Vortex generation suppression device, pump comprising vortex generation suppression device, and pump installation with pump provided in water suction tank

Abstract

To provide a vortex generation suppression device capable of effectively suppressing generation of an air suction vortex in a water suction tank during pump operation in the water suction tank.SOLUTION: A vortex generation suppression device 10 is provided outside a lower part of a casing 5 in the lower part of the casing 5 of a pump 100 installed in a water suction tank T, and has a pair of obstruction parts 11 extending along an outer peripheral surface of the lower part of the casing 5. The pair of obstruction parts 11 are provided on a downstream outer surface of the outer peripheral surface of the lower part of the casing 5 with respect to a narrowed portion where a distance between the outer peripheral surface of the lower part of the casing 5 and a side wall surface 6 of the water suction tank T is the narrowest. Each obstruction part 11 has a circulation part 12 penetrating between the lower part of the casing 5 and the obstruction part 11, and is provided at an incline in a vertical direction with respect to a water flow direction.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a vortex suppression device that suppresses the generation of vortices, a pump equipped with a vortex suppression device, and a pump facility equipped with a pump in a suction tank. [Background technology]

[0002] Conventionally, water such as rainwater flows into a suction tank of a pumping facility, is sucked up by a vertical pump, and is sent to a treatment facility downstream of the suction tank. A standard suction tank has a pair of side walls, a rear wall, and a bottom, and the pump is installed in front of the rear wall with its suction port facing downward.

[0003] When the pump is operated, water in the suction tank flows into the pump from the suction port and is sent through the pump to a downstream treatment facility. When the pump is operated, an air-suction vortex V1 and a submerged vortex V2 may be generated in the suction tank T, as shown in Figures 10A and 10B. Figure 10A is a vertical cross-sectional view of a conventional pump 900 and the suction tank T. Figure 10B is a horizontal cross-sectional view of the same pump 900 and the suction tank T.

[0004] When the water flow F1 from the upstream side of the suction tank T flows around the side surface of the pump 900 toward the rear wall surface 7, if the flow separates from the surface of the pump 900, the flow velocity distribution of the flow becomes uneven, and multiple vortices are generated downstream of the pump 900. The air suction vortex V1 is generated as this vortex grows, and is a vortex flow that flows from the water surface toward the suction port 5c. The air suction vortex V1 entrains air above the water surface and sucks it into the suction port 5c. The submerged vortex V2 is a vortex that is sucked into the suction port 5c when the pressure of the vortex generated from the bottom surface 8 or side wall surface 6 of the suction tank T drops below the steam pressure.

[0005] If the air suction vortex V1 and the submerged vortex V2 are drawn into the pump 900 through the water inlet 5c, there is a risk of violent vibration and loud noise occurring during pump operation. As a vortex suppression device for suppressing the generation of the air suction vortex V1 and the submerged vortex V2, a device as described in Patent Document 1 has been proposed. According to this device, a vortex suppression member is attached to the lower end of the bellmouth of the pump to suppress the generation of vortices. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2023-83628 A Summary of the Invention [Problem to be solved by the invention]

[0007] The vortex suppression device described in Patent Document 1 restricts the water flow from the rear wall surface to the pump's suction port by providing an obstacle at the bottom end of the pump facing the rear wall surface of the suction sump, thereby restricting the water flow from the upstream side to the rear wall surface, thereby preventing the generation of vortexes and the drawing of vortexes into the pump. However, in recent years, pumps have become larger and have larger capacities, and the amount of water drawn into the suction sump has increased, so there is a risk that the vortex suppression device described in Patent Document 1 will not be effective enough in suppressing vortex generation.

[0008] In other words, because the amount of water flowing from the upstream side of the suction tank toward the rear wall surface becomes large, even if the water flow to the suction port is restricted as described above, the water flow around the side of the pump will not be sufficiently controlled, and an air-sucking vortex may occur downstream of the pump.

[0009] If the flow around the sides of the pump is not well controlled and the flow separates from the outside of the pump, a low pressure area is formed near the back of the pump, and the pressure difference between the front and rear of the pump increases. This increases the force that the pump receives from the water flow, and the fluctuation of this force places a load on the pump casing.

[0010] The present invention has been made in consideration of the above problems, and has an object to effectively suppress the occurrence of air-suction vortexes in the suction sump during pump operation in the sump. [Means for solving the problem]

[0011] According to one aspect of the present invention, there is provided a pump installed in a suction tank, comprising: A vortex suppression device provided on the outside of a lower part of a casing connected to a water intake port that stands upright in a tank and faces downward, The casing lower portion has a pair of obstacles provided on the outside of the casing lower portion and extending along an outer peripheral surface of the casing lower portion; The pair of obstructions are provided on the outer periphery of the lower part of the casing on the downstream side of a narrowed portion where a gap between the outer periphery of the lower part of the casing and a side wall surface of the suction tank is narrowest, Each obstacle portion has a flow passage portion that passes between the lower portion of the casing and the obstacle portion, and is provided at an incline in the vertical direction with respect to the water flow direction.

