Collaborative Optimization Design Of Aerodynamic Noise And Air Output In Automobile Air-conditioning HVAC System

With the increasing improvement of people’s living standards and the increasing shortage of energy resources,electric vehicles have attracted more and more attention.The cabin comfort of electric vehicles is mainly affected by noise.The vibration and noise caused by excitation sources such as engines no longer exist in electric vehicles.Aerodynamic noise has become the main factor affecting cabin comfort.Reducing the aerodynamic noise in the vehicle has become a major factor.The research direction of major car companies and universities.The aerodynamic noise in the cabin mainly comes from the HVAC system of the air conditioner.When there is a greater demand for the air output of the air conditioner,it will inevitably increase its aerodynamic noise.It is of great significance to improve the air output and aerodynamic noise characteristics of the HVAC system.Following this idea,this paper takes the HVAC system of a micro-electric vehicle as the research object,adopts the method of numerical simulation,analyzes the flow field by monitoring the air output of the air outlet and the far-field noise,and finally constructs the parameters of the centrifugal fan of the HVAC system The multi-objective and multidisciplinary collaborative optimization strategy finds the optimal design of air output and noise balance.The main research contents of this paper are as follows:Perform geometric repair and mesh division on the HVAC digital model,and verify the grid independence.Complete the steady-state and transient numerical calculations,analyze the flow field and sound field of the calculation results,and analyze that the centrifugal fan components in the HVAC system have a greater impact on the overall noise level.For multiple sets of parameters of the centrifugal fan,the sensitivity analysis method based on orthogonal experiment design is used to distinguish the correlation of each variable with respect to the air volume and noise discipline.It is concluded that the relevant variables are the inner diameter of the impeller and the inlet angle under the single discipline for the air volume.And the width of the outlet;in a single subject for noise,the relevant variables are the inner diameter of the impeller,the inlet angle,the width of the outlet,and the volute tongue clearance.The optimal Latin hypercube sampling method is used to select a certain number of sample points within the variable range,and the digital model corresponding to the sample points is constructed by using the grid deformation technology and numerical simulation is performed to obtain the specific values of the air volume and noise level of each sample.Based on the Kriging approximate model,the response relationship between variables on the air output and noise is constructed,and the fitting accuracy of the approximate model is verified by the cross-error verification method.Finally,the MIGA algorithm is used to optimize the response surface,and the maximum and minimum air volume within the variable range are found to be 181.95m3/h and 125.05m3/h,and the maximum and minimum noise are 122.35 dB and 112.26 dB.According to the single-objective optimization result,a mathematical model of collaborative optimization strategy is constructed,and a framework of collaborative optimization strategy with high air volume and low noise is built.Three different weight optimizations are set,and a more balanced group is selected as the final optimization result.The variable parameters of the optimization result are deformed again and numerical simulation verification is completed.The air output of the optimization result is 170.33m3/h,which is 13% higher than the original model 150.79m3/h,and the sound pressure level of the far-field monitoring point 1 is level.Compared with the original model,67.71 dB decreased by 1.59 dB,and the sound pressure level of monitoring point 2 was 68.55 dB decreased by 1.75 dB compared with the original model.Finally,the following conclusions are obtained through the simulation and optimization analysis of the automobile HVAC system:(1)The main noise source of the HVAV system comes from its internal centrifugal fan and nearby areas,especially at low and medium frequencies.The main noise of the HVAC system comes from the rotating noise of its fan.The turbulent noise of air flow is broadband noise,and the noise covers the whole frequency band.(2)Among the four parameters of centrifugal fan inlet angle,inner diameter,outlet width,and volute tongue gap,the inlet angle,the inner diameter of the impeller,and the outlet width have a strong correlation with the air output,and the outlet width is the main influencing factor;the inlet angle and the inner diameter of the impeller,The exit width and the volute tongue gap have a strong correlation with aerodynamic noise.(3)The results of the collaborative optimization strategy show that the method is feasible when applied to the multi-disciplinary and multi-objective optimization problem of HVAC system optimization.