The axial flow pump impeller is provided with 2 to 7 blades which are rotated in the casing of the circular tube. The upper part of the impeller pump casing is provided with a fixed guide vane, which is used to eliminate the rotational motion of the liquid, and make it into an axial movement, and the kinetic energy of the rotary motion is changed into a pressure energy. The axial flow pump is usually a single stage, and a few are made into a two stage. Large flow range of 180 to 3 million 600 thousand cubic meters / hour; head usually in the 20 meters below. Axial flow pump is usually vertical, the impeller submerged in the water, there are horizontal or inclined axial flow pump. Small axial flow pump impeller installation position higher than the water, the need to use the vacuum pump exhaust water diversion. Blade fixed and adjustable two kinds of structure of axial flow pump. Large axial flow pump operating conditions (mainly refers to the flow) in the operation often need to make larger changes, the installation angle of the blade can make the pump in different conditions to keep running in high efficiency area. The installation angle of the blade of a small pump is usually fixed. Axial flow pump belongs to a high specific speed in pump power, than the number from 500 to 1600. Pump flow - head, flow - shaft power characteristic curve in the small flow area is relatively steep, it should be avoided in this unstable small flow area. Axial flow pump at zero flow of the maximum shaft power, so the pump must be opened before the start of the valve on the discharge line to reduce the power of the engine. Axial flow pump is mainly used in low lift and large flow of the occasion, such as the regulation of the water level in the irrigation, drainage, dock drainage, canal locks, or used as a large power plant circulating water pump. Axial flow pump with high lift head (made of two stages) can be used for water jet propulsion of shallow water vessels.
