| On account of energy source crisis and improvement of motorcars speed, since last century people are paying more and more emphasis on the applying of aerodynamics to automobile work. It was researched early overseas, but recent years the domestic research also has made great progress. This paper analyses the trucks' outer flow field, its flowing circs inside the engine cabin and its scattering heat trait and connected with the subject cooperated with Dongfeng Automobiles Corporation Ltd., which named "the analysis of a Dongfeng D310 lorry's outer flow, the flowing analysis inside the engines and scattering heat character". Furthermore on the basis of analysis and research of lorrys' character of the flow field in this paper introduces the basic theory, the methods of request numerical method, the grid system, the choice of turbulence model and the introduction of CFD software. And according to the analysis result this paper introduces camion's characters of and scattering heat in engine and the character of flowing field all around on which the author puts forward some improvement steps. The content of this paper as follows:1.Because of the improvement of automobiles' speed and the crisis of energy source induct the aerodynamics. Introducing the aerodynamic effect on motorcars' various capability.2.The control equation is three-dimensional uncompressable RANS equation, applies control volume to disperse it in spatial and request its answer iteratively by SIMPLE method. And adopt GAMBIT software to build the structure-unstructure admixture grid, FLUENT software to dispose its data.3.Arithmetic validating by the car's outer flow field numericalsimulation. The validation result shows that the surface pressure distribution adapts to the experimental result appropriately, which validates that the calculation method of this paper is feasible, the pressure distribution, flow characteristics and aerodynamic drag of the camion are obtained. The results have shown with good precision on small grids amount. Finally, the ways to decrease aerodynamic drag are indicated. The calculation result adapts to the distributing rule of great type of freight automobiles, and the calculation of the drag is smaller than the similar vehicle type used in the classical wind tunnel experiment overseas,this is only because the the cargo box of this camion is not included.4.The numerical simulation on the flowing field of engine cabin is in use of inner-outer coupling calculation method .The computing grid of the cabin in engine and the outer flowing field is established. During the course, media theory, porous jump boundary condition were introduced to simulate the radiator's draught condition, meanwhile fan's capability was used in calculating course. The method of calculating the engine cabin's scattering heat character is conversion of air mass and heat flux. On base of the relation of the conversion of flux and heat, and the outcome tested by the research and exploitation center for commercial camion of Dongfeng Automobiles Corporation Ltd. A a dispose on flowing air mass and flowing heat is maded, and the heat carried by radiator is educed. This paper adopts the conversion relation of heat and temperature to dispose the cooling impact. The quantity of heat carried by radiator reflects the decrease of water in it, thus conclude the cooling water temperature falling. This paper uses two types flux of cooling water: 175L/min and 280L/min to educe that the temperature of cooling water inthe mouth of radiators falling 11℃ and 8℃ respectively.5.Connecting with the calculation result of this dissertation, The characters of camion's flowing field and its effect on motorcars is simply analyzed when it is moving.
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