Axially split pump impeller with offset blades and axially split pump

Abstract

The utility model relates to the technical field of axially split pumps, in particular to an axially split pump impeller with offset blades and an axially split pump. The axially split pump impeller with the offset blades comprises a front cover plate, a hub, a plurality of long blades and a plurality of short blades, the hub is arranged in the front cover plate, and the long blades and the short blades are arranged between the hub and the front cover plate; the multiple long blades are evenly arranged around the axis of the impeller, and the short blades are arranged between every two adjacent long blades. Projections of one end, far away from the axis of the impeller, of each long blade and one end, far away from the axis of the impeller, of each short blade in the axial direction of the impeller are distributed on the circumference of the same circle; each short blade is provided with a pressure face and a suction face which are opposite. According to the axially split pump impeller with the offset blades, the flow field in the blade channels can be improved, the pressure gradient of an outlet of the impeller can be greatly reduced, the wake flow area of the outlet of the impeller is reduced, and smooth transition of the speed and pressure from the wake flow area to a jet flow area is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of split case pumps, in particular to a split case pump impeller with offset blades and a split case pump. Background Art

[0002] In the prior art, short blades are often added to the cover plate in low specific speed double-suction split-center pumps to improve pump efficiency and reduce energy consumption. Adding short blades to the impeller can effectively reduce the diffusion of the impeller outlet and improve the performance by increasing the slip coefficient, thereby increasing the pump head, or reducing hydraulic losses and improving efficiency. At present, the efficiency of the pump is often improved and energy consumption is reduced by welding short blades in the middle position between two adjacent long blades on the cover plate. For example, the Chinese utility model patent with authorization announcement number CN218325450U discloses a low specific speed single-stage double-suction centrifugal pump with a long-short blade composite impeller, which improves the pump head and efficiency by welding short blades in the middle position between adjacent long blades of the impeller.

[0003] However, when the above split-case pump was simulated and tested, it was found that there was still much room for improvement in the flow field stability within the impeller and the uniformity of the impeller outlet pressure gradient. Utility Model Content

[0004] (I) The problem to be solved by the present invention is: when the above split-center pump is simulated and tested, it is found that there is still much room for improvement in the flow field stability in the impeller and the uniformity of the pressure gradient at the impeller outlet.

[0005] (II) Technical solution

[0006] A split-center pump impeller with offset blades comprises a front cover plate, a hub, a plurality of long blades and a plurality of short blades, wherein the hub is arranged in the front cover plate, and the long blades and the short blades are arranged between the hub and the front cover plate;

[0007] A plurality of the long blades are evenly arranged around the impeller axis, and the short blade is arranged between two adjacent long blades;

[0008] The projections of one end of the long blade away from the impeller axis and one end of the short blade away from the impeller axis in the axial direction of the impeller are distributed on the circumference of the same circle;

[0009] The short blade has a pressure surface and a suction surface opposite to each other, and a distance between the pressure surface of the short blade and the long blade adjacent to the pressure surface is different from a distance between the suction surface of the short blade and the long blade adjacent to the suction surface;

[0010] The curvature of one end of the short blade close to the impeller axis is greater than that of the other end thereof.

[0011] According to an embodiment of the utility model, the ratio of the distance between the pressure surface of the short blade and the long blade adjacent to the pressure surface to the distance between the suction surface of the short blade and the long blade adjacent to the suction surface is 0.7-1.

[0012] According to an embodiment of the present invention, the ratio of the length of the short blade to the length of the long blade is 1 / 4-1 / 2.

[0013] According to an embodiment of the utility model, the ratio of the distance between the end of the short blade close to the impeller axis and the impeller axis to the distance between the end of the long blade away from the impeller axis and the impeller axis is 0.65-0.9.

[0014] According to an embodiment of the utility model, a key groove is provided on the inner wall of the hub.

[0015] According to an embodiment of the present invention, the impeller has two impeller axial inlets, and the impeller is radially provided with a plurality of water outlets.

