CFD Simulation Analysis And Test Verification Of Automobile Front Windshield Defrosting

Parking in the outdoor,front windshield will be coated with a layer of frost when the temperature drops below zero in the north of China in winter,which has a serious impact on ride comfort,and even threaten the safety of driving.Therefore,defrosting performance of automobile has been incorporated into active safety performance standards and enforced both at home and abroad.<Gb11555-2009 performance and test methods of defrosting and defogging systems of automobile windshield > strictly stipulates the defrosting test methods and performance.The design of automobile windscreen defrosting system is an important part of the whole vehicle design,and CFD simulation analysis is usually adopted in the process of design and development.The simulation method is to calculate the melting rate of the frost layer on the windshield surface then check whether it is satisfied with the regulation standard,because the heat and mass transfer changes of the frost layer are involved in the simulation process,the simulation results using transient simulation are more accurate.However,transient simulation takes more computing resources and longer computing cycle.In the market competition is becoming more intense and shorter design cycle of the vehicle,such analysis method is difficult to meet the needs of the development cycle of the vehicle.However,there is always over design or have a large calculation deviation for the method of steady-state analysis of frost thickness which leads to the simulation process,the accuracy of the results insufficient.According to the result of wind speed,flow distribution and wind resistance in the steady-state analysis,and combined with the test data of a number of vehicle models,this study innovatively proposed a set of defrosting air duct design method combining CFD steady-state analysis and engineering design specifications based on the steady-state analysis method,which improved the efficiency of defrosting air duct design efficiency and had certain universality.Finally,the method had been applied to the defrosting duct in a certain vehicle to improve the design,and the defrosting performance test of the whole vehicle was conducted to verify the results,which showed that the method in this study was accurate and reliable,meeting the requirements of engineering design.This method can effectively improve the efficiency of CFD simulation design of vehicle defrost performance.