Pump core, multi-stage pump and design method of multi-stage pump

Abstract

The invention relates to a pump core, a multistage pump and a design method thereof, and relates to the technical field of multistage pumps, the pump core comprises an impeller, the impeller comprises a front cover plate, blades and a rear cover plate, and the diameter of the rear cover plate is smaller than that of the front cover plate. The method has the advantage of being high in efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of multi-stage pumps, in particular to a pump core, a multi-stage pump and a design method thereof. BACKGROUND

[0002] A multi-stage pump is a centrifugal pump that obtains high lift by the series work of multiple impellers. The multi-stage pump is usually used to pressurize a circulating cooling system in the energy storage field. The traditional multi-stage pump has a complex structure, a large volume and low efficiency. SUMMARY

[0003] In view of the deficiencies in the prior art, one of the purposes of the present application is to provide a pump core, a multi-stage pump and a design method thereof, which have the advantage of high efficiency.

[0004] The above purpose of the present application is achieved by the following technical solutions: A pump core comprises an impeller, the impeller comprising a front cover plate, blades and a rear cover plate, the diameter of the rear cover plate being smaller than the diameter of the front cover plate.

[0005] In a preferred example, the present application can be further configured as: the diameter of the rear cover plate / the diameter of the front cover plate = 0.8-0.99.

[0006] In a preferred example, the present application can be further configured as: the inter-stage axial length of adjacent impellers is , , , , wherein, is the inside distance between the front cover plate and the rear cover plate of the impeller, in mm, is an axial length calculation coefficient, the value range being 1-3, the rated flow of the multi-stage pump being , in m 3 / h, the impeller inlet diameter being , in mm, the front cover plate diameter being , in mm, is the rear cover plate diameter, in mm.

[0007] The present application also discloses a design method of a pump core, comprising the following steps: S1: calculating the reference speed of the impeller inlet ; S2: calculating the axial outflow under the condition that the diameter of the rear cover plate is smaller than the diameter of the front cover plate ; S3: calculating the outflow speed of the impeller according to the cut axial outflow ; S4: determine the axial length according to the inter-stage axial length calculation formula .

[0008] In a preferred example, the application can be further configured to, in step S1, wherein the rated flow of the multi-stage pump is , unit: m 3 / h, the inlet diameter , unit: mm.

[0009] In a preferred example, the application can be further configured to, in step S2, wherein the front cover plate diameter is , unit: mm, is the rear cover plate diameter, unit: mm; is the inside distance between the front cover plate and the rear cover plate of the impeller, unit: mm.

[0010] In a preferred example, the application can be further configured to, in step S3, wherein the front cover plate diameter is , unit: mm, is the rear cover plate diameter, unit: mm.

[0011] In a preferred example, the application can be further configured to, in step S4, wherein, is the inside distance between the front cover plate and the rear cover plate of the impeller, unit: mm, is the axial length calculation coefficient, the value range is 1-3.

[0012] The application also discloses a multi-stage pump adopting the pump core or the pump core obtained by the design method.

[0013] The application has the following advantages: By reducing the diameter of the rear cover plate of the impeller and designing the inter-stage axial length according to the diameter reduction, the efficiency is improved, that is, the multi-stage pump does not use the positive guide vane in order to reduce the diameter. The fluid from the impeller directly impacts the pump shell in the radial direction and then enters the counter guide vane, causing a great loss of impact on the pump shell. By making the diameter of the rear cover plate of the impeller smaller than that of the front cover plate, part of the fluid of the impeller enters the counter guide vane along the axial direction through the reduced part, reducing the loss of impact on the pump shell. Further, by controlling the axial length, the fluid is fully developed and uniform, further reducing the loss of entering the counter guide vane. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a schematic view of the cross-sectional structure of the application.

[0015] Figure 2Figure 1 is a schematic diagram of the impeller structure of the present application.

[0016] Figure 1 is a schematic diagram of the impeller structure of the present application. DETAILED DESCRIPTION

[0017] The present application is further described in detail below with reference to the accompanying drawings.

[0018] Reference Figure 1 and Figure 2 , the present application discloses a pump core, comprising an impeller, the impeller comprising a front cover plate 1, a blade and a rear cover plate 2, the diameter of the rear cover plate 2 is smaller than the diameter of the front cover plate 1, the diameter of the rear cover plate / the diameter of the front cover plate = 0.8~0.99. There can be multiple impellers, the diameter of the rear cover plate 2 of one or more impellers can be smaller than the diameter of the corresponding front cover plate 1, the difference between the diameter of the rear cover plate 2 and the diameter of the corresponding front cover plate 1 of each impeller can be the same or different, for example, the diameter of the rear cover plate 2 of the first impeller is 0.1 unit length smaller than the diameter of the corresponding front cover plate 1, the diameter of the rear cover plate 2 of the second impeller is 0.2 unit length smaller than the diameter of the corresponding front cover plate 1, or the diameter of the rear cover plate 2 of each impeller is the same unit length smaller than the diameter of the corresponding front cover plate 1.

[0019] The inter-stage axial length of adjacent impellers is , , , , , wherein is the inside distance between the front cover plate and the rear cover plate of the impeller, unit: mm, is the axial length calculation coefficient, the value range is 1-3, the rated flow of the multi-stage pump is , unit: m 3 / h, the impeller inlet diameter is , unit: mm, the front cover plate diameter is , unit: mm, is the rear cover plate diameter, unit: mm.

