An erosion-resistant device, design method and water pump

Abstract

This application relates to an erosion-resistant device, belonging to the technical field of water pumps, including a mounting plate. The mounting plate is annular and located on the inner bottom surface of the guide housing. There is at least one groove on the mounting plate, and the groove is annularly arranged. The groove and the inner side wall of the guide housing cause the water flow to form a turbulent flow. The depth H1 of the groove, unit: m, satisfies: #imgabs0#1, where a is the minimum distance between the upper surface of the erosion-resistant device and the front cover plate of the impeller, #imgabs1#m, #imgabs2# is the axial vertical distance from the corresponding position of the guide housing base at any radial distance of the mounting plate to the front cover plate of the impeller, unit: m, and H is the axial height at the #imgabs3# corresponding to the mounting plate. This application has the advantage of being able to reduce the probability of wear of the guide housing.

Description

Technical Field

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

[0002] Sediments and particles drive water flow to continuously impact and rub water pump components as the impeller rotates. The solid-liquid two-phase flow transport medium with a large proportion will reduce the pump performance. After long-term operation, even situations such as wear failure of hydraulic components and wear and fracture of the diffuser shell often occur, seriously affecting the normal use of the water pump; that is, under the action of the impeller, part of the sediment has a diversion that converges to the bottom of the diffuser shell after passing through the impeller outlet, and since the area between the front cover plate of the impeller and the diffuser shell is not the main flow range of the medium, a region with a relatively small flow velocity is formed from the impeller axis outward, causing sediment to accumulate. Therefore, under the action of the circulating flow generated on the outer periphery of the impeller, the sediment impacts the side wall of the diffuser shell at a high speed, resulting in wear and even fracture.

[0003] The existing technical path is to reduce friction through methods of material enhancement, such as setting wear-resistant coatings, wear-resistant material layers, elastic rubber layers, or arc structures.

[0004] For example, the Chinese utility model patent CN209724797U discloses a diffuser shell with an improved structure. By setting inserts on the inner wall of the diffuser shell body, the inserts are matched with the impeller assembly cavity, and the shape of the inserts is adapted to the shape of the inner wall of the corresponding part of the diffuser shell body, thereby achieving the technical effect of being able to avoid the diffuser shell from being impacted and worn through by sediment and improving the service life of the diffuser shell; however, this solution resists sediment impact through the characteristics of the material itself. In an environment with a higher sediment content and rotational speed, the elasticity and hardness of the material are not sufficient to offset the sediment impact and thus fail. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, 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 being able to reduce the probability of wear of the diffuser shell.

[0006] The above object of the present application is achieved through the following technical solutions:

[0007] An erosion-resistant device includes a mounting plate. The mounting plate is annular and located on the inner bottom surface of the diffuser shell. At least one groove is provided on the mounting plate. The groove is annularly arranged. The groove and the inner side wall of the diffuser shell cause the water flow to 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 front cover plate of the impeller, m, The axial vertical distance from the position of the base of the flow guiding shell corresponding to any radial distance of the mounting plate to the front cover plate of the impeller, unit: m, and H is the axial height at the position corresponding to the mounting plate. The axial height at the position.

[0008] In a preferred example of the present application, it can be further configured that: the distance between the midline of the groove and the axis of the impeller is equal when the midline of the groove rotates circumferentially.

[0009] In a preferred example of the present application, it can be further configured that: the distance between the midline of the groove and the axis of the impeller is unequal when the midline of the groove rotates circumferentially.

[0010] In a preferred example of the present application, it can be further configured that: the distance between the midline of the groove and the axis of the impeller increases with the angle when the midline of the groove rotates circumferentially, with the flow velocity direction of the circulating flow as the positive direction of the angle.

[0011] In a preferred example of the present application, it can be further configured that: the groove does not contact the inner side wall of the flow guiding shell.

[0012] In a preferred example of the present application, it can be further configured that: 0.8.

[0013] In a preferred example of the present application, it can be further configured that: the cross-sectional area formed by the product of the width and the depth of the groove ranges from 0.01 to 20 mm².

[0014] In a preferred example of the present application, it can be further configured that: 0.5.

