Analysis Of External Flow Field And Research On Drag Reduction Of Partial Exterior Styling On A 12-Meter Coach

With the development of economy and popularization of high-grade highways,automobiles are getting more and more attention in the transportation process of people.At the same time,the petroleum resources consumed by automobiles and the emission of exhaust gases are also increasing.The 12-meter coach is a kind of automobiles and because of the low operating speed in the past,the coach received less aerodynamic drag and its aerodynamic performance was neglected.But with the development of high-grade roads,the proportion of road transport and the operating speed is increased;the aerodynamic performance began to be noticed.By the method of numerical simulation,the author analyzed the external flow field of a 12-meter coach,and according to the analysis results,some research on drag reduction is carried out to reduce the aerodynamic drag of coach.The main contents of this paper are:(1)Through three engineering software which are UG,HyperMesh and STAR-CCM+,the author established a set of numerical simulation analysis scheme that was suitable for analysis of the external flow field of coach,source and application method of each parameter in the simulation process has been introduced.And the numerical simulation results are compared with the wind tunnel test data to verify the accuracy of the simulation scheme.(2)The front wall modeling is the most direct reflection of the characteristics of the coach,so a comparative analysis of the external flow fields of three 12-meter coaches which are provided with different front wall modeling.After that,the front wall modeling of the 12-meter coach was parameterized,the influence of the single factor change of the front wall modeling on the aerodynamic performance is analyzed in detail;And through the optimization scheme of "design of experiment-approximate model-combination optimization algorithm",the author has obtained the optimal combination scheme of the front wall modeling with respect to the front wall top radius and front wall side radius.(3)By using the control variable method,the body attachment has been modeling on a 12-meter coach,after that,the external flow field characteristics around the tail spoiler,air conditioner,skylight,rearview mirror,and chassis have been analyzed,and specific drag reduction schemes are proposed for the tail spoiler and the chassis attachment which have great influence on wind resistance respectively.(4)Using the tail spoiler drag reduction scheme three to the 12-meter test coach,the sliding test and the constant-speed fuel consumption test show that the coach after the tail spoiler is installed can achieve optimal performance in terms of driving resistance and fuel consumption.Through the analysis of external flow field and research on drag reduction of partial exterior styling on a 12-meter coach,the author put forward relevant design guidelines and drag reduction schemes and build a design and development component library for the aerodynamics suite of coaches in order to guide the coach design and enhance market competitiveness.And the research results have significant influence in reducing fuel consumption and protecting environment.