Centrifugal pump and impeller thereof

Abstract

This invention provides a centrifugal pump and its impeller. The impeller includes a front cover plate and a rear cover plate, with multiple blades disposed between the front and rear cover plates. All or a portion of the blades have pressure relief notches on their working surfaces, located at the trailing edges of the blades. The pressure relief notches in this application are equivalent to artificially creating a pressure relief channel on the outlet working surface side of the blades. At low flow rates, high-pressure fluid near the outlet of the blade working surface can leak a portion of the fluid to the working surface of adjacent blades in advance through the pressure relief notches. This controlled, localized, and premature backflow breaks the conditions for the formation of a large-scale, intense rotating stall cluster, releases localized high pressure, alleviates flow channel blockage, makes the flow relatively more stable, and significantly reduces the amplitude and frequency of pressure pulsations caused by rotating stall, thereby greatly reducing vibration and noise.

Description

Technical Field

[0001] This utility model belongs to the technical field of centrifugal pumps, specifically relating to a centrifugal pump and its impeller. Background Technology

[0002] A centrifugal pump is a type of pump that uses the centrifugal force generated by the rotation of an impeller to transport liquids. For example... Figure 1 The centrifugal pumps shown in the prior art exhibit unstable fluid flow in the impeller inlet and outlet regions when operating at flow rates far below design flow (i.e., low-flow conditions). Flow separation easily occurs near the outlet on the working face (i.e., the pressure face) of the blades, forming localized backflow vortices. These vortices can clog the flow channels and may develop into unsteady, rotating stall clusters (rotational stall), which can lead to severe pressure pulsations, vibrations, and noise. Utility Model Content

[0003] In order to overcome the above-mentioned technical defects, this utility model provides a pump and its impeller, which can solve the technical problem that vibration and noise will occur when operating under conditions below the design flow rate in the prior art.

[0004] This utility model is implemented according to the following technical solution:

[0005] This utility model provides an impeller, which includes a front cover plate and a rear cover plate. A plurality of blades are provided between the front cover plate and the rear cover plate. All or part of the working surfaces of the blades are provided with pressure relief notches, and the pressure relief notches are located at the trailing edge of the blades.

[0006] Compared to existing technologies, the pressure relief notch in this application is equivalent to artificially creating a pressure relief channel on the exit working face side of the blade. At low flow rates, the high-pressure fluid near the blade working face exit can leak a portion of the fluid to the working face of adjacent blades in advance through the pressure relief notch. This controlled, localized, and premature backflow breaks the conditions for the formation of a large-scale, intense rotating stall cluster, releases localized high pressure, alleviates flow channel blockage, makes the flow relatively more stable, and significantly reduces the amplitude and frequency of pressure pulsations caused by rotating stall, thereby greatly reducing vibration and noise.

[0007] In one embodiment, the pressure relief notch includes a first sidewall and a second sidewall inclined relative to the first sidewall, the first sidewall being connected to the second sidewall so that the pressure relief notch is V-shaped on the working surface of the blade.

[0008] In one embodiment, a connecting line is provided between the first sidewall and the second sidewall, the connecting line having a starting end and an ending end, the starting end being located on the Bezier curve of the working surface of the blade.

[0009] In one embodiment, the connecting line is located on the Bezier curve of the working surface of the blade.

[0010] In one embodiment, the shape of the first sidewall is not symmetrical to the shape of the second sidewall along the connecting line.

[0011] In one embodiment, the shape of the first sidewall and the shape of the second sidewall are symmetrically arranged along the connecting line.

[0012] In one embodiment, both the first sidewall and the second sidewall are curved surfaces.

[0013] In one embodiment, both the first sidewall and the second sidewall are planar.

[0014] In one embodiment, the blade having the pressure relief notch is arranged adjacent to the blade without the pressure relief notch.

[0015] This utility model also provides a centrifugal pump, which includes the impeller as described above. Attached Figure Description

[0016] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings, wherein:

[0017] Figure 1 A three-dimensional view of an impeller from the prior art;

[0018] Figure 2 This is a perspective view of the impeller of this utility model;

[0019] Figure 3 This is a top view of the impeller of this utility model;

[0020] Figure 4 for Figure 3 Sectional view of AA;

[0021] Figure 5 This is a front view of the impeller of this utility model;

[0022] Figure 6 for Figure 5 BB section view.