[0015] The present application also discloses a design method for an erosion-resistant device for designing an erosion-resistant device as described above: S1: Obtain the average velocity V of particles at the corner of the flow guiding shell without the erosion-resistant device through CFD software simulation, unit: m / s;

[0016] S2: Calculate the wear rate of the erosion-resistant device , unit: m / h:

[0017]

[0018] Wear rate The unit of is kg / (m 2 ·s), where p is the number of particles; is the mass flow rate of particles impinging on the wall surface, unit: kg / s; is the contact area of the erosion-resistant device, unit: m 2 ; is the dimensionless wear rate, unit: kg / kg, representing the amount of material mass loss caused by the action of particles of unit mass on the wall surface;

[0019] 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, which is an empirical formula applicable to liquid-solid two-phase flow wear. The expression is as follows:

[0020]

[0021]

[0022] In the formula: BH is the Brinell hardness of the wall material, unit: N / mm 2 ;

[0023] F s is the sharpness of solid particles and is the particle shape coefficient;

[0024] V p is the particle impact velocity, which refers to the velocity of the particle moving from a distance towards the wall rather than the impact velocity after entering the near-wall region affected by the boundary layer; n is the velocity exponent value of 2.41;

[0025] θ is the impact angle, expressed in radians;

[0026] C is the empirical coefficient;

[0027] Substitute the average particle velocity V for V p to obtain the average wear rate:

[0028] Then the average wear rate of the erosion-resistant device is:

[0029]

[0030] Assume the density of the erosion-resistant device material , unit: kg / m³, then the wear rate of this device (unit converted to m / h) is:

[0031]

[0032] S3: Calculate the radial thickness when the flow diversion protrusion is of multiple orders , unit: m:

[0033] Assume the radial thickness L of the erosion-resistant device, unit: m, the axial height H, unit: m, and the protrusion forming the groove is defined as the wear-resistant ring; the movement trajectory of particles in the water pump is mainly determined by the relative magnitudes of centrifugal force and Coriolis force, rotating around the inner wall surface at the bottom of the guide shell. Assume the required service life of the water pump is T, unit: h, the number of orders 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 service life:

[0034] , then ;

[0035] S4: Calculate the groove depth H1, unit: m:

[0036] The movement trajectory of particles in the water pump is mainly determined by the relative magnitudes of the centrifugal force and the Coriolis force. Then, the wear rate of the water pump component in the axial direction is The axial component of, denoted as

[0037]

[0038] S5: Calculate the axial height H of the erosion-resistant device, unit: m:

[0039] The erosion-resistant device is provided with multiple wear-resistant rings for the functions of diversion and reflux. The absence of the wear-resistant ring will affect the function. At the same time, to ensure that the operation of the impeller of the fluid is not disturbed, the minimum distance between the upper surface of the erosion-resistant device and the front cover of the impeller is a, unit: m, and the value is ;

[0040] Take any radial distance of the erosion-resistant device, unit: m. The axial vertical distance from the position of the bottom of the guide shell to the front cover of the impeller is , unit: m, and it is obtained that , or:

[0041] 1

[0042] S6: Calculate the dimensional relationship between the groove width and the groove depth and the groove width W, unit: m:

[0043] Calculate the minimum value of the groove width. Through simulation or experiment, it is obtained that when the sediment and particle concentration in the water pump component is q Kg / m 3 , there is a risk of wear to 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 is:

[0044]

[0045] is the perimeter corresponding to the on the outer wall of the groove. Since dq needs to be no greater than the concentration q, therefore, taking can ensure the concentration range; then:

[0046]

[0047] S7: Calculate the radial thickness L of the erosion-resistant device, unit: m;

[0048]

[0049] S8: Calculate the minimum radial thickness of the wear-resistant ring at different stages of the multi-stage pump Unit: m, and the groove depth , unit: m:

[0050] The higher the number of stages, the greater the wear risk. Let the number of stages of the water pump be m, and the wear rate of the m-th stage water pump be , then the minimum radial thickness of the wear-resistant ring at the m-th stage water pump:

[0051]

[0052] The groove depth of the erosion-resistant device at the m-th stage water pump: .

[0053] This application also discloses a water pump: adopting the above-mentioned erosion-resistant device.

[0054] This application has the following advantages. The groove can divide the shunt flowing to the bottom of the guide casing into grooves for flow isolation and form a turbulent flow. Combining with the side wall of the groove, it not only reduces the flow velocity of the medium near the inner wall of the guide casing but also generates an upward backflow, thus preventing sediment from accumulating in the groove part and reducing the wear of the guide casing. Description of the Drawings

[0055] Figure 1 is the schematic cross-sectional structure diagram of the pump in this application.

[0056] Figure 2 is the schematic diagram of the groove structure in this application Figure 1 .

[0057] Figure 3 is the schematic diagram of the groove structure in this application Figure 2 .

[0058] Figure 4 is the schematic diagram of the groove structure in this application Figure 3 .

[0059] Figure 5 is the schematic diagram of the groove structure in this application Figure 4 .

[0060] Figure 6 is the schematic diagram of the radius of the outer wall of the groove in this application.

