Consideration of the Basic Factors Affecting Road Vehicle Drag and Their Associated Affects
Consideration of the basic factors affecting road vehicle drag and their associated affects
0718572
School of Engineering, University of Warwick
Coventry, West Midlands, U.K
Abstract: It is possible to improve the aerodynamic efficiency of road vehicles and reap many benefits. Fuel consumption being one of them, this report identifies how basic theoretical and experimental fluid mechanics can work in harmony to allow one to understand the key mechanisms that affect the aerodynamic properties of road vehicles and suggest ways in which to analyse them. From this it is possible to learn and improve upon current design practices to ensure cleaner more fuel efficient, environmentally friendly road vehicles of the future. 1. Introduction
In the 70’s with the emergence of the worldwide oil crisis nations were being urged to adopt energy conservation methods. The United Nations estimate the world’s population is set to reach 8 billion by 2025 based on current rate of growth. The demand on producing energy is placing great stress on our environment. Considering almost every household owns at least 1 car by 2025 there could be 1 billion cars alone on the road requiring fuel of some sort. Therefore it is necessary to produce road vehicles that are fuel efficient. Aerodynamic drag and fuel consumption are linked, simply the poorer the aerodynamic efficiency of your road vehicle the more fuel it needs to consume in order to power it. It is estimated that the aerodynamic drag effects fuel consumption of the average car by some 30% at urban cycles and 75% at highway speeds [1]. Therefore it is of paramount concern for manufacturers to reduce the drag force that affects road vehicles. 2. What is Drag?
Drag is a mechanical force generated by a solid object moving through a fluid. An indication of how good or bad a solid object travels through a fluid is termed the coefficient of drag value, Cd.
Cd=Fd12ρV2A
0718572
School of Engineering, University of Warwick
Coventry, West Midlands, U.K
Abstract: It is possible to improve the aerodynamic efficiency of road vehicles and reap many benefits. Fuel consumption being one of them, this report identifies how basic theoretical and experimental fluid mechanics can work in harmony to allow one to understand the key mechanisms that affect the aerodynamic properties of road vehicles and suggest ways in which to analyse them. From this it is possible to learn and improve upon current design practices to ensure cleaner more fuel efficient, environmentally friendly road vehicles of the future. 1. Introduction
In the 70’s with the emergence of the worldwide oil crisis nations were being urged to adopt energy conservation methods. The United Nations estimate the world’s population is set to reach 8 billion by 2025 based on current rate of growth. The demand on producing energy is placing great stress on our environment. Considering almost every household owns at least 1 car by 2025 there could be 1 billion cars alone on the road requiring fuel of some sort. Therefore it is necessary to produce road vehicles that are fuel efficient. Aerodynamic drag and fuel consumption are linked, simply the poorer the aerodynamic efficiency of your road vehicle the more fuel it needs to consume in order to power it. It is estimated that the aerodynamic drag effects fuel consumption of the average car by some 30% at urban cycles and 75% at highway speeds [1]. Therefore it is of paramount concern for manufacturers to reduce the drag force that affects road vehicles. 2. What is Drag?
Drag is a mechanical force generated by a solid object moving through a fluid. An indication of how good or bad a solid object travels through a fluid is termed the coefficient of drag value, Cd.
Cd=Fd12ρV2A
References: [1] Thevenin, D. & Janiga, G., (2008). CFD-based Optimization for Automotive Aerodynamics., Optimization and Computational Fluid Dynamics. Berlin: Springer., 191-214. [2] Crowe, C. & Elger, D. & Williams, B. & Roberson, J., (2010). Dimensional Analysis and Similitude., Engineering Fluid Mechanics. United States: John Wiley & Sons., 252-254. [3] Morel, T. (1978). Aerodynamic drag of bluff body shapes characteristic of hatch-back cars. SAE Paper 7802670 [4] Ahmed, S.R., Ramm, R., Faltin, G [8] Bettes, W.H., (1982). The Aerodynamic Drag of Road Vehicles — Past, Present, and Future. Engineering and Science. 45:3, 4. [9] Fox, W.R. & McDonald, A.T. & Pritchard, P.J., (2004). Dimensional Analysis and Similitude., Introduction to Fluid Mechanics. 6th ed. United States: John Wiley & Sons. 286-293. [10] Fletcher, C.A.J., (1991) [11] Cardano, D et al., 2008, PIV in the Car Industry: State-of-the-Art and Future Perspectives . Topics in Applied Physics. 112, 363-376.