Erosion-resistant device, design method and water pump

Abstract

The invention relates to an erosion-resistant device, and relates to the technical field of water pumps, the erosion-resistant device comprises a mounting plate, the mounting plate is annular and is located on the inner bottom surface of a flow guide shell, the mounting plate is provided with at least one groove, the groove is annular, the groove and the inner side wall of the flow guide shell enable water flow to form turbulent flow, the depth of the groove is H1, the unit is m, and # imgabs0 # 1 is met, a is the minimum distance between the upper surface of the erosion-resistant device and the impeller front cover plate, # imgabs1 # m and # imgabs2 # are the axial vertical distances between the position of the flow guide shell base corresponding to any radial distance of the mounting plate and the impeller front cover plate, the unit is m, and H is the axial height of the position, corresponding to # imgabs3 #, of the mounting plate. The guide shell has the advantage that the abrasion probability of the guide shell can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of water pumps, and in particular to a erosion-resistant device, a design method and a water pump. Background Art

[0002] As the impeller rotates, the silt and particles drive the water flow to continuously impact and rub the pump components. The solid-liquid two-phase flow transport medium that accounts for a large proportion will reduce the pump performance. After long-term operation, the hydraulic components often wear out and fail, and the guide shell wears and breaks, which seriously affect the normal use of the water pump. That is, under the action of the impeller, some of the silt is diverted to the bottom of the guide shell after passing through the impeller outlet, and because the area between the impeller front cover and the guide shell is not the range of the main flow of the medium, a region with a lower flow velocity is formed from the impeller axis to the outside, causing the silt to gather. Therefore, under the action of the circulating flow generated on the periphery of the impeller, the silt hits the side wall of the guide shell at high speed, causing wear and even fracture.

[0003] The existing technical approach is to reduce friction through material enhancement, such as providing a wear-resistant coating, a wear-resistant material layer, an elastic rubber layer or an arc-shaped structure.

[0004] For example, Chinese utility model patent CN209724797U discloses a guide shell with an improved structure, in which an insert is arranged on the inner wall of the guide shell body, the insert cooperates with the impeller assembly cavity, and the shape of the insert is adapted to the shape of the inner wall of the corresponding part of the guide shell body, thereby achieving the technical effect of preventing the guide shell from being impacted and worn by mud and sand and improving the service life of the guide shell; however, this scheme resists the impact of mud and sand by the characteristics of the material itself. In an environment with higher mud content and rotation speed, the elasticity and hardness of the material are not enough to offset the impact of mud and sand and fail. Summary of the invention

[0005] In view of the deficiencies in the prior art, one of the purposes of the present application is to provide an erosion-resistant device, a design method and a water pump, which have the advantage of reducing the probability of wear of the guide shell.

[0006] The above-mentioned purpose of the present application is achieved through the following technical solutions: An erosion-resistant device includes a mounting plate, which is annular and located on the inner bottom surface of a guide shell. The mounting plate is provided with at least one groove, which is annular. The groove and the inner side wall of the guide shell form a turbulent flow. The depth H1 of the groove, in m, satisfies: 1, a is the minimum distance between the upper surface of the erosion-resistant device and the impeller front cover, m, is the axial vertical distance from the guide casing base to the impeller front cover corresponding to any radial distance of the mounting plate, unit: m, H is the corresponding The axial height of .

[0007] In a preferred example, the present application can be further configured as follows: the center line of the groove is at an equal distance from the impeller axis when rotating circumferentially.

[0008] In a preferred example, the present application can be further configured as follows: the center line of the groove has different distances from the impeller axis during circumferential rotation.

[0009] In a preferred example, the present application can be further configured as follows: the distance between the center line of the groove and the impeller axis increases with the angle as it rotates circumferentially, with the flow velocity direction of the circulating flow being the positive direction of the angle.

[0010] In a preferred example, the present application can be further configured as follows: the groove does not contact the inner side wall of the guide shell.

[0011] In a preferred example, the present application can be further configured as follows: 0.8.