[0020] The present application also discloses a design method of a pump core, the diameters of the front cover plate 1 and the rear cover plate 2 are the same, in order to facilitate description, taking the size of the rear cover plate 2 obtained after cutting and trimming the rear cover plate 2 as an example, comprising the following steps: S1: calculating the reference speed of the impeller inlet ; S2: calculating the axial outflow under the condition that the diameter of the rear cover plate 2 is smaller than the diameter of the front cover plate 1 ; S3: calculating the outflow speed according to the axial outflow after cutting ; S4: determine axial length by combining inter-stage axial length calculation formula (Axial length L is only associated with the size of the rear cover plate 2 of the corresponding impeller).

[0021] More specifically S1: calculate the reference velocity of the impeller inlet according to the fluid mechanics velocity calculation formula As shown in formula (1): (1) S2: distribute the flow using the outflow area to calculate the axial outflow after cutting the rear cover plate 2 As shown in formulas (2) and (3): (2) (3) Wherein: d is the and the cutting radial length, unit: mm, the front cover plate diameter is , unit: mm, is the diameter of the impeller rear cover plate 2 after cutting, unit is ; is the inside distance between the front cover plate and the rear cover plate of the impeller, unit is .

[0022] S3: according to the axial outflow after cutting , the outflow velocity can be calculated As shown in formula (4): (4) S4: determine axial length by combining inter-stage axial length calculation formula As shown in formula (5): (5) Wherein: is the axial length calculation coefficient, if the pump length requirement is short, take ; if the pump efficiency requirement is high, take ; if the pump vibration noise requirement is low, take .

[0023] Take a multi-stage pump as an example, a multi-stage pump rated flow , inlet diameter , impeller rear cover plate 2 diameter , rear cover plate 2 cutting length , inside distance between the front cover plate and the rear cover plate 2 of the impeller .

[0024] S1: calculate the reference velocity of the impeller inlet according to the fluid mechanics velocity calculation formula As shown in formula (1): (1) S2: Adopt the outflow area to distribute the flow, and calculate the axial outflow after the back cover plate 2 is cut , as shown in formulas (2) and (3): (2) (3) In the formula, d is the radial length after cutting, the unit is mm, and the diameter of the front cover plate is , is the diameter of the back cover plate 2 of the impeller after cutting, and the unit is ; is the inside distance between the front and back cover plates 2 of the impeller, and the unit is .

[0025] S3: According to the axial outflow after cutting , the outflow velocity can be calculated , as shown in formula (4): (4) S4: The axial length can be calculated and determined in combination with the inter-stage axial length calculation formula , as shown in formula (5): (5) In the formula, is the axial length calculation coefficient, if the pump length requirement is short, take ; if the pump efficiency requirement is high, take ; if the pump vibration and noise requirement is low, take . Select . Finally, the inter-stage axial length of the multi-stage pump is obtained according to the above calculation.

[0026] The application also discloses a multi-stage pump adopting the pump core or the pump core obtained by the design method. When the multi-stage pump adopts the pump core or the pump core obtained by the design method, the diameter of the back cover plate of one or more impellers in the pump core is smaller than the diameter of the corresponding front cover plate.

[0027] The implementation principle of the embodiment is that the diameter of the back cover plate 2 of the impeller is reduced, and the inter-stage axial length is designed according to the diameter reduction amount, so that the efficiency is improved.

[0028] The embodiments of the specific embodiment are preferred embodiments of the application, but do not limit the protection scope of the application, so that: any equivalent changes made according to the structure, shape, principle of the application should be covered in the protection scope of the application.

Claims

1. A pump core, characterized by: The impeller comprises a front cover plate, blades and a rear cover plate, and the diameter of the rear cover plate is smaller than that of the front cover plate.

2. A pump core according to claim 1, characterized in that: The diameter of the rear cover plate / the diameter of the front cover plate = 0.8~0.

99.

3. A pump core according to claim 1, characterized in that: The inter-stage axial length of adjacent impellers is , , , , wherein, is the inside distance of the front and rear shroud of the impeller, in mm, is the axial length calculation coefficient, the value range is 1-3, the rated flow of the multi-stage pump is , in m 3 / h, the impeller inlet diameter is , in mm, the front shroud diameter is , in mm, is the rear shroud diameter, in mm.

4. A method of designing a pump core, characterized by: The method comprises the following steps: S1 : Calculate the reference velocity at the impeller inlet ; S2: calculating the axial outflow with the rear cover plate having a smaller diameter than the front cover plate ; S3: depending on the axial outflow , the outflow velocity of the impeller is calculated ; S4: Determine the inter-stage axial length according to the inter-stage axial length calculation formula .

5. The method of designing a pump core according to claim 4, wherein: In step S1, wherein the multi-stage pump rated flow rate , unit: m 3 / h, the impeller inlet diameter , unit: mm.

6. The method of designing a pump core according to claim 4, wherein: In step S2, wherein the front cover plate diameter is mm, is the rear cover plate diameter, in mm; is the distance between the inner sides of the front and rear cover plates of the impeller, in mm.

7. The method of designing a pump core according to claim 4, wherein: In step S3, wherein the front cover plate diameter is in mm, is the rear cover plate diameter in mm.

8. The method of designing a pump core according to claim 4, wherein: In step S4, wherein, is the inner distance between the front and rear cover plates of the impeller, in mm, is the axial length calculation coefficient, with a value range of 1-3.

9. A multi-stage pump characterized by: The pump core obtained by using the pump core or the design method of the pump core according to any one of claims 1-3 and 4-8.

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