A composite double-suction fire pump impeller for low cavitation

Abstract

The application discloses a composite double-suction fire pump impeller for low cavitation, which comprises an inlet impeller 2, a splitter impeller 3 and a double-suction impeller 4 which are sequentially arranged on a pump shaft 1. The multiple impeller composite structure effectively improves the flow state, and the impellers complement each other to achieve certain synergistic effect on the flow path. The blade inlet angle of the inlet blade 21 is beta1, the blade inlet angle of the splitter blade 31 is beta2, and the blade inlet angle of the double-suction blade 41 is beta3, wherein (a beta1 + b beta2) / (b beta2 + c beta3) = 0.6-0.85, a is the number of the inlet blades 21, b is the number of the splitter blades 31, and c is the number of the double-suction blades 41. Compared with the prior art, the application optimizes the inlet angle of the blades, modifies the composite impeller structure, significantly improves the flow state, reduces the required net positive suction head of the pump, and effectively reduces the noise and vibration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluid machinery, in particular to a fire pump, more particularly to a composite double-suction fire pump impeller for low cavitation. BACKGROUND

[0002] Pump cavitation is a cycle process of producing bubbles at low pressure and crushing bubbles at high pressure, and the destructive power comes from the huge impact generated when the bubbles are crushed. Cavitation has a significant adverse effect on the operation efficiency of the pump and the equipment itself, and its main hazards are reflected in the erosion damage to the flow parts, leading to performance degradation, causing vibration and noise, and affecting process stability. To improve the cavitation performance of the pump, it needs to be improved from multiple aspects such as the design of the pump itself, external device conditions, and operation and maintenance. Therefore, in order to improve the cavitation performance of the double-suction fire pump, it is particularly important to reasonably optimize the design of the pump impeller, such as obtaining a composite double-suction fire pump impeller for low cavitation to solve the above problems.

[0003] The prior art CN212744345U discloses a high anti-cavitation performance vertical single-stage fire pump. After the fire pump is started, the water flow enters the pump body suction chamber from the fire pump inlet at a certain flow rate. The liquid before the impeller inlet is reduced in the circumferential direction of the water flow under the action of the tongue baffle, and a relatively stable axial velocity is obtained, which improves the flow field distribution of the impeller inlet and improves the anti-cavitation performance of the fire pump, ensuring the normal operation of the fire pump in a wide operating range.

[0004] The above prior art relates to the application of the related impeller, but the above structure has design limitations, and in the actual application process of the fire pump, there are still problems such as vibration, noise, poor stability, low efficiency, etc. Therefore, in view of these problems, the present application proposes a composite double-suction fire pump impeller for low cavitation. SUMMARY

[0005] The purpose of the present application is to solve the problems existing in the prior art and to provide a composite double-suction fire pump impeller for low cavitation.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] A composite double-suction fire pump impeller for low cavitation comprises a pump shaft 1, an inlet impeller 2, a splitter impeller 3, and a double-suction impeller 4; the inlet impeller 2, the splitter impeller 3, and the double-suction impeller 4 are sequentially mounted on the pump shaft 1; the inlet impeller 2 comprises inlet blades 21 and an inlet shroud 22; the splitter impeller 3 comprises splitter blades 31 and a splitter cylinder 32; and the double-suction impeller 4 comprises double-suction blades 41, a double-suction shroud 42, and a hub 43; characterized in that the inlet shroud 22 intersects with the double-suction shroud 42 in the axial direction and divides the double-suction shroud 42 into a double-suction shroud front section 421 and a double-suction shroud rear section 422; a plurality of shroud inflow holes 423 are arranged on the double-suction shroud front section 421, wherein the diameters of the shroud inflow holes 423 close to the leading edges of the double-suction blades 41 are greater than the diameters of the shroud inflow holes 423 away from the leading edges of the double-suction blades 41; the blade inlet angle of the inlet blades 21 is β1, the blade inlet angle of the splitter blades 31 is β2, and the blade inlet angle of the double-suction blades 41 is β3; and (aβ1+bβ2) / (bβ2+cβ3)=0.6-0.85, wherein a is the number of the inlet blades 21, b is the number of the splitter blades 31, and c is the number of the double-suction blades 41.

[0008] Further, the axial length of the double-suction shroud front section 421 is L1, and the axial length of the double-suction shroud rear section 422 is L2, wherein L1 / L2=0.3-0.5.

[0009] Further, the inlet end of the splitter cylinder 32 is connected to the trailing edges of the inlet blades 21, and the outlet end of the splitter cylinder 32 is connected to the leading edges of the double-suction blades 41.

[0010] Further, the double-suction shroud front section 421 comprises an inlet cylinder section and an outlet horn section which are separated by the leading edges of the double-suction blades 41.

