An anti-cavitation impeller

Abstract

The application discloses an anti-cavitation impeller, and relates to the technical field of centrifugal pumps. Each group of blade units comprises an inlet edge forward blade and a regular blade, and the inlet edge forward blade and the regular blade are arranged alternately in the circumferential direction; the radially outermost edge of the inlet edge of the inlet edge forward blade is located radially outward of the radially outermost edge of the inlet edge of the regular blade; the radially innermost edge of the inlet edge of the regular blade is located radially inward of the radially innermost edge of the inlet edge of the inlet edge forward blade; and the spacing angles between any two adjacent groups of blade units are not equal. Therefore, the impeller of the embodiment of the application can maintain stable anti-cavitation performance in a wide flow range, is not only suitable for the delivery of high-temperature easy-vaporization medium with a super-low net positive suction head, but also lays a good flow field foundation for subsequent adaptation to gas-liquid two-phase flow conditions, and effectively improves the operation stability and working condition adaptability of the chemical centrifugal pump.

Description

Technical Field

[0001] This application relates to the field of centrifugal pump technology, and in particular to an anti-cavitation impeller. Background Technology

[0002] As the chemical industry develops towards high-end and refined processes, the transport of high-temperature, easily vaporized media has become crucial in core processes such as hydrocracking and light hydrocarbon separation. Under these conditions, the saturated vapor pressure of the media is high, making cavitation highly likely to occur at the pump inlet, severely affecting the pump's stability and lifespan. Simultaneously, some process sections also require the transport of gas-liquid two-phase flows; the coupling effect of cavitation and two-phase flow further exacerbates the risk of equipment failure.

[0003] To improve cavitation resistance, existing chemical centrifugal pumps often employ traditional solutions such as extending the inlet edge of the full blade or adding an inducer in front of the impeller. However, these solutions have significant drawbacks: while extending the inlet edge of the full blade improves cavitation resistance to some extent, it easily causes blockage of the impeller inlet flow channel, exacerbating backflow under low flow conditions. This results in unstable cavitation resistance over a wide operating range, making it unsuitable for applications with extremely stringent requirements for cavitation margin. Utility Model Content

[0004] This application provides an anti-cavitation impeller, which solves the problems mentioned in the background art.

[0005] This application provides an anti-cavitation impeller, including a hub and multiple sets of blade units arranged circumferentially on the hub. Each set of blade units includes an inlet-side extended blade and a conventional blade, and the inlet-side extended blade and the conventional blade are arranged alternately in the circumferential direction. The outermost radial edge of the inlet edge of the inlet-side extended blade is located radially outside the outermost radial edge of the inlet edge of the conventional blade. The innermost radial edge of the inlet edge of the conventional blade is located radially inside the innermost radial edge of the inlet edge of the inlet edge extended blade. The spacing angle between any two adjacent sets of blade units is not equal.

[0006] In one possible implementation, within the same set of blade units, the first spacing angle between the inlet-side forward blade and the conventional blade is not equal to the second spacing angle between two adjacent blades in two adjacent sets of blade units.

[0007] In one possible implementation, the length by which the inlet edge of the forward-extending blade extends axially toward the suction side along the impeller is 5% to 8% of the impeller inlet diameter.

[0008] In one possible implementation, the inlet placement angle of the inlet-side forward-extending blade is smaller than the inlet placement angle of the adjacent conventional blade.

[0009] In one possible implementation, the inlet angle of the inlet-side forward-extending blade is 3° to 5° smaller than the inlet angle of the adjacent conventional blade.

[0010] In one possible implementation, the leading edge of the inlet side forward extension blade has a streamlined or rounded structure.

