Co-optimized Design Of Vehicle Aerodynamic Characteristics And Radiator Water Temperature Based On Isight Software

As an indispensable means of transportation in people’s daily life,the safety,comfort and fuel economy are important criteria used to determine the performance of the car.During car driving,The relative resistance between the car and the air and the heat dissipation in the cabin will affect the safety,comfort and economics of the car.But at the same time,there is a check and balance relationship between its various performances.At present,there are relatively few studies at home and abroad that take into account the aerodynamic characteristics of the car and the heat dissipation characteristics of the radiator in the cabin.Therefore,this article takes this as the focus of research.Based on the multi-objective optimization design platform,the aerodynamic characteristics of the car during the driving process and the heat dissipation characteristics of the radiator in the cabin are collaboratively optimized and analyzed to meet the performance indicators of the car.The main research contents of this article are as follows:(1)First,the K-Epsilon solution equation and Reynolds-Averaged Navier-Stokes equation can be taken in the three-dimensional CFD simulation software,Starccm,as the vehicle flow field solution equation.And then the cutting body grid is used to discrete the simulation calculation solution area.At the same time,the inlet boundary of the wind tunnel is set as the speed inlet,the outlet boundary is set as the pressure outlet,the side and top of the wind tunnel are considered as the sliding wall surface,and the car and the ground are all set as non-slipping wall surfaces.The accuracy and reliability of the numerical simulation platform built are verified by comparing the simulation values of the flow field with the experimental values of the wind tunnel.Based on solving the RANS equation,the solution of the vehicle flow field is obtained,and then the aerodynamic drag coefficient is used as the Cost function to solve the gradient of the vehicle flow field by using the Adjoint solution equation.Then the sensitivity distribution cloud map of the influence law of the vehicle body structure on the aerodynamic drag coefficient is obtained.Analysis of the cloud image can select the body structure that has a greater impact on the aerodynamic drag coefficient.(2)Based on the KULI one-dimensional software,the cooling system module is simulated and analyzed.During the analysis,the condenser outlet temperature and radiator inlet air volume are extracted by the three-dimensional CFD simulation analysis,and use it as the boundary input condition to create a porous media model to simulate the cooling air heat transfer Pressure loss after component.The reliability of the model is verified by comparing the radiator water temperature obtained from the simulation model with the experimental value of the thermal analysis of the heat sink.(3)The Free-Form Deformation technology can be used to parametrical the aerodynamic sensitive areas and cooling system modules: In this paper,a block control body is created based on the deformation software Sculptor,and then the area to be deformed is embedded in the block control body,and the position of the control node is parameterized to achieve the mesh deformation of the target area.The abovementioned mesh deformation technology can ensure that the deformed mesh has higher quality and smoother geometry.(4)Based on the multi-objective optimization platform to achieve joint simulation of multiple software:Design variables are sampled within their design space,and then the DOE test design is performed on these sample points,and a combined approximate model is built on the basis of the DOE test design results,and then the global optimization algorithm is used to find the optimal solution.Finally,the predicted value of the optimal solution obtained by the optimization algorithm is compared with the simulated value to ensure the accuracy of the optimized algorithm.At the same time,the aerodynamic characteristics and heat dissipation characteristics of the model before and after the model are compared and analyzed to verify the applicability and efficiency of the research design in this paper.