same time,people’s pursuit of a better life requires cars to have good driving comfort and good isolation.With the increase of vehicle speed,aerodynamic factors have become external factors that cannot be ignored when the vehicle is running.Aerodynamic resistance and aerodynamic noise of the vehicle have become one of the key factors affecting the fuel economy and driving comfort of the vehicle.Reducing aerodynamic drag and aerodynamic noise when the car speeding is the key to improve fuel economy and driving comfort,reduce the aerodynamic drag of the vehicle and the aerodynamic noise and involves multidisciplinary optimization of the related approaches,and a multidisciplinary approach in the collaborative optimization algorithm can well solve the resistance and noise coupling problem.This paper is based on the real vehicle model of an SUV,whose rearview mirror is the specific object of study.From the perspective of aerodynamics,the research is carried out with low resistance and low noise as the optimization objective.Aerodynamic drag and aerodynamic noise can be divided into two sub disciplines,based on the original model of flow field analysis,which find out the rearview mirror will affect the aerodynamic drag and aerodynamic noise of the variable,the variable for optimization analysis,the introduction of the collaborative optimization algorithm,aerodynamic noise and aerodynamic drag,respectively,by the single optimal results,set up the coordination optimization model of low resistance,low noise,and complete the final results optimization and analysis.The specific research contents are as follows:The calculation domain of the model was established,the grid was initially divided,and the independence of the grid was verified.The grid in the rearview mirror was encrypted and multiple grid encryption areas were set.This area,the influence of the left window of the side rearview mirror airflow set up eight aerodynamic noise monitoring,according to the related engineering experience,the calculation of steady state and transient aerodynamic analysis was carried out on the calculation results,it is concluded that the original rearview mirror modelling can cause larger turbulent kinetic energy loss in the rear,affect the back of the flow field,and generate strong aerodynamic noise.Based on the analysis of the flow field of the model,it is found that the reason of the large aerodynamic resistance and aerodynamic noise in the rearview mirror of this model may be the unreasonable,included the Angle between the rearview mirror and the body,and the unreasonable distance between the rearview mirror and the body.According to the simulation results of the original model analysis to the rearview mirror as opposed to a body’s Angle,the rearview mirror body distance as the variable of optimization design,without changing the car overall modelling style and in violation of the relevant laws and regulations on the basis of roads,to determine the variable scope of two variables,and by the Latin hypercube sampling method in which the variable range select 20 groups of samples.Using grid deformation technology,the deformation strategy of first rotating the Angle and then shifting distance of the original model was optimized and simulated according to the samples,and the aerodynamic resistance optimal group and aerodynamic noise optimal group were compared and analyzed with the original model respectively.The kriging approximate model was used to construct the response surface,and error analysis was conducted based on the determination coefficient R^2.The resistance value and the sample point of one of the noise monitoring points that met the accuracy were determined and used for the subsequent optimization calculation.The multiisland genetic algorithm was used to independently optimize the resistance and aerodynamic noise values,and the minimum maximum resistance of the single-side rearview mirror was 5.75 n and 12.70 n,respectively,and the minimum and maximum aerodynamic noise values of the monitoring point were 113.26 db and 126.29 db,respectively.According to the single target optimization result of the genetic algorithm,the mathematical expression and the basic process of collaborative optimization are established,and the collaborative optimization platform with low resistance and low noise is built.Three different optimization weights were set,and one group was selected from the optimization results as the final optimization results,and error analysis was conducted.The final optimization result is: the final optimization value of the resistance value is 7.27 n,and the result is 2.43 n lower than the original model,a decrease of 25.05%,and the error with the predicted value is 4.34%.The final optimized value of the sound pressure level was 113.93 dB,which was 8.48 dB lower than the original model,a decrease of 6.93 percent,and the error with the predicted value was 0.43 percent.Through this study,it is found that on this model,appropriately increasing the rearward angle of the rearview mirror without affecting the field of view,and appropriately increasing the distance between the rearview mirror and the body can effectively reduce aerodynamic noise and aerodynamic drag Value size.And provide a certain reference for the shape and layout of the rearview mirror when the car is developed.