[0011] One or more technical solutions provided in the embodiments of this application have at least the following technical effects:

[0012] This application employs a multi-blade unit structure with a mixed arrangement of "inlet-side forward-extended blades + conventional blades," with the two alternating in the circumferential direction. This effectively avoids the inlet channel blockage problem caused by the traditional all-blade forward-extended scheme. Simultaneously, by setting the outermost radial edge of the inlet-side forward-extended blades to the radially outer side of the conventional blades to guide the fluid smoothly into the outer channel, and setting the innermost radial edge of the conventional blades to the radially inner side of the inlet-side forward-extended blades to suppress the backflow distortion of the inner channel under low flow conditions, the two work together to form a "radial layered flow guidance" pattern, improving the uniformity of the inlet flow field. Furthermore, by limiting the spacing angle between any two adjacent sets of blade units to be unequal, the periodic superposition effect of flow channel vortices in the traditional uniform blade cascade is broken, avoiding the deterioration of local low-pressure areas caused by flow field resonance. Therefore, the impeller of this application can maintain stable anti-cavitation performance within a wide flow range (such as 0.7-1.2 times the design flow rate), reduce the required cavitation margin, and effectively solve the technical problem of unstable anti-cavitation performance of existing solutions under harsh working conditions. It is suitable for ultra-low cavitation margin transportation of high temperature and easily vaporized media and gas-liquid two-phase flow conditions. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the anti-cavitation impeller provided in an embodiment of this application;

[0015] Figure 2 This is a schematic diagram comparing the inlet edge of the forward-extending blade and the inlet edge of a conventional blade, as provided in the embodiments of this application.

[0016] Icons: 1-Imported edge forward-extending blade; 2-Conventional blade. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0019] This application provides an anti-cavitation impeller. For example... Figure 1 As shown, the anti-cavitation impeller includes a hub and multiple sets of blade units arranged circumferentially around the hub. Each set of blade units includes an inlet-side extended blade 1 and a conventional blade 2, with the inlet-side extended blade 1 and the conventional blade 2 arranged alternately in the circumferential direction; as shown... Figure 2 As shown, the outermost radial edge of the inlet edge of the inlet edge extended blade 1 is located radially outside the outermost radial edge of the inlet edge of the conventional blade 2; the innermost radial edge of the inlet edge of the conventional blade 2 is located radially inside the innermost radial edge of the inlet edge of the inlet edge extended blade 1; the spacing angle between any two adjacent sets of blade units is not equal.

[0020] It should be noted that this application adopts a multi-set blade unit structure with a mixed arrangement of "inlet-side forward-extended blade 1 + conventional blade 2", and the two are arranged alternately in the circumferential direction, which effectively avoids the inlet flow channel blockage problem caused by the traditional all-blade forward-extended scheme. At the same time, by setting the radial outermost edge of the inlet-side forward-extended blade 1 to the radial outer side of the conventional blade 2 to guide the fluid to smoothly enter the outer flow channel, and setting the radial innermost edge of the conventional blade 2 to the radial inner side of the inlet-side forward-extended blade 1 to suppress the backflow distortion of the inner flow channel under low flow conditions, the two work together to form a "radial layered flow guidance" pattern, which improves the uniformity of the inlet flow field. On this basis, the spacing angle between any two adjacent sets of blade units is not equal, which breaks the periodic superposition effect of the flow channel vortex in the traditional uniform blade cascade and avoids the deterioration of the local low-pressure area caused by flow field resonance. Therefore, the impeller of this application can maintain stable anti-cavitation performance within a wide flow range (such as 0.7-1.2 times the design flow rate), reduce the required cavitation margin, and effectively solve the technical problem of unstable anti-cavitation performance of existing solutions under harsh working conditions. It is suitable for ultra-low cavitation margin transportation of high temperature and easily vaporized media and gas-liquid two-phase flow conditions.

[0021] In this embodiment, within the same set of blade units, the circumferential angle between the inlet-side forward-extending blade 1 and the conventional blade 2 is defined as the first spacing angle, and the circumferential angle between two adjacent blades in two adjacent sets of blade units is defined as the second spacing angle; the first spacing angle and the second spacing angle are not equal. By constructing a flow channel structure with differentiated distribution within and between sets in the circumferential direction, the periodicity of the flow field is further broken, and the superposition of vortex resonance at specific frequencies is avoided, thereby effectively suppressing the formation of local low-pressure areas and improving the impeller's anti-cavitation stability over a wide flow range.

