JP5023125B2 - Axial flow turbine - Google Patents

Description

  The present invention relates to an axial flow turbine such as a steam turbine or a gas turbine.

  In Patent Document 1, a plurality of turbine stages each including a stationary blade fixed to an outer peripheral diaphragm and an inner peripheral diaphragm and a moving blade fixed to a turbine rotor rotating around a turbine central axis are provided in a working fluid flow path. An axial flow turbine having a function of converting kinetic energy generated when a high-pressure working fluid expands toward a low-pressure portion in a flow path into a rotational force by a turbine stage composed of stationary blades and moving blades is disclosed. .

  In an axial flow turbine having multiple paragraphs as described in Patent Document 1, there is a demand to increase the flow rate, which is the mass of the working fluid flowing per unit time, in order to increase the output per paragraph. By increasing the flow rate and increasing the output per paragraph, it is possible to increase the amount of power generation without changing the number of paragraphs.

  Here, in order to increase the flow rate, it is effective to increase the annular area, which is the area of the portion through which the working fluid flows as viewed from the turbine rotation axis direction. In the case of an axial turbine, the annulus area is the product of the blade length and the average diameter obtained by adding the outer and inner diameters of the blades and dividing by two times the circle ratio. Therefore, in order to increase the ring zone area, the blade length and the average diameter are increased.

JP 2003-27901 A

  However, when the blade length and average diameter are increased, the peripheral speed, which is the rotational speed of the moving blade, also increases. The peripheral speed of the moving blade becomes the largest at the outer peripheral end having the largest radial position, that is, at the tip of the moving blade. When the peripheral speed of a moving blade reaches a certain critical speed, for example, close to or exceeds twice the speed of sound at that location, the relative speed of the flow of working fluid flowing into the moving blade relative to the moving blade (hereinafter referred to as dynamic (Indicated as blade relative inflow velocity) is supersonic. When the moving blade relative inflow velocity becomes supersonic, a shock wave accompanied by a discontinuous pressure rise is generated on the upstream side of the moving blade. When a shock wave is generated, in addition to the entropy increase due to the shock wave itself, the shock wave interferes with the boundary layer of the blade surface, the boundary layer thickness increases due to the discontinuous pressure increase, and further the separation causes entropy. An increase occurs. Due to the entropy increase due to the shock wave, the rotational force corresponding to the increased flow rate, that is, the output may not increase even though the annular zone area of the turbine stage is increased and the flow rate of the working fluid is increased. Therefore, it is important to eliminate or weaken the shock wave generated at the moving blade inflow part in order to realize an increase in output per paragraph by increasing the ring area beyond the limit peripheral speed, and for that reason Therefore, it is necessary to reduce the relative inflow speed of the rotor blade.

  Accordingly, an object of the present invention is to provide an axial flow turbine capable of suppressing the generation of shock waves and improving turbine stage efficiency.

  In order to achieve the above object, the present invention provides an axial flow including a turbine stage that is configured by a stationary blade fixed to an outer peripheral diaphragm and a moving blade fixed to a turbine rotor and provided in a working fluid flow path. In the turbine, a part of the working fluid discharged from the stationary blade is attracted to the outer peripheral side of the outer peripheral diaphragm and in a direction inclined in the turbine rotor rotation direction with respect to the turbine radial direction, so that the working fluid flows in the moving blade. A working fluid attracting means is provided to flow down to the downstream side.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of a shock wave can be suppressed in an axial flow turbine, and turbine stage efficiency can be improved.

It is sectional drawing showing the principal part structure of the turbine stage part of the axial flow turbine which concerns on the 1st Embodiment of this invention. It is sectional drawing which looked at the AA cross section shown in FIG. 1 from the turbine axial direction upstream. It is explanatory drawing which looked at the flow-path side wall surface of the outer peripheral side diaphragm of the axial flow turbine which concerns on the 1st Embodiment of this invention from the turbine radial direction. It is explanatory drawing which represents typically the flow of the working fluid in the axial flow turbine which concerns on the 1st Embodiment of this invention. It is explanatory drawing which represents typically the relationship of a stationary blade outflow speed, a moving blade circumferential speed, and the relative inflow speed of a moving blade when the circumferential speed of a moving blade is large. It is explanatory drawing which represents typically the effect which suppresses the increase in the moving blade relative inflow speed of the axial flow turbine which concerns on the 1st Embodiment of this invention. It is sectional drawing showing the principal part structure of the turbine stage part of the axial flow turbine concerning the 2nd Embodiment of this invention. It is sectional drawing showing the principal part structure of the axial flow turbine intermediate | middle stage concerning the 3rd Embodiment of this invention. It is sectional drawing which looked at the BB cross section illustrated in FIG. 8 from the turbine axial direction upstream. It is explanatory drawing which looked at the flow path side surface of the outer peripheral side diaphragm of the steam turbine which concerns on the 4th Embodiment of this invention from the turbine radial direction. It is explanatory drawing which looked at the flow path side surface of the outer peripheral side diaphragm of the axial flow turbine which concerns on the 5th Embodiment of this invention from the turbine radial direction.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the equivalent component through each drawing.

  As a first embodiment of the present invention, an example in which the present invention is applied to the final paragraph of an axial flow turbine will be described below.

  First, the basic structure of the axial turbine according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a meridional cross-sectional view illustrating a main structure of a turbine stage portion of an axial flow turbine according to a first embodiment of the present invention. 2 is a cross-sectional view of the AA cross section shown in FIG. 1 as viewed from the upstream side in the turbine axial direction. FIG. 3 is a view of the channel side wall surface 5a of the outer peripheral diaphragm 5 of FIG. 1 as viewed from the turbine radial direction.