[0023] Explanation of reference numerals in the attached figures:

[0024] 10 Front cover plate, 20 Rear cover plate, 30 Blade, 301 Working surface, 310 Pressure relief notch, 311 First side wall, 312 Second side wall, 313 Connecting line, 3131 Starting end. Detailed Implementation

[0025] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0026] To better illustrate this utility model, a further detailed description of this utility model is provided below with reference to the accompanying drawings.

[0027] It should be understood that the described embodiments are merely some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0028] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0029] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0030] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0031] In existing technologies, when centrifugal pumps operate at flow rates far below their design flow rate (i.e., low-flow conditions), the fluid flow in the impeller inlet and outlet regions becomes unstable. Flow separation easily occurs near the outlet on the working surface of the blades (i.e., the pressure surface), forming localized backflow vortices. These vortices can clog the flow channels and may develop into unsteady, rotating stall clusters (rotational stall), which can lead to severe pressure pulsations, vibrations, and noise. Furthermore, the shaft power curve of centrifugal pumps (especially low specific speed pumps) typically increases with decreasing flow rate in the low-flow region. This means that during low-flow operation, the centrifugal pump requires more power, potentially exceeding its rated power, posing a risk of motor overload.

[0032] Example 1

[0033] Combination Figures 2 to 6 As shown, in order to solve the above problems, this utility model provides an impeller that is used in a centrifugal pump. The impeller includes a front cover plate 10 and a rear cover plate 20. A plurality of blades 30 are provided between the front cover plate 10 and the rear cover plate 20. The working surface 301 of all the blades 30 is provided with a pressure relief notch 310, which is located at the trailing edge of the blades 30.

[0034] Compared to existing technologies, the pressure relief notch 310 in this application is equivalent to artificially creating a pressure relief channel on the outlet working surface 301 side of the blade 30. At low flow rates, the high-pressure fluid near the outlet of the working surface 301 of the blade 30 can leak a portion of the fluid to the working surface 301 of the adjacent blade 30 in advance through the pressure relief notch 310. This controlled, localized, and premature backflow breaks the conditions for the formation of a large-scale, intense rotating stall cluster, releases local high pressure, alleviates flow channel blockage, makes the flow relatively more stable, and significantly reduces the amplitude and frequency of pressure pulsations caused by rotating stall, thereby greatly reducing vibration and noise.

[0035] Furthermore, the local backflow caused by the leakage gap is an energy dissipation mechanism. The fluid in the working surface 301 (high-pressure zone) of the current blade 30 leaks through the leakage gap to the working surface 301 (low-pressure zone) of the next adjacent blade 30. Most of the work done by this fluid is consumed in eddies and friction losses and converted into heat energy, rather than being effectively output (head). This additional hydraulic loss is particularly significant under low flow conditions, making the shaft power curve of the centrifugal pump flatter or even decrease in the low flow region, thus avoiding the risk of motor overload.

[0036] Regarding the shape of the pressure relief notch 310, in this embodiment, the pressure relief notch 310 includes a first sidewall 311 and a second sidewall 312 inclined relative to the first sidewall 311. The first sidewall 311 and the second sidewall 312 are connected, so that the pressure relief notch 310 is V-shaped on the working surface 301 of the blade 30. This V-shaped leakage notch allows fluid in the working surface 301 (high-pressure area) of the current blade 30 to leak prematurely to the working surface 301 (low-pressure area) of the next adjacent blade 30. Furthermore, the V-shaped design can suppress stall at low flow rates and improve the stability of the centrifugal pump operating below the design flow rate to some extent. The above design makes the head-flow rate curve (i.e., the HQ curve) of the centrifugal pump flatter at the low flow rate end, reducing the possibility of abrupt changes in head with flow rate and widening the flow rate range in which the centrifugal pump can operate stably (without severe vibration and noise).

[0037] In addition, the "V"-shaped design alters the shape of the exit edge of blade 30, which to some extent disrupts the intensity of periodic disturbances and helps reduce the pulsation amplitude of the blade 30's passage frequency. This is because the sharp right angles or small rounded corners of the exit edge of blade 30 in existing technologies are one of the main sources of pressure pulsation at the blade 30's passage frequency.

[0038] In this embodiment, a connecting line 313 is provided between the first sidewall 311 and the second sidewall 312. The connecting line 313 has a starting end 3131 and an ending end. The starting end 3131 is located on the Bézier curve of the working surface 301 of the blade 30. The connecting line 313 can be understood as the transition line connecting the first sidewall 311 and the second sidewall 312 when machining the "V"-shaped leakage notch of the blade 30. The core application of the Bézier curve (the arc-shaped streamline of the working pressure surface of the blade 30) is the skeleton line of the blade 30. The working surface 301 of the blade 30 is composed of countless Bézier curves. In the design, 5-7 Bézier curves are generally taken from the front cover plate to the rear cover plate to form the basic outline of the blade working surface.

