Pump chamber structure and pump

Abstract

The invention relates to a pump chamber structure and a pump, and relates to the technical field of water pumps, the pump chamber structure comprises a pump cavity and an impeller, the pump cavity and / or the impeller are / is provided with a drainage structure, the drainage structure comprises a plurality of grooves, and the width and the depth of each groove are both 2 microns. After being used for a long time, the hydrophobic coating still has the advantage of good hydrophobic effect.

Description

Technical Field

[0001] The present application relates to the technical field of water pumps, and in particular to a pump chamber structure and a pump. Background Art

[0002] The pump is a very common modern general-purpose machine that consumes a lot of electricity. It is used in many fields such as chemical industry, power generation, and construction, and has a large demand in the market. When the pump is running, the fluid will produce a large energy loss through the centrifugal impeller and guide vanes. These losses mainly come from the friction resistance generated by the friction between the fluid and the inner wall of the impeller. One of the existing ways to reduce friction resistance is to add a coating on the impeller to reduce friction resistance, but as the use time increases, the coating will fall off. Summary of the invention

[0003] In view of the deficiencies in the prior art, one of the purposes of the present application is to provide a pump chamber structure and a pump, which have the advantage of still having a good hydrophobic effect after long-term use.

[0004] The above-mentioned purpose of the present application is achieved through the following technical solutions:

[0005] A pump chamber structure comprises a pump cavity and an impeller. The pump cavity and / or the impeller are provided with a hydrophobic structure, the hydrophobic structure comprises a plurality of grooves, and the width and depth of the grooves are both 1.5-2.5 μm.

[0006] In a preferred example, the present application can be further configured as follows: the interval between adjacent grooves is 1.5-2.5 μm.

[0007] In a preferred example, the present application can be further configured as follows: the grooves are arranged equidistantly and diffuse in a circular shape radially from the center of the axial cross section to the outer circumference.

[0008] In a preferred example, the present application can be further configured as follows: the grooves are arranged along the concentric circumferential direction of the pump shaft cross-section circle.

[0009] In a preferred example, the present application can be further configured as follows: the width w of the groove and the spacing s between the grooves should satisfy the following relationship: cosθ * =f r cosθ+(1-f r ), where f r is the solid area fraction, f r <0.2;θ * is the surface composite contact angle, θ * >150°, the groove depth d satisfies the following conditions, Where σ is the surface tension of the liquid, ρ is the density of the liquid, and g is the acceleration due to gravity.

[0010] The present application also discloses a pump: the pump chamber structure mentioned above is adopted.

[0011] This application has the following advantages:

[0012] The hydrophobic structure will lower the position of the turbulent / non-turbulent interface of the liquid on the solid surface and increase the uniform momentum area. Moreover, the decrease of the turbulent / non-turbulent interface of the liquid and the increase in the number of uniform momentum areas are carried out simultaneously, which will cause the resistance of the super-hydrophobic solid surface to decrease. The super-hydrophobic surface will reduce the generation of large-scale structures and concentrated energy, making the flow field energy distribution of the inner wall of the pump chamber connected to the guide vanes of the multi-stage centrifugal pump relatively stable, reducing the energy transfer of the flow field in the inner wall liquid in the normal direction, and then, more uniform dynamic areas appear in the inner wall surface flow field. In the inner wall surface flow field, after the force in the normal direction of the solid surface is reduced, the energy is converted from the previous large-scale structure to the small-scale structure, the flow field shear stress on the surface of the inner wall area is reduced, and the resistance to liquid flow is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the pump chamber structure of this application.

[0014] Figure 2 It is a schematic diagram of the structure of the multi-stage centrifugal pump of this application.

[0015] Figure 3 It is a schematic diagram of the super-hydrophobic groove structure of the present application.

[0016] Figure 4 It is a schematic diagram of the micro-nano dual structure on the surface of this application.

[0017] Figure 5 It is a schematic diagram of the groove and liquid schematic structure of this application.

[0018] Figure numerals: 1, pump chamber; 2, impeller; 3, groove. DETAILED DESCRIPTION

[0019] The following is combined with Figure 1-5 This application is described in further detail.

[0020] Reference Figure 1, is a pump chamber structure disclosed in the present application, including a pump chamber 1 and an impeller 2, a hydrophobic structure is provided on the pump chamber 1 and / or the impeller 2, the hydrophobic structure includes a plurality of grooves 3, the width and depth of the grooves 3 are both 2μm, the interval between adjacent grooves 3 is 1.5μm, the grooves 3 are arranged equidistantly, and radially diffuse in a circular shape from the center of the axial section to the outer circumference, and the grooves are arranged along the concentric circumferential direction of the pump shaft section circle. At present, the definition of a super-hydrophobic surface is that when a droplet is stationary on its surface, the stable contact angle is greater than 150°, and the rolling contact angle is less than 10°. It is generally believed that the larger the contact angle, the better the hydrophobicity of the corresponding surface. The contact angle refers to the angle between the tangent of the gas-liquid interface on the liquid side and the solid-liquid boundary line when the droplet contacts the wall, and is represented by θ. When θ<90°, it is a hydrophilic surface, when θ>90°, it is a hydrophobic surface, and when θ>150°, it is a super-hydrophobic surface. The study found that the method of increasing the contact angle by changing the chemical composition of the solid surface material can only increase the contact angle to 120° at most, while the apparent contact angle of the superhydrophobic material needs to be more than 150°. Therefore, it is necessary to change the surface roughness to meet the requirements of the superhydrophobic wall.