[0016] According to an embodiment of the present invention, the curvature and the placement angle of the end of the long blade away from the impeller axis and the end of the short blade away from the impeller axis are the same.

[0017] A split case pump comprises the above split case pump impeller with offset blades.

[0018] Beneficial effects of the utility model:

[0019] The utility model provides a split pump impeller with offset blades, comprising a front cover plate, a hub, a plurality of long blades and a plurality of short blades, wherein the hub is arranged inside the front cover plate, and the long blades and the short blades are arranged between the hub and the front cover plate; the plurality of long blades are evenly arranged around the impeller axis, and the short blades are arranged between two adjacent long blades; the projections of one end of the long blade away from the impeller axis and one end of the short blade away from the impeller axis in the axial direction of the impeller are distributed on the circumference of the same circle; the short blade has a relative pressure surface and a suction surface, and the distance between the pressure surface of the short blade and the long blade adjacent to the pressure surface is different from the distance between the suction surface of the short blade and the long blade adjacent to the suction surface; the curvature of the short blade close to one end of the impeller axis is greater than the curvature of the other end thereof.

[0020] The short blades in the present application are no longer centrally arranged between two adjacent long blades, but are offset, so that the short blades can not only improve the flow field in the blade channel, but also significantly reduce the pressure gradient at the impeller outlet, reduce the wake area at the impeller outlet, and achieve a smooth transition of speed and pressure from the wake area to the jet area. Since the offset short blades are located near the boundary between the wake area and the jet area, and the front curvature of the short blades is increased, the flow compensation from the jet area to the wake area can be better achieved, thereby achieving the purpose of improving the flow field and reducing the outlet pressure gradient. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A front view of the first embodiment of the present utility model;

[0023] Figure 2 A side view provided for the first embodiment of the utility model;

[0024] Figure 3 A cross-sectional view provided for Embodiment 1 of the present utility model;

[0025] Figure 4 This is a distribution diagram of long blades and short blades provided in Example 1 of the utility model.

[0026] Icons: 1, front cover; 101, water outlet; 102, wheel hub; 2, long blades; 3, short blades. DETAILED DESCRIPTION

[0027] The technical solution of the utility model will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] Embodiment 1:

[0029] like Figure 1-Figure 4As shown, an embodiment of the utility model provides a split pump impeller with offset blades, comprising a front cover plate 1, a hub 102, a plurality of long blades 2 and a plurality of short blades 3, the hub 102 being arranged in the front cover plate 1, and the long blades 2 and the short blades 3 being arranged between the hub 102 and the front cover plate 1; the plurality of long blades 2 are evenly arranged around the impeller axis, and the short blade 3 is arranged between two adjacent long blades 2; the projections of one end of the long blade away from the impeller axis and one end of the short blade 3 away from the impeller axis in the axial direction of the impeller are distributed on the circumference of the same circle; the short blade 3 has a relative pressure surface and a suction surface, and the distance between the pressure surface of the short blade 3 and the long blade 2 adjacent to the pressure surface is different from the distance between the suction surface of the short blade 3 and the long blade 2 adjacent to the suction surface; the curvature of the short blade 3 at one end close to the impeller axis is greater than the curvature of the other end thereof.

[0030] It should be noted that in the impeller with short blades 3 in the past, the short blades 3 are centrally arranged between two adjacent long blades 2, and the short blades 3 can be regarded as the end of the long blades 2 away from the impeller axis, that is, it can be regarded as rotating a long blade 2 by a certain angle and then shortening the length of the long blade 2, leaving a part of the long blade 2 away from the impeller axis. When conducting simulation tests on this split-center pump with short blades 3, it was found that the flow field stability in the impeller and the uniformity of the impeller outlet pressure gradient still have much room for improvement.