[0012] In a preferred example, the present application can be further configured as follows: the cross-sectional area formed by the product of the groove width and the groove depth is in the range of 0.01-20 mm².

[0013] In a preferred example, the present application can be further configured as follows: 0.5.

[0014] The present application also discloses a design method of an erosion-resistant device, which is used to design the above-mentioned erosion-resistant device: S1: obtaining the average velocity V of particles at the corner of the guide shell without the erosion-resistant device through CFD software simulation, unit: m / s; S2: Calculation of wear rate of erosion-resistant devices , unit: m / h: Wear rate The unit is kg / (m 2 ·s), where p is the number of particles; is the mass flow rate of particles impacting the wall, unit: kg / s; is the contact area of ​​the erosion-resistant device, unit: m 2 ; is the dimensionless wear rate, unit: kg / kg, which indicates the material mass loss caused by the unit mass of particles acting on the wall surface; The calculation of surface wear is mainly controlled by particle velocity, particle size, impact angle and material hardness parameters. The E / CRC wear model is used to calculate the wear rate. This model is applicable to the wear empirical formula of liquid-solid two-phase flow. The expression is as follows: Where: BH is the Brinell hardness of the wall material, unit: N / mm 2 ; F s The sharpness of the solid particles is the particle shape factor; V p is the particle impact velocity, which refers to the velocity of the particle moving from a distance to the wall rather than the impact velocity after entering the near wall and being affected by the boundary layer; n is the velocity exponent value of 2.41; θ is the impact angle, expressed in radians; C is the empirical coefficient; Replace V with the average particle velocity V p The average wear rate is obtained: The average wear rate of the erosion-resistant device is: Density of material for erosion resistant device , unit is kg / m³, then the wear rate of the device is (unit converted to m / h): S3: Calculate the radial thickness of the diverter protrusion when it is multi-order , unit: m: Assume that the radial thickness of the erosion-resistant device is L, unit: m, and the axial height is H, unit: m. The protrusion forming the groove is defined as the wear-resistant ring. The movement trajectory of the particles in the water pump is mainly determined by the relative magnitude of the centrifugal force and the Coriolis force, and they rotate around the inner wall at the bottom of the guide shell. Assume that the life time required for the normal use of the water pump is T, unit: h, the order of the wear-resistant ring is x, and the radial thickness of the wear-resistant ring is , The minimum value of , calculate the conditions for a single wear-resistant ring structure to meet the life span: ,but ; S4: Calculate the groove depth H1, unit: m: The motion trajectory of particles in the water pump is mainly determined by the relative magnitude of the centrifugal force and the Coriolis force, so the wear rate of the water pump components in the axial direction is The axial component of S5: Calculate the axial height H of the erosion-resistant device, unit: m: The erosion-resistant device is equipped with multiple wear-resistant rings for diversion and reflux. The lack of wear-resistant rings will affect the function. At the same time, in order to ensure that the impeller operation of the fluid is not disturbed, the minimum distance between the upper surface of the erosion-resistant device and the impeller front cover is a, unit: m, value ; Take any radial distance of the erosion-resistant device , unit: m, the axial vertical distance between the corresponding guide casing base and the impeller front cover is , unit: m, we get ,or: 1 S6: Calculate the relationship between the groove width and groove depth and the groove width W, unit: m: Calculate the minimum groove width. Through simulation or experiment, the concentration of sediment and particles in the pump parts is q Kg / m 3 There is a risk of wear on the component structure. The weight of the sand entering the groove after the pump runs smoothly is , unit kg, then the concentration per unit volume: The outer wall of the groove The corresponding perimeter at the point, since dq needs to be no greater than the concentration q, therefore, Can guarantee the concentration range; then: S7: Calculate the radial thickness L of the erosion-resistant device, unit: m; S8: Calculate the minimum radial thickness of the wear ring of a multistage pump at different stages Unit: m, and groove depth , unit: m: The higher the number of stages, the greater the risk of wear. Assuming the number of water pump stages is m, the wear rate of the m-th stage water pump is , then the minimum radial thickness of the wear ring at the m-th stage water pump is: Groove depth of the erosion-resistant device at the mth-stage water pump: .

