JP5582802B2 - Fluid flow structure - Google Patents

Description

  The present invention relates to a fluid distribution structure that is provided in, for example, a pump, a water wheel, a pump water wheel, and the like, and a swirling fluid that swirls in an upstream cavity flows through a flow passage to a downstream cavity.

  For example, a conventional pump turbine is configured by mounting an impeller composed of a shroud, a crown, a plurality of runner vanes, and a cone on a lower end portion of a rotating shaft. Therefore, when the impeller is rotated by driving the rotating shaft, the fluid sucked into the impeller casing from the suction casing is increased in pressure by the rotation of the impeller, and is raised and discharged in the impeller casing. The

  In such a pump turbine, the fluid is raised and sent to the discharge side while increasing the pressure of the fluid in the suction casing by the rotation of the impeller. Therefore, the fluid pressure is low on the suction casing side and high on the impeller casing, and a large downward thrust force acts on the rotating shaft. As a result, there is a problem that the bearing that supports the rotating shaft is enlarged.

  As a technique for solving such a problem, for example, there is one described in Patent Document 1 below. In the centrifugal turbomachine described in Patent Document 1, a hub is connected to a rotatable rotating shaft on the back surface facing the casing, and blades are fixed to the hub to form an impeller. A turning restraining plate is provided on the surface facing the rear surface of the hub.

JP 2009-008021 A

  In the conventional centrifugal turbomachine described above, the swirl suppression plate is provided on the surface of the casing facing the back surface of the hub, thereby suppressing the swirl flow in the back pressure chamber and reducing the axial thrust force. However, even in this case, there is a possibility that the pump efficiency may be reduced by suppressing the swirling flow in the back pressure chamber.

  Also, by forming a balance hole that opens from the back side of the crown to the runner vane outlet side in the pump turbine, the impeller casing on the high pressure side and the suction casing on the low pressure side communicate with each other, and the back side of the impeller There are some which reduce the thrust force and reduce the thrust force acting on the rotating shaft. However, in this structure, a swirling flow is generated on the back side of the impeller, and even if this swirling flow flows into the balance hole, the angular momentum is preserved, and a strong swirling flow develops in the balance hole. When a strong swirl flow is generated in the balance hole, the static pressure near the center of the swirl flow is lowered, and cavitation may occur to cause erosion. In addition, the pressure loss inside the balance hole becomes large, the flow rate of the fluid passing through the balance hole cannot be secured sufficiently, and it becomes difficult to reduce the pressure on the rear side of the impeller, and the thrust force is reduced. become unable.

  The present invention solves the above-described problem, and even if a swirl flow is generated in the cavity upstream from the inlet of the flow passage, the swirl in the flow passage is suppressed and the downstream side through the flow passage is suppressed. An object of the present invention is to provide a fluid flow structure that can supply a sufficient flow rate of fluid to the cavity.

  In order to achieve the above object, a fluid circulation structure of the present invention includes an upstream cavity that contains a swirling fluid, a flow passage that communicates with the upstream cavity, and a distal end portion of the flow passage. In the fluid circulation structure in which the swirling fluid swirling in the upstream cavity flows to the downstream cavity through the flow passage, and intersects the swirling direction of the swirling fluid. A swirl suppression surface is provided in which swirl fluid collides to suppress swirl.

  Therefore, when the swirling fluid swirling in the upstream cavity flows into the downstream cavity through the flow passage, the swirling fluid collides with the swirl suppression surface, so that the swirling component of this fluid is removed or reduced. The swirling of the fluid flowing into the flow passage is suppressed, and a sufficient amount of fluid can be supplied from the upstream cavity through the flow passage to the downstream cavity. That is, since the swirling fluid has different angular momentum depending on the swirling radius, the fluid flowing into the flow path becomes a strong swirling flow due to the difference in angular momentum. However, when the above-described turning suppression surface is provided, when the fluid having different angular momentum depending on the turning radius collides with this turning suppression surface, the turning component of the fluid is removed or reduced, and the difference in angular momentum is reduced. Since it decreases, swirling of the fluid flowing into the flow path can be suppressed.

  In the fluid circulation structure of the present invention, the swirl suppression surface is set longer than a representative cross-sectional dimension of the flow passage in a direction intersecting a swirl direction of the swirl fluid.

  Therefore, by ensuring an appropriate amount of the swirl suppression surface at an appropriate position, the swirling fluid swirling in the upstream cavity can properly collide with the swirl suppression surface, and the swirl component of this fluid can be efficiently removed or reduced. it can. Here, the representative cross-sectional dimensions are, for example, the inner diameter when the cross-sectional shape of the flow passage is circular, the inner diameter of the circumscribed circle when it is polygonal, and the dimension in the longitudinal direction of the cross-section when it is oval or elliptical ( Long diameter).

  In the fluid circulation structure of the present invention, the swirl suppression surface is located on the downstream side of the swirling fluid in the flow passage and is formed with an acute angle inclined by 45 degrees or more with respect to the swirling direction of the swirling fluid. It is characterized by that.

  Therefore, when the swirling fluid swirling in the upstream cavity collides with the swirl suppression surface, the collided swirling fluid flows along the swirl suppression surface. At this time, when the velocity component of the swirling fluid flowing along the swirl suppression surface is decomposed into a swirl component and a normal component orthogonal to the swirl component, “swirl component ≦ normal component” can be satisfied. That is, when the acute angle is 45 degrees, the swirl component and the normal component of the swirling fluid flowing along the swirl suppression surface are “swirl component = normal component”. Then, as the acute angle increases (approaching orthogonality), the “swing component <normal component”. Thereby, the swirling fluid swirling in the upstream cavity collides with the swirl suppression surface, so that the swirling component of the fluid can be efficiently reduced as the acute angle approaches orthogonal.

  In the fluid circulation structure of the present invention, the swirl suppression surface is located on the downstream side of the swirling fluid in the flow passage and is formed orthogonal to the swirling direction of the swirling fluid.

  Therefore, the swirling fluid swirling in the upstream cavity collides perpendicularly to the swirl suppression surface, so that the swirling component of the fluid can be reliably removed or reduced.

  In the fluid circulation structure of the present invention, a base end portion of the flow passage is communicated with a swirling surface in which the swirling fluid swirls in the upstream cavity, and a swirl suppression chamber is provided at a communication portion between the upstream cavity and the flow passage. It is provided and the said rotation suppression surface is formed in this rotation suppression chamber, It is characterized by the above-mentioned.