[0012] According to this, the water flow crossing the obstacle flows along the lower surface of the obstacle and is divided into the outside of the obstacle and the flow section inside the obstacle. At this time, the flow rate of the water flow is increased compared to that of the conventional pump due to the narrowing of the flow path cross-sectional area, and the obstacle acts as a resistance to the flow. As a result, the flow along the surface of the casing is effectively disturbed and stirred, that is, turbulent. By turbulizing the flow, the vortex generation suppression device shifts the separation position where the flow separates from the outer surface of the casing to the downstream side of the pump. Therefore, the generation of vortices due to the effect of flow separation is suppressed downstream of the pump, and as a result, the vortex generation suppression device can suppress the generation of air-suction vortices.

[0013] In the vortex suppression device according to the second aspect of the present invention, each of the pair of obstacles is provided so that its downstream end in the water flow direction is lower than its upstream end.

[0014] This allows the water flow, which is inclined downward with respect to the water flow direction at the bottom of the pump, to flow along the underside of the obstacle at a constant flow rate. In addition, the obstacle acts as a resistance to the flow, effectively turbulentizing the flow along the surface of the casing and shifting the separation position downstream of the pump. As a result, the vortex suppression device can suppress the generation of air-sucking vortices.

[0015] In the vortex suppression device according to the third aspect of the present invention, each of the pair of obstruction portions is a plate-like body whose longitudinal direction extends along the outer circumferential surface of the casing lower portion when viewed from above the pump.

[0016] According to this, by arranging the plate-like body at an incline in the vertical direction, the cross-sectional area of ​​the flow path in the suction tank is effectively narrowed, and the water flow passing through the obstacle is faster than other parts in the suction tank. In addition, the obstacle acts as a resistance to the flow, so that the flow along the surface of the casing is effectively turbulent, shifting the separation position downstream of the pump. As a result, the vortex generation suppression device can suppress the generation of air-suction vortexes.

[0017] In the vortex suppression device according to the fourth aspect of the present invention, each of the pair of obstruction parts has a downstream end and an upstream end in the water flow direction connected to the casing.

[0018] According to this, even when a casing having a partially narrowed outer diameter is used, the obstruction portion relieves stress concentration on the narrowed portion of the casing. As a result, the vortex suppression device can suppress the generation of air-sucking vortices while ensuring sufficient mechanical strength.

[0019] In the vortex suppression device according to the fifth aspect of the present invention, the pair of obstruction portions are configured as a single member by connecting the downstream ends of the obstruction portions in the water flow direction.

[0020] As a result, the vortex suppression device has a simplified structure, which provides cost benefits and allows the device to effectively suppress the generation of air-suction vortices.

[0021] A pump according to a sixth aspect of the present invention is a pump equipped with a vortex suppression device, The vortex suppression device is provided at the bottom of the casing connected to the water intake.

[0022] According to this, the pump's vortex suppression device turbulently changes the flow along the surface of the casing, shifting the separation position downstream of the pump. This suppresses the generation of vortices due to the effect of flow separation downstream of the pump, and as a result, the pump can suppress the generation of air-suction vortices.

[0023] The pump equipment according to the seventh aspect of the present invention is a pump equipment including a pump having a vortex suppression device in a suction tank, The pump is installed in front of the rear wall of the suction tank, A portion of the water flowing from the upstream side toward the rear wall surface in the suction tank flows around the outside of the pump to the rear side of the pump and is sucked into the pump's suction port, causing it to flow in a direction that slopes downward relative to the water flow direction.

[0024] According to this, the pump vortex suppression device installed in the suction tank of the pump equipment turbulently changes the flow along the surface of the casing, shifting the separation position to the downstream side of the pump. This suppresses the generation of vortices due to the effect of flow separation downstream of the pump, and as a result, the pump equipment suppresses the generation of air-suction vortices in the suction tank. Effect of the Invention

[0025] According to the present invention, it is possible to effectively suppress the occurrence of air-suction vortexes in the suction sump during pump operation in the suction sump. [Brief description of the drawings]