[0022] In this embodiment, the length of the inlet edge of the inlet-side forward-extending blade 1 extending axially toward the suction side of the impeller is 5% to 8% of the impeller inlet diameter.

[0023] It should be noted that this numerical range was obtained through simulation optimization and experimental verification. By limiting the length of the inlet edge of the forward-extending blade 1 extending axially towards the suction side to 5% to 8% of the impeller inlet diameter, sufficient pre-compression and guiding distance are provided for the fluid while avoiding excessive occupation of the inlet space by the forward-extending blade 1, which would lead to flow channel blockage and increased flow velocity. This effectively reduces the local velocity gradient and pressure drop at the blade leading edge, thereby achieving an optimal balance between improving cavitation resistance and maintaining inlet flow capacity, and further ensuring the impeller's cavitation resistance stability over a wide flow range.

[0024] In this embodiment, the inlet angle of the inlet-side extended blade 1 is smaller than the inlet angle of the adjacent conventional blade 2. The inlet angle of the inlet-side extended blade 1 is 3° to 5° smaller than the inlet angle of the adjacent conventional blade 2.

[0025] It should be noted that by setting the inlet placement angle of the inlet-side forward-extending blade 1 to be 3° to 5° smaller than that of the adjacent conventional blade 2, this application effectively avoids the problem of excessive fluid angle of attack that may result from the inlet-side forward-extending blade 1 extending axially towards the suction side and making initial contact with the incoming flow. This angle difference makes the inlet placement angle of the leading edge of the inlet-side forward-extending blade 1 match the actual liquid flow angle, preventing flow separation and flow separation vortices from forming on the suction surface of the inlet-side forward-extending blade 1. This suppresses the phenomenon of increased cavitation in the local low-pressure area caused by flow separation, and further improves the impeller's anti-cavitation stability and the uniformity of the inlet flow field over a wide flow range.

[0026] In this embodiment, the leading edge of the inlet edge forward blade 1 is a streamlined or rounded structure, which can effectively reduce the flow loss when the fluid impacts the leading edge of the blade, avoid the sudden drop in local pressure caused by the flow around the sharp corner, thereby further improving the uniformity of pressure distribution at the impeller inlet and suppressing the initial formation of cavitation.

[0027] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0028] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. An anti-cavitation impeller, comprising a hub and multiple sets of blade units disposed circumferentially on the hub, characterized in that, Each blade unit includes an inlet-side forward-extending blade (1) and a conventional blade (2), and the inlet-side forward-extending blade (1) and the conventional blade (2) are arranged alternately in the circumferential direction; The outermost radial edge of the inlet edge of the forward blade (1) is located radially outside the outermost radial edge of the inlet edge of the conventional blade (2). The innermost radial edge of the inlet side of the conventional blade (2) is located radially inside the innermost radial edge of the inlet side of the forward blade (1). The spacing angle between any two adjacent sets of blade units is not equal.

2. The anti-cavitation impeller according to claim 1, characterized in that, Within the same set of blade units, the first spacing angle between the inlet edge forward blade (1) and the conventional blade (2) is not equal to the second spacing angle between two adjacent blades in two adjacent sets of blade units.

3. The anti-cavitation impeller according to claim 1, characterized in that, The length of the inlet edge of the forward-extending blade (1) extending axially toward the suction side of the impeller is 5% to 8% of the impeller inlet diameter.

4. The anti-cavitation impeller according to claim 1, characterized in that, The inlet placement angle of the inlet-side forward-extending blade (1) is smaller than the inlet placement angle of the adjacent conventional blade (2).

5. The anti-cavitation impeller according to claim 4, characterized in that, The inlet angle of the inlet-side forward-extending blade (1) is 3° to 5° smaller than the inlet angle of the adjacent conventional blade (2).

6. The anti-cavitation impeller according to claim 1, characterized in that, The leading edge of the inlet side forward blade (1) has a streamlined structure or a rounded corner structure.

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