What are the characteristics of the different types of impellers?

There are various types of impellers, commonly centrifugal impellers, axial impellers, mixed flow impellers and rotary impellers, etc., and the following is the introduction of their respective characteristics:

There are various types of impellers, commonly centrifugal impellers, axial impellers, mixed flow impellers and rotary impellers, etc., and the following is the introduction of their respective characteristics:

Centrifugal impeller

Structural characteristics: generally composed of wheel disk, wheel cover and blade. The blade is usually backward curved, there are also radial and forward curved. Backward curved blades can effectively reduce the impeller outlet air velocity, improve energy conversion efficiency.

Working principle: rely on the centrifugal force generated by the impeller rotating fluid to obtain energy, fluid from the center of the impeller suction, under the action of centrifugal force along the blade flow to the outer edge of the impeller.

Performance characteristics: it can produce high pressure, suitable for high head, small flow conditions. Relatively high efficiency, wide working range, strong adaptability to the fluid, can transport clean water, sewage, oil and other fluids. However, the flow rate is relatively small, and there may be instability at low flow rates.

Application Scenario: Widely used in industrial fields, such as boiler feed pumps, chemical process pumps, chilled water pumps in air-conditioning systems, etc.; in the field of construction, used in water supply systems for high-rise buildings; in the field of agriculture, used in farmland irrigation and drainage, etc.

Axial impeller

Structural characteristics: the shape of the impeller is similar to a propeller, composed of hub and blades, blades are generally twisted, and the number of blades is small, usually 2 - 8 pieces.

Working principle: the fluid flows into the impeller along the axial direction, under the action of the blades, the fluid obtains the thrust along the axial direction and flows out of the impeller along the axial direction, and the increase of its energy mainly comes from the axial thrust of the blades on the fluid.

Performance characteristics: characterized by large flow rate, low head, high efficiency in large flow conditions. Simple and compact structure, small volume, light weight, stable operation, low noise. However, the axial impeller is more sensitive to the viscosity of the fluid, and when conveying viscous fluid, the efficiency will be significantly reduced.

Application Scenario: Commonly used in large-scale water conservancy projects, such as large-scale water pumping stations in urban water supply and drainage systems, farmland drainage and irrigation projects; in the industrial field, such as mine ventilation, circulating water pumps in thermal power plants, etc.; in the field of ships, used in the ship's propulsion system.

Mixed-flow impeller

Structural characteristics: mixed-flow impeller shape between centrifugal and axial impeller, the blade has both centrifugal impeller radial flow characteristics, but also axial flow impeller axial flow characteristics, usually for the twisted blade.

Working principle: when the fluid enters the impeller, it has both axial and radial velocities, when flowing in the impeller, the axial and radial velocities of the fluid change, and the fluid obtains energy under the joint action of centrifugal force and axial thrust.

Performance characteristics: both centrifugal and axial impeller advantages, with high flow and head, high efficiency, high efficiency zone wide range. It is highly adaptable to different flow and head conditions and can maintain good performance in a wide range of working conditions.

Application Scenario: In water conservancy and hydropower engineering, it is commonly used in mixed-flow turbine, which is suitable for power stations with medium head and flow; in industrial pumps, it is used in some processes with specific requirements on flow and head, such as pulp pumps in paper-making industry, sludge pumps in sewage treatment plants, etc.

Rotary impeller

Structural characteristics: the impeller is usually spiral or twisted sheet, the shape and arrangement of the blades make the fluid in the impeller to form a strong cyclone movement.

Working principle: The rotation of the impeller makes the fluid produce rotary motion, forming a cyclone field. Under the action of cyclone, the solid particles or impurities in the fluid will be separated to the outer layer of the fluid under the action of centrifugal force, while the center area is pure fluid, thus realizing a certain degree of solid-liquid separation or gas-liquid separation.

Performance characteristics: good self-absorption ability, can effectively deal with fluids containing solid particles or gas. The stirring effect on the fluid is strong, which helps mixing, stirring and other processes. However, due to the complexity of the cyclone movement, its energy loss is relatively large, and its efficiency is generally not as high as that of centrifugal and mixed-flow impeller.

Application scenarios: commonly used in some need to deal with impurity-containing fluids, such as mine drainage, coal slurry water treatment, etc.; in sewage treatment plants, used in sludge return pumps and aeration equipment, etc., can effectively mix and stir the sewage to promote the growth and metabolism of microorganisms; in some chemical mixing equipment, cyclone impellers will also be used to achieve the mixing of liquids and mass transfer process.