Blade of axial flow pump and manufacturing method

Abstract

The invention discloses a blade of an axial flow pump and a manufacturing method, and belongs to the technical field of axial flow pumps, the blade comprises a blade main body, and the pressure surface and the suction surface of the blade main body are fixedly connected with a first wing cutter strip and a second wing cutter strip 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, when the flow is reduced, secondary backflow formed on the hub side at the outlet of the impeller can be weakened in a physical interception mode.

Description

Technical Field

[0001] The invention belongs to the technical field of axial flow pumps, and in particular relates to a blade of an axial flow pump and a manufacturing method thereof. Background Art

[0002] An axial flow pump is a device that uses a rotating impeller to exert force on the liquid so that the liquid is transported along the axial direction.

[0003] When the axial flow pump is in optimal working condition, the fluid flows smoothly along the surface of the blades.

[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 toward the outer edge at the impeller outlet, which speeds up the flow rate at the outer edge of the impeller outlet and slows down the hub side, forming a secondary reflux on the hub side at the impeller outlet. At the same time, due to the decrease in flow rate, the angle of attack of the blade inlet increases, and the fluid enters the impeller flow channel and shoots toward the working surface, making it easy for the back of the blade to separate and expand, and the noise to increase, and the performance of the pump decreases.

[0005] When the flow rate is further reduced, a large amount of fluid at the impeller outlet is crowded to the outside of the flow channel, making it impossible for the fluid from the outer edge inlet to enter. Under the traction of the fluid on the hub side, rotation toward the outer source side occurs before the inlet. Coupled with the influence of blade tip leakage, a large secondary recirculation area also appears on the rim side of the impeller inlet.

[0006] As the flow rate continues to decrease, the secondary reflux area at the impeller inlet and outlet increases, and the flow through the impeller becomes a diagonal flow, so the head increases rapidly. At this time, the flow state is very complex, and the vibration and noise increase again. When the flow rate decreases to near the dead point, the secondary reflux at the inlet and outlet expands to the entire flow channel, and a large range of radial flow occurs in the impeller. Summary of the invention

[0007] The object of the present invention is to provide a blade of an axial flow pump and a manufacturing method thereof, so as to solve the above-mentioned problems.

[0008] In order to achieve the above-mentioned purpose, the blade of an axial flow pump of the present invention includes a blade body, and the pressure surface and suction surface of the blade body are respectively fixedly connected with a first wing blade strip and a second wing blade strip; the first wing blade strip and the second wing blade strip are respectively fixed at the same blade height of the blade body; the first wing blade strip and the second wing blade strip are equal in chord length to the blade height corresponding to the blade body.

[0009] Furthermore, the end faces of the first blade strip and the second blade strip are both rectangular. Furthermore, the first blade strip and the second blade strip have the same specifications.

[0010] The same specifications are easy to process, and there is no need to consider the welding surface during later welding. The first wing blade and the second wing blade have the same specifications and can be used universally, which is convenient to use.

[0011] Furthermore, observing the end faces of the first wing blade strip and the second wing blade strip, the edge where the first wing blade strip and the second wing blade strip are in contact with the blade body is the width edge, and the other adjacent edge is the height edge, the height edge is 1-2 cm, and the width edge is 0-1 cm.

[0012] Furthermore, the first blade strip and the second blade strip are made of the same material as the blade body.

[0013] The first wing blade and the second wing blade are designed to be made of the same material as the blade body, so that they can be quickly shaped whether they are welded or cast as one piece.

[0014] Furthermore, the first blade strip and the second blade strip are both arranged at 30% of the blade height of the blade body.

[0015] When the operating condition is less than the flow rate of the design condition, the centrifugal force of the fluid in the impeller is greater than the pressure gradient in the radial direction, and the fluid deflects toward the outer edge at the impeller outlet, causing the flow velocity at the outer edge of the impeller outlet to increase and the hub side to slow down, forming a secondary reflux on the hub side at the impeller outlet. Therefore, a blade is set at 30% of the blade height, because it is close to the hub, it can effectively prevent secondary reflux.

[0016] Furthermore, a method for manufacturing a blade of an axial flow pump comprises the following steps: S1: Design and process the blade body, the first wing blade and the second wing blade; design the end faces of the first wing blade and the second wing blade into a rectangle with a width side of 0.6 cm and a height side of 1.2 cm.

