Axial flow fans have a wide range of applications; they involve airflow moving in the same direction as the shaft of the fan blades, such as in electric fans and outdoor unit fans for air conditioners. They are called "axial flow" because the gas flows parallel to the fan's shaft. Axial flow fans are typically used in situations where high flow rates are required but low pressure is sufficient. They are fixed in place to move air. Axial flow fans are mainly composed of the fan impeller and housing, featuring a simple structure but with high data requirements.