[0011] Further, the shroud inflow holes 423 are located on the outlet horn section.

[0012] Further, a plurality of splitter holes 33 are arranged on the axial middle part of the splitter cylinder 32, and the diameters of the splitter holes 33 are equal.

[0013] Further, the inlet blades 21 and the double-suction blades 41 are both forward-curved blades, and the splitter blades 31 are backward-curved blades.

[0014] Further, the inlet blades 21 and the double-suction blades 41 are both circular-arc blades, and the splitter blades 31 are plate blades.

[0015] Further, the distance between the double-suction shroud front section 421 and the splitter cylinder 32 first remains unchanged and then increases along the flow direction.

[0016] Further, a+c<b.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] 1. The inlet impeller 2, splitter impeller 3, double suction impeller 4 are sequentially installed on the pump shaft 1 in the application, the inlet impeller 2 includes inlet blades 21, inlet shroud 22, the splitter impeller 3 includes splitter blades 31, splitter cylinder 32, the double suction impeller 4 includes double suction blades 41, double suction shroud 42, hub 43; compared with the prior art, the application adopts the multi-impeller composite structure to effectively improve the flow state, and the auxiliary flow path between the impellers plays a certain synergistic effect.

[0019] 2. The inlet shroud 22 and the double suction shroud 42 intersect in the axial direction and divide the double suction shroud 42 into a double suction shroud front section 421 and a double suction shroud rear section 422 in the application, a plurality of shroud inflow holes 423 are arranged on the double suction shroud front section 421, the hole diameter of the shroud inflow hole 423 close to the leading edge of the double suction blade 41 is greater than that of the shroud inflow hole 423 away from the leading edge of the double suction blade 41; the inlet end of the splitter cylinder 32 is connected with the tail edge of the inlet blade 21, and the outlet end of the splitter cylinder 32 is connected with the leading edge of the double suction blade 41. The double suction shroud front section 421 includes an inlet cylinder section and an outlet horn section formed by the leading edge of the double suction blade 41. The shroud inflow hole 423 is located on the outlet horn section. A plurality of splitter holes 33 are arranged on the axial middle part of the splitter cylinder 32, and the hole diameters of the splitter holes 33 are equal. Compared with the prior art, the application adopts the small hole injection structure to effectively pressurize the inlet fluid and improve the net positive suction head of the device.

[0020] 3. The blade inlet angle of the inlet blade 21 is β1, the blade inlet angle of the splitter blade 31 is β2, and the blade inlet angle of the double suction blade 41 is β3 in the application, (aβ1+bβ2) / (bβ2+cβ3)=0.6-0.85, wherein a is the number of inlet blades 21, b is the number of splitter blades 31, and c is the number of double suction blades 41. Wherein a+c<b. Compared with the prior art, the application optimizes the inlet angle of the blade, modifies the composite impeller structure, can significantly improve the flow state, reduce the net positive suction head of the pump, and effectively reduce the noise and vibration.

[0021] 4. The axial length of the double suction shroud front section 421 is L1, and the axial length of the double suction shroud rear section 422 is L2 in the application, wherein L1 / L2=0.3-0.5. The distance between the double suction shroud front section 421 and the splitter cylinder 32 first remains unchanged and then increases along the flow direction. Optimizing the double suction shroud front section structure makes the streamline longer, which is beneficial to the smooth acceleration and turning of the fluid, can effectively improve the flow state under various flow rates, and improve the conveying efficiency.

[0022] 5. In the application, the inlet blades 21 and the double-suction blades 41 are both forward-curved blades, and the splitter blades 31 are backward-curved blades. The inlet blades 21 and the double-suction blades 41 are both circular-arc blades, and the splitter blades 31 are plate blades. The above blades are designed to better make the fluid pass from the front to the back, optimize the flow state, reduce the interference between the flow paths, and thus reduce the vibration and noise. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0024] Fig. 1 Fig. 1 is a structural schematic diagram of the impeller of the present application;

[0025] Fig. 2 Fig. 2 is an enlarged schematic diagram of part of the structure of the impeller of the present application.

[0026] The above drawings are as follows: pump shaft 1, inlet impeller 2, splitter impeller 3, double-suction impeller 4, inlet blade 21, inlet cover plate 22, splitter blade 31, splitter cylinder 32, splitter hole 33, double-suction blade 41, double-suction cover plate 42, hub 43, front section 421 of double-suction cover plate, rear section 422 of double-suction cover plate, cover plate inflow hole 423, axial length L1 of front section 421 of double-suction cover plate, axial length L2 of rear section 422 of double-suction cover plate. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0028] The present application will be further described in detail below in combination with the drawings.

