JP2007046550A - Rotary fluid machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce friction loss of a face in contact with water of a runner of a rotary fluid machine. <P>SOLUTION: This rotary fluid machine has the runner 5 arranged in water, a main shaft 9 connected with the runner 5 and rotating together with the runner 5, and a micro-bubble gushing-out means for gushing out micro-bubbles on the face in contact with water of the runner 5. The micro-bubble gushing-out means includes a flow passage 11 in the main shaft which is formed in the inside of the main shaft 9 and whose one end is opened on a runner connection face, a flow passage 12 in the runner which is formed in the runner 5, whose one end is opened at a position communicating with an opening on the runner connection face in the flow passage 11 in the main shaft, and which is provided with a nozzle 13 opened on a face in contact with water of a crown 7 of the runner 5 at the other end, a flow passage 14 in the runner whose one end is communicated with the flow passage 12 in the runner and which is provided with a nozzle 15 opened on an end face on the upstream side of a blade 6 in an intermediate part, and a flow passage 16 in the runner whose one end is communicated with the flow passage 14 in the runner and which is provided with a nozzle 17 opened on a face in contact with water of a shroud 8 of the runner 5 at the other end. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rotating fluid machine such as a water turbine or a pump turbine, and more particularly to a rotating fluid machine that takes into account reduction of friction loss.

  For example, in hydroelectric power generation, water stored by a dam or the like flows into a water turbine through a water channel. The water that flows into the water turbine passes through the casing, stay vanes, and guide vanes that make up the water turbine, and is guided to a runner that is a moving blade, that is, an impeller, thereby converting the fluid energy of the water into the rotational energy of the impeller. Is done. In hydroelectric power generation, the rotational energy is converted into electrical energy by a generator.

  In general, there are friction loss, bending loss, collision loss, mixing loss, and expansion loss as hydraulic loss affecting the efficiency of such a turbine. (For example, refer nonpatent literature 1 etc.).

  Among them, the friction loss is a loss due to the friction of the solid surface (water contact surface) where the flow and the flow come into contact, and is derived from the boundary layer of the solid surface, and mainly changes depending on the roughness of the solid surface and the flow velocity.

  As a fluid friction reducing device for a hydraulic machine, there is a device in which a slit-like opening is formed on a wall surface forming a water flow path, a porous plate is provided therein, and air is injected from there to a water flow path . The injected air is turned into a microjet, and bubbles having a particle size on the order of micrometers called microbubbles cover the wall surface, thereby reducing friction loss on the wall surface (see, for example, Patent Document 1).

  The pump turbine is a rotating fluid machine that converts the rotational energy of the pump turbine runner, that is, the impeller, into the fluid energy of water, contrary to the turbine used in the hydroelectric power generation, but in the process of energy conversion, As in the case, a loss due to friction of the solid surface where the flow and the flow contact, that is, a friction loss occurs.

JP-A-8-177706 (pages 3, 4 and 2) Japan Society of Mechanical Engineers standard "performance conversion method of water wheel and pump" JSME S008-1989

  In general, in a water turbine and a pump turbine, it is known that the flow velocity is the largest at the impeller. Therefore, the solid surface friction loss on the blade surface, crown surface, shroud surface, etc. of the impeller, which is a high flow velocity portion, greatly affects the turbine efficiency. Further, the microbubbles adhere and stay on the solid surface, thereby generating a friction loss reducing effect on the surface.

  In the above prior art, microbubbles are injected into the fluid from the wall surface of the stationary part. Therefore, in the above prior art, the microbubbles adhere and stay on the wall surface of the stationary part, and the friction loss reducing effect in the stationary part occurs. However, when the microbubbles flow into the rotationally driven impeller, they always pass through the seal gap that exists between the stationary wall surface and the rotating surface. When passing through the seal gap, the microbubbles flowing along the stationary wall surface may peel off from the wall surface. Therefore, in the above prior art, it is difficult to attach and retain microbubbles on the wall surface of the impeller that is rotationally driven.

  Furthermore, in the above prior art, it is difficult to say that the microbubbles injected on the upstream side of the impeller concentrate and stay on the blade surface of the impeller when flowing into the impeller. Therefore, in the above prior art, it is difficult to efficiently deposit and retain the injected microbubbles on the impeller wall surface, and the effect of reducing the friction loss on the impeller wall surface cannot be expected.

  The subject of this invention is reducing the friction loss in the surface of the impeller of the rotary fluid machine represented by the water wheel and the pump water wheel.