  Therefore, by providing the swirl suppression chamber at the communication portion between the upstream cavity and the flow passage, the swirl restraint surface is located at the base end portion of the flow passage, that is, the inlet side, and the swirl flow in the flow passage. Can be efficiently suppressed.

  In the fluid circulation structure of the present invention, the swirl suppression chamber is formed as a recess in the swirling surface of the upstream cavity, and the base end portion of the flow passage is communicated with the bottom surface of the recess, and the end surface of the recess is The turning suppression surface is formed.

  Therefore, by forming the swirl suppression chamber as a recess in the swirl surface of the upstream cavity, the swirl suppression surface can be easily formed, and workability can be improved.

  In the fluid circulation structure of the present invention, the recess is formed to have a substantially equal length along the swirling direction of the swirling fluid with respect to the representative cross-sectional dimension of the base end portion of the flow passage. The swirl suppression surface is formed on a downstream end surface of the swirling fluid in the recess, and is formed in a large length along a direction intersecting the swirl direction.

  Therefore, the recess should be the representative cross-sectional dimension at the base end of the flow passage (for example, the inner diameter for round holes, the inner diameter of the circumscribed circle for polygonal holes, and the longitudinal dimension for oblong and elliptical holes). On the other hand, by making a long groove (long hole) along the direction intersecting the swirling direction of the swirling fluid, the swirl suppression chamber and the swirl suppression surface can be easily formed, and further workability is improved. be able to.

  In the fluid circulation structure of the present invention, the concave portion is deepened toward the downstream side of the swirling fluid, and an inclined surface that intersects the swirl suppression surface is formed.

  Accordingly, since the swirling fluid swirling in the upstream cavity collides with the swirl suppression surface along the inclined surface, the swirling fluid can be efficiently collided with the swirl suppression surface, and the swirling component of this fluid can be efficiently removed. Or it can be reduced.

  In the fluid flow structure of the present invention, the flow passage is any one of a round hole, a long round hole, an elliptical hole, and a polygonal hole, and the representative cross-sectional dimension is the inner diameter of the round hole, and the long round hole and the elliptical hole. Is the dimension in the longitudinal direction, and the polygonal hole is the inner diameter of the circumscribed circle.

  According to the fluid circulation structure of the present invention, in the structure in which the swirling fluid swirling in the upstream cavity flows to the downstream cavity through the flow passage, the swirling fluid collides with the swirling direction by intersecting the swirling direction of the swirling fluid. Therefore, even if a swirl flow is generated in the upstream cavity, the development of swirl in this flow path is suppressed, and the upstream cavity passes through the flow path to the downstream cavity. A sufficient amount of fluid can be supplied.

FIG. 1 is a cross-sectional view of a main part of a multistage centrifugal pump representing a fluid circulation structure according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram illustrating a swirl suppression chamber (concave portion) in the fluid circulation structure of the first embodiment. FIG. 3 is a schematic diagram illustrating the shape of the swirl suppression chamber (concave portion) in the fluid circulation structure of the first embodiment. FIG. 4A is a schematic diagram illustrating the shape of a swirl suppression chamber (concave portion) in the fluid circulation structure of the first embodiment. 4-2 is a cross-sectional view (IV-IV cross-sectional view of FIG. 4-1) showing the shape of a swirl suppression chamber (concave portion) in the fluid flow structure of Example 1. FIG. FIG. 5 is a schematic configuration diagram illustrating a multistage centrifugal pump to which the fluid flow structure of the first embodiment is applied. FIG. 6 is a schematic diagram illustrating a swirl suppression chamber (concave portion) in the fluid circulation structure according to the second embodiment of the present invention. FIG. 7 is a schematic diagram illustrating a swirl suppression surface in the fluid circulation structure according to the third embodiment of the present invention. FIG. 8 is a schematic configuration diagram showing a pump turbine to which a fluid circulation structure according to Embodiment 4 of the present invention is applied. FIG. 9A is a schematic configuration diagram illustrating a modification of the fluid circulation structure of the present invention. FIG. 9-2 is a schematic configuration diagram illustrating a modification of the fluid circulation structure of the present invention.

  Exemplary embodiments of a fluid circulation structure according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example.

  FIG. 1 is a cross-sectional view of a main part of a multistage centrifugal pump representing a fluid circulation structure according to a first embodiment of the present invention. FIG. 2 is a schematic view showing a swirl suppression chamber (concave portion) in the fluid circulation structure of the first embodiment. 3 is a schematic diagram showing the shape of the swirl suppression chamber (recess) in the fluid flow structure of Example 1, and FIG. 4-1 is a schematic diagram showing the shape of the swirl suppression chamber (recess) in the fluid flow structure of Example 1. 4-2 is a sectional view showing the shape of the swirl suppression chamber (recessed portion) in the fluid circulation structure of the first embodiment (IV-IV sectional view of FIG. 4-1), and FIG. 5 is a fluid circulation of the first embodiment. It is a schematic block diagram showing the multistage centrifugal pump to which the structure was applied.

  In Example 1, the fluid circulation structure of the present invention will be described by applying it to a feed water pump used in a combined power plant, for example. This power plant is a combination of a gas turbine and a steam turbine. The high-temperature exhaust gas discharged from the gas turbine is sent to an exhaust heat recovery boiler, and steam is generated using the heating unit of the exhaust heat recovery boiler. The generated steam is sent to a steam turbine for driving. Then, the steam used in the steam turbine is cooled by a condenser to become condensate, returned to the exhaust heat recovery boiler by the condensate pump and the feed water pump, overheated by the heating unit, regenerated, and re-steamed. Sent to the turbine.

  In such a complex plant, the condensate from the condenser is sent to the heating unit of the exhaust heat recovery boiler by the condensate pump and the feed water pump. In this case, the water supply pump plays an important role of circulating water in the complex plant. That is, since the feed water pump requires the ability to supply water from a low flow rate to a large flow rate, a multistage centrifugal pump is applied. And this multistage centrifugal pump is provided with two impeller assemblies comprising a plurality of stages of impellers, and each impeller assembly is disposed so that the back surfaces thereof face each other, so that the thrust force acting on the rotating shaft Is reduced. In addition, this multistage centrifugal pump forms a bypass passage that returns the water supply from the downstream impeller assembly to the water supply from the upstream impeller assembly, and increases the circulation flow rate, thereby reducing inefficiency in low flow operation. Stable phenomenon is suppressed.