[0015] The present application also discloses a water pump: the water pump adopts the above-mentioned erosion-resistant device.

[0016] The present application has the following advantages: the groove can separate the flow at the bottom of the guide shell and form a turbulent flow. The side wall of the groove can reduce the flow velocity of the medium near the inner wall of the guide shell and generate an upward reflux, thereby preventing sediment from accumulating in the groove part and reducing the wear on the guide shell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the cross-sectional structure of the pump of this application.

[0018] Figure 2 This is a schematic diagram of the groove structure of this application Figure 1 .

[0019] Figure 3 This is a schematic diagram of the groove structure of this application Figure 2 .

[0020] Figure 4 This is a schematic diagram of the groove structure of this application Figure 3 .

[0021] Figure 5 This is a schematic diagram of the groove structure of this application Figure 4 .

[0022] Figure 6 It is a schematic diagram of the radius of the outer side wall of the groove of this application.

[0023] Figure 7 It is a schematic diagram of the height and width of the erosion-resistant device of the present application.

[0024] Figure 8 is any radial distance of the erosion-resistant device of the present application Schematic diagram.

[0025] Fig. 9 It is a schematic diagram of particle diversion and reflux in this application.

[0026] Fig.10 It is a comparison diagram of the embodiments of the present application and the comparative example.

[0027] Figure numerals: 1, mounting plate; 11, groove; 12, wear-resistant ring. DETAILED DESCRIPTION

[0028] The following is combined with Figure 1-10 This application is described in further detail.

[0029] Fig. 9 In the figure, the arrow direction is the particle movement direction. Fig.10 In the examples, the comparative example is a water pump without the erosion-resistant device of the present application, and the example is a water pump with the erosion-resistant device of the present application.

[0030] The present application discloses an erosion-resistant device, including a mounting plate 1. The mounting plate 1 is annular and can be integrally formed with the guide shell and is located on the inner bottom surface of the guide shell. At least one groove 11 is provided on the mounting plate 1. The groove 11 is annular. The groove 11 and the inner wall of the guide shell form a turbulent flow for the water flow. The width of the groove 11 ranges from 0.01 to 10 mm, and the interval between adjacent grooves 11 is 0.5 to 10 mm. The protrusion forming the groove 11 is defined as a wear-resistant ring 12, that is, the width of the wear-resistant ring 12 is 0.5 to 10 mm, and the width of the wear-resistant ring 12 may also be unequal. The center line of the groove 11 is at an equal distance from the impeller axis when rotating circumferentially. In other embodiments, the center line of the groove 11 is at an unequal distance from the impeller axis when rotating circumferentially, refer to Figure 3 , with the flow velocity direction of the circulation as the positive direction of the angle, the distance between the center line of the groove 11 and the impeller axis increases with the angle as it rotates circumferentially. The groove 11 is in contact with or not in contact with the inner wall of the guide shell. That is, the groove 11 includes but is not limited to circular, wavy and flat spiral shapes, and the cross-section of the groove 11 includes but is not limited to V-shaped, C-shaped or rectangular, etc. When there are multiple grooves 11, the groove widths of the grooves 11 may not be equal. The mounting plate 1 may be cylindrical or plate-shaped. The groove 11 may be formed by two adjacent wear-resistant rings 12, or by a wear-resistant ring 12 and the inner wall of the guide shell. When the mounting plate 1 is cylindrical, it may also be formed by a wear-resistant ring 12 and the inner wall of the mounting plate 1.

[0031] The upper surface of a single or multiple wear-resistant rings 12 may be a plane, a conical surface or other revolution surface. That is, the cross section of the upper surface of the erosion-resistant device may be a revolution or non-revolution surface formed by a curve, an oblique line, a broken line or the like.