[0031] The specific reason is that the flow in the centrifugal pump impeller consists of a wake zone with a relatively low speed and a nearly inviscid jet zone. The wake zone is close to the suction surface, and the jet zone is close to the pressure surface. The dividing point between the wake zone and the jet zone of the split-center pump with medium and low specific speed is mostly not on the center line of two adjacent blades.

[0032] The short blade 3 in the present application is no longer centrally arranged between two adjacent long blades 2, but is offset. In this way, the short blade 3 can not only improve the flow field in the blade channel, but also significantly reduce the pressure gradient at the impeller outlet, reduce the wake area at the impeller outlet, and achieve a smooth transition of speed and pressure from the wake area to the jet area.

[0033] Specifically, since the offset short blade 3 is located near the boundary between the wake zone and the jet zone, and the front curvature of the short blade 3 is increased, it is to better achieve flow compensation from the jet zone to the wake zone, thereby achieving the purpose of improving the flow field and reducing the outlet pressure gradient.

[0034] Therefore, the optimal position of the offset blade is not on the centerline of the blade path, but close to one side of the wake area.

[0035] It should be known that the blade path refers to the flow channel between two adjacent blades; and the approximate dividing line between the wake area and the jet area can be obtained through CFD software simulation.

[0036] What you need to know is that Figure 1 and Figure 2 As shown, the impeller has two axial inlets, and a plurality of water outlets 101 are radially arranged on the impeller. A keyway is arranged on the inner wall of the hub 102, and the keyway is used to connect with the pump shaft.

[0037] In this embodiment, Figure 3 As shown, the distance between the pressure surface of the short blade 3 and the long blade 2 adjacent to the pressure surface is different from the distance between the suction surface of the short blade 3 and the long blade 2 adjacent to the suction surface, that is, the short blade 3 is offset between the two long blades 2.

[0038] After simulation testing of a split pump with a split pump impeller with offset blades, it was found that the flow field in the impeller was more stable and the pressure gradient at the impeller outlet was more uniform.

[0039] It should be noted that, from one end of the short blade 3 close to the impeller axis to the other end, the curvature of the short blade 3 first increases and then decreases, that is, the curvature of the end of the short blade 3 close to the impeller axis is greater than that of the end of the short blade 3 far from the impeller axis.

[0040] like Figure 4 As shown, Figure 4 The BG line segment in the figure represents a short blade 3, the long line segment where the AD line segment above the BG line segment is located is a long blade 2, and the line segment where the point C below the BG line segment is located is a long blade 2. For the convenience of description, the long blade 2 above the BG line segment is named the first long blade, and the long blade 2 below the BG line segment is named the second long blade.

[0041] It can be seen that from Figure 4 It can be seen that point A of the first long blade, point C of the second long blade and point B of the short blade 3 are distributed on the circumference of the same circle, and the length of the arc segment AB between point A of the first long blade and point B of the short blade 3 is smaller than the length of the arc segment BC between point C of the second long blade and point B of the short blade 3. That is, the short blade 3 is closer to the first long blade.

[0042] Furthermore, the curvature of the FG segment of the short blade 3 is greater than the curvature of the BF segment, that is, the curvature of the FG segment of the short blade 3 is greater than the curvature of the BF segment of the short blade 3, and the FG segment of the short blade 3 is curved toward the second longest blade.

[0043] Preferably, in this embodiment, in two adjacent long blades 2 and a short blade 3 located between the two adjacent long blades 2, the ratio of the distance between the pressure surface of the short blade 3 and the long blade 2 adjacent to the pressure surface to the distance between the suction surface of the short blade 3 and the long blade 2 adjacent to the suction surface is 0.7-1. Figure 4As shown, the ratio of the length of the arc segment AB between point A of the first long blade and point B of the short blade 3 represented by BG to the length of the arc segment BC between point C of the second long blade and point B of the short blade 3 represented by BG is 0.7-1, preferably 0.8.