  Hereinafter, the multistage centrifugal pump of Example 1 will be described in detail. As shown in FIG. 5, in the multistage centrifugal pump 11 of the first embodiment, the outer casing 12 has a hollow cylindrical shape, and the suction port 13 is provided on the outer peripheral portion on one side in the longitudinal direction. A discharge port 14 is formed at the center of the nozzle. In the outer casing 12, two inner casings 15 and 16 made of a plurality of ring members having a so-called ring-cut structure are disposed. In this case, the first inner casing 15 is located between the suction port 13 and the discharge port 14, and the second inner casing 16 is located on the side opposite to the suction port 13 with respect to the discharge port 14. The outer casing 12 has the casing cover 17 fixed to one end and the casing cover 18 fixed to the other end, so that the outer casing 12, the inner casings 15 and 16, and the casing covers 17 and 18 are integrated. In the region excluding the suction port 13 and the discharge port 14, a sealing structure is formed.

  The outer casing 12 has a rotating shaft 19 disposed at the center so as to penetrate the inner casings 15 and 16, and is rotatably supported by bearings (not shown) provided on the casing covers 17 and 18. The outer casing 12 accommodates a first stage impeller 21a as a suction impeller for sucking fluid corresponding to the suction port 13 therein. The first inner casing 15 has a plurality of impellers (impellers) 21b to 21e disposed therein, and the second inner casing 16 has a plurality of impellers (impellers) 22a to 22d disposed therein. Yes. These impellers 21a to 21e and 22a to 22d are fixed to the rotary shaft 19 via a key, and can be integrally rotated.

  In this case, the impellers 21a to 21e constituting the upstream impeller assembly and the impellers 22a to 22d constituting the downstream impeller assembly are arranged so that the back surfaces of the respective blades face each other. ing. The rotating shaft 19 is connected to a prime mover (not shown) outside the outer casing 12. Therefore, when the rotary shaft 19 is rotationally driven by this prime mover, the first stage impeller 21a rotates, so that the fluid can be sucked from the suction port 13, and the impellers 21b to 21e pressurize the fluid sucked inside. The impellers 22a to 22d can further pressurize the fluid and send it to the discharge port 14 side (right side in FIG. 5). Can be paid.

  The outer casing 12 and the inner casing 15 are located between the impeller 21a and the impeller 21b, and a first water supply passage 23 that communicates both is formed. The outer casing 12 and the inner casing 16 are positioned between the impeller 21e and the impeller 22a, and a second water supply passage 24 that communicates both is formed. The outer casing 12 and the inner casing 16 are located between the impeller 22d and the discharge port 14, and a third water supply passage 25 that communicates both is formed. In addition, the outer casing 12 is located between the final stage impeller 22d and the intermediate stage impeller 21e, and a bypass passage 26 that communicates both is formed.

  Therefore, in the multistage centrifugal pump 11 of the first embodiment, when the rotary shaft 19 is rotationally driven by the prime mover, the impellers 21a to 21e and the impellers 22a to 22d rotate, and the condensate is discharged from the suction port 13 by the impeller 21a. 12 is sucked into 12 and sent to the impeller 21b through the water supply passage 23, and the pressure is increased by the impellers 21b to 21e. At this time, the condensate is boosted in the process of passing through the impellers 21a to 21e, and then the dynamic pressure of the condensate is converted to static pressure by a diffuser (not shown).

  The condensed water boosted by the impeller 21e is sent to the impeller 22a through the water supply passage 24 and is boosted by the impellers 22a to 22d. At this time, the condensate is boosted in the process of passing through the impellers 22a to 21d, and then the dynamic pressure of the condensate is converted to static pressure by a diffuser (not shown). The condensate whose pressure has been increased by the impeller 22d is partly (for example, 20% of the flow rate) from the high-pressure upstream cavity 31 through the bypass passage 26 to the low-pressure downstream cavity 32 and the impeller 21e. It is fed to the discharge side, and the remainder (for example, 80% of the flow rate) is sent to the discharge port 14 through the third water supply passage 25 and discharged from the discharge port 14.

  In this case, the impellers 21a to 21e on one side in the axial direction of the rotating shaft 19 and the impellers 22a to 22d on the other side are arranged so that the back surfaces of the respective blades face each other. The water supply direction is reversed. Therefore, the direction of the thrust force that acts on the rotating shaft 19 from the impellers 21a to 21e and the direction of the thrust force that acts on the rotating shaft 19 from the impellers 22a to 22d are reversed and cancel each other, so that the rotating shaft The overall thrust force acting on the rotating shaft 19 is reduced, and the bearing supporting the rotating shaft 19 can be reduced in size and weight.

  Further, a bypass passage 26 that communicates the impeller 22d and the impeller 21e is provided. Then, a part of the condensate whose pressure is increased by the impeller 22d flows to the impeller 21e through the bypass passage 26, and the flow rate of the condensate circulating in the multistage centrifugal pump 11 increases. Therefore, when the impellers 21a to 21e and the impellers 22a to 22d are set to a low rotation speed and the low flow rate operation of the multistage centrifugal pump 11 is performed, an unstable phenomenon can be suppressed by ensuring a sufficient circulation flow rate.

  By the way, in the multistage centrifugal pump 11 having a function of circulating a part of the condensate pressurized by the impeller 22d from the bypass passage 26 to the impeller 21e, the condensate pressurized by the impeller 22d rotates. Since the swirl flow is centered on the shaft 19, the angular momentum is preserved even after the swirl flow flows into the bypass passage 26, and the inside of the bypass passage 26 becomes a strong swirl flow. Then, the static pressure in the vicinity of the center of the swirling flow is reduced in the bypass passage 26, and cavitation occurs to cause erosion or increase in pressure loss, thereby securing a sufficient flow rate in the bypass passage 26. It becomes difficult.

  Therefore, in the multistage centrifugal pump 11 having the fluid circulation structure of the first embodiment, the condensate (swirl fluid) that is swung up by the final stage impeller 22d passes through the bypass passage (flow passage) 26 and the intermediate stage impeller. In the structure flowing to 21e, a swivel suppression surface is provided that crosses the swirl direction of the condensate (swirl fluid) and prevents the condensate (swirl fluid) from colliding to suppress swirl.

  Below, the rotation suppression surface in the fluid circulation structure of Example 1 is demonstrated in detail using FIG.1 and FIG.2.