[0032] The cross-sectional area formed by the product of the groove width and the groove depth ranges from 0.01 to 20 mm². The groove depth H1, in m, satisfies: ,or: 1, a is the minimum distance between the upper surface of the erosion-resistant device and the impeller front cover, m, H is the axial height of the mounting plate, unit: m, The axial vertical distance between the guide casing base and the impeller front cover plate corresponding to any radial distance of the mounting plate, unit: m. When it is outside the projection range of the impeller, The axial vertical distance between the guide casing base position and the extended line of the lower surface of the impeller front cover plate corresponding to any radial distance of the mounting plate. When it is within the groove range, H is the upper surface of the groove and The distance from the intersection point to the bottom.

[0033] The present application also discloses a design method. Figure 2For example, the following steps are included. It should be noted that the numbers S1, S2, etc. are only for the convenience of description and do not necessarily represent a certain order.

[0034] S1: The average velocity V of particles at the corner of the guide shell without erosion resistance device is obtained by CFD software simulation, unit: m / s; S2: Calculation of wear rate of erosion-resistant devices , unit: m / h: Wear rate The unit is kg / (m 2 ·s), where p is the number of particles; is the mass flow rate of particles impacting the wall, unit: kg / s; is the contact area of ​​the erosion-resistant device, unit: m 2 ; It is the dimensionless wear rate, unit: kg / kg, which represents the material mass loss caused by the unit mass of particles acting on the wall.

[0035] The calculation of surface wear is mainly controlled by particle velocity, particle size, impact angle and material hardness parameters. The present invention uses the E / CRC (Erosion / Corrosion Research Center) wear model to calculate the wear rate. The model is applicable to the wear empirical formula of liquid-solid two-phase flow, and the expression is as follows: Where: BH is the Brinell hardness of the wall material, unit: N / mm 2 ; F s The sharpness of the solid particles is the particle shape coefficient. According to the actual selection, F s =1.0 means sharp polygonal particles, F s =0.5 for round and blunt particles, F s =0.2 means regular spherical particles; V p is the particle impact velocity, which refers to the velocity of the particle moving from a distance to the wall rather than the impact velocity after entering the near wall and being affected by the boundary layer; n is the velocity exponent value of 2.41; θ is the impact angle, expressed in radians; C is the empirical coefficient, with a specific value of 2.17×10 -7 ; A i(i=1~5) The specific values ​​are 5.3983, -10.1068, 10.9327, -6.3283, 1.4234; Replace V with the average particle velocity V p The average wear rate is obtained: The average wear rate of the erosion-resistant device is: Material density of erosion resistant device , unit kg / m³, then the wear rate of the device is: S3: Calculate the radial thickness of the diverter protrusion when it is multi-order , unit: m: Assume that the erosion-resistant device, i.e. the mounting plate (more specifically, the distance from the inner ring of the structure to the inner wall of the guide shell) has a radial thickness of L, unit: m, an axial height of H, unit: m, and the annular diversion protrusion is defined as a wear-resistant ring; the movement trajectory of particles in the water pump is mainly determined by the relative magnitude of the centrifugal force and the Coriolis force, and they rotate around the inner wall surface at the bottom of the guide shell. Assume that the life time required for the normal use of the water pump is T, unit: h, the order of the wear-resistant ring of the erosion-resistant device is x, and the radial thickness of the wear-resistant ring is , The minimum value of , calculate the conditions for a single wear-resistant ring structure to meet the life span: ,but ; S4: Calculate the groove depth H1 (m): Because the movement trajectory of particles in the water pump is mainly determined by the relative magnitude of centrifugal force and Coriolis force. The wear rate of the water pump components in the axial direction is The axial component of .