[0017] S2: Weld the width edges of the first blade strip and the second blade strip to the suction side and pressure side of the blade body at 30% of the blade height respectively; S3: Grind the weld; ensure that the weld is smooth and free of burrs, and the maximum thickness of the weld is less than 50% of the height side length of the first wing blade or the second wing blade. Beneficial Effects

[0018] The first blade strip and the second blade strip are designed. When the flow rate decreases, the centrifugal force of the fluid in the impeller is greater than the pressure gradient in the radial direction, and the fluid deflects toward the outer edge at the impeller outlet. However, the flow of the fluid toward the outer edge will be reduced due to the obstruction of the first blade strip and the second blade strip, and the flow of the fluid on the surface of the blade body will be physically isolated. This will reduce the secondary recirculation formed on the hub side at the impeller outlet. By reducing the secondary recirculation, the channel vortex formed on the blade is reduced, and the cavitation performance of the blade is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a front view of the blades of the axial flow pump of the present invention; Figure 2 A top view of the blades of the axial flow pump of the present invention; Figure 3 This is the streamline diagram of the blade surface of the axial flow pump with wing knife when the axial flow pump has a small flow rate (0.8Q); Figure 4 This is the streamline diagram of the blade surface of the axial flow pump without wing knife when the axial flow pump has a small flow rate (0.8Q); 1. Blade body; 2. First blade strip; 3. Second blade strip. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1: See Figure 1 and Figure 2 , a blade of an axial flow pump comprises a blade body 1.

[0022] A first blade strip 2 is arranged at 30% of the blade height on the suction side of the blade body 1. A second blade strip 3 is arranged at 30% of the blade height on the pressure side of the blade body 1.

[0023] One end of the first blade strip 2 and the second blade strip 3 are both located at the leading edge of the blade body 1 , and the other end thereof are both located at the trailing edge of the blade body 1 .

[0024] 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.

[0025] Blade height refers to the maximum height of the fluid passing through the blade body 1. It is a conventional technical term in this field.

[0026] In this embodiment, the length of the first blade strip 2 is equal to the chord length at 30% of the blade height on the pressure surface.

[0027] The length of the second blade strip 3 is equal to the chord length at 30% of the blade height on the suction side.

[0028] Since the pressure surface and the suction surface are completely identical, the first blade strip 2 and the second blade strip 3 are also completely identical.

[0029] The end faces of the first blade strip 2 and the second blade strip 3 are rectangular. When viewed from the end faces, one side of the first blade strip 2 and the second blade strip 3 is fitted with the surface wall corresponding to the blade body 1. The side where the first blade strip 2 and the second blade strip 3 are fitted with the blade body 1 is the width side, and the other side adjacent to the blade body 1 is the height side. The height side is 1-2 cm, and the width side is 0-1 cm. In this embodiment, the height side is 1.2 cm, and the width side is 0.6 cm.

[0030] The material of the first blade strip 2 and the second blade strip 3 is the same as that of the blade body 1. The present invention fixes them to the blade body 1 by welding. In other embodiments, they can also be connected to the blade body 1 by integral casting.

[0031] Embodiment 2: After the first blade strip and the second blade strip are installed, 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, and the fluid is deflected toward the outer edge at the impeller outlet. Figure 3 and Figure 4 On the right side, the flow of fluid to the outer edge is reduced due to the obstruction of the first blade strip and the second blade strip, and the flow of fluid on the surface of the blade body is physically isolated, thereby weakening the secondary backflow formed on the hub side at the impeller outlet.

[0032] from Figure 3 It can be seen that when the flow rate is less than the design flow rate, the present solution is better than the blade without the first blade strip and the second blade strip. Figure 3 and Figure 4 On the right side, less fluid is crowded to the outside of the flow channel at the impeller outlet, and the streamline at the inlet is relatively smooth, which reduces the secondary reflow on the rim side of the impeller inlet. Reducing the secondary reflow weakens the channel vortex formed on the blade and improves the cavitation performance of the blade.

[0033] Embodiment 3: A method for manufacturing blades of an axial flow pump, comprising the following steps: S1: Design and process the blade body, the first wing blade and the second wing blade; design the end faces of the first wing blade and the second wing blade into a rectangle with a width side of 0.6 cm and a height side of 1.2 cm.

[0034] S2: Weld the width edges of the first blade strip and the second blade strip to the suction side and pressure side of the blade body at 30% of the blade height respectively; S3: Grind the weld; ensure that the weld is smooth and free of burrs, and the maximum thickness of the weld is less than 50% of the height side length of the first wing blade or the second wing blade.

[0035] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of 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 wing blade strip and the second wing blade strip have the same specifications.

4. The blade of an axial flow pump according to claim 3, characterized in that: Observing the end faces of the first wing blade strip and the second wing blade strip, the edge where the first wing blade strip and the second wing blade strip are in contact with the blade body is the width edge, and the other adjacent edge is the height edge. The height edge is 1-2 cm, and the width edge is 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.

7. A method for manufacturing blades of an axial flow pump, characterized in that: The blade of the axial flow pump according to claim 6 comprises the following steps: S1: Design and process the blade body, the first blade strip and the second blade strip; design the end faces of the first blade strip and the second blade strip into a rectangle with a width side of 0.6 cm and a height side of 1.2 cm; S2: Weld the width edges of the first blade strip and the second blade strip to the suction side and pressure side of the blade body at 30% of the blade height respectively; S3: Grind the weld; ensure that the weld is smooth and free of burrs, and the maximum thickness of the weld is less than 50% of the height side length of the first wing blade or the second wing blade.

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