The theoretical maximum wind energy utilization coefficient Cp of wind turbines is 0.593. For actual wind turbines, the greater the Cp, the higher the efficiency of the wind turbine.
The aerodynamic theory of wind turbines was first established by Betz of Germany in 1926. Baez assumed that the wind turbine rotor is ideal, that is, there is no hub, there are infinite blades, and there is no resistance when the airflow passes through the rotor. In addition, it is assumed that the airflow is uniform through the entire rotor, and the speed before and after passing through the rotor is axial. In this ideal state, the theoretical maximum efficiency of the wind turbine is Cp=0.593. This shows that the energy obtained by the wind turbine from the natural wind is limited, and part of its power loss can be explained as the rotational kinetic energy left in the wake. Therefore, the actual wind energy utilization coefficient of wind turbine Cp<0.593.
The actual useful power output of the wind turbine is:
Ps=1/2pSV3Cp
A front end as big as an electric locomotive has very high wind resistance. Oh, why not install a wind turbine on the front of the car to generate electricity and recover energy?
It is easier to use a ready-made motor. How did your teacher test it, whether to use natural wind or a fan to start the generator? It's hard to tell when it comes to natural wind. The wind must be strong enough to start the generator. The stronger the wind, the faster the motor spins and the more electricity it generates. The same is true for motors and blades. But the proportions must be appropriate, not a big motor with a small maple leaf. The blades can be those of a fan, and the motor must be one with magnets. Do the experiment slowly. When the wind speed and light bulb remain unchanged, the brighter the light, the higher the voltage.
There are two types of wind at the front of the car:
One is the wind generated by its own kinetic energy (relative wind). Where does this energy come from? It is converted into electricity by itself. Do you want to convert it into electricity again? Isn't it a waste of energy to go around like this?
The second is the natural wind from the outside, which can be divided into three types: 1. Wind from behind; 2. Wind from the side; 3. Wind from the front.
1 can be used; 2 can also be used; 3 may be used, but it is estimated that the available power is not very high. Think about it, how much power can such a large wind turbine generate on the front of a car?
The most important thing is that the first wind is the main wind for the vehicle. The second wind can be almost ignored and is of no use at all.
So, in order not to mess around and waste energy, in reality no one will install a wind turbine on the car.