[0026] [Figure 1A] 1 is a vertical sectional view of a pump facility including a pump having a vortex suppression device according to a first embodiment of the present invention. [Figure 1B]FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A. [Figure 1C] FIG. 1B is a longitudinal cross-sectional view taken along line BB in FIG. 1A. [Diagram 2] FIG. 2 is a perspective view of a pump having the vortex suppression device, as viewed from the downstream side of the water flow and obliquely from above. [Diagram 3] FIG. 2 is a perspective view of a pump having the vortex suppression device as viewed obliquely from below. [Figure 4] 1B is an enlarged view of a main portion of FIG. 1A, showing the state of water flow in the vicinity of the vortex generation suppression device; FIG. [Diagram 5] FIG. 5 is a cross-sectional view taken along line CC in FIG. 4, showing the state of water flow around a pump equipped with the vortex suppression device and a conventional pump. [Figure 6A] FIG. 5 is a vertical sectional view of a pump facility including a pump having a vortex suppression device according to a second embodiment of the present invention. [Figure 6B] FIG. 6B is a cross-sectional view taken along line DD in FIG. 6A. [Figure 6C] FIG. 6B is a vertical cross-sectional view taken along line EE in FIG. 6A. [Figure 7A] FIG. 11 is a vertical sectional view of a pump facility including a pump having a vortex suppression device according to a third embodiment of the present invention. [Figure 7B] FIG. 7B is a cross-sectional view taken along line FF in FIG. 7A. [Figure 8A] FIG. 11 is a vertical sectional view of a pump facility including a pump having a vortex suppression device according to a fourth embodiment of the present invention. [Figure 8B] FIG. 8B is a cross-sectional view taken along line GG in FIG. 8A. [Figure 8C] FIG. 8B is a longitudinal cross-sectional view taken along line HH in FIG. 8A. [Figure 9] FIG. 8C is an enlarged view of a main portion of FIG. 8B, showing the state of water flow around a pump equipped with the vortex suppression device and a conventional pump. [Figure 10A] FIG. 11 is a vertical cross-sectional view showing a conventional pump and water suction tank. [Figure 10B] FIG. 1 is a cross-sectional view showing a conventional pump and a water suction tank. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, a pipe connection device according to an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are given the same reference numerals and the description will not be repeated. In the following description, terms indicating positions or directions such as "upper", "lower", "horizontal" and "vertical" may be used. These terms are used for convenience to facilitate understanding of the embodiment, and are not limited to positions or directions when actually implemented.

[0028] First embodiment A vortex generation suppression device 10 according to a first embodiment of the present invention will be described with reference to Figs. 1A to 1C, 2 and 3. Fig. 1A is a longitudinal sectional view of a pump facility 1 including a pump 100 having a vortex generation suppression device 10 according to the first embodiment of the present invention. Fig. 1B is a transverse sectional view taken along line AA in Fig. 1A. Fig. 1C is a longitudinal sectional view taken along line BB in Fig. 1A. Fig. 2 is a perspective view of the pump 100 as viewed from the downstream side of the water flow and obliquely from above. Fig. 3 is a perspective view of the pump 100 as viewed from below.

[0029] 1A and 1B, a pump facility 1 includes a suction tank T and a pump 100 provided in the suction tank T and having a vortex suppression device 10.

[0030] The suction tank T has a pair of side walls 6, a rear wall 7, and a bottom 8. In the suction tank T, a water flow F1 is generated from the upstream side toward the rear wall 7. Hereinafter, the direction of the water flow F1 from the upstream side toward the rear wall 7 in the suction tank T will be referred to as the water flow direction.

[0031] Pump 100 is provided in front of rear wall surface 7 and sandwiched between a pair of side wall surfaces 6. Pump 100 has a cylindrical casing 5 placed in suction tank T, a bell mouth 5b (an example of a casing lower part) connected to the lower part of casing 5 and standing upright in the suction tank, and an annular flange 5d placed above bell mouth 5b. Bell mouth 5b has a suction port 5c facing the bottom surface 8. Pump 100 may be configured as a vertical shaft pump in which casing 5 stands upright in the suction tank, or as a horizontal shaft pump in which casing 5 is bent horizontally.

[0032] In this embodiment, the outer diameter of the bellmouth 5b becomes smaller relative to the outer diameter of the casing 5 from the connection portion with the flange 5d downward, passes through the throat portion 5e (see Figs. 1C and 3) where the outer diameter is smallest, and becomes larger toward the water intake port 5c. However, the shape of the bellmouth 5b is not limited to this embodiment, and may be configured so that, for example, the bellmouth 5b becomes larger relative to the outer diameter of the casing 5 the further downward.

[0033] Although not shown, pump 100 has a rotatable main shaft inserted into casing 5, an impeller that rotates together with the main shaft, and a rotary drive device that rotates the main shaft.

[0034] As shown in Figures 1A to 1C, 2 and 3, the vortex generation suppression device 10 comprises a pair of first obstacle portions 11 (examples of obstacle portions) provided on the outer surface of the casing 5 below the flange 5d and outside the bellmouth 5b, and a second obstacle portion 17 provided below the water intake 5c.

