Car Aerodynamics - Essay Example

First Car Aerodynamics The study of the aerodynamics of road vehicles is called automotive aerodynamics. The primary objectives of this study is to reduce various problems faced by the road vehicles at high speeds due to aerodynamic unsteadiness like reducing wind noise, preventing unwanted lift forces, minimizing noise production and reducing drag, though drag caused by wide wheels is very dominant in most cars. In racing vehicles it is also important to generate forces that cause downward aerodynamics for better stability and traction. The wheel arcs and lights are also shaped to have small surfaces that are integrated to for better aerodynamics. An aerodynamic automobile is designed to streamline the wind, it does not have piercing edges that cross the wind stream above the windshield and have a type of tail, which is called a liftback or Kammback or fastback. Different automotive companies like the Volkswagen, Loremo and Aptera, try to reduce the tail area of their small vehicles like the 1-liter models. They are designed to have a smooth and flat floor for the Venturi effect to be supported and generate the desired downwards-aerodynamic energy. The wind entering the engine cove is used for combustion, passengers and cooling, and then it is re-injected by an outlet under the floor. Air is slowed and pressurized in a diffuser for rear and mid engines, it loses a little pressure while it is passed through the engine cove and is filled in the slipstream. A seal between the high pressure around the gearbox and low pressure area around the wheels is required by these cars. The suspension in these cars is either retracted or streamlined and the engine cove floor is closed. Streamlined shape is given to the roof rails, antenna and door handle. A round fairing as a nose is given to side mirrors. Though racing cars need airflow through the wheel base for break cooling and a lot of air is emitted from the radiator into the wheel bay, it is said to cause increase in drag. “Most aerodynamic design work is actually done initially on a computer, then the design is checked and modified by placing a vehicle with that design in a wind tunnel” (Erjavec 158). Wind tunnel and computer modeling are used to analyze and study automotive aerodynamics. The tunnel is sometimes furnished with a rolling road to achieve most accurate results from a wind tunnel test. The rolling road is a movable floor like the floor of at treadmill and moves at a particular speed as the air flows in. This affects the results by preventing the formation of a boundary layer on the working area floor. Aerodynamic drag is present in all kinds of objects. The density, temperature, and pressure of the fluid, the drag coefficient, and the frontal area of the object affect the force of drag on a particular object. “Drag determines the car’s top speed, and can be as important as the engine power. For road use, drag has a big effect on fuel economy. A streamlined car has low drag, and will get good gas mileage” (Puhn 49). The aerodynamic drag of a car plays a significant role in the car’s capability to accelerate. The ratio of a car’s engine power to the drag of the car’s body is of more value than the car’s power-to-weight ratio, which plays an important role at low speed levels where the drag of a car is not important. If we assume that a car has appropriate gears, it is possible to increase the top speed of a car only by adding power, or by improving the aerodynamics. “The most visually obvious of the car’s aerodynamic features are the front and rear wings affixed onto the car’s chassis. These wings work on a principle similar to that of aircraft wings” (Noble and Hughes 62). The wing of a car is primarily used to produce a downforce on the vehicle. For some cars the angle of attack of the wing is regulated in order to increase the down force present around the rear wheels. However, this also increases the drag of the car. The creation and testing of wing is usually very costly. The application of wings on any drive train type depends on the goal. Adding wings can be useful to any car that can oversteer, which also includes front wheel drive cars. Nowadays, adding wings to cars have became a fashion statement. These wings are generally of no use and usually affect the car’s performance. A spoiler on the other hand is designed to spoil, or reduce the unfavorable movement of air across the body of the moving vehicle. These spoilers are usually mistaken for wings, and people usually call spoilers wings. “Spoilers need to be big enough and mounted at the right angle to help control airflow, and passenger cars generally never go fast enough for aerodynamics, or a spoiler, to make a significance difference” (Martin, Tuschak, and Forde 59). The primary function of the front wings of a vehicle is to create a downward force that can boost the hold of the front tires of a vehicle. Adding the front wing to a car improves the turning capacity in fast corners and totals to about 25 to 30% of the amount of downward force of a car. Generally, open-wheeled cars and Formula 1 racecar conduct constant modifications on the front wing of their cars based on data that is gathered from race to race. This is done to develop less or more downward force in order to suit the specifications of the racecourse. In many cases, the wings of these race cars are designed during the race itself when the vehicle arrives at the pit stop, after gathering information about the wear and tear of the tyres and the feedback from the driver. When the car has a full fuel tank, in car adjustments are also made to maximize the aerodynamic downforce and the top speed of the car. As the car uses more and more fuel, it gets lower to the ground. This causes the car to raise the ride height at its front, which usually creates an understeer. This problem and the related handling issues can be countered, with the help of a front wing that is adjustable from within the car itself. The front wing of a vehicle is designed to work best with clean unobstructed air, which becomes a problem for car engineers. For example, in F1 races the car behind the lead car usually suffers lowered downward force levels. This reduction in the downforce and related drag of the car is good only when it comes to top speed and slip streaming, however in completely unsettles the car when it comes to fast sweeping corners. The front wing is designed as an aero foil that is suspended from the nose cone of a vehicle; it comes with movable flaps that are used as part of the design in order to regulate the setting of the downward force or the angle of attack. The ends of the wings are fixed with plates called end plates that are designed to help force the airflow under or over the wing depending on the requirement. They are also designed to help with the turbulents that are generated due to the front wheels. The design of the front wing of a car is very important as it controls the airflow over the rest of the vehicle, it is also continuously refined in order to produce an edge over the rest of the competition in a given race. “Aerodynamic forces are generally proportional to the square of the air speed, there car aerodynamics become rapidly more important as speed increases. Like darts, aeroplanes, etc., cars can be stabilised by fins and other rear aerodynamic devices” (Miller 21). Reference List -Miller, Joseph. Be Your Own Auto Repair Technician. Global Media: USA, 2007. Print. -Puhn, Fred. How to Make Your Car Handle. HP Books: USA. 1981. Print. -Noble, Jonathan and Hughes, Mark. Formula One Racing for Dummies. Wiley Publishing: England. 2003. Print. -Martin, Mark, Tuschak Beth, and Forde, Mike. NASCAR for Dummies. Wiley Publishing, Inc: USA. 2009. Print. -Erjavec, Jack. Automotive Technology: A systems Approach. Cengage Learning: USA. 2005. Print. Read More