  An object of the present invention is to provide a rotating fluid machine having an impeller disposed in water and a main shaft that is coupled to the impeller and rotates together with the impeller. This can be solved by providing bubble discharge means.

  By discharging microbubbles directly onto the water contact surface of the impeller, the microbubbles released from the water contact surface of the impeller do not need to exceed the seal gap at the stage of covering the water contact surface while moving along the water flow. It becomes easy to be covered with bubbles. Friction loss is reliably reduced by covering the wetted surface of the impeller with the discharged microbubbles.

  The micro-bubble releasing means is formed in the main shaft, one end of which is opened in the impeller coupling surface, and the opening in the impeller coupling surface of the main shaft is formed in the impeller. And the other end and the middle of the impeller have a flow path in the impeller that opens on the water contact surface of the impeller.

  In other words, the microbubble discharge means for discharging the microbubbles from the rotating impeller specifically supplies the air that is the source of the microbubbles or the water containing the microbubbles into the main shaft, that is, the rotating shaft of the impeller. The impeller is supplied through the formed main shaft flow path. Further, the air that is the source of the microbubbles supplied to the impeller or water containing the microbubbles is supplied to the water contact surface through the flow passage in the impeller formed in the impeller. The water contact surfaces here are a crown surface, a blade surface, and a shroud surface, and in particular, an upstream end of a surface facing the shroud of the crown, an upstream end of a surface facing the crown of the shroud, and an upstream end surface of the blade surface. It is desirable to supply water containing air or microbubbles to the water contact surface through the formed opening communicating with the flow path in the impeller.

  Moreover, it is desirable to fill the opening with, for example, a porous material for atomizing air.

  According to the present invention, microbubbles can be discharged directly to the surface of a rotating impeller that is placed in water, so that unnecessary microbubble emission is reduced and friction loss on the impeller surface is efficiently reduced. can do.

<First Embodiment>
Hereinafter, a first embodiment of a rotary fluid machine according to the present invention will be described with reference to the drawings. In the present embodiment, microbubbles are directly emitted from the runner to the surface of an impeller (hereinafter referred to as a runner) that is disposed in water and rotates. In addition, the present embodiment is an example in the case where the present invention is applied to a general hydroelectric turbine, but the present invention is not limited to what is used for so-called pump turbines used in pumped-storage power generation. Of course, it is applicable also to a water turbine.

  FIG. 1 is a horizontal sectional view showing the overall configuration of the centrifugal water turbine, and FIG. 2 is a longitudinal sectional view of a main shaft and an impeller portion of the centrifugal water turbine shown in FIG. As shown in FIGS. 1 and 2, the centrifugal water wheel is arranged in a ring shape above and below the outer peripheral portion of the runner 5, a rotating impeller (hereinafter referred to as a runner) 5, a main shaft 9 coupled to the runner 5 and rotating. A stay vane 3 which is a stationary vane disposed between the speed ring 2 formed, a casing 1 forming a spiral flow path on the outer periphery of the speed ring 2, and the speed ring 2 disposed in a ring shape above and below, and A guide vane 4 is provided.

  The runner 5 includes a crown 7 disposed on the upper side and coupled to the main shaft 9 at the center, and a shroud disposed concentrically with the main shaft 9 on the lower side of the crown 7 so as to face the crown 7. 8 and a plurality of blades 6 disposed between the lower surface of the crown 7 and the upper surface of the shroud 8 so as to be connected to each other.

  During water turbine operation, for example, water from the upper pond (upper dam, not shown) flows into the spiral flow path of the casing 1 and passes between the stay vanes 3 sandwiched between the speed rings 2. The water that has passed between the stay vanes 3 then passes between the guide vanes 4, is guided to the runner 5, and hits the blades 6. The runner 5 rotates by this water flow. This rotational power is transmitted to a generator (not shown) coupled to the main shaft 9 via the runner 5 and the main shaft 9 and converted into electric energy.

  A main shaft flow path 11 is formed in the rotating main shaft 9, and a runner inner flow path 12 communicating with the main shaft flow path 11 is formed in the crown 7 of the runner 5 in the radial direction. A nozzle 13 for generating microbubbles communicates with the runner channel 12 and opens at the lower surface of the outer peripheral side end of the crown 7, and the runner communicates with the runner channel 12 inside the outer periphery of each blade 6. The inner flow path 14 is formed in the vertical direction. A nozzle 15 communicating with the runner internal flow path 14 opens at the outer peripheral side end face of the blade 6, and the runner internal flow path 16 is formed in the outer peripheral end of the shroud 8 communicating with the runner internal flow path 14. A nozzle 17 communicating with the in-runner channel 16 is opened on the upper surface of the outer peripheral end of the shroud 8.