[0036] S5: Calculate the axial height H of the erosion-resistant device, unit: m: The erosion-resistant device is equipped with multiple wear-resistant rings for diversion and reflux. The lack of wear-resistant rings will affect the function. At the same time, in order to ensure that the impeller operation of the fluid is not disturbed, the minimum distance between the upper surface of the erosion-resistant device and the impeller front cover is a, unit: m, value ; Take any radial distance of the erosion-resistant device , unit: m, the axial vertical distance between the corresponding guide casing base and the impeller front cover is , unit: m, we get ,or: 1 S6: Calculate the relationship between the groove width and groove depth and the groove width W, unit: m: Calculate the minimum groove width. Through simulation or experiment, the concentration of sediment and particles in the pump parts is q Kg / m 3 There is a risk of wear on the component structure. The weight of the sand entering the groove after the pump runs smoothly is , then the concentration per unit volume is: The outer wall of the groove The corresponding perimeter at the point, since dq needs to be no greater than the concentration q, therefore, Can guarantee the concentration range; then: Under different wear concentrations, obtained through software and experiments The optimal range is 0.01-20mm²; At the same time, when the groove width W of the erosion-resistant device is too wide to achieve the diversion wear-resistant effect, W is preferably 0.01-10 mm; S7: Calculate the radial thickness L (m) of the erosion-resistant device; S8: Calculate the minimum radial thickness of the wear ring of the erosion device of a multistage pump at different stages Unit: m and groove depth , unit: m: According to the results of the water pump wear test, the higher the level, the greater the wear risk. Assuming the water pump level is m, the wear rate of the m-th level water pump is , then the minimum radial thickness of the wear ring of the erosion-resistant device at the m-th stage water pump is: Groove depth of the erosion-resistant device at the mth-stage water pump: .

[0037] The present application also discloses a water pump: the water pump adopts the above-mentioned erosion-resistant device.

[0038] The implementation principle of this embodiment is as follows: by arranging a groove extending toward the axis along the inner wall of the guide shell, the groove can separate the flow at the bottom of the guide shell and form a turbulent flow, which not only reduces the medium flow velocity near the side wall of the guide shell but also generates an upward reflux to prevent sediment from accumulating in the groove part. The wear-resistant ring shunts the medium flow at the side wall of the guide shell at the groove, forms a reflux or eddy current at the wear-resistant ring, reduces the flow velocity there and prevents sediment from accumulating there.

[0039] 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 erosion-resistant device, characterized in that: It includes a mounting plate, which is annular and located on the inner bottom surface of the guide shell. The mounting plate is provided with at least one groove, which is annular. The groove and the inner wall of the guide shell form a turbulent flow. The depth H1 of the groove, unit: m, satisfies: 1, a is the minimum distance between the upper surface of the erosion-resistant device and the impeller front cover, m, is the axial vertical distance from the guide casing base to the impeller front cover corresponding to any radial distance of the mounting plate, unit: m, H is the corresponding The axial height at is in m.

2. The erosion-resistant device according to claim 1, characterized in that: The center line of the groove is at the same distance from the impeller axis when rotating in the circumferential direction.

3. The erosion-resistant device according to claim 1, characterized in that: The distance between the center line of the groove and the impeller axis varies during circumferential rotation.

4. The erosion-resistant device according to claim 3, characterized in that: The distance between the center line of the groove and the impeller axis increases with the angle when the groove rotates in the circumferential direction, with the velocity direction of the circulating flow as the positive direction of the angle.

5. The erosion-resistant device according to claim 1, characterized in that: The groove does not contact the inner side wall of the guide shell.

6. The erosion-resistant device according to claim 1, characterized in that: 0.8。 7. The erosion-resistant device according to claim 1, characterized in that: The cross-sectional area formed by the product of the groove width and the groove depth ranges from 0.01 to 20 mm².

8. The erosion-resistant device according to claim 1, characterized in that: 0.5。 9. A method for designing an erosion-resistant device, used for designing an erosion-resistant device as claimed in any one of claims 1 to 8, characterized in that: The method comprises the following steps: a wear step, calculating the wear rate that the medium can produce; A height calculation step, calculating the axial height H and the groove depth H1 of the erosion-resistant device; The relationship calculation step calculates the relationship between the groove width and the groove depth and the width W of the groove.

10. A water pump, characterized in that: A erosion-resistant device as described in any one of claims 1 to 8 is used.

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