[0061] Figure 7 is the schematic diagram of the height and width of the erosion-resistant device in this application.

[0062] Figure 8 is any radial distance of the erosion-resistant device in this application Schematic diagram.

[0063] Figure 9 It is a schematic diagram of particle shunting and refluxing in this application.

[0064] Figure 10 It is a comparison diagram of the embodiments and comparative examples of this application.

[0065] Reference numerals: 1, mounting plate; 11, groove; 12, wear-resistant ring. Detailed implementation manners

[0066] The following further elaborates on this application in conjunction with the attached Figures 1-10 drawings.

[0067] Figure 9 In [the figure], the arrow direction is the particle movement direction. Figure 10 In [the figure], the comparative example is a water pump without the erosion-resistant device in this application, and the embodiment is a water pump with the erosion-resistant device of this application installed.

[0068] This application discloses an erosion-resistant device, including a mounting plate 1. The mounting plate 1 is annular, and the mounting plate 1 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 arranged in a ring shape. The groove 11 and the inner side wall of the guide shell cause the water flow to form a turbulent flow. The width value range of the groove 11 is 0.01 - 10 mm, and the interval between adjacent grooves 11 is 0.5 - 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 - 10 mm, and the widths of the wear-resistant rings 12 may not be equal. The midline of the groove 11 is at an equal distance from the impeller axis when rotating circumferentially. In other embodiments, the distance between the midline of the groove 11 and the impeller axis is not equal when rotating circumferentially. Referring to Figure 3 , with the flow velocity direction of the circulating flow as the positive direction of the angle, the distance between the midline of the groove 11 and the impeller axis increases with the increase of the angle when rotating circumferentially. The groove 11 is in contact or not in contact with the inner side wall of the guide shell. That is, the groove 11 includes but is not limited to circular, wavy, and planar 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 widths of the grooves 11 may not be equal. The mounting plate 1 can be cylindrical or plate-shaped. The groove 11 can be formed by two adjacent wear-resistant rings 12, or can be formed by a wear-resistant ring 12 and the inner side wall of the guide shell. When the mounting plate 1 is cylindrical, it can also be formed by a wear-resistant ring 12 and the inner side wall of the mounting plate 1.

[0069] The surface formed by the upper surface of a single or multiple wear-resistant rings 12 can be a plane, a conical surface, or other rotating surfaces. That is, the cross-section of the upper surface of the erosion-resistant device can be a rotating body or a non-rotating body surface formed by shapes such as curves, oblique lines, and broken lines.

[0070] The cross-sectional area formed by the product of the width and depth of the groove ranges from 0.01 to 20 mm². The depth H1 of the groove, in units of m, satisfies: or: 1, where a is the minimum distance between the upper surface of the erosion-resistant device and the front cover plate of the impeller, m, H is the axial height of the mounting plate, in units of m, is the axial vertical distance from the position of the base of the guide shell corresponding to any radial distance of the mounting plate to the front cover plate of the impeller, in units of m. When is outside the projection range of the impeller, is the axial vertical distance from the position of the base of the guide shell corresponding to any radial distance of the mounting plate to the extension line of the lower surface of the front cover plate of the impeller. When is within the groove range, H is the distance from the intersection of the upper surface of the groove and to the bottom.

[0071] This application also discloses a design method. Taking Figure 2 as an example, it includes the following steps. It should be noted that labels such as S1 and S2 are only for convenience of description and do not represent an inevitable sequence.

[0072] S1: Obtain the average velocity V of the particles at the corner of the guide shell without the erosion-resistant device through CFD software simulation, in units of m / s;

[0073] S2: Calculate the wear rate of the erosion-resistant device , in units of m / h:

[0074]

[0075] The wear rate is in units of kg / (m 2 ·s), where p is the number of particles; is the mass flow rate of the particles impacting on the wall surface, in units of kg / s; is the contact area of the erosion-resistant device, in units of m 2 ; is the dimensionless wear rate, in units of kg / kg, representing the mass loss of the material caused by the action of particles of unit mass on the wall surface.

