A common radiator size for a V8 engine is around 20"" by 17"". (See Figure 4) To properly cover this area the fan must have a diameter of 18"" to 19"". The design that I will discuss will be for a 18"" diameter fan with a 4"" diameter hub. (See Figure 1) Therefore each blade will be 7"" long.
Design Requirements.
There are many factors that must be considered when designing a cooling fan. The fan will experience many different situations and must be able to withstand them and still function. A list of requirements that will be considered in this report is listed below:.
1. Temperature changes - the fan must be able to withstand temperatures of 300 F to below freezing.
2. Chemical resistance - the fan must be able to withstand any of the vehicle fluids, cleaners, paint, and road salt.
3. Weathering - the fan must be able to withstand sunlight, ozone, heat cycling, abrasions, and storage conditions.
4. Efficiency - the fan must be able to produce enough air to cool the radiator, while consuming the least amount of power from the engine.
5. Centrifugal forces - the rotation of the fan due to the engine will cause a high centrifugal force on the fan. The maximum rpm of the fan will be 10,000 rpm.
6. Bending forces - when the fan accelerates quickly there will be a bending force on the fan blades due to friction with the air.
7. Vibrations - the engine it self vibrates when it runs. There are other vibrations due to the road surface and the suspension of the vehicle.
8. Manufacturing ease - the fan must be able to be manufactured easily.
9. Cost - the fan needs to be economical to the manufacturer and the consumer.
10. Aesthetics - because this is going to be a product that a consumer will buy, it needs to be aesthetically pleasing to the consumer.
Material Analysis.
There is a huge range of materials that can be selected for this type of situation. The five materials that best fit the design requirements are listed below:.