[0029] As Figs. 1-2As shown, a composite double-suction fire pump impeller for low cavitation includes a pump shaft 1, an inlet impeller 2, a splitter impeller 3, and a double-suction impeller 4; the inlet impeller 2, the splitter impeller 3, and the double-suction impeller 4 are sequentially mounted on the pump shaft 1; the inlet impeller 2 includes inlet blades 21 and an inlet shroud 22, the splitter impeller 3 includes splitter blades 31 and a splitter cylinder 32, and the double-suction impeller 4 includes double-suction blades 41, a double-suction shroud 42, and a hub 43, characterized in that the inlet shroud 22 intersects the double-suction shroud 42 in the axial direction and divides the double-suction shroud 42 into a double-suction shroud front section 421 and a double-suction shroud rear section 422, and a plurality of shroud inflow holes 423 are arranged on the double-suction shroud front section 421, wherein the hole diameter of the shroud inflow hole 423 close to the leading edge of the double-suction blade 41 is larger than that of the shroud inflow hole 423 away from the leading edge of the double-suction blade 41.

[0030] In addition, the blade inlet angle of the inlet blade 21 is β1, the blade inlet angle of the splitter blade 31 is β2, and the blade inlet angle of the double-suction blade 41 is β3, and (aβ1+bβ2) / (bβ2+cβ3)=0.6-0.85, wherein a is the number of inlet blades 21, b is the number of splitter blades 31, and c is the number of double-suction blades 41.

[0031] Further, the axial length of the double-suction shroud front section 421 is L1, and the axial length of the double-suction shroud rear section 422 is L2, wherein L1 / L2=0.3-0.5.

[0032] Further, the inlet end of the splitter cylinder 32 is connected to the trailing edge of the inlet blade 21, and the outlet end of the splitter cylinder 32 is connected to the leading edge of the double-suction blade 41.

[0033] Further, the double-suction shroud front section 421 includes an inlet cylinder section and an outlet horn section formed by the leading edge of the double-suction blade 41.

[0034] Further, the shroud inflow hole 423 is located on the outlet horn section.

[0035] Further, the axial middle part of the splitter cylinder 32 is provided with a plurality of splitter holes 33, and the hole diameters of the splitter holes 33 are equal.

[0036] Further, the inlet blade 21 and the double-suction blade 41 are both forward-curved blades, and the splitter blade 31 is a backward-curved blade.

[0037] Further, the inlet blade 21 and the double-suction blade 41 are both circular-arc blades, and the splitter blade 31 is a plate blade.

[0038] Further, the distance between the double-suction shroud front section 421 and the splitter cylinder 32 first remains unchanged and then increases along the flow direction.

[0039] Further, a+c<b.

[0040] The inlet impeller 2, the splitter impeller 3 and the double-suction impeller 4 are sequentially installed on the pump shaft 1 in the application, the inlet impeller 2 comprises inlet blades 21 and an inlet cover plate 22, the splitter impeller 3 comprises splitter blades 31 and a splitter cylinder 32, and the double-suction impeller 4 comprises double-suction blades 41, a double-suction cover plate 42 and a hub 43; compared with the prior art, the multi-impeller composite structure is adopted in the application to effectively improve the flow state, and the impellers complement each other to have a certain synergistic effect on the flow path.

[0041] The inlet cover plate 22 and the double-suction cover plate 42 intersect in the axial direction and divide the double-suction cover plate 42 into a double-suction cover plate front section 421 and a double-suction cover plate rear section 422, a plurality of cover plate inflow holes 423 are arranged on the double-suction cover plate front section 421, the hole diameter of the cover plate inflow hole 423 close to the leading edge of the double-suction blade 41 is greater than that of the cover plate inflow hole 423 away from the leading edge of the double-suction blade 41, the inlet end of the splitter cylinder 32 is connected with the tail edge of the inlet blade 21, and the outlet end of the splitter cylinder 32 is connected with the leading edge of the double-suction blade 41. The double-suction cover plate front section 421 comprises an inlet cylinder section and an outlet horn section which are separated by the leading edge of the double-suction blade 41. The cover plate inflow hole 423 is located on the outlet horn section. A plurality of splitter holes 33 are arranged on the axial middle part of the splitter cylinder 32, and the hole diameters of the splitter holes 33 are equal. Compared with the prior art, the small-hole injection structure is adopted in the application to effectively increase the pressure of the inlet fluid and improve the net positive suction head of the device.