[0076] 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. This model is applicable to the wear empirical formula of liquid-solid two-phase flow, and the expression is as follows:

[0077]

[0078]

[0079] Where: BH is the Brinell hardness of the wall material, unit: N / mm 2 ;

[0080] F s is the sharpness of the solid particles and is the particle shape factor, which is selected according to the actual situation. F s = 1.0 represents sharp polygonal particles, F s = 0.5 represents round and blunt particles, F s = 0.2 represents regular spherical particles;

[0081] 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 region affected by the boundary layer; n is the velocity exponent value of 2.41;

[0082] θ is the impact angle, expressed in radians;

[0083] C is the empirical coefficient, and the specific value is 2.17×10 -7 ;

[0084] A i (i = 1~5), and the specific values are 5.3983, -10.1068, 10.9327, -6.3283, 1.4234 respectively;

[0085] Replace the average particle velocity V with V p to obtain the average wear rate:

[0086] Then the average wear rate of the erosion-resistant device is:

[0087]

[0088] Assume the density of the erosion-resistant device material , unit kg / m³, then the wear rate of this device is:

[0089]

[0090] S3: Calculate the radial thickness when the diversion protrusion is of multiple orders , unit: m:

[0091] Set the erosion-resistant device, that is, the radial thickness L of the mounting plate (more specifically, the distance from the inner circle of the structure to the inner wall of the diversion shell), unit: m, the axial height H, unit: m, and the annular diversion protrusion is defined as the wear-resistant ring; the movement trajectory of the particles in the water pump is mainly determined by the relative magnitudes of the centrifugal force and the Coriolis force, and rotates around the inner wall surface at the bottom of the diversion shell. Let the required service life of the water pump be T, unit: h, the order of the wear-resistant ring of the erosion-resistant device be x, and the radial thickness of the wear-resistant ring be , The minimum value of , calculate the condition for a single wear-resistant ring structure to meet the service life:

[0092] , then ;

[0093] S4: Calculate the groove depth H1 (m):

[0094] Because the movement trajectory of the particles in the water pump is mainly determined by the relative magnitudes of the centrifugal force and the Coriolis force. Then the wear rate of the water pump components in the axial direction is The axial component of .

[0095]

[0096] S5: Calculate the axial height H of the erosion-resistant device, unit: m:

[0097] The function of setting multiple wear-resistant rings in the erosion-resistant device is to divert and reflux. The absence of the wear-resistant ring will affect the function. At the same time, to ensure that the operation of the impeller of the fluid is not disturbed, the minimum distance between the upper surface of the erosion-resistant device and the front cover plate of the impeller is a, unit: m, and the value ;

[0098] Take any radial distance of the erosion-resistant device, unit: m, and the axial vertical distance from the corresponding position of the diversion shell base to the front cover plate of the impeller is , unit: m, and it is obtained that , or:

[0099] 1

[0100] S6: Calculate the dimensional relationship between the groove width and the groove depth and the groove width W, unit: m:

[0101] Calculate the minimum value of the groove width. Through simulation or experiment, it is obtained that when the concentration of sediment and particles in the water pump components is q Kg / m 3 , there is a risk of wear to the component structure. The weight of the sand entering the groove after the pump runs smoothly is , then the concentration per unit volume:

[0102]

[0103] For the outer wall of the groove At the corresponding perimeter, since dq needs to be no greater than the concentration q, therefore, take Can ensure the concentration range; then:

[0104]

[0105] Under different wear concentrations, obtained through software and experiments The optimal range is 0.01 - 20 mm²;

[0106] Meanwhile, when the groove width W of the erosion - resistant device is too wide to achieve the shunt and wear - resistant effect, then W is preferably 0.01 - 10 mm;

[0107] S7: Calculate the radial thickness L (m) of the erosion - resistant device;

[0108]

[0109] S8: Calculate the minimum radial thickness of the wear - resistant ring of the erosion - resistant device under different stages of the multi - stage pump Unit: m and the groove depth , unit: m:

[0110] According to the water pump wear - resistant test results, the higher the number of stages, the greater the wear risk. Let the number of stages of the water pump be m, and the wear rate of the m - th stage water pump is , then the minimum radial thickness of the wear - resistant ring of the erosion - resistant device at the m - th stage water pump:

[0111]

[0112] The groove depth of the erosion - resistant device at the m - th stage water pump: .

[0113] This application also discloses a water pump: adopting the above - mentioned erosion - resistant device.

[0114] The implementation principle of this embodiment is: by setting grooves that expand from the inner wall of the guide housing towards the axis, so that the grooves can divide the shunt towards the bottom of the guide housing into sub - grooves for isolation and form turbulent flow, which not only reduces the medium flow velocity near the side wall of the guide housing but also generates an upward backflow to prevent sediment from accumulating in the groove part. The wear - resistant ring forms a shunt for the medium flow at the side wall of the guide housing at the groove, forms a backflow or eddy current at the wear - resistant ring, reduces the flow velocity at that place and prevents sediment from gathering there.

[0115] The embodiments of the specific implementation manners are all preferred embodiments of the present application, and do not limit the protection scope of the present application. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application shall be covered within 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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