[0035] The pair of first obstacle portions 11 are plate-like bodies whose longitudinal direction extends along the outer peripheral surface of the bell mouth 5b when viewed from above the pump 100, and are provided on the outside of the outer surface of the bell mouth 5b downstream of the narrowed portion where the distance between the outer peripheral surface of the bell mouth 5b and the side wall surface 6 of the suction tank T is narrowest.

[0036] In detail, the pair of first obstacle parts 11 are connected to the lower surface of the flange 5d at their upstream end in the longitudinal direction, facing each other in a direction perpendicular to the water flow direction in a top view of the pump 100. The pair of first obstacle parts 11 are connected to the outer surface of the lower part of the bell mouth 5b at a position rotated in the water flow direction by a predetermined angle, for example, 45°, from the position where each end is disposed about the pump axis z in a top view of the pump 100. At that time, each first obstacle part 11 is connected to the lower surface of the flange 5d and the outer surface of the bell mouth 5b so as to have a flow part 12 penetrating between the outer surface of the bell mouth 5b and each first obstacle part 11.

[0037] As described above, the pair of first obstacle portions 11 have one and the other longitudinal ends connected to the underside of the flange 5d and the outer surface of the bell mouth 5b, and are configured so that, as shown in FIG. 1A, the approximate inclination angle θ with respect to the horizontal plane in a side view of the pump 100 is inclined downward at a predetermined inclination angle, for example, 45°.

[0038] 1A, in particular, in the lower part of the pump 100, in addition to the water flow F1 flowing from the upstream side of the suction tank T toward the rear wall surface 7, there is a water flow F2 flowing from above the pump 100 downward toward the water intake 5c. These water flows F1 and F2 join together to generate a water flow F3 (hereinafter referred to as an oblique water flow F3) that flows in a direction inclined downward with respect to the water flow direction. The oblique water flow F3, like the water flow F1, also causes an air-sucking vortex.

[0039] The applicants have experimentally confirmed that the oblique water flow F3 is a flow that is inclined downward at approximately 45° with respect to the water flow direction. Therefore, by providing the pair of first obstacle portions 11 on the outside of the bellmouth 5b of the casing 5 as described above, the oblique water flow F3 can flow along the lower surface of the first obstacle portion 11 while maintaining a flow velocity. As shown in FIG. 2, the oblique water flow F3 flows along the lower surface of the first obstacle portion 11 and is diverted toward the outside of the first obstacle portion 11 and the flow portion 12 on the inside of the first obstacle portion 11.

[0040] As shown particularly in Figures 1C and 3, the second obstacle section 17 has a cylindrical member 18 whose axial direction extends toward the pump axis, four obstacle plates 19 provided on the outer surface of the cylindrical member 18 and whose upper ends are provided on the inner surface of the bellmouth 5b, and a bearing section 18b provided on the inside of the cylindrical member 18.

[0041] In a top view of the pump 100, the four obstacle plates 19 have their inner ends connected to the outer surface of the cylindrical member 18, extend in a cross shape in the radial direction of the cylindrical member 18, and have their upper ends connected to the inner surface of the bell mouth 5b. At this time, the upper ends of the obstacle plates 19 extend and are connected to the vicinity of the throat portion 5e of the bell mouth 5b. The bearing portion 18b is typically a bearing, and is provided inside the upper portion of the cylindrical member 18 to rotatably support the lower end of the main shaft S of the pump 100.

[0042] Next, the state of the water flow F3 around the vortex generation suppression device 10 will be described with reference to Figures 4 and 5. Figure 4 is an enlarged view of a main part of Figure 1A, showing the state of the oblique water flow F3 in the vicinity of the vortex generation suppression device 10. Figure 5 is a cross-sectional view taken along line CC in Figure 4, showing a comparison of the state of the oblique water flow F3 around the pump 100 equipped with the vortex generation suppression device 10 and the conventional pump 900. The upper view of Figure 5 shows the state of the oblique water flow F3 around the conventional pump 900, and the lower view of Figure 5 shows the state of the oblique water flow F3 around the pump 100 equipped with the vortex generation suppression device 10.

[0043] 4 and 5, the oblique water flow F3 flows at a constant flow rate along the lower surface of the first obstacle 11, and is diverged toward the outside of the first obstacle 11 and the flow section 12 inside the first obstacle 11. At this time, the corners 11e formed in the first obstacle 11, in particular the corners 11e, act as resistance to the flow, and the oblique water flow F3 is effectively disturbed and agitated downstream of the first obstacle 11 (F11, F12 in the figures). The corners 11e may be formed of R-sections with a certain curvature (the same applies to the embodiments described later).

