Impellers can be classified into open, semi-open, and closed types. Open impellers lack shrouds on either side of the blades; they feature a simple structure and are suitable for handling media containing impurities or particles. Semi-open impellers have a shroud on one side, offering advantages in terms of wear resistance and transport capacity. Closed impellers feature shrouds on both sides of the blades, minimizing flow disturbance and typically delivering higher operating efficiency.
Impellers can also be categorized by blade configuration: forward-curved, backward-curved, and radial. Forward-curved impellers are characterized by high flow rates and are often used in equipment requiring large air volumes. Backward-curved impellers offer high efficiency and stable operation, making them widely used in fans and similar equipment. Radial impellers direct airflow primarily along the radial direction and are noted for their compact structure and distinct pressure characteristics.
Impellers are also classified by application, such as those for fans, water pumps, vacuum pumps, and other specialized equipment. Requirements regarding material, dimensions, rotational speed, and structure vary depending on the equipment. For instance, water pump impellers are primarily designed for liquid transport, whereas impellers in fans and vacuum equipment handle gas flow; therefore, design choices must account for the specific working medium and operating conditions.
Impeller classification is not mutually exclusive; a single impeller can be categorized simultaneously based on structure, blade configuration, and intended use. Selecting an impeller requires a comprehensive assessment of factors such as flow rate, pressure, rotational speed, medium characteristics, and the equipment's operating environment. Only by selecting an impeller structure that matches the equipment's operating conditions can stable performance be ensured while minimizing energy loss and future maintenance costs.