  In the multistage centrifugal pump 11 according to the first embodiment, as illustrated in FIGS. 1 and 2, the outer casing 12 is disposed so that the final stage impeller 22 d and the intermediate stage impeller 21 e face each other on the back surface. An upstream cavity 31 having a ring shape centering on the rotation shaft 19 is formed on the back side of the final stage impeller 22d, while a ring shape about the rotation shaft 19 is formed on the back side of the intermediate stage impeller 21e. A downstream cavity 32 is formed. In this case, the upstream cavity 31 is supplied with condensate that has been boosted in order by the impellers 21a to 21e and the impellers 22a to 22d, and the downstream cavity 32 is mainly boosted in order by the impellers 21a to 21e. Since the condensed water is supplied, a pressure difference is generated between the upstream cavity 31 and the downstream cavity 32, and the pressure of the upstream cavity 31 is higher than the pressure of the downstream cavity 32. Yes. In addition, since the condensate pressure | voltage-risen by 22 d of last stage impellers turns into a swirl flow, and flows into the upstream cavity 31, the condensate swirling here is called a swirl fluid.

  The outer casing 12 is provided with a bypass passage 26 as a flow passage of the present invention that connects the upstream cavity 31 and the downstream cavity 32 between the final stage impeller 22d and the intermediate stage impeller 21e. . A plurality of bypass passages 26 are provided at equal intervals in the circumferential direction at positions shifted from the rotation axis of the rotation shaft 19 to the outside in the radial direction by a predetermined distance. Although the bypass passage (flow passage) 26 of the present embodiment is a passage having the same diameter in the longitudinal direction, it may be tapered in the longitudinal direction, or may be in communication with a passage having a different diameter, for example, the upstream cavity 31 side. The small-diameter first passage and the large-diameter second passage communicating with the downstream cavity 32 may be configured to communicate with each other with a step. In addition, although the circular cross section is uniformly arranged in the circumferential direction, it may be an oval, elliptical, polygonal cross section, or may not be equally arranged.

  The upstream cavity 31 defines a bottom surface on which the swirling fluid swirls, that is, a surface on the bypass passage 26 side, as a swiveling surface 31a. The swirling fluid is centered on the axis of the rotating shaft 19 and is formed on the swirling surface 31a. Turn along. The base end portion of the bypass passage 26 is communicated with the swirling surface 31 a in which the swirling fluid swirls in the upstream side cavity 31, and the swirl suppression chamber 33 is provided at the communicating portion between the upstream side cavity 31 and the bypass passage 26. . On the other hand, the tip of the bypass passage 26 opposite to the base end is communicated with the downstream cavity 32. The bypass passage (flow passage) 26 does not necessarily need to be orthogonal to the swivel surface 31a, and may be inclined at a predetermined angle in a predetermined direction.

  In the first embodiment, the swirl suppression chamber 33 is formed as a recess dug down to the bypass passage 26 side on the swirling surface 31 a of the upstream cavity 31, and the base of the bypass passage 26 is formed on the bottom of the swirl suppression chamber 33. The ends are in communication.

  The swirl suppression chamber 33 is formed to have substantially the same length along the swirling direction of the swirling fluid with respect to the inner diameter (representative cross-sectional dimension) of the base end portion of the bypass passage 26, while It is formed in a large length along the intersecting direction, that is, the radial direction. That is, the swirl suppression chamber 33 is formed as a long groove (concave portion) along the radial direction of the rotating shaft 19 on the swiveling surface 31a of the upstream cavity 31, and the front end surface 34 is formed on the upstream side of the swirling fluid. The rear end surface formed on the downstream side functions as the turning suppression surface 35. In the present embodiment, since the bypass passage 26 has a circular cross section, the representative cross-sectional dimension is its inner diameter. When the bypass passage 26 has a polygonal cross section, the inner diameter of the circumscribed circle, an oval or an ellipse In the case of a cross section of a shape, the longitudinal dimension may be used.

  In this case, the swirl suppression surface 35 that is the front end surface 34 and the rear end surface in the swirl suppression chamber 33 intersects with the swirl direction of the swirl fluid and is set longer than the inner diameter (representative cross-sectional dimension) of the bypass passage 26 in the intersecting direction. The However, it is desirable that the swirl suppression surface 35 be located on the downstream side of the swirling fluid in the bypass passage 26 and be formed orthogonal to the swirling direction of the swirling fluid.

  Specifically, the bypass passage 26 includes a center line Os passing through the axis of the rotary shaft 19 along the radial direction, and a center line passing through a predetermined radial position from the axis of the rotary shaft 19 and orthogonal to the center line Os. This is an opening having an inner diameter D (representative cross-sectional dimension, see FIG. 3) centered on the intersection with Oc. The swirl suppression chamber 33 is a recess having the same width as the inner diameter D of the opening of the bypass passage 26 and long in the radial direction of the rotating shaft 19. Here, the front end surface 34 and the rotation suppression surface 35 of the rotation suppression chamber 33 are parallel to the center line Os described above, and the front end surface 34 and the rotation suppression surface 35 are formed by the curved surface 37 on the axis side of the rotation shaft 19. It is continuous and is continued by the curved surface 38 on the outer peripheral side of the rotating shaft 19. In this case, the front end surface 34 and the rotation suppression surface 35 are made parallel in consideration of the workability of the rotation suppression chamber 33, but the front end surface 34 and the rotation suppression surface 35 are shaped along the radial direction of the rotary shaft 19, The swivel suppression chamber 33 may be fan-shaped. Moreover, although the front end surface 34 and the rotation suppression surface 35 of the rotation suppression chamber 33 are made continuous by the curved surfaces 37 and 38, both or one of them may be a flat surface.

  In addition, the turning suppression chamber 33 (the turning suppression surface 35) with respect to the bypass passage 26 is not limited to such a shape and position. For example, as shown in FIG. 3, the swirl suppression surface 35 is optimally formed at a position that is in contact with the inner diameter D of the bypass passage 26 on the most downstream side in the swirling direction of the swirling fluid. However, the swirl suppression surface 35 has Ca = D / 2 on the upstream side and Cb = D / on the downstream side with respect to the position in contact with the most downstream side of the inner diameter D of the bypass passage 26 in the swirling direction of the swirling fluid. It is desirable if it is within a region shifted by two. Further, it is desirable that the turning suppression surface 35 is longer than the inner diameter D of the bypass passage 26 in the radial direction of the rotating shaft 19 (direction orthogonal to the turning direction of the turning fluid). However, the turning restraining surface 35 has Ra = D on the axial center side of the rotating shaft 19 from the inner diameter D of the bypass passage 26 in the radial direction of the rotating shaft 19 (direction orthogonal to the turning direction of the swirling fluid). It is optimal to be in a region where Rb = D or more can be secured on the side.