  An external compressed air pipe is connected to the main shaft flow path 11 of the main shaft 9 via a rotary shaft flow path connecting means (not shown), and an air tank and a compressor are connected to the compressed air pipe.

  The main shaft flow path 11, the runner flow paths 12, 14, 16 and the nozzles 13, 15, 17 constitute microbubble discharge means for discharging microbubbles from the rotating runner.

  A plurality of nozzles 13 are dispersedly arranged at intervals so as to extend over the entire circumference of the crown 7, but may be formed in a circumferential shape. The plurality of nozzles 15 are distributed in the vicinity of the tips of the blades 6 at intervals in the vertical direction, but may have a vertically long shape in accordance with the shape of the blade tips. A plurality of nozzles 17 are dispersedly arranged on the outer peripheral side end upper surface of the shroud 8 so as to extend over the entire circumference, but may be formed in a circumferential shape.

  Although not particularly illustrated, each of the nozzle 13, the nozzle 15 and the nozzle 17 is provided with a porous material or a slit at the opening end in order to atomize the air into micro bubbles on the order of micrometers. It has a structure that does not obstruct the internal flow.

  In the water wheel having the above-described structure, when the water passes through the runner 5, the surface of the crown 7 facing the shroud 8 (water contact surface), the surface of the blade 6 (water contact surface), and the crown 7 of the shroud 8 when the water wheel is operated. Microbubbles are injected through the nozzle 13, the nozzle 15, and the nozzle 17 so as to reduce the friction loss generated on the opposing surface (water contact surface). Although not shown, the microbubble air is supplied from the upstream side of the main shaft 9 via the main shaft flow path 11 by a compressed air source such as a compressor. You may include in this microbubble discharge | release means the compressed air source which connects this compressed air source and a compressed air source, and a main axis | shaft.

  In the above configuration, compressed air is supplied to the nozzle 13, the nozzle 15, and the nozzle 17, but an ejector that sucks water into the compressed air pipe is interposed, and the nozzle 13 and the nozzle 13 are mixed with water and compressed air. 15 may be supplied to the nozzle 17.

  According to the present embodiment, the nozzles 13, 15, and 17 for sending out the microbubbles are arranged at the most upstream position of the water flow passing through the runner of the rotating water turbine, and the microbubbles sent out from these nozzles. Flows along the surface of the runner crown 7 facing the shroud 8 (water contact surface), the surface of the blade 6 (water contact surface), the surface of the shroud 8 facing the crown 7 (water contact surface), Cover the surface (water contact surface). The microbubbles sent out from the nozzles 13, 15 and 17 are sent directly to the surface (water contact surface) of the rotating part without passing through the seal gap between the stationary part and the rotating part. Without peeling from the wall surface, the surface of the rotating part (water contact surface) is covered to reduce friction loss.

<Second Embodiment>
FIG. 3 shows a longitudinal sectional view of the main shaft and the runner portion of the water turbine according to the second embodiment of the present invention. The present embodiment differs from the embodiment shown in FIG. 2 in that the runner inner channel 19 and the runner inner channel 19 branch in the runner inner channel 12 and extend toward the seal portion on the upper surface of the crown 7. Nozzle 22 that communicates with the upper surface of the crown 7 and opens toward the outer peripheral side, and nozzle 21 that communicates with the runner inner passage 12 and opens at the upper surface of the outer peripheral edge of the crown 7 in the radial direction. The nozzle 23 is provided in communication with the outer peripheral end of the radial direction 16 and opens toward the lower surface of the shroud 8. The nozzle 23 communicates with the flow path 14 in the runner and is formed in the shroud 8 toward the inner peripheral side in the radial direction. The runner internal flow path 18 reaching the inner peripheral side end, and the nozzle 24 that communicates with the inner peripheral end of the runner internal flow path 18 and opens on the outer peripheral surface of the shroud 8 are provided. The nozzles 22 and 24 are each formed in two stages in the vertical direction.

  Since other configurations are the same as those of the first embodiment, illustration and description thereof are omitted. Although not specifically shown, the nozzle 21, the nozzle 22, the nozzle 23, and the nozzle 24 are used to atomize air into micro bubbles on the order of micrometers, as in the case of the first embodiment. The tip is provided with a porous material, a slit, or the like, and has a structure that does not hinder the flow inside the water turbine.

