Abstract: when the vehicle speed increases, its resistance obviously increases as well.
研究表明：車速達到70km/h時，汽車阻力占行駛阻力的壹半。
Research shows that when vehicle speed reaches 70km/h, its resistance takes up half of the driving resistance.
汽車速度過高對汽車的穩定性、安全性也有著很大影響。
The excessive vehicle speed has great influence on the stability and safety of the vehicle.
現階段空氣動力學研究壹般都采用風洞試驗、數值模擬、理論研究。
The current aerodynamics research generally adopts wind tunnel test, numerical simulation and theoretical research.
風洞試驗室運用最為廣泛，但其投資過高、周期長等缺點。
The wind tunnel test is the most commonly used, but it has disadvantages such as too much investment, long cycle and etc.
隨著計算機的發展，數值模擬取得了很大的發展（CFD）。
With the development of computer, the numerical simulation has had huge development (CFD).
CFD是以電子計算機為工具，應用各種離散化的數學方法，對流體力學的各類問題進行數值試驗、計算機模擬和分析研究，以解決各種問題。
CFD uses different mathematical method of discretization by means of computer to test, stimulate, analyze and research various problems of hydromechanics and etc. so as to deal with these problems.
CFD具有試驗周期短、費用低等優點。
CFD has these advantages such as short test cycle, low cost and so on.
目前的模擬是CFD和風洞試驗相結合的方法，互相促進，CFD還不能完全取代風洞試驗。
CFD and wind tunnel test are adopted in current simulation and they mutually promote, but CFD cannot totally replace wind tunnel test.
本文首先對汽車流場發展和研究意義和CFD軟件包做了介紹。
This paper first introduces the development of flow field and CFD software package.
第二章中對CFD的理論基礎進行了講解。
It illustrates the theoretical principle of CFD in the 2nd chapter.
第三章主要說明利用GAMBIT建立汽車模型、網格劃分以及邊界條件的確定。
In the 3rd chapter it mainly explains the utilization of GAMBIT to make car model, the grid generation and the determination of edge condition.
在第四章中說明FLUENT進行模擬的壹般步驟。
The 4th chapter gives out the general procedures of FLUENT simulation.
第五章中對不同的汽車前部後部造型進行模擬對比，了解汽車前後造型設計的基本思路。
In the 5th chapter simulated comparisons are made about the shape of the front and rear part of different vehicles in order to understand the basic idea of their design.
汽車前部發動機蓋應與水平面成壹定斜度，汽車頂部與發動機蓋在同壹曲面上，汽車尾部為魚尾巴形的汽車造型最優。
The front vehicle hood should form a certain slope with the horizontal plane. The vehicle roof and hood should be on the same curved surface. Those vehicles with fishtail-shaped rear part have the optimum shaping.
還對汽車的不同離地距離和不同行駛速度進行了分析對比。
Analysis and comparison is also made in different ground clearances and running speeds of vehicle.
汽車離地距離小，汽車升力增加，氣動阻力減少。
When the vehicle ground clearance decreases, the lift will increases, thus reducing the aerodynamic resistance.
汽車速度增加是周圍空氣速度和阻力將明顯加大。
The increase of vehicle speed obviously increases the ambient air speed and resistance.
合理的確定造型和最優的離地距離對汽車阻力減少影響很大。
The reasonable shape and optimum ground clearance has huge influence on the decrease of vehicle resistance.
-----------------------------------------------------------------------------------------------
Copyright@2010 Lawrence. All rights reserved.