[0021] The method for determining the geometric parameters (width w, depth d, spacing s) of the super-hydrophobic groove 3 is as follows:

[0022] According to fluid dynamics, the contact angle θ of the superhydrophobic surface and the gas composite state (Cassie-Baxter model) are key factors. The groove 3 width w and the spacing s should satisfy the following relationship:

[0023] cosθ * =f r cosθ+(1-f r )

[0024] Among them, f r is the solid area fraction, f r <0.2 to maintain strong hydrophobicity; θ * is the surface composite contact angle, θ * >150°. According to the capillary force stability of the surface structure, the depth d of the groove 3 should meet the following conditions to keep the gas state stable:

[0025]

[0026] Where σ is the surface tension of the liquid and ρ is the density of the liquid in kg / m 3 , g is the acceleration due to gravity, unit is m / s 2 .

[0027] Finally, the preliminary parameter range is determined: groove 3 width w: 1.5~2.5μm, groove 3 spacing s:

[0028] 1.5~2.5μm, groove 3 depth d: 2~10μm. Through the parameter range obtained by preliminary calculation, the pump is three-dimensionally modeled, and the flow field in the pump is numerically simulated in combination with the fluid dynamics CFD to analyze the super-hydrophobic and drag reduction effects, so as to optimize the size of the groove 3 before laser processing. Because the impeller material is mostly cast iron, the micro-groove 3 processed by ordinary processing methods cannot withstand the friction with the liquid for a long time. The processed micro-groove 3 structure is easily damaged by the fluid impact friction for a long time during operation, thereby reducing or even losing the super-hydrophobic drag reduction performance. Most groove 3 processing methods are not suitable for long-term use conditions. The use of laser cladding technology can form a cladding layer on the surface of the material. The wear resistance, corrosion resistance, heat resistance and oxidation resistance of the newly formed cladding layer are significantly improved compared with the raw materials, thereby achieving surface modification, which can effectively prevent the micro-groove 3 from being damaged by fluid impact friction.

[0029] In processing Figure 3 When machining the super-hydrophobic groove structure shown in the figure, the center point of the workpiece and the laser are fixed, and the workpiece is rotated during machining to realize the machining of the annular groove structure. After completing the machining of one annular groove, the laser is radially displaced by the spacing distance between adjacent grooves to machine the adjacent annular groove structures, and the above operation is repeated to finally realize the machining of the annular array groove structure.

[0030] Precision laser processing technology is used to process the super-hydrophobic drag reduction grooves. Laser cladding is used to process the non-groove part between two adjacent grooves in the super-hydrophobic groove 3 structure to form a heightened cladding layer, and the non-groove part between two adjacent grooves is processed in the same way, thereby achieving a relative reduction in the groove part and forming a super-hydrophobic groove structure. During the processing, the width of the cladding layer is controlled by controlling the laser power, and the groove is subsequently processed to achieve a square groove shape.

[0031] When processing a multi-stage centrifugal pump with a super-hydrophobic drag reduction structure, a super-hydrophobic drag reduction groove structure is added to the working surface of the key flow-through components (impellers and guide vanes) of the multi-stage centrifugal pump to achieve a super-hydrophobic effect, thereby reducing fluid resistance, reducing energy consumption and improving pump efficiency. Before processing, the base material of the impeller and guide vane (such as stainless steel, aluminum alloy or composite material) is determined to ensure its suitable processing and chemical modification, and the surface is cleaned by ultrasonic cleaning or sandblasting to remove oil and oxide layer, laying a good foundation for subsequent processing. After the super-hydrophobic groove is processed, chemical vapor deposition (CVD) or dip coating technology can be used to coat the processed surface with low surface energy materials (such as fluorides or silane compounds), and the coating is cured at a specific temperature to improve adhesion and durability, and realize super-hydrophobic modification operation. For the processing of the impeller, the super-hydrophobic drag reduction grooves on the inner wall of the rear cover plate, the outer wall of the rear cover plate, and the inner wall of the front cover plate can be processed separately, and then the front and rear cover plates can be welded together.

[0032] The super-hydrophobic structure can also use a double micro-nano structure on the surface. This microstructure can prevent the droplet from completely filling the surface pits, but only stays on the top of the rough protrusions and maintains balance (see attached). Figure 4 As shown). There is a thin air film between the droplet and the structure surface, which prevents the water droplet from penetrating into the surface pits and also prevents the adsorption of pollutants. The surface micro-nano dual structure refers to the formation of protrusions on the surface, and the surface of the protrusions is also provided with grooves 3. In this embodiment, the cross section of the protrusion is in the shape of an arc, and in other embodiments it is also in the shape of a broken line.