[0044] As can be seen from the upper diagram of Fig. 5, in the case of the conventional pump 900, as described above, the water flow F1 separates from the surface of the pump 900 as it crosses the pump 900, which causes the flow velocity distribution of the flow to become non-uniform, generating multiple vortices F19 downstream of the pump 900, and these vortices F19 grow to generate air-suction vortices V1. Note that "separation" refers to a phenomenon in which a fluid is unable to flow along an object due to the influence of the viscosity of the fluid, the shape of the object, etc., and the fluid flow separates from the surface of the object. When a flow separates from an object, a low-pressure area accompanied by a backflow or vortex is formed downstream of the object.

[0045] In contrast, in the case of the pump 100 equipped with the vortex generation suppression device 10 shown in the lower diagram of FIG. 5, the first obstacle portion 11 is provided in the flow path, and the flow path cross-sectional area formed between the outer surface of the bellmouth 5b and each side wall surface 6, 6 is narrowed from the upstream side to the downstream side, and the speed of the water flow F3 crossing the first obstacle portion 11 is greater than that of the water flow F3 crossing the conventional pump 900. Furthermore, as shown in the upper diagram of FIG. 5, before the flow is separated and a vortex F19 is generated, the first obstacle portion 11 is provided in the flow, and the water flow F3 crossing the first obstacle portion 11 is diverted toward the outside of the first obstacle portion 11 and the circulating portion 12 as described above, and the flow speed is also increased, so that the corner portion 11e in particular becomes a resistance to the flow, and the flow is effectively disturbed and agitated (F11, F12 in the diagram). In other words, the vortex generation suppression device 10 transitions the water flow F3 from a laminar flow to a turbulent flow. In this case, the first obstacle portion 11 is provided on the outside of the outer surface of the casing 5 downstream of the narrowed portion, so that the first obstacle portion 11 acts as a resistance to the flow, particularly downstream of the pump 100.

[0046] Generally, a flow transitions from laminar to turbulent, that is, becomes turbulent, making it difficult for the flow to separate from the surface of an object. Controlling flow separation by such turbulence is commonly performed. For example, dimples on a golf ball make the flow on the ball surface turbulent by providing multiple recesses on the ball surface, and delay the separation of the flow from the ball surface downstream of the ball. When a flow separates from the surface of an object, a low-pressure area is formed on the rear back surface of the object, and the pressure difference between the front and rear surfaces of the object becomes resistance in the flow of the object. In other words, by delaying the separation of the flow downstream using dimples, the golf ball can reduce resistance in the flow.

[0047] As described above, the vortex generation suppression device 10 also applies turbulence to control flow separation, and in particular, by turbulising the flow along the surface of the bell mouth 5b downstream of the pump 100, the separation position at which the flow separates from the surface of the bell mouth 5b is shifted downstream of the pump 100. This suppresses the generation of vortex F19 due to the effect of flow separation downstream of the pump 100 (F16 in the figure), and as a result, the vortex generation suppression device 10 suppresses the generation of air-suction vortex V1.

[0048] By shifting the separation position downstream of the pump 100, the low-pressure area generated on the back surface of the pump 100 is reduced, and the pressure difference between the front surface and the back surface of the pump 100 is reduced, thereby reducing the force that the pump 100 receives from the water flow F1. As a result, the vortex suppression device 10 can reduce the load on the casing 5 of the pump 100.

[0049] Furthermore, because one and the other longitudinal ends of the pair of first obstacle portions 11 are connected to the underside of the flange 5d and the outer surface of the bellmouth 5b, even when a casing 5 having a partially tapered outer diameter like the bellmouth 5b in this embodiment is used, the first obstacle portions 11 act as reinforcing materials to share part of the force acting on the casing 5 and mitigate stress concentration in the portion of the casing 5 where the outer diameter is tapered. As a result, the vortex generation suppression device 10 can suppress the generation of an air-suction vortex V1 while ensuring sufficient mechanical strength.

[0050] Although not shown, the second obstacle portion 17 is provided in the middle of the flow path of the water flowing into the intake port 5c, and the obstacle plate 19 acts as a resistance to the water flow, weakening the force of the water flow. As a result, the second obstacle portion 17 suppresses the generation of underwater vortexes, particularly in the lower part of the pump 100. At that time, the inner end of the obstacle plate 19 is connected to the outer surface of the cylindrical member 18, so that the stress concentration at the connection part can be reduced more than when the inner ends of the obstacle plates 19 are connected to each other. In addition, the upper end of the obstacle plate 19 extends to the vicinity of the throat portion 5e of the bell mouth 5b and has a sufficient connection length, so that the stress applied to the connection part can be reduced. As a result, the second obstacle portion 17 can effectively suppress the generation of underwater vortexes while maintaining sufficient mechanical strength.