  Further, the swirl suppression chamber 33 (the swirl suppression surface 35) with respect to the bypass passage 26 is not limited to such a shape and angle. For example, as shown in FIG. 3, it is optimal to form the swirl suppression surface 35 along a direction orthogonal to the swirl direction of the swirl fluid. However, as shown in FIG. 4A, the swirl suppression surface 35 only needs to be formed with an acute angle inclined by 45 degrees or more with respect to the swirling direction of the swirling fluid. In other words, it is desirable that it is within an area that is shifted by θb = 45 degrees in the clockwise direction and θb = 45 degrees in the counterclockwise direction from the center line Os. According to this configuration, when the velocity component of the swirling fluid flowing along the swirl suppression surface 35 is decomposed into a swirl component and a normal component orthogonal to the swirl component, “swirl component ≦ normal component” can be satisfied. it can. That is, when the acute angle is 45 degrees, that is, θa, θb = 45 degrees, the swirl component and normal component of the swirling fluid flowing along the swirl suppression surface 35 are “swirl component = normal component”. Then, as the acute angle increases (as the acute angle approaches 90 degrees), that is, as θa and θb approach 0 degrees, “swivel component <normal component”. As a result, the swirling fluid swirling in the upstream cavity 31 collides with the swirling suppression surface 35, so that the swirling component of the fluid can be efficiently reduced. Further, as shown in FIG. 4B, it is desirable that the turning suppression surface 35 be in a region that is shifted by θc = 30 degrees with respect to a surface that passes through the center line Os and is orthogonal to the turning surface 31a.

  Here, the position and angle of the swivel suppression surface 35 in the swirl suppression chamber 33 have been described, but the front end surface 34 is not limited to such a shape. However, since the front end face 34 does not have a function of suppressing the turning of the condensate flowing into the bypass passage 26, the front end face 34 may not be located at a position where the function of the turning suppression surface 35 is hindered. Specifically, even if the swirl suppression surface 35 is displaced in the swirling direction of the swirling fluid, the front end surface 34 is within a region that does not deviate by more than D / 2 downstream from the position that is in contact with the innermost diameter D of the bypass passage 26. If there is anything. Even if the angles θa, θb, and θc of the turning suppression surface 35 are shifted, the front end surface 34 is not required to have an angle that closes the bypass passage 26 by more than 1/2.

  As a result, if the shape of the front end face 34 and the turning restraint surface 35 satisfies the position and angle described above, the shape of the turning restraining chamber 33 is a long groove along the radial direction of the rotating shaft 19 as in this embodiment. The shape is not limited to (long hole shape), and may be any shape such as a rectangle, a square, and an ellipse. In other words, the front end surface 34 and the turning suppression surface 35 are not limited to flat surfaces but may be curved surfaces.

Accordingly, as shown in FIGS. 1 and 2, the swirling fluid generated in the upstream cavity 31 has a velocity v at a position on the axial center side of the rotary shaft 19 in the bypass passage 26, that is, at a position of the radius r _{1. 1} , v ₁ ≠ v ₂ when the speed is v ₂ at the position on the outer peripheral side in the bypass passage 26, that is, the position of the radius r ₂ Therefore, turning the fluid upstream cavity 31, to the bypass passage 26, the speed v ₁ and the velocity v ₂ of the position of the radius r ₂ at the position of radius r ₁ are different, the swivel fluid in the bypass passage 26 When entering, the angular momentum remains, and the condensate flows in the bypass passage 26 while turning.

  However, in the first embodiment, the swirl suppression chamber 33 having the swirl suppression surface 35 is provided at the base end portion (inlet portion) of the bypass passage 26, so that the swirling fluid in the upstream cavity 31 enters the bypass passage 26. At this time, the swirling fluid collides with the swirl suppression surface 35 and then flows into the bypass passage 26. Therefore, the angular momentum of the swirling fluid is reduced by colliding with the swiveling suppression surface 35, and the condensate enters the bypass passage 26 after swirling is suppressed. As a result, in the bypass passage 26, the condensate flows smoothly without swirling, the occurrence of cavitation and the increase in pressure loss are suppressed, and a sufficient flow rate can be ensured.

  As described above, in the fluid circulation structure according to the first embodiment, the upstream side cavity 31 having a ring shape with the rotary shaft 19 as the center is formed on the back side of the final stage impeller 22d, while the back side of the intermediate stage impeller 21e. A downstream cavity 32 having a ring shape is formed on the side of the rotary shaft 19, a bypass passage 26 is formed to connect the upstream cavity 31 and the downstream cavity 32, and condensate swirling in the upstream cavity 31 The swirling fluid is configured to flow to the downstream cavity 32 through the bypass passage 26, and a swirl suppression surface 35 that suppresses swirling when the swirling fluid collides is provided by intersecting the swirling direction of the swirling fluid.

  Therefore, when the condensate swirling fluid swirling in the upstream cavity 31 flows to the downstream cavity 32 through the bypass passage 26, the swirling fluid collides with the swirl suppression surface 35, thereby removing the swirling component of this fluid. Alternatively, the swirling of the fluid flowing into the bypass passage 26 is suppressed, and a sufficient amount of condensate can be supplied from the upstream cavity 31 through the bypass passage 26 to the downstream cavity 32. That is, the condensate swirl fluid has different angular momentum depending on the swirl radius, so the condensate flowing into the bypass passage 26 becomes a swirl fluid due to the difference in angular momentum. However, when the turning suppression surface 35 is provided as in the first embodiment, the condensate having a different angular momentum depending on the turning radius is removed or reduced when the condensate has a swirling component that collides with the turning suppression surface 35. As a result, the difference in angular momentum is reduced, so that the condensate swirling into the bypass passage 26 can be suppressed, and a water supply amount about three times that of the conventional water supply amount can be secured.

  In the fluid circulation structure of the first embodiment, the swirl suppression surface 35 is formed longer than the inner diameter of the bypass passage 26 in a direction intersecting the swirl direction of the swirl fluid. Therefore, by ensuring an appropriate amount of the swivel suppression surface 35 at an appropriate position, the swirling fluid swirling in the upstream cavity 31 properly collides with the swirl suppression surface 35 and efficiently removes or reduces the swirl component of this fluid. be able to.