[0042] In the application, the blade inlet angle of the inlet blade 21 is β1, the blade inlet angle of the splitter blade 31 is β2, and the blade inlet angle of the double-suction blade 41 is β3, (aβ1+bβ2) / (bβ2+cβ3)=0.6-0.85, wherein a is the number of the inlet blades 21, b is the number of the splitter blades 31, and c is the number of the double-suction blades 41. Wherein a+c<b. Compared with the prior art, the inlet angle of the blade is optimized, the composite impeller structure is modified, the flow state can be significantly improved, the net positive suction head of the pump can be reduced, and the noise and vibration can be effectively reduced.

[0043] In the application, the axial length of the double-suction cover plate front section 421 is L1, and the axial length of the double-suction cover plate rear section 422 is L2, wherein L1 / L2=0.3-0.5. The distance between the double-suction cover plate front section 421 and the splitter cylinder 32 first remains unchanged and then becomes larger along the flow path direction. The double-suction cover plate front section structure is optimized, the streamline is lengthened, the fluid is smoothly accelerated and diverted, the flow state under various flow rates can be effectively improved, and the conveying efficiency is improved.

[0044] In the application, the inlet blades 21 and the double-suction blades 41 are all forward-curved blades, and the splitter blades 31 are backward-curved blades. The inlet blades 21 and the double-suction blades 41 are all circular-arc blades, and the splitter blades 31 are plate blades. The above-mentioned blades are designed to better make the fluid continuous, optimize the flow state, reduce the interference between the flow paths, and thus reduce the vibration and noise.

[0045] The above-mentioned embodiments are illustrative of the present application, but are not a limitation of the present application. It can be understood that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the protection scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A composite double-suction fire pump impeller for low cavitation, comprising a pump shaft (1), an inlet impeller (2), a diversion impeller (3), and a double-suction impeller (4); the inlet impeller (2), the diversion impeller (3), and the double-suction impeller (4) are sequentially mounted on the pump shaft (1); the inlet impeller (2) comprises inlet blades (21) and an inlet cover plate (22), the diversion impeller (3) comprises diversion blades (31) and a diversion cylinder (32), and the double-suction impeller (4) comprises double-suction blades (41), a double-suction cover plate (42), and a hub (43), characterized in that: The inlet cover plate (22) and the double suction cover plate (42) intersect in the axial direction and divide the double suction cover plate (42) into a front section (421) and a rear section (422). The front section (421) of the double suction cover plate is provided with multiple rings of cover plate inlet holes (423). The diameter of the cover plate inlet hole (423) near the leading edge of the double suction blade (41) is larger than that of the cover plate inlet hole (423) far from the leading edge of the double suction blade (41). The blade inlet angle of the inlet blade (21) is β1, the blade inlet angle of the diversion blade (31) is β2, and the blade inlet angle of the double suction blade (41) is β3. (aβ1+bβ2) / (bβ2+cβ3)=0.6~0.85, where a is the number of blades of the inlet blade (21), b is the number of blades of the diversion blade (31), and c is the number of blades of the double suction blade (41).

2. The composite double-suction fire pump impeller for low cavitation as described in claim 1, characterized in that, The axial length of the front section (421) of the double suction cover is L1, and the axial length of the rear section (422) of the double suction cover is L2, where L1 / L2 = 0.3 to 0.

5.

3. The composite double-suction fire pump impeller for low cavitation as described in claim 1, characterized in that, The inlet end of the flow divider (32) is connected to the trailing edge of the inlet blade (21), and the outlet end of the flow divider (32) is connected to the leading edge of the double suction blade (41).

4. The composite double-suction fire pump impeller for low cavitation as described in claim 1, characterized in that, The front section (421) of the double suction cover includes an inlet tube section and an outlet horn section formed by the leading edge of the double suction blades (41).

5. The composite double-suction fire pump impeller for low cavitation as described in claim 4, characterized in that, The inlet hole (423) of the cover plate is located on the outlet horn section.

6. The composite double-suction fire pump impeller for low cavitation as described in claim 1, characterized in that, The flow divider (32) has multiple flow divider holes (33) in the middle of its axial direction, and the diameter of each flow divider hole (33) is equal.

7. The composite double-suction fire pump impeller for low cavitation as described in claim 1, characterized in that, The inlet blade (21) and the double suction blade (41) are both forward-curved blades, while the diversion blade (31) is a backward-curved blade.

8. The composite double-suction fire pump impeller for low cavitation as described in claim 1, characterized in that, The imported blade (21) and the double suction blade (41) are both arc-shaped blades, while the diversion blade (31) is a plate-shaped blade.

9. The composite double-suction fire pump impeller for low cavitation as described in claim 1, characterized in that, The distance between the front section (421) of the double suction cover and the flow divider (32) remains constant and then increases along the flow path.

10. The composite double-suction fire pump impeller for low cavitation as described in claim 1, characterized in that, Where a+c<b.

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