Co-simulation Research On Aerodynamic Noise Of Vehicle Rearview Mirror Based On Flow Field And Acoustic Field

With the rapid development of domestic expressway network,under the circumstance that the speed limit of expressway is generally over 100 km/h,aerodynamic noise has become the main source of vehicle noise,and people have higher and higher requirements for comfort and safety of vehicle.Reducing vehicle aerodynamic noise has become the main research direction of major automobile enterprises and universities.Using numerical simulation method to study vehicle aerodynamic noise can not only reduce costs and improve efficiency,but also clearly understand the causes of aerodynamic noise generated by airflow around the body surface.It can provide scientific basis for reducing automotive aerodynamic noise and improving vehicle performance in the vehicle design stage.In this paper,a self-owned brand sedan is taken as the research object,and the co-simulation method of flow field and sound field is applied to monitor the influence of the rear view mirror on the interior noise by monitoring the noise of the driver's ear.The research content of this paper is divided into the following four parts:The first part,pre-processing the model before calculation.A 1:1 model of a car is established on the basis of retaining useful details,and the flow field grid and sound field grid were completed.The second part,the co-simulation method is used to calculate the coupling between the flow field and the sound field of the original model aerodynamic noise.Firstly,the pulsating pressure and flow field transient information of the 11 monitoring points of the side window of the cab and the sound pressure level at the right ear of the driver are calculated;then the road test is carried out on the real vehicle to measure the sound pressure level at the right ear of the driver;finally,the simulation results and experimental results are compared and verified,and the error value is 4.28%,which determines the feasibility of the co-simulation scheme.The third part,optimized automotive aerodynamic noise using intelligent optimization method.After the post-processing analysis of the numerical results of the vehicle external flow field,the design variables of the following noise optimization are determined.The 21 sample points selected by the optimal Latin hypercube are modeled and the numerical calculation of their flow field is carried out.Then,the response relationship between 11 design variables and aerodynamic noise is constructed by usingKriging approximation model.The best approximation model is optimized by multi-island genetic algorithm,and the design variables are obtained when the vehicle aerodynamic noise is the smallest.The fourth part,Based on the optimization result,the optimized vehicle model is built.The same co-simulation method is used to calculate aerodynamic noise of the optimized vehicle model,so as to verify the error of the optimization result,and comparative analysis.The error is only 4.28 %.Finally,through the mining of the sample data set and the comparative analysis of the optimized results,the following conclusions are obtained:(1)The sound pressure level of the driver in the right ear of the original model is71.29 dB,and the sound pressure level of the model after optimization is 67.23 dB,and the noise is reduced by 5.7%.(2)The horizontal installation position of the support column in the two design variables in this study is the main influencing factor of the vehicle aerodynamic noise.For the model,the influence level of the vertical and horizontal installation position of the support column on the aerodynamic noise of the vehicle is 62.6%,37.4%.(3)The vertical installation position of the support column is negatively correlated with the vehicle's aerodynamic noise,and the horizontal installation position of the support column is positively correlated with the vehicle's aerodynamic noise.(4)The farther the side of the car is from the A-pillar and the rear view mirror,the lower the noise level is,and the airflow state at their location must also be considered.This paper provides a more feasible co-simulation scheme for the numerical calculation of vehicle aerodynamic noise,and forms an effective intelligent optimization process with high engineering application value.