  As shown in FIG. 1, the turbine stage of the axial flow turbine includes a high-pressure portion P0 and a working fluid flow on the upstream side (hereinafter simply referred to as upstream) in the working fluid flow direction in the working fluid flow path 4 through which the working fluid 19 flows. It is provided between the low-pressure portion P1 on the downstream side in the direction (hereinafter simply referred to as the downstream side). An outer peripheral diaphragm 5 is provided via a fixing member 14 on a turbine radial direction inner peripheral side (hereinafter simply referred to as an inner peripheral side) of a turbine casing (not shown), and an inner peripheral diaphragm 6 is provided on the inner peripheral side thereof. Is provided. A turbine rotor 1 that rotates about the turbine central axis 18 is provided on the inner peripheral side of the inner peripheral diaphragm 6. The turbine stage has a plurality of stationary blades 3 fixed in the turbine circumferential direction between the outer circumferential diaphragm 5 and the inner circumferential diaphragm 6, and the circumferential direction so that the turbine rotor 1 faces the downstream side of the stationary blade 3. And a plurality of moving blades 2 provided on the blade. In the case of a multi-stage type axial flow turbine, this turbine stage is repeatedly provided in the turbine axial direction a plurality of times. The paragraph closest to the working fluid inlet of the high pressure portion P0 is referred to as the first paragraph, and the paragraph closest to the working fluid outlet of the low pressure portion P1 is referred to as the last paragraph.

  A shroud 10 is provided at the outer peripheral end of the rotor blade 2. A seal structure 11 is provided on the inner peripheral surface of the outer peripheral diaphragm 5 facing the shroud 10 to reduce the working fluid that leaks without passing through the moving blade portion. Further, as shown in FIG. 1, an exhaust chamber that forms an annular diffuser flow path formed by an outer peripheral flow path wall 7 and an inner peripheral flow path wall 8 at the outlet side of the final stage of the axial flow turbine. 9 is provided.

  Between the stationary blade 3 outlet and the moving blade 2 inlet of the outer peripheral side diaphragm 5, the outer peripheral side wall surface 5 b of the outer peripheral side diaphragm 5 penetrates to the inner peripheral side wall surface (flow channel side wall surface 5 a). A communicating air hole 12 is provided. Further, on the outer peripheral side of the outer peripheral diaphragm 5, a bypass channel 15 is provided that communicates with the vent hole 12 and the working fluid channel 4 in the vicinity of the final stage outlet on the downstream side of the moving blade 2. The bypass flow path 15 includes an annular flow path 16 and a slit 17.

  In the annular flow path 16, the inner peripheral side wall surface is constituted by the outer peripheral side wall face 5 b of the outer peripheral side diaphragm 5, and the outer peripheral side wall face is constituted by the outer peripheral side flow path wall 7. As shown in FIG. 2, the annular flow path 16 is an annular flow path formed by extending in the turbine circumferential direction between the outer peripheral side diaphragm 5 and the outer peripheral side flow path wall 7.

  The slit 17 is provided between the outer peripheral diaphragm 5 and the outer peripheral flow path wall 7 so as to extend in the turbine circumferential direction (hereinafter simply referred to as the circumferential direction). As shown in FIG. 2 A flow path that opens near the inlet of the exhaust chamber 9 on the downstream side.

  In the present embodiment, the vent hole 12, the annular flow path 16, and the slit 17 communicate with each other, bypassing the moving blade 2 with a part of the working fluid 19 discharged from the stationary blade 3, A flow path leading to the working fluid flow path 4 is configured.

  The structure of the vent hole 12 will be described in detail with reference to FIGS. As shown in FIG. 2, the vent hole 12 is a rotation direction 20 of the turbine rotor 1 with respect to the turbine radial direction from the inner peripheral side to the outer peripheral side of the outer peripheral side diaphragm 5 (hereinafter, simply referred to as a rotational direction). It is formed to be inclined in the direction. As the most extreme example, the inclination angle is a tangential direction of the rotation direction as shown in FIG. In FIG. 2, three ventilation holes 12 are shown as representatives, but actually, a plurality of ventilation holes 12 are provided over the entire circumference in the circumferential direction, spaced apart at regular intervals.

  FIG. 3 shows a view of the channel side wall surface 5a of the outer peripheral diaphragm 5 of FIG. 1 as viewed from the turbine radial direction. Note that the arrow 20 represents the rotational direction of the turbine rotor 1. As shown in FIG. 3, a plurality of vent holes 12 are provided spaced apart in the circumferential direction. Further, the vent hole 12 is provided along the outlet direction 21 of the stationary blade and extending toward the downstream side from the rear edge position of the stationary blade 3 while being inclined in the rotational direction 20 with respect to the turbine shaft direction 22. . The width of the vent hole 12 is several times the length obtained by adding the thickness of the trailing edge of the stationary blade to the thickness of the working fluid adhering to the back side and the ventral side of the blade. The flow passage area of the vent hole 12 for adjusting the flow rate of the working fluid 23 is adjusted by adjusting the length in the turbine axial direction. In the present embodiment, the circumferential position of the vent holes 12 need not be limited to the stationary blade trailing edge.

  The vent hole 12 may be formed by penetrating the outer peripheral diaphragm 5 itself, but the ring-shaped slit formed in the outer peripheral diaphragm extending in the circumferential direction is inserted into the outer peripheral side from the inner peripheral