Research Of Automotive Windshield Defrosting And Defogging Performance

With the further development of automotive industry,the demands on vehicle safety and comfort become higher and higher.As the enforcement of active safety standards,defrosting and defogging performance of the vehicle windshield is getting more and more attention from researchers.Frost and fog often form on glass,in the autumn,winter and rainy days.Frost and fog attached on the automotive glass is not only related to the comfort of passengers,but also greatly affect the driver's field of vision,result in serious security risk.Therefore,the research on automobile glass defrosting and defogging performance has a very important significance.Currently,the most common method to defrost and defog is to blown hot air to vehicle windshield.Heat and mass transfer take place among air flow,glass and frost.A good defrost and defog system should ensure that the driver could get a clear vision quickly.Viewing area divided reasonable is the premise of defrosting performance.Air flow parameters will also directly affect the defrosting and defogging result.There is a need for further study.In this paper,the windshield defrosting and defogging performance has been studied.Utilizing the method of Computational Fluid Dynamics,the defrosting and defogging Transient processes are calculated.The numerical optimization algorithm is introduced to optimize the defroster and defogging air duct.To solve the problem of defrosting slowly at the key area of the driver's field of vision,proposed a new scheme.Combined with dynamic mesh,numerical simulation is applied to verify its feasibility.The results have some guiding significance for the design and development of defrosting defogging system.The main contents of this paper are as follows:First,establish a mathematical model of vehicle windshield defrost and defogging,Using CFD software to calculate defrosting and defogging process,get the time required to defrost and defogging.And analyzed frost and fog's phase changing with time in different air supply conditions and environmental conditions,obtained the influence of different factors on defrosting and defogging performance.Provide the basis for later research.Then,based on the former studies,the defroster and defogging duct system is optimized.For the blindness and other problems existed in traditional method of air duct improvement,the numerical optimization algorithm is applied to the improvement of defroster duct.After the optimization,air flow distribution on the windshield surface is much more uniform,defrosting and defogging effect has been significantly improved.At last,to solve the problem of defrosting slowly at the key area of the driver's field of vision,the critical area of view is subdivided.Besides,propose a new method for the windshield defroster:designing guide vanes at defrost outlets,the direction of the defroster air flow could change over time.First remove the frost and fog located at critical vision area.Then,the guide vanes return to their original position,other locations' frost layer is removed,a rapid clear vision of the driver is achieved.