  In the water wheel of the present embodiment having the above-described configuration, for example, water from the upper pond (upper dam, not shown) flows into the spiral flow path of the casing 1 and is sandwiched between the speed rings 2 during the water wheel operation. It passes between the stay vane 3 and the guide vane 4 and is guided to the runner 5, and the runner 5 is rotated by this water flow. At the same time, water flows as a leakage flow on the upper side of the crown 7 located on the opposite side of the blade 6 and on the outer side of the shroud 8. In a gap region formed on the upper side of the crown 7 and on the outer side of the shroud 8, a disk friction loss is generated between the leak flow stationary part (not shown in particular) and the runner 5 that is the rotating part.

  In the present embodiment, for example, during the operation of the water turbine, through the nozzle 21, the nozzle 22, the nozzle 23, and the nozzle 24 so that the disk friction loss generated in the gap region formed on the upper side of the crown 7 and the outer side of the shroud 8 is reduced. Microbubbles are discharged to the upper water-contacting surface of the crown 7 and the outer water-contacting surface of the shroud 8 that are in contact with the gap region. The discharged microbubbles spread along the water contact surface as the runner 5 rotates.

  As a result, the upper wetted surface of the crown 7 in contact with the gap region and the outer wetted surface of the shroud 8 are covered with microbubbles, and the friction between the leakage flow stationary portion and the upper wetted surface of the crown 7 and the outer wetted surface of the shroud 8 is covered. Loss is reduced.

  Further, it is desirable to adjust the number of nozzles per unit area and the area of the nozzles per unit area as appropriate in order to adjust the flow rate of the microbubbles. In addition, the position and number of the nozzles 15 installed on the surface of the blade 6 may be set as appropriate depending on the number of the nozzles 15 provided on the surface of the blade 6.

According to the present embodiment, in addition to the effect of the first embodiment, an effect that the disk friction loss generated in the gap region formed on the upper side of the crown 7 and the outer side of the shroud 8 is reduced can be obtained.
<Third Embodiment>
A third embodiment of the present invention will be described with reference to FIG. The present embodiment is intended for an impeller including a crown 7, a shroud 8, and a blade 6, that is, a pump turbine that rotates a runner 5 with a main shaft 9 to send water outward in the radial direction.

  In the present embodiment, the microbubble discharge means for discharging the microbubbles from the rotating runner is formed in the crown 7 so as to communicate with the flow path 11 within the main shaft 9 and the flow path 11 within the main shaft. The runner passage 25, the runner passage 25, the runner passage 27 formed in the blade 6 in the direction of connecting the crown 7 and the shroud 8, and the runner passage 27 are communicated. The runner passage 30 is formed in the shroud 8 up to a position upstream of the upstream end of the blade 6 and the runner passage 25 and is upstream of the upstream end of the blade 6. The nozzle 26 opened on the water contact surface facing the shroud 8 of the crown 7 at the position, the nozzle 28 opened to the upstream end face of the blade 6 in communication with the runner inner passage 27, and the runner passage 30. Shroud 8 crown 7 And a nozzle 29 opened in the opposite contact surface of the water is constituted.

  Although not specifically shown, the nozzle 26, the nozzle 28, and the nozzle 29 are arranged at the tip in order to atomize the air into micro bubbles on the order of micrometers, as in the case of the first embodiment. A porous material or a slit is provided, and the structure does not hinder the flow inside the water turbine.

  The nozzles 26 are circumferentially distributed on the water contact surface of the crown 7 facing the shroud 8, and the nozzles 29 are similarly distributed on the water contact surface of the shroud 8 facing the crown 7. Further, the nozzles 29 are distributed and arranged on the upstream end face of each blade 6 in a direction connecting the crown 7 and the shroud 8. Each nozzle may be formed in a continuous groove shape. In that case, it is desirable that the porous material is continuously filled.

  An external compressed air pipe is connected to the main shaft flow path 11 via a rotary shaft flow path connecting means (not shown), and an air tank and a compressor are connected to the compressed air pipe.

  When the pump turbine having the above-described configuration is operated, compressed air is supplied to the nozzle 26, the nozzle 28, and the nozzle 29, and an ejector that sucks water into the compressed air pipe is interposed to supply water and compressed air. You may make it supply to the nozzle 26, the nozzle 28, and the nozzle 29 in the mixed state.