[0033] The addition of super-hydrophobic grooves can effectively reduce the contact area between the liquid and the wall and reduce the flow resistance. The super-hydrophobic groove design can inhibit cavitation and fouling, extend the service life of the pump, improve the overall efficiency of the centrifugal pump, and meet the needs of energy conservation and emission reduction.

[0034] The present application also discloses a pump: the pump chamber structure mentioned above is adopted.

[0035] Reference Figure 2 , the following takes a multi-stage centrifugal pump as an example,

[0036] A hydrophobic structure is added to the inner wall of the impeller 2 cavity of the multistage centrifugal pump and the outer wall of the rear cover plate and the guide vane wall. That is, a groove 3 with a width of 2μm and a depth of 2μm is opened every 1.5μm on the inner wall to form a super-hydrophobic structure. Normally, the ability of a liquid to spread on a solid surface is called wettability, and the solid surface has two evaluation criteria for wettability, which are the surface static contact angle and the rolling angle. In the super-hydrophobic surface system, the contact angle of super-hydrophobicity is greater than 150°, and this structure will reduce the synergy between the roughness of the microstructure of the object surface and the low surface energy material. There will be relatively strong residual chemical bonds on the surface of hydrophilic objects, and it is the presence of these residual chemical bonds that makes liquids easily adsorbed on the surface of objects. Different from the surface of hydrophilic objects, the surface energy of super-hydrophobic surfaces is low, and the residual chemical bonds that exist are weaker, and the adsorption capacity of liquids on the surface of objects is smaller, and the resistance of liquids flowing on super-hydrophobic surfaces is also smaller. For a multi-stage centrifugal pump, liquid enters from the water inlet, and the impeller 2 rotates at high speed to do work on the liquid. The guide vane receives the high-speed rotating liquid and inputs the liquid into the impeller 2 of the next stage until the final water outlet section. During this process, the liquid will flow in the inner wall connected to the guide vane. Adding a hydrophobic structure to the inner wall surface will make the liquid flow more smoothly compared to the traditional wall surface. At the same time, the addition of the hydrophobic structure will reduce the flow pulse of the wall fluid and improve the efficiency of the multi-stage centrifugal pump. That is, during this process, the liquid will flow through the pump chamber 1 area, and the inner wall of the pump chamber 1 will increase the hydrophobic structure. Since this structure reduces the roughness of the microstructure of the object surface and the synergistic effect between the low surface energy materials, the affinity of the object surface to the liquid is reduced, and the resistance when the liquid flows is reduced. The energy loss during the transmission between the liquid stages is reduced.

[0037] The implementation principle of the present embodiment is: the hydrophobic structure will make the turbulence / non-turbulence interface position of the solid surface liquid decline, and the uniform momentum zone can be increased. And the decline of the turbulence / non-turbulence interface of the liquid and the increase of the uniform momentum zone number are carried out synchronously, which will cause the resistance of the super-hydrophobic solid surface to decline. The super-hydrophobic surface can reduce the large-scale structure and energy concentration, so that the flow field energy distribution of the inner wall of the pump chamber 1 connected by the guide vane of the multi-stage centrifugal pump is relatively stable, and the energy of the flow field in the inner wall liquid is reduced to be transmitted in the normal direction, and then, more uniform power areas appear in the inner wall surface flow field. In the inner wall surface flow field, after the force in the normal direction of the solid surface is reduced, energy is converted into small-scale structure by the previous large-scale structure, and the flow field shear stress on the inner wall area surface is reduced, and the resistance to liquid flow declines.

[0038] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A pump chamber structure, characterized in that: The invention comprises a pump chamber (1) and an impeller (2), wherein the pump chamber (1) and / or the impeller (2) are provided with a hydrophobic structure, wherein the hydrophobic structure comprises a plurality of grooves (3), wherein the grooves (3) have a width of 1.5-2.5 μm and a depth of 2-10 μm.

2. A pump chamber structure according to claim 1, characterized in that: The interval between adjacent grooves (3) is 1.5-2.5 μm.

3. A pump chamber structure according to claim 1, characterized in that: The grooves (3) are arranged at equal intervals and spread out in a circular shape from the center of the axial cross section to the outer circumference in a radial manner.

4. A pump chamber structure according to claim 1, characterized in that: The groove (3) is arranged along the concentric circumferential direction of the pump shaft cross-section circle.

5. A pump chamber structure according to claim 1, characterized in that: The width w of the groove (3) and the spacing s between the grooves (3) should satisfy the following relationship: cosθ * =f r cosθ+(1-f r ), where f r is the solid area fraction, f r <0.2;θ * is the surface composite contact angle, θ * >150°, the depth d of the groove (3) satisfies the following conditions, Where σ is the surface tension of the liquid, ρ is the density of the liquid, and g is the acceleration due to gravity.

6. A pump, characterized in that: A pump chamber structure as described in any one of claims 1 to 4 is adopted.

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