Cross flow fans are also impeller fans. Unlike centrifugal fans and axial fans, the axial width of the impeller is much larger than the diameter of the impeller, and the flow direction of the air flow is across the impeller, so it is also called a cross flow fan. The slender impeller at the outlet of the wall-mounted household air conditioner indoor unit is a cross flow fan. This type of fan is also installed above the gates of some large shopping malls and hotels, also called air curtains, which function as heat insulation and dust isolation.

working principle

    Cross flow fan, also called cross flow fan, was first proposed by French engineer Mortier in 1892. The impeller is multi-blade, long cylindrical, and has forward multi-wing blades. Its structure is shown in the structure diagram.when the impeller roatates, the airflow enters the blade cascade from the open part of the impeller, passes through the interior of the impeller, and is discharged into the volute from the other side of the cascade to form a working airflow. The air flow in the impeller is very complicated, the air velocity field is unstable, and there is a vortex in the impeller, the center is located near the volute tongue. The existence of the vortex causes a circulation flow at the output end of the impeller. Outside the vortex, the air stream in the impeller is arc-shaped. Therefore, the flow velocity of each point on the outer circumference of the impeller is not consistent. The closer to the vortex center, the higher the speed, and the closer to the volute, the lower the speed. The air velocity and pressure at the air outlet of the fan are not uniform, so the flow coefficient and pressure coefficient of the fan are average values. The postion of the vortex has a greater impact on the performance of the cross flow fan. The center of the vortex is close to the inner circumference of the impeller and close to the volute tongue, and the performance of the fan is better. If the center of the vortex if farther from the vortex tongue, the area of circulating flow will increase, the efficiency of the fan will be reduced, and the flow rate will be low. The degree of stability increases.