  Further, in the fluid circulation structure of the first embodiment, the swirl suppression surface 35 is located on the downstream side of the swirling fluid in the bypass passage 26 and is formed orthogonal to the swirling direction of the swirling fluid. Therefore, the condensate swirling fluid swirling in the upstream cavity 31 collides perpendicularly to the swivel suppression surface 35, whereby the swirling component of the fluid can be efficiently removed or reduced.

  In the fluid circulation structure of the first embodiment, the base end portion of the bypass passage 26 is communicated with the swirling surface 31 a in which the condensate swirling fluid in the upstream cavity 31 swirls, and the upstream cavity 31 and the bypass passage 26 communicate with each other. A swirl suppression chamber 33 is provided in the part, and a swirl suppression surface 35 is formed in the swirl suppression chamber 33. Therefore, by providing the swirl suppression chamber 35 at the communication portion between the upstream cavity 31 and the bypass passage 26, the swirl suppression surface 35 is located at the base end of the bypass passage 26, and the swirl flow in the bypass passage 26 is reduced. Generation can be efficiently suppressed.

  Further, in the fluid circulation structure of the first embodiment, the swirl suppression chamber 33 is formed as a recess in the swirling surface 31a of the upstream cavity 31, and the base end portion of the bypass passage 26 communicates with the bottom surface of the recess, and the rear end surface of the recess A turning suppression surface 35 is formed on the surface. Therefore, by forming the swivel suppression chamber 33 as a recess in the swivel surface 31a of the upstream cavity 31, the swivel restraint surface 35 can be easily formed and workability can be improved.

  Further, in the fluid circulation structure of the first embodiment, the concave portion as the swirl suppression chamber 33 is substantially the same along the swirling direction of the swirling fluid with respect to the representative sectional dimension (for example, inner diameter) of the base end portion of the bypass passage 26. On the other hand, the swirling suppression surface 35 is formed on the rear end surface of the swirling fluid on the downstream side of the swirling fluid in a direction that intersects the swirling direction of the swirling fluid. Accordingly, the swirl suppression chamber 33 and the swirl suppression surface are formed by making the recess a long groove (long hole) along the direction intersecting the swirl direction of the swirling fluid with respect to the representative sectional dimension (for example, inner diameter) of the bypass passage 26. 35 can be easily formed, and further workability can be improved.

  FIG. 6 is a schematic diagram illustrating a swirl suppression chamber (concave portion) in the fluid circulation structure according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the fluid circulation structure of the second embodiment, as shown in FIG. 6, the base end portion of the bypass passage 26 is communicated with the upstream cavity 31, and the swiveling surface 31 a of the upstream cavity 31 is connected to the bypass passage 26. Correspondingly, an inclined surface 41 is formed, so that a swirl suppression chamber 42 is provided at the communication portion between the upstream cavity 31 and the bypass passage 26. In the second embodiment, the swirl suppression chamber 42 is formed as a recess dug into the swirling surface 31 a of the upstream cavity 31 toward the bypass passage 26, and this recess, that is, the inclined surface 41 serving as the bottom surface of the swirl suppression chamber 35 is formed. The base end portion of the bypass passage 26 is communicated.

  As in the first embodiment, the swirl suppression chamber 42 is formed to be approximately equal to or larger than the inner diameter D (representative cross-sectional dimension) of the base end portion of the bypass passage 26 along the swirling direction of the swirling fluid. On the other hand, it is formed large along the direction intersecting the swirling direction of the swirling fluid, that is, along the radial direction. That is, the swirl suppression chamber 42 is formed with the inclined surface 41 having a predetermined width deeper toward the downstream side of the swirling fluid on the swirling surface 31 a of the upstream cavity 31, thereby forming a recess along the radial direction of the rotating shaft 19. It is formed as a (long hole), and this inclined surface 41 intersects with a swirl suppression surface 43 as a rear end surface on the downstream side of the swirling fluid.

  Therefore, when the swirling fluid generated in the upstream cavity 31 enters the bypass passage 26, it enters the swirl suppression chamber 42 along the inclined surface 41 and flows into the bypass passage 26 after colliding with the swirl suppression surface 43. It becomes. Therefore, the angular momentum of the swirling fluid is reduced by colliding with the swiveling suppression surface 43, and the condensate enters the bypass passage 26 after swirling is suppressed. As a result, in the bypass passage 26, the condensate flows smoothly without swirling, the occurrence of cavitation and the increase in pressure loss are suppressed, and a sufficient flow rate can be ensured.

  As described above, in the fluid circulation structure according to the second embodiment, the base end portion of the bypass passage 26 is communicated with the upstream cavity 31, and the upstream side is located at the communication portion between the upstream cavity 31 and the bypass passage 26. A swirl suppression chamber 42 is formed by forming an inclined surface 41 deeper toward the downstream side of the swirling fluid on the swirl surface 31a of the cavity 31, and a swirl suppression surface 43 is formed at the rear end surface thereof.

  Accordingly, when the condensate swirling fluid swirling in the upstream cavity 31 enters the bypass passage 26, the swirling fluid collides with the swivel suppression surface 43 via the inclined surface 41, thereby removing the swirling component of this fluid. The swirling of the fluid flowing into the bypass passage 26 is suppressed, and a sufficient amount of condensate can be supplied from the upstream cavity 31 through the bypass passage 26 to the downstream cavity 32. At this time, since the swirling fluid swirling in the upstream cavity 31 collides with the swivel suppression surface 43 along the inclined surface 41, the swirling fluid can efficiently collide with the swirl suppression surface 43, and the swirling component of this fluid Can be efficiently removed or reduced.

  FIG. 7 is a schematic diagram illustrating a swirl suppression surface in the fluid circulation structure according to the third embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the fluid circulation structure of the third embodiment, as shown in FIG. 7, the base end portion of the bypass passage 26 communicates with the upstream cavity 31, and the bypass passage 26 is connected to the swiveling surface 31 a of the upstream cavity 31. Further, a swirl suppression protrusion 51 is provided on the downstream side in the swirling direction of the swirling fluid. In the third embodiment, the turning suppression protrusion 51 is formed as a protrusion adjacent to the bypass passage 26 on the turning surface 31 a of the upstream cavity 31, and the turning suppression surface 52 is formed on the end face of the protrusion, that is, the turning suppression protrusion 51. doing.

