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What is the Structure of the Axial Flow Pump?

Nov. 19, 2020

The axial flow pump is a vane pump with large flow, low lift and high specific speed. The liquid flow of the axial flow system flows along the direction of the shaft, but the basic principle of its design is basically the same as that of the centrifugal pump.

The main parts of the axial flow pump are inlet pipe, impeller, guide vane, outlet pipe, pump shaft, bearing and shaft seal. Axial flow pumps can be divided into three types: vertical, horizontal and inclined according to the installation of the main shaft.

1. Inlet pipe

The horn tube is the suction chamber of the medium and small vertical axial flow pump. It is made of cast iron. Its function is to evenly guide the water to the impeller with minimal loss. The inlet part of the horn tube is arc-shaped, and the inlet diameter is about 1.5 times the diameter of the impeller. In large axial flow pumps, the suction chamber is generally made in the form of a flow channel.

2. Impeller

The impeller is the most important working part, which is composed of blades, wheels, water guide cones, etc.

The blades of the axial flow pump are twisted and mounted on the wheels. According to the possibility of blade adjustment, there are three types: fixed, semi-adjusted and fully-adjusted. The fixed blade is integrated with the wheel valley, and the installation angle of the blade cannot be adjusted. The semi-adjustable blade is fastened to the wheel saddle with a nut, and a reference line is engraved on the root of the blade, and several position lines with corresponding installation angles are engraved on the wheel.


Different blade installation angles will have different performance curves, and the blade installation angle can be adjusted according to needs during use. The semi-regulated impeller blades need to be shut down and the impeller removed before adjustment. Full-adjustable blades change the installation angle of the blades through a set of mechanical or hydraulic adjustment mechanisms. It can change the installation angle of the blade without stopping the machine or only stopping the machine without removing the impeller.

3. Guide vane

The guide vane is located in the guide vane tube above the impeller and fixed on the guide vane tube. Its main function is to eliminate the rotational movement of the fluid and reduce head loss. At the same time, part of the kinetic energy of the fluid can be converted into pressure energy.

Axial Flow Pump

4. Shafts and bearings

The shaft of small and medium-sized axial flow pumps is solid. For large axial flow pumps, in order to arrange the blade adjustment mechanism, the pump shaft is made hollow. An operating oil pipe or operating rod is arranged in the shaft cavity.

The bearings of axial flow pumps can be divided into three categories according to their functions: radial bearings, thrust bearings and guide bearings. Thrust bearings are used to withstand the axial force generated during pump operation. Radial bearing The guide bearing is mainly used to bear the radial force of the rotating parts and play the role of radial positioning. The guide bearing is installed in the guide vane cone to reduce the swing of the shaft. The guide bearing is usually lubricated by medium or external washing fluid.

5. Shaft seal

The axial flow pump can be equipped with packing or mechanical seal according to the requirements of the application, similar to the shaft seal of the centrifugal pump.

6. Pump housing

The pump casing of the axial flow pump is cylindrical, and because it has fixed guide vanes, it is called a guide vane pump casing. The guide vanes are arranged behind the impeller and are conical in shape with multiple guide vanes. The outlet of the axial flow pump is a bent pipe. The inlets of small and medium-sized axial flow pumps mostly use horn-shaped short pipes, while the large axial flow pumps mostly use elbow or bell-shaped inlets.

The above information is provided by axial flow pump supplier.


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