The core principle of a ventilation fan is based on the synergistic effect of fluid mechanics and mechanical dynamics. The rotation of the impeller generates centrifugal force or axial thrust, increasing gas pressure and directing it to flow in a specific direction.
The working process of a ventilation fan can be divided into three stages:
Gas Intake Stage: When the impeller rotates at high speed, friction and pressure difference are generated between the blades and the gas, drawing surrounding gas into the central region of the impeller. Axial flow fans guide the gas axially through the tilt angle of the blades, while centrifugal fans diffuse the gas outwards through the centrifugal force generated by rotation.
Energy Transfer Stage: The impeller's kinetic energy is transferred to the gas through the blades, simultaneously increasing its pressure energy (static pressure) and velocity energy (dynamic pressure). Blade design (such as airfoil and radius of curvature) directly affects energy conversion efficiency; modern fans often use backward-curved blades to reduce noise and improve energy efficiency.
Gas Exhaust Stage: After being pressurized, the gas is rectified by a volute (centrifugal) or a deflector (axial flow) and discharged in a predetermined direction. The matching degree between the outlet shape and the blade angle determines the balance between airflow and pressure. For example, louvered air outlets can adjust the airflow direction, suitable for scenarios requiring directional ventilation.
