Blade of axial flow pump

Abstract

The utility model discloses a blade of an axial flow pump, which belongs to the technical field of axial flow pumps and comprises a blade body, and a first wing blade and a second wing blade are fixedly connected to a pressure surface and a suction surface of the blade body respectively. The first wing cutter strip and the second wing cutter strip are respectively fixed at the same blade height of the blade main body; and the chord lengths of the first wing blade and the second wing blade are equal to those of the blade height corresponding to the blade main body. By means of the first wing cutter strips and the second wing cutter strips, secondary backflow formed on the hub side at the outlet of the impeller can be weakened in a physical interception mode when flow is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of axial flow pumps, and particularly relates to a blade of an axial flow pump. Background Art

[0002] An axial flow pump is a device that generates a force on a liquid by rotating an impeller to transport the liquid along the axial direction.

[0003] When the axial flow pump is in the best working condition, the fluid flows smoothly along the blade surface.

[0004] When the flow rate decreases, the flow pattern changes. The centrifugal force of the fluid in the impeller is greater than the pressure gradient in the radial direction. The fluid deflects outward at the impeller outlet, resulting in an increase in the flow velocity at the outer edge of the impeller outlet and a decrease at the hub side. A secondary flow is formed at the hub side of the impeller outlet. At the same time, due to the decrease in the flow rate, the incidence angle at the blade inlet increases, and the fluid shoots towards the working surface when entering the impeller flow channel, making it easy for flow separation to occur on the blade back surface, and phenomena such as easy expansion and increased noise are likely to occur, and the performance of the pump decreases.

[0005] When the flow rate further decreases, a large amount of fluid at the impeller outlet crowds to the outer side of the flow channel, making it impossible for the fluid in the inlet direction on the outer edge side to enter. Under the traction of the fluid on the hub side, a rotation towards the outer source side occurs before the inlet, and with the influence of tip leakage, a large secondary flow region also appears on the rim side of the impeller inlet.

[0006] After the flow rate continues to decrease, the secondary flow regions at the impeller inlet and outlet increase, and the flow through the impeller becomes diagonal flow, so the head increases rapidly. The flow state at this time is very complex, the vibration and noise increase again. When the flow rate decreases to near the shut-off point, the secondary flow at the inlet and outlet expands to the entire flow channel, and a large range of radial flow appears in the impeller. Content of the Utility Model

[0007] The purpose of the utility model is to provide a blade of an axial flow pump to solve the above problems.

[0008] To achieve the above purpose, a blade of an axial flow pump of the utility model includes a blade body. A first wing knife strip and a second wing knife strip are respectively fixedly connected to the pressure surface and the suction surface of the blade body; the first wing knife strip and the second wing knife strip are respectively fixed at the same blade height of the blade body; the first wing knife strip and the second wing knife strip are both equal in chord length to the corresponding blade height of the blade body.

[0009] Further, the end face shapes of the first wing knife strip and the second wing knife strip are both rectangular

[0010] Further, the first wing knife strip and the second wing knife strip have the same specifications.

[0011] The same specifications are easy to process. During later welding, there is no need to consider the welding surface. The first wing knife strip and the second wing knife strip have the same specifications and can be used interchangeably, which is convenient to use.

[0012] Further, let the side where the first wing knife strip and the second wing knife strip are in contact with the blade body be the width side, and the adjacent side on the other side be the height side. The height side is 1 - 2 cm, and the width side is 0 - 1 cm.

[0013] Further, the first wing knife strip and the second wing knife strip are made of the same material as the blade body.

[0014] Designing the first wing knife strip, the second wing knife strip and the blade body to be of the same material enables quick shaping whether by welding or integral casting.

[0015] Further, both the first wing knife strip and the second wing knife strip are arranged at 30% of the blade height of the blade body.

[0016] When the operating condition has a flow rate less than the designed flow rate, the centrifugal force of the fluid in the impeller is greater than the effect of the radial pressure gradient. The fluid deflects towards the outer edge at the impeller outlet, causing the flow velocity at the outer edge of the impeller outlet to increase and the flow velocity at the hub side to slow down, forming a secondary flow at the hub side of the impeller outlet. Therefore, wing knives are arranged at 30% of the blade height. Because it is close to the hub, it can effectively prevent the secondary flow. Beneficial effects

[0017] The first wing knife strip and the second wing knife strip are designed. When the flow rate decreases, the centrifugal force of the fluid in the impeller is greater than the effect of the radial pressure gradient, and the fluid deflects towards the outer edge at the impeller outlet. However, the flow of the fluid towards the outer edge is reduced due to the obstruction of the first wing knife strip and the second wing knife strip, and the flow of the fluid on the surface of the blade body is isolated physically. Thus, the secondary flow formed at the hub side of the impeller outlet is weakened. By reducing the secondary flow, the passage vortex formed on the blade is weakened, and the cavitation performance of the blade is improved. Brief description of the drawings

[0018] Figure 1 It is the front view of the axial - flow pump blade of the present utility model;

[0019] Figure 2 It is the top view of the axial - flow pump blade of the present utility model;

[0020] Figure 3 It is the surface streamline diagram of the axial - flow pump blade with wing knives at a small flow rate (0.8Q) of the axial - flow pump;

[0021] Figure 4 It is the surface streamline diagram of the axial - flow pump blade without wing knives at a small flow rate (0.8Q) of the axial - flow pump;

[0022] 1. Blade body; 2. First wing knife strip; 3. Second wing knife strip. Detailed implementation manners

[0023] To make the purposes, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions of the present utility model will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are some but not all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0024] Embodiment 1: See Figure 1 and Figure 2 , a blade of an axial flow pump, including a blade body 1.