[0051] The first obstacle portion 11 may be configured to have a portion that is partially larger than the outer diameter of the flange 5d and / or the outer diameter of the bellmouth 5b when viewed from above the pump 100, or may be configured to have a portion that is partially smaller than the outer diameter of the flange 5d and / or the outer diameter of the bellmouth 5b in the present embodiment. The first obstacle portion 11 has a curved shape that follows the outer circumferential surface of the casing 5, but may be configured of a straight member that does not follow the outer circumferential surface of the casing 5. Even when configured in this manner, the vortex generation suppression device 10 can achieve the same effects as those described above.

[0052] Second embodiment Next, a vortex generation suppression device 20 according to a second embodiment of the present invention will be described with reference to Figures 6A, 6B, and 6C. Figure 6A is a vertical cross-sectional view of a pump facility 2 including a pump 200 having a vortex generation suppression device 20 according to the second embodiment of the present invention. Figure 6B is a cross-sectional view taken along line DD in Figure 6A. Figure 6C is a vertical cross-sectional view taken along line EE in Figure 6A.

[0053] The pair of first obstacle portions 21 are plate-like bodies whose longitudinal direction extends along the water flow from the upstream side to the downstream side when viewed from the top of the pump 200, and like the first obstacle portion 11 in the first embodiment, are provided on the outside of the outer surface of the bell mouth 5b of the casing 5, downstream of the narrowest constriction portion where the distance between at least the outer surface of the bell mouth 5b and the side wall surface 6 of the suction tank T is the narrowest.

[0054] In detail, one end portion of each of the pair of first obstacle portions 21 on the upstream side in the longitudinal direction is connected to the upper part of the bellmouth 5b, facing each other in a direction intersecting the water flow direction, as viewed from above the pump 200. The other end portion of each of the pair of first obstacle portions 21 on the downstream side in the longitudinal direction is connected to the outer surface of the bellmouth 5b at a position where the inclination of the casing radial direction with respect to the water flow direction is, for example, 45°, also as viewed from above the pump 200. In this case, each of the first obstacle portions 21 is connected to the outer surface of the bellmouth 5b so as to have a flow portion 22 penetrating between the outer surface of the bellmouth 5b and each of the first obstacle portions 21.

[0055] That is, the vortex generation suppression device 20 is configured to have no flange 5d (see, for example, FIG. 1A) compared to the vortex generation suppression device 10 of the first embodiment, and one end portion on the upper end side in the longitudinal direction is connected to the outer surface of the upper part of the bellmouth 5b, not to the lower surface of the flange 5d. Alternatively, the vortex generation suppression device 20 may be configured to be connected so as to straddle from a part of the lower surface of the flange 5d to the outer surface of the bellmouth 5b.

[0056] As with the first obstacle portions 11 according to the first embodiment, the pair of first obstacle portions 21 are connected to the outer surface of the bellmouth 5b as described above, and are configured so that the approximate inclination angle θ with respect to the water flow direction is a predetermined inclination angle, for example, 45° downward, as shown in Fig. 6A. Therefore, the oblique water flow F3 flows along the lower surface of the first obstacle portions 21.

[0057] As in the vortex generation suppression device 10 according to the first embodiment, when the oblique water flow F3 flows along the lower surface of the first obstacle portion 21, the pair of first obstacle portions 21 in the flow path narrows the flow path cross-sectional area from the upstream side to the downstream side. As a result, the water flow F3 crossing the first obstacle portion 21 has a higher flow velocity than the water flow F3 flowing between the outer surface of the casing 5 and the side wall 6. In addition, the oblique water flow F3 is diverted toward the outside of the first obstacle portion 21 and the flow portion 22 inside the first obstacle portion 21. At that time, the corner portion (reference numeral omitted) formed in the first obstacle portion 21 becomes a resistance to the flow, and the oblique water flow F3 is effectively turbulent on the downstream side of the first obstacle portion 21. As a result, the vortex generation suppression device 40 shifts the separation position to the downstream side of the pump 200. As a result, the vortex generation suppression device 40 can suppress the generation of an air-suction vortex.

[0058] Third embodiment Next, a vortex generation suppression device 30 according to a third embodiment of the present invention will be described with reference to Figures 7A and 7B. Figure 7A is a vertical cross-sectional view of a pump facility 3 including a pump 300 having a vortex generation suppression device 30 according to the third embodiment of the present invention. Figure 7B is a horizontal cross-sectional view taken along line FF in Figure 7A.

