Background and Identification
A fan is a machine designed for producing airflow, often for cooling purposes. A fan includes a rotating set of vanes or blades that act on the air, causing movement. The fan’s runner, rotor, or impeller includes the hub and blades. Some fans are contained within some form of housing or case. Ceiling fans, on the other hand, typically do not include a case.
A case or housing is designed to direct the airflow or increase safety. The housing prevents objects like hands from contacting the fan blades. Most household fans are powered by electric motors. Some fans use other sources of power like hydraulic motors, internal combustion engines, and hand cranks.
Fans produce high-volume air flows with low pressure. In contrast, compressors produce low-volume flows with high pressure. Household fans are typically designed for climate control and personal comfort. Many fan blades rotate when exposed to air streams. Wind turbines and anemometers are designed similarly to fans. Vehicle engine cooling systems and machinery cooling systems also include fans.
Although fans are designed to cool people, they do not actually cool air. Rather, fans increase the evaporation rate of sweat, which naturally cools the body. Fans can be ineffective at cooling a person’s body if the ambient air contains high levels of humidity and is near body temperature.
- Axial-flow fans
- Centrifugal fan
- Crossflow fan