  Similar to the first and second embodiments, the swivel restraint protrusion 51 (swirl restraint surface 52) is downstream of the bypass passage 26 in the swirling direction of the swirling fluid, with respect to the inner diameter D (representative sectional dimension) of the bypass passage 26. It is formed large along the direction intersecting the swirling direction of the swirling fluid, that is, along the radial direction. In this case, the turning suppression protrusion 51 may be formed integrally with the outer casing 12 that defines the upstream cavity 31 or may be formed separately from the turning surface 31a.

  Therefore, when the swirling fluid generated in the upstream cavity 31 enters the bypass passage 26, it collides with the swivel suppression surface 52 and then flows into the bypass passage 26. Therefore, the angular momentum of the swirling fluid is reduced by colliding with the swirl suppression surface 52, and the condensate enters the bypass passage 26 after swirling is suppressed. As a result, in the bypass passage 26, the condensate flows smoothly without swirling, the occurrence of cavitation and the increase in pressure loss are suppressed, and a sufficient flow rate can be ensured.

  As described above, in the fluid circulation structure according to the third embodiment, the base end portion of the bypass passage 26 is communicated with the upstream side cavity 31, and the downstream side of the swirling fluid in the swirling direction of the swirling fluid from the bypass passage 26 in the upstream side cavity 31. The swivel restraining surface 52 is formed that is positioned and intersects the swirling direction of the swirling fluid to collide with the swirling fluid and suppress swirling.

  Therefore, when the condensate swirling fluid swirling in the upstream cavity 31 enters the bypass passage 26, the swirling fluid collides with the swirl suppression surface 52, so that the swirling component of the fluid is removed or reduced. The swirling of the flowing fluid is suppressed, and a sufficient amount of condensate can be supplied from the upstream cavity 31 through the bypass passage 26 to the downstream cavity 32.

  FIG. 8 is a schematic configuration diagram showing a pump turbine to which a fluid circulation structure according to Embodiment 4 of the present invention is applied.

  In Example 4, the fluid circulation structure of the present invention will be described by applying it to a pump turbine. This pump turbine is a so-called Francis type pump turbine, which has a function as a pump for pumping water and a function as a turbine for generating power. That is, the pump turbine according to the fourth embodiment functions as a pump that takes in water from a water intake through a water conduit and a hydraulic iron pipe, and generates power with the water taken in and discharges the water to a drain through a water discharge channel. Functions as a water wheel.

  Hereinafter, the pump turbine according to the fourth embodiment will be described in detail. As shown in FIG. 8, the pump turbine 61 of the fourth embodiment includes a rotating shaft 62 whose base end (upper end in FIG. 8) is connected to a generator (not shown), and a distal end (lower end) of the rotating shaft 62. And a runner 63 that rotates integrally therewith. Then, the rotating shaft 62 rotates along with the rotation of the runner 63 to generate electricity, and the generator 63 rotates the runner 63 to pump water.

  The rotary shaft 62 is disposed along the vertical direction and is rotatably supported by the water turbine casing 64 via a bearing 65. The runner 63 is connected to the lower end portion of the rotating shaft 62 through a key 62a so as to be integrally rotatable.

  The runner 63 includes a disc-shaped crown 66 fixed to the tip end portion of the rotating shaft 62 by a key 62 a, a ring-shaped shroud 67 arranged coaxially with the crown 66, and the crown 66 and the shroud 67. It is composed of a plurality of runner vanes 68 sandwiched between them.

  A water inlet 69 through which water flows into the runner 63 is provided in the turbine casing 64 at the outer periphery of the runner 63, and a water outlet 70 through which water flows out of the runner 63 is positioned in the rotation axis direction of the runner 63. The suction casing 71 is connected to the water turbine casing 64. Therefore, when the pump turbine 61 functions as a turbine, the water flows from the water inlet 69 to the water outlet 70 after rotating the runner 63 from the water inlet 69 as shown by an arrow A in FIG. On the other hand, when the pump turbine 61 functions as a pump, as shown by an arrow B in FIG. 8, the water flows from the water outlet 70 to the water inlet 69 by the rotation of the runner 63.

  In the runner 63, a crown 66 is fixed to a lower end portion of the rotation shaft 62 via a key 62 a, and a cone 72 is fixed to a rotation center portion of the crown 66 by a plurality of bolts 73. The runner vanes 68 are arranged at equal intervals along the circumferential direction of the runner 63 so as to connect the crown 66 and the shroud 67.

  In the runner 63, a rotation gap S1 is provided between the water turbine casing 64 and the crown 66, and a stepped seal 74 is provided in the rotation gap S1. A rotation gap S2 is provided between the water turbine casing 64 and the shroud 67, and a stepped seal 75 is provided in the rotation gap S2.

  In the pump turbine 61 of the fourth embodiment, the turbine casing 64 is formed with a high-pressure upstream cavity 81 having a ring shape around the rotating shaft 62 on the back side of the runner 63 (crown 66). On the front side of the (crown 66), a low-pressure downstream cavity 82 having a ring shape with the rotary shaft 62 as the center is formed. In this case, since the water pressure acts on the upstream cavity 81 from the water inlet 69, a pressure difference is generated between the upstream cavity 81 and the downstream cavity 82, and the pressure in the upstream cavity 81 is reduced. The pressure in the downstream cavity 82 is higher.

  The crown 66 is formed with a balance passage 83 as a flow passage of the present invention that communicates the upstream cavity 81 and the downstream cavity 82. A plurality of the balance passages 83 are provided at equal intervals in the circumferential direction at positions shifted from the rotation axis of the rotation shaft 62 to the outside in the radial direction by a predetermined distance.

  The upstream cavity 81 defines a bottom surface on which the swirling fluid swirls, that is, a surface on the balance passage 83 side as a swiveling surface 81a, and the swirling fluid is centered on the axis of the rotating shaft 62 and on the swirling surface 81a. Turn along. A base end portion of the balance passage 83 is communicated with a swirling surface 81 a in which the swirling fluid in the upstream cavity 81 swirls, and a swirl suppression chamber 84 is provided at a communication portion between the upstream cavity 81 and the balance passage 83. In the fourth embodiment, the swirl suppression chamber 84 is formed as a recess dug down to the balance passage 83 side on the swirling surface 81 a of the upstream cavity 81, and the base of the balance passage 83 is formed on the bottom of the swirl suppression chamber 84. The ends are in communication.