[0059] As shown in FIG. 7, the vortex generation suppression device 30 has a first obstacle portion 31. The first obstacle portion 31 is configured as one member by connecting the first obstacle portions 11, 11 of the vortex generation suppression device 10. Specifically, the first obstacle portion 31 is configured as one member by bending the downstream end portions of the first obstacle portions 11, 11 in the longitudinal direction upward at the bent portion 31b, extending along the outer surface of the lower part of the bellmouth 5b, and connecting the downstream end faces on the downstream side of the bellmouth 5b. The first obstacle portion 31 is connected to the outer surface of the lower part of the bellmouth 5b at the lower surface 31c of the portion extending along the outer surface of the lower part of the bellmouth 5b. Alternatively, the first obstacle portion 31 may not be connected to the outer surface of the lower part of the bellmouth 5b, and may have a gap between the lower surface of the first obstacle portion 31 and the outer surface of the lower part of the bellmouth 5b.

[0060] The vortex generation suppression device 30 has the same configuration as the vortex generation suppression device 10 according to the first embodiment in the upstream side of the bent portion 31b of the first obstacle portion 31, and therefore exhibits the same effects as the vortex generation suppression device 10. That is, as described above, when the water flow F3 flows along the lower surface of the first obstacle portion 31 upstream of the bent portion 31b, the corner portion (reference numeral omitted) formed in the first obstacle portion 31 in particular becomes a resistance to the flow, and the flow is effectively turbulent. As a result, by shifting the separation position to the downstream side of the pump 300, the vortex generation suppression device 30 has a cost advantage due to being configured as a single member, and can effectively suppress the generation of an air-suction vortex.

[0061] Fourth embodiment Next, the configuration of a vortex generation suppression device 40 according to a fourth embodiment of the present invention will be described with reference to Fig. 8A to Fig. 8C. Fig. 8A is a vertical cross-sectional view of a pump facility 4 including a pump 400 having a vortex generation suppression device 40 according to the fourth embodiment of the present invention. Fig. 8B is a horizontal cross-sectional view taken along line GG in Fig. 8A. Fig. 8C is a vertical cross-sectional view taken along line HH in Fig. 8A.

[0062] 8A to 8C, the vortex generation suppression device 40 has a pair of first protrusions 41 provided on the casing 5 in addition to the components of the vortex generation suppression device 10 according to the first embodiment.

[0063] The pair of first protrusions 41 are a pair of long plate-like members provided on the outer surface of the casing 5 of the pump 400, extending in the longitudinal direction (up-down direction) of the casing 5. The pair of first protrusions 41 are provided on the outer surface of the casing 5 facing each other in a direction perpendicular to the water flow direction when viewed from above the pump 400. The pair of first protrusions 41 are arranged along the radial direction of the casing 5, and one end in the width direction is connected to the outer surface of the casing 5.

[0064] The pair of first protrusions 41 are provided at the narrowed portion on the outer surface of the casing 5. That is, as shown in Figures 8A and 8B, the pair of first protrusions 41 are provided on the outer surface of the casing 5 on either side of the diameter of the casing 5 in a direction perpendicular to the water flow direction.

[0065] 8C, the pair of first ridges 41 have a plurality of recesses 41b and protrusions 41c along the longitudinal direction of the first ridges 41 at their ends in the radial direction of the casing 5. The recesses 41b are formed, for example, by the first ridges 41 being penetrated in a rectangular shape in the thickness direction of the first ridges 41, with the penetrated portions opening in the radial direction of the casing 5. The protrusions 41c are formed as portions of the first ridges 41 that are not penetrated.

[0066] 8A and 8B, the vortex generation suppression device 40 may be configured to further include, in addition to the first ridge 41, a pair of long plate-shaped second ridges 42 and a pair of third ridges 43 provided on the outer surface of the casing 5 and extending in the longitudinal direction of the casing 5. Similar to the first ridge 41, the second ridges 42 and the third ridges 43 may be configured so that a plurality of recesses and protrusions (reference numbers omitted) are provided along the longitudinal direction of the second ridges 42 and the third ridges 43 at the radial ends of the casing 5.

[0067] In this case, the pair of second protrusions 42 face each other in a direction perpendicular to the water flow direction, and are provided downstream of the water flow F1 from the pair of first protrusions 41. The pair of third protrusions 43 face each other in a direction intersecting the water flow direction, and are provided upstream of the water flow F1 from the pair of first protrusions 41.

[0068] Next, referring to Fig. 9, the state of the water flow F1 around the pump 400 equipped with the vortex generation suppression device 40 and the conventional pump 900 will be compared and described. Fig. 9 is a cross-sectional view showing the state of the water flow F1 around the pump 400 equipped with the vortex generation suppression device 40 and the conventional pump 900. The upper diagram of Fig. 9 shows the state of the water flow F1 around the conventional pump 900, and the lower diagram of Fig. 3 shows the state of the water flow F1 around the pump 100 equipped with the vortex generation suppression device 10.

