The working principle and characteristics of centrifugal pumps
1. Working principle of centrifugal pumps
Before starting the water pump, first fill the pump and inlet pipe with water. After the pump runs, under the centrifugal force generated by the high-speed rotation of the impeller, the water in the impeller flow channel is thrown around and pressed into the volute. The impeller inlet forms a vacuum, and the water in the pool is sucked in along the suction pipe under external atmospheric pressure to supplement this space. Subsequently, the water sucked in is thrown out by the impeller through the volute and enters the outlet pipe. From this, it can be seen that if the impeller of a centrifugal pump continues to rotate, it can continuously absorb and press water, and water can continuously rise from low to high or distant places. In summary, centrifugal pumps are called centrifugal pumps due to the centrifugal force generated by the high-speed rotation of the impeller, which lifts water to a higher level.
2. General characteristics of centrifugal pumps
(1) The flow direction of water along the centrifugal pump is suction along the axial direction of the impeller, and it flows out perpendicular to the axial direction, that is, the direction of inlet and outlet water flow is 90 ° to each other.
(2) Due to the vacuum suction formed by the impeller inlet of the centrifugal pump, it is necessary to inject water into the pump and suction pipe before starting, or use a vacuum pump to extract air to form a vacuum. The pump casing and suction pipe must be strictly sealed and must not leak, otherwise a vacuum cannot be formed and water cannot be sucked in.
(3) Due to the impossibility of forming absolute vacuum at the impeller inlet, the suction height of the centrifugal pump cannot exceed 10 meters. In addition, the actual allowable installation height (the distance between the pump axis and the suction water surface) is much less than 10 meters due to the loss caused by water flow through the suction pipeline. If the installation is too high, it will not absorb water; In addition, due to the lower atmospheric pressure in mountainous areas compared to plains, the installation height of the same water pump in mountainous areas, especially in mountainous areas, should be reduced, otherwise it cannot absorb water.