[0025] A first wing knife strip 2 is provided at 30% of the blade height on the suction surface of the blade body 1. A second wing knife strip 3 is provided at 30% of the blade height on the pressure surface of the blade body 1.

[0026] One ends of both the first wing knife strip 2 and the second wing knife strip 3 are located at the leading edge position of the blade body 1, and the other ends are both located at the trailing edge position of the blade body 1.

[0027] Here, the pressure surface refers to the surface where the fluid generates pressure on the blade body 1. The suction surface refers to the surface where the fluid generates suction on the blade body 1. These are conventional technical terms in the art.

[0028] The blade height refers to the maximum height when the fluid passes through the blade body 1. This is a conventional technical term in the art.

[0029] In this embodiment, the length of the first wing knife strip 2 is equal to the chord length at 30% of the blade height on the pressure surface.

[0030] The length of the second wing knife strip 3 is equal to the chord length at 30% of the blade height on the suction surface.

[0031] Since the pressure surface and the suction surface are completely the same, the first wing knife strip 2 and the second wing knife strip 3 are also completely the same.

[0032] The end faces of the first wing knife strip 2 and the second wing knife strip 3 are rectangular. Looking at them from their end faces, one side of the first wing knife strip 2 and the second wing knife strip 3 is fitted to the corresponding surface wall of the blade body 1. Let the side where the first wing knife strip 2 and the second wing knife strip 3 are fitted to the blade body 1 be the width side, and the other adjacent side be the height side. Then the height side is 1 - 2 cm, and the width side is 0 - 1 cm. In this embodiment, the height is 1.2 cm and the width is 0.6 cm.

[0033] The materials of the first wing knife strip 2 and the second wing knife strip 3 are the same as that of the blade body 1. In the present utility model, they are fixed on the blade body 1 by welding. In other embodiments, they can also be connected to the blade body 1 by integral casting.

[0034] Embodiment 2: After installing the first wing knife strip and the second wing knife strip, the blade body will be divided into two parts along the blade height direction. When the flow rate decreases, the centrifugal force of the fluid in the impeller is greater than the pressure gradient in the radial direction. The fluid deflects outward at the impeller outlet. See Figure 3 and Figure 4 on the right side, the flow of the fluid outward is reduced due to the obstruction of the first wing knife strip and the second wing knife strip, and the flow of the fluid on the surface of the blade body is isolated physically. Thereby, the secondary flow formed on the hub side at the impeller outlet is weakened.

[0035] From Figure 3 it can be seen that when the flow rate is less than the designed flow rate, compared with the blade without the first wing knife strip and the second wing knife strip, see Figure 3 and Figure 4 on the right side, less fluid at the impeller outlet is crowded to the outer side of the flow channel, and at the same time, the streamline at the inlet is relatively smoother, reducing the secondary flow on the rim side at the impeller inlet. Reducing the secondary flow thus weakens the passage vortex formed on the blade and improves the cavitation performance of the blade.

[0036] Enlightened by the above ideal embodiments according to the present utility model, through the above description, the relevant staff can make various changes and modifications completely within the scope not deviating from the technical idea of this utility model. The technical scope of this utility model is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A blade of an axial flow pump, comprising a blade body, characterized in that: The pressure surface and the suction surface of the blade body are respectively fixedly connected with a first blade strip and a second blade strip; The first blade strip and the second blade strip are respectively fixed at the same blade height of the blade body; The first blade strip and the second blade strip have the same chord length as the blade main body at the blade height.

2. The blade of an axial flow pump according to claim 1, characterized in that: The end faces of the first blade strip and the second blade strip are both rectangular.

3. The blade of an axial flow pump according to claim 2, characterized in that: The first blade strip and the second blade strip have the same specifications.

4. The blade of an axial flow pump according to claim 3, characterized in that: The sides where the first and second wing blades are in contact with the blade body are defined as width sides, and the adjacent sides on the other side are defined as height sides. The height sides are 1-2 cm, and the width sides are 0-1 cm.

5. The blade of an axial flow pump according to claim 3, characterized in that: The first blade strip and the second blade strip are made of the same material as the blade body.

6. The blade of an axial flow pump according to claim 2, characterized in that: The first blade strip and the second blade strip are both arranged at 30% of the blade height of the blade body.

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