  The swirl suppression chamber 84 is formed to have substantially the same length along the swirling direction of the swirling fluid with respect to the inner diameter D (representative cross-sectional dimension) of the base end portion of the balance passage 83 as in the above-described embodiments. On the other hand, it is formed in a large length along the direction intersecting the swirling direction of the swirling fluid, that is, along the radial direction. That is, the swirl suppression chamber 84 is formed as a recess (long hole) along the radial direction of the rotation shaft 62 on the swirling surface of the upstream cavity 81, and the rear end surface formed on the downstream side of the swirling fluid is the swirl suppression surface 85. Function as.

  Therefore, when the swirling fluid generated in the upstream cavity 81 enters the balance passage 83, it enters the swirl suppression chamber 84 and collides with the swirl suppression surface 85 and then flows into the balance passage 83. Therefore, the angular momentum of the swirling fluid is reduced by colliding with the swirl suppression surface 85 (the swirl suppression chamber 84), and the water enters the balance passage 83 after the swirl is suppressed. As a result, in the balance passage 83, the irrigation water flows smoothly without swirling, the occurrence of cavitation and the increase in pressure loss are suppressed, and a sufficient flow rate can be ensured.

  As described above, in the fluid circulation structure of the fourth embodiment, the upstream cavity 81 having a ring shape is formed on the back side of the runner 63, while the downstream cavity 82 having a ring shape is formed on the front side of the runner 63. In addition, a balance passage 83 that connects the upstream cavity 81 and the downstream cavity 82 is formed, and the swirling fluid of the water swirling in the upstream cavity 81 flows through the balance passage 83 to the downstream cavity 82. In addition, a swirl suppression surface 85 (a swirl suppression chamber 84) is provided that intersects with the swirling direction of the swirling fluid and collides with the swirling fluid to suppress swirling.

  Therefore, when the swirling fluid for the water swirling in the upstream cavity 81 enters the balance passage 83, the swirling fluid collides with the swirl suppression surface 85, so that the swirling component of this fluid is removed or reduced. The swirling of the flowing fluid is suppressed, and a sufficient amount of water can be supplied from the upstream cavity 81 to the downstream cavity 82 through the balance passage 83. As a result, the differential pressure between the upstream cavity 81 and the downstream cavity 82 can be appropriately reduced, the thrust force acting on the rotating shaft 62 can be reduced, and the durability can be improved.

  In each of the above-described embodiments, the swirl suppression chamber and the swirl suppression surface are provided at the base end portion (inlet portion) of the flow passage. However, the present invention is not limited to this configuration, and the outlet portion is located downstream of the inlet portion of the flow passage. It may be provided in the intermediate part excluding, or a plurality may be provided in the inlet part and intermediate part.

  9A and 9B are schematic configuration diagrams illustrating modifications of the fluid circulation structure of the present invention. For example, as shown in FIG. 9A, a plurality of (in this case, four) swirl suppression chambers 90 are provided so as to form a cross around the bypass passage 92, and each swirl suppression chamber 90 is swirled. A suppression surface 91 may be provided. Also, as shown in FIG. 9-2, a plurality of (here, eight) swirl suppression chambers 90a are provided radially around the bypass passage 92a, and the swirl suppression surfaces 91a are respectively provided in the swirl suppression chambers 90a. May be provided.

  Moreover, in each Example mentioned above, although the fluid distribution structure of this invention was applied to the multistage centrifugal pump or pump-turbine in a complex plant, it is applicable not only to this field | area but to any fluid machine.

  In the fluid circulation structure according to the present invention, a swirl flow is generated in the upstream side cavity by providing a swirl suppression surface that intersects with the swirl direction of the swirl fluid and the swirl fluid collides to suppress swirl. Also, a sufficient amount of fluid can be supplied from the upstream cavity to the downstream cavity through the flow passage, and the swirling fluid in the upstream cavity such as a pump, a water turbine, or a pump turbine is downstream through the flow passage. The present invention can be applied to a fluid machine having a structure that flows in a side cavity.

DESCRIPTION OF SYMBOLS 11 Multistage centrifugal pump 12 External casing 13 Suction port 14 Discharge port 15,16 Internal casing 19 Rotating shaft 21a-21e, 22a-22d Impeller 23, 24, 25 Water supply path 26, 92, 92a Bypass path (flow path)
31 Upstream cavity 32 Downstream cavity 33, 42, 90, 90a Swirl suppression chamber (recess)
34 Front end surface 35, 43, 52, 91, 91a Turning suppression surface (rear end surface)
41 Inclined surface 51 Rotation suppression protrusion 61 Pump turbine 62 Rotating shaft 63 Runner 66 Crown 67 Shroud 68 Runner vane 81 Upstream cavity 82 Downstream cavity 83 Balance passage (flow passage)
84 Swirl suppression chamber (recess)
85 Turning suppression surface (rear end surface)

Claims (3)

An upstream cavity containing swirling fluid;
A flow passage whose base end communicates with the upstream cavity;
A downstream cavity communicated with the front end of the flow passage,
In the fluid circulation structure in which the swirling fluid swirling in the upstream cavity flows to the downstream cavity through the flow passage,
The set of turning suppressing surface on which the orbiting fluid swivel collide is suppressed by intersecting the turning direction of the turning fluid,
The swirl suppression surface is set such that the length in the direction intersecting the swirl direction of the swirl fluid is longer than the inner diameter of the flow passage,
The swirl suppression surface is located on the downstream side of the flow path in the flow path of the swirl fluid, and is formed orthogonal to the swirl direction of the swirl fluid,
A base end portion of the flow passage is communicated with a swirling surface in which the swirling fluid swirls in the upstream cavity, and a swirl suppression chamber is provided at a communication portion between the upstream cavity and the flow passage. The turning restraining surface is formed;
The swirl suppression chamber is formed as a recess on the swirling surface of the upstream cavity, and the base end of the flow passage is communicated with the bottom surface of the recess, and the swirl suppression surface is formed on the end surface of the recess,
The recess is formed to have substantially the same length along the swirling direction of the swirling fluid with respect to the inner diameter of the base end portion of the flow passage, and along the direction intersecting the swirling direction of the swirling fluid. The swirl suppression surface is formed on the downstream end surface of the swirling fluid in the concave portion.
A fluid circulation structure characterized by that. The recess, the fluid distribution structure of claim 1, wherein the inclined surfaces intersecting the pivot inhibiting surface becomes deeper toward the downstream side of the swirling fluid to the swivel surface is formed. Wherein said flow passage is a round hole, Nagamaruana is either elliptical hole, the inner diameter, the round hole is the inner diameter, on the long round hole and oval hole, which is a longitudinal dimension Item 3. The fluid circulation structure according to Item 1 or 2 .

Images