[0039] Furthermore, the connecting line 313 is located on the Bezier curve of the working surface 301 of the blade 30. Using the Bezier curve as a reference, it is convenient to process the "V"-shaped leakage gap.

[0040] In this embodiment, the shape of the first sidewall 311 and the shape of the second sidewall 312 are not symmetrically arranged along the connecting line 313, that is, the shape of the first sidewall 311 and the shape of the second sidewall 312 are not the same and are not mirror images.

[0041] In this embodiment, both the first sidewall 311 and the second sidewall 312 are curved surfaces, so that the curved surfaces can better facilitate the flow to the working surface 301 of the next blade 30.

[0042] Example 2

[0043] This embodiment is basically the same as embodiment 1, except that in this embodiment, the shape of the first sidewall 311 and the shape of the second sidewall 312 are symmetrically arranged along the connecting line 313.

[0044] Example 3

[0045] This embodiment is basically the same as embodiment 1, except that in this embodiment, the first sidewall 311 and the second sidewall 312 are both planar.

[0046] Example 4

[0047] This embodiment is basically the same as embodiment 1, except that in this embodiment, a portion of the working surface 301 of the blade 30 is provided with a pressure relief notch 310. The pressure relief notch 310 is located at the trailing edge of the blade 30. Specifically, the blade 30 with the pressure relief notch 310 is arranged adjacent to the blade 30 without the pressure relief notch 310.

[0048] Example 5

[0049] This utility model also provides a centrifugal pump, which includes the impeller as described above. The centrifugal pump is applicable to pumps that frequently operate over a wide flow range (especially those requiring frequent operation at low flow rates), applications with strict requirements on vibration and noise (such as building water supply, ships, and precision equipment cooling), low specific speed centrifugal pumps (whose HQ curve is steeper and low flow rate issues are more pronounced), and applications where preventing low flow rate overload is crucial.

[0050] It is important to note that this application primarily addresses issues related to low-flow-rate operation. The "V"-shaped leakage notch is mainly designed to address the instability and overload problems of centrifugal pumps under low-flow-rate conditions, not to improve the efficiency of the centrifugal pump under normal operating conditions. Therefore, near the design point of the centrifugal pump and under high-flow-rate conditions, the leakage notch will introduce additional hydraulic losses (leakage losses), which may lead to a slight decrease in pump efficiency under these conditions. Therefore, the design needs to weigh the pros and cons and make improvements based on the aforementioned application scenarios to ensure a positive net benefit within the target operating range (especially the range requiring stable low-flow-rate operation).

[0051] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, this utility model is not limited to the specific embodiments disclosed and described above, and some modifications and changes to this utility model should also fall within the protection scope of the claims of this utility model. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on this utility model.

Claims

1. An impeller comprising a front cover plate and a rear cover plate, wherein a plurality of blades are disposed between the front cover plate and the rear cover plate, characterized in that: All or part of the blades have pressure relief notches on their working surfaces, and the pressure relief notches are located at the trailing edge of the blades.

2. The impeller according to claim 1, characterized in that: The pressure relief notch includes a first sidewall and a second sidewall that is inclined relative to the first sidewall. The first sidewall is connected to the second sidewall so that the pressure relief notch is V-shaped on the working surface of the blade.

3. The impeller according to claim 2, characterized in that: A connecting line is provided between the first sidewall and the second sidewall. The connecting line has a starting end and a ending end, and the starting end is located on the Bezier curve of the working surface of the blade.

4. The impeller according to claim 3, characterized in that: The connecting line is located on the Bezier curve of the working surface of the blade.

5. The impeller according to claim 3, characterized in that: The shape of the first sidewall is not symmetrical to the shape of the second sidewall along the connecting line.

6. The impeller according to claim 3, characterized in that: The shapes of the first sidewall and the second sidewall are symmetrically arranged along the connecting line.

7. The impeller according to claim 2, characterized in that: Both the first sidewall and the second sidewall are curved surfaces.

8. The impeller according to claim 1, characterized in that: Both the first sidewall and the second sidewall are planar.

9. The impeller according to claim 1, characterized in that: The blades with the pressure relief notch are arranged adjacent to the blades without the pressure relief notch.

10. A centrifugal pump characterized by Includes the impeller as described in any one of claims 1-9.

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