[0044] Preferably, in this embodiment, the ratio of the distance between the end of the short blade 3 close to the impeller axis and the impeller axis to the distance between the end of the long blade 2 far from the impeller axis and the impeller axis is 0.65-0.9. Figure 4 The ratio of the distance between the G end of the short blade 3 represented by BG and the impeller axis to the distance between the A point of the first long blade and the impeller axis is 0.65-0.9, preferably 0.7.

[0045] In addition, it should be noted that the curvature and placement angle of the end of the short blade 3 away from the impeller axis and the end of the long blade 2 away from the impeller axis are the same, that is, Figure 4 In the figure, the bending degree and placement angle of the BE segment in the short blade 3 represented by BG and the AD segment in the first long blade are the same.

[0046] Preferably, in this embodiment, the ratio of the length of the short blade 3 to the length of the long blade 2 is 1 / 4-1 / 2, preferably 1 / 3. It should be noted that if the short blade 3 is too short, the effect of improving the flow state inside the blade channel will not be achieved, and if it is too long, the hydraulic loss will be increased and the efficiency of the pump will be affected.

[0047] In the present impeller, by adding short blades 3 in the impeller, the flow field distribution characteristics in the impeller blade channel can be effectively improved, the vortex in the blade channel can be reduced, the velocity gradient and pressure gradient of the impeller outlet flow surface can be reduced, the pressure pulsation of the impeller and the vibration and noise caused by the dynamic and static interference can be suppressed, and the efficiency of the whole pump can be improved at the same time.

[0048] Embodiment 2:

[0049] The second embodiment of the present utility model provides a split case pump, which comprises the split case pump impeller with offset blades in the first embodiment.

[0050] In the description of the present invention, it should be noted that the terms "upper" and "lower" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0051] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the insides of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A split pump impeller with offset blades, characterized in that: It comprises a front cover plate (1), a wheel hub (102), a plurality of long blades (2) and a plurality of short blades (3), wherein the wheel hub (102) is arranged in the front cover plate (1), and the long blades (2) and the short blades (3) are arranged between the wheel hub (102) and the front cover plate (1); A plurality of the long blades (2) are evenly arranged around the impeller axis, and the short blade (3) is arranged between two adjacent long blades (2); The projections of one end of the long blade away from the impeller axis and one end of the short blade (3) away from the impeller axis in the axial direction of the impeller are distributed on the circumference of the same circle; The short blade (3) has a relative pressure surface and a suction surface, and the distance between the pressure surface of the short blade (3) and the long blade (2) adjacent to the pressure surface is different from the distance between the suction surface of the short blade (3) and the long blade (2) adjacent to the suction surface; The curvature of one end of the short blade (3) close to the impeller axis is greater than the curvature of the other end.

2. A split pump impeller with offset blades according to claim 1, characterized in that: The ratio of the distance between the pressure surface of the short blade (3) and the long blade (2) adjacent to the pressure surface to the distance between the suction surface of the short blade (3) and the long blade (2) adjacent to the suction surface is 0.7-1.

3. A split pump impeller with offset blades according to claim 1, characterized in that: The ratio of the length of the short blade (3) to the length of the long blade (2) is 1 / 4-1 / 2.

4. A split pump impeller with offset blades according to claim 1, characterized in that: The ratio of the distance between the end of the short blade (3) close to the impeller axis and the impeller axis to the distance between the end of the long blade (2) far from the impeller axis and the impeller axis is 0.65-0.

9.

5. A split pump impeller with offset blades according to claim 1, characterized in that: A keyway is provided on the inner wall of the wheel hub (102).

6. A split-case pump impeller with offset blades according to claim 1, characterized in that: The impeller has two impeller axial inlets, and the impeller is radially provided with a plurality of water outlets (101).

7. A split-case pump impeller with offset blades according to claim 1, characterized in that: The curvature and placement angle of the end of the long blade (2) away from the impeller axis and the end of the short blade (3) away from the impeller axis are the same.

8. A split case pump, characterized in that: A split-case pump impeller with offset blades comprising any one of claims 1-7.

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