  In the pump turbine of the above configuration, during operation, air for forming microbubbles from the upstream side of the main shaft 9 passes through the main shaft passage 11, the runner passages 25, 27, and 30 by the compressor (not shown). It is supplied to the nozzle 28 and the nozzle 29. The nozzle 26, the nozzle 28, and the nozzle 29 are disposed at the upstream end of the water contact surface facing the shroud 8 of the crown 7, the water contact surface of the blade 6, and the water contact surface facing the crown 7 of the shroud 8. The air supplied to the nozzle 26, the nozzle 28, and the nozzle 29 becomes microbubbles when leaving each nozzle and is sent out into the water and spreads downstream along the respective water contact surfaces.

  As a result, the water contact surface facing the shroud 8 of the crown 7, the water contact surface of the blade 6, and the water contact surface facing the crown 7 of the shroud 8 are covered with microbubbles, and when the water passes through the runner 5, Friction loss generated on the water contact surface facing the shroud 8, the water contact surface of the blade 6 and the water contact surface facing the crown 7 of the shroud 8 is reduced.

  According to the present embodiment, at the most upstream position of the water flow passing through the water contact surface facing the shroud 8 of the runner crown 7, the water contact surface of the blade 6, and the water contact surface facing the crown 7 of the shroud 8, Nozzles 26, 28 and 29 for sending out microbubbles are arranged, and the microbubbles sent out from these nozzles are in contact with the water surface facing the shroud 8 of the runner crown 7 and the water contact surface of the blade 6. The shroud 8 flows along the water contact surface facing the crown 7 and covers the water contact surfaces. The microbubbles sent out from the nozzles 26, 28 and 29 are sent directly to the water contact surface of the rotating part without passing through the seal gap between the stationary part and the rotating part, and thus peel off from the wall surface through the seal gap. The friction loss is reduced by covering the water contact surface of the rotating part.

It is a horizontal sectional view showing the whole composition of the centrifugal water turbine concerning a 1st embodiment of the present invention. It is a longitudinal cross-sectional view showing the main axis | shaft and impeller part of the centrifugal water turbine which concerns on the 1st Embodiment of this invention. It is a longitudinal cross-sectional view showing the main axis | shaft and impeller part of the centrifugal water turbine which concerns on the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view showing the main axis | shaft and impeller part of the centrifugal water turbine which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Speed ring 3 Stay vane 4 Guide vane 5 Runner 6 Blade 7 Crown 8 Shroud 9 Main shaft 11 Main shaft flow path 12 Runner internal flow path 13 Nozzle 14 Runner internal flow path 15 Nozzle 16 Runner internal flow path 17 Nozzle 18, 19 Runner Inner channels 21, 22, 23, 24 Nozzle 25 Runner inner channel 26 Nozzle 27 Runner inner channel 28, 29 Nozzle 30 Runner inner channel

Claims (6)

  A rotating fluid machine having an impeller disposed in water and a main shaft coupled to the impeller and rotating together with the impeller, the microbubble discharge for discharging microbubbles to a water contact surface of the impeller A rotating fluid machine comprising means.   2. The rotary fluid machine according to claim 1, wherein the microbubble discharge means is formed in the main shaft, one end is formed in the impeller coupling surface, and one end is formed in the impeller. A rotation characterized by having an impeller inner passage opening at a position communicating with the opening of the impeller coupling surface of the inner passage and having the other end and an intermediate portion opening on a water contact surface of the impeller. Fluid machinery.   3. The rotating fluid machine according to claim 2, wherein the impeller is connected to the main shaft and is disposed opposite to the crown that forms one end face in the axial direction of the impeller, and the axial direction of the impeller. A shroud that forms the other end surface, and a plurality of blades that support the shroud by coupling the crown and the shroud to each other, and the opening of the water contact surface is an upstream end portion of the crown The rotary fluid machine is formed on any one or more of a surface facing the shroud, a surface facing the crown at the upstream end of the shroud, and an upstream end surface of the blade.   4. The rotary fluid machine according to claim 3, wherein the opening of the water contact surface further includes a surface of the shroud opposite to a surface facing the crown, and a surface of the crown opposite to the surface facing the shroud. A rotating fluid machine characterized by being formed in one or both of them.   5. The rotary fluid machine according to claim 2, wherein a porous material is filled in an opening on a water contact surface of the flow path in the impeller, and the flow path in the impeller communicates with the outside of the impeller through the porous material. Rotating fluid machine characterized by. 6. The rotary fluid machine according to claim 2, wherein the other end of the flow path in the main shaft opens to the surface of the main shaft, and the microbubble discharge means is coupled to the opening to the surface of the main shaft through an airtight seal. A rotary fluid machine comprising a compressed air source connected via a rotary shaft channel connecting means.

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