[0069] 9, in the conventional pump 900, an air-suction vortex V1 is generated downstream of the pump 900, as described above. In contrast, in the case of a pump 400 equipped with a vortex generation suppression device 40 shown in the lower diagram of FIG. 9, the first protrusion 41 is provided on the outer surface of the casing 5 at the narrowed portion, so that the speed of the water flow F1 crossing the first protrusion 41 is greater than the water flow F1 crossing the conventional pump 900.

[0070] 9, before the flow separates and generates a vortex F19, the first ridges 41 are provided in the flow, and as a result, the water flow F1 crossing the first ridges 41 has a high flow rate as described above, and the corners (reference numbers omitted) formed in the recesses 41b and the protrusions 41c in particular provide resistance to the flow, effectively disrupting and stirring the flow (F13 in the figure). In other words, the vortex generation suppression device 10 turbulently generates the water flow F1.

[0071] The second ridge portion 42, like the first ridge portion 41, effectively disrupts the flow and makes it turbulent again, particularly at the corners (reference numerals omitted) of the second ridge portion 42, which act as flow resistance on the downstream side of the pump 400 where the separation position has been shifted (F14 in the figure). The third ridge portion 43 is provided on the upstream side of the first ridge portion 41 and the second ridge portion 42, and thus makes the flow turbulent before the water flow F1 passes through the first ridge portion 41 and the second ridge portion 42 (F15 in the figure). As a result, the vortex generation suppression device 40 can effectively suppress the generation of the air suction vortex V1 by shifting the separation position downstream of the pump 400 (F17 in the figure).

[0072] As described above, the vortex generation suppression device 40 effectively disturbs and agitates the water flow F1 in the upper part of the suction tank T mainly by the first ridge portion 41, the second ridge portion 42, and the third ridge portion 43, and effectively disturbs and agitates the water flow F3 in the lower part of the suction tank T by the first obstacle portion 11, thereby effectively suppressing the generation of the air-sucking vortex V1. Furthermore, the vortex generation suppression device 40 weakens the water flow sucked into the suction port 5c by the second obstacle portion 17, thereby effectively suppressing the generation of the underwater vortex V2.

[0073] The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above embodiments, and can be implemented in various forms without departing from the spirit of the present invention. The drawings are mainly schematic illustrations of each component for ease of understanding, and the thickness, length, number, spacing, etc. of each component shown in the drawings are different from the actual ones due to the convenience of drawing. In addition, the material, shape, dimensions, etc. of each component shown in the above embodiments are merely examples and are not particularly limited, and various modifications are possible within a range that does not substantially deviate from the configuration of the present invention. [Explanation of symbols]

[0074] 1. Pump equipment 5 Casing 5b Bellmouth 5c Water intake 5d flange 6 Side wall 7 Rear wall 8 Bottom 10. Vortex suppression device 11 First Obstacle Section 12 Distribution Department 17 2nd Obstacle Section 100 Pump 900 Conventional pump V1 Air-suction vortex V2 Underwater Vortex F1 water flow F3 Diagonal water flow

Claims

1. In a pump installed in a suction tank, A vortex suppression device provided on the outside of a lower part of a casing connected to a water intake port that stands upright in a tank and faces downward, The casing lower portion has a pair of obstacles provided on the outside of the casing lower portion and extending along an outer peripheral surface of the casing lower portion; The pair of obstructions are provided on the outer periphery of the lower part of the casing on the downstream side of a narrowed portion where a gap between the outer periphery of the lower part of the casing and a side wall surface of the suction tank is narrowest, Each obstacle has a flow passage that penetrates between the lower part of the casing and the obstacle, and is provided at an incline in the vertical direction with respect to the water flow direction. A vortex generation suppression device characterized by:

2. Each of the pair of obstacles is provided so that the downstream end in the water flow direction is lower than the upstream end.

2. The vortex suppression device according to claim 1.

3. Each of the pair of obstructions is a plate-like body whose longitudinal direction extends along the outer circumferential surface of the lower part of the casing when viewed from above the pump.

3. The vortex suppression device according to claim 1 or 2.

4. The pair of obstacles are each connected to the casing at a downstream end and an upstream end in the water flow direction.

3. The vortex suppression device according to claim 1 or 2.

5. The pair of obstacles are connected at their downstream ends in the water flow direction to form a single member.

3. The vortex suppression device according to claim 1 or 2.

6. A pump equipped with the vortex suppression device according to claim 1 or 2, A vortex suppression device is installed at the bottom of the casing connected to the water intake. A pump characterized by:

7. A pump facility including the pump according to claim 6 in a water suction tank, The pump is installed in front of the rear wall of the suction tank, In the suction tank, part of the water flow from the upstream side toward the rear wall surface flows around the outside of the pump and to the rear side of the pump, and is sucked into the pump suction port, so that it flows in a direction that is inclined downward with respect to the water flow direction. A pump installation comprising:

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