低風阻車輛外型設計方法

Abstract

空氣阻力耗能在車輛高速行駛下佔了絕大多數的比重，本研究探討車輛外型改變對於空氣阻力的影響，利用CFD軟體的輔助，藉由分析太陽能車以及一般小客車外型的混合動力車外型的過程，提出降低車輛空氣阻力的方法原則。 根據分析歸納出的結果，減緩流場性質改變梯度可以大幅減少行車的空氣阻力，調整太陽能車零升力可以有效減少誘導阻力的產生，引導氣流空過車身亦可以降低空阻耗能。 掌握這些設計原則本研究所設計出的太陽能車擁有極佳的氣動力學表現，CdA值僅0.07，並且參加2005年WSC以優越的性能贏得第五名。混合動力車的外型改善也使Cd值減為0.244，較一般車輛有更低得空氣阻力係數。

The air resistance has consumed the most proportion of energy when the vehicles run on high speed. This research will try to find out the influence of car shape on the air resistance. By analysing the shape of solar car hybrid car with CFD software, put forward the principles of reducing vehicle air resistance. According to the analysis, there are some ways to reduce vehicle air resistance. To ease the speed change of air when it flows over the car will reduce the air resistance. Zero lift will reduce the induced drag that resists the solar car. To guide the air flows over the car shape will get the low air resistance. By using these principles we design the great shape of solar car which CdA has only 0.07. We get 5th in WSC2005. And our hybrid car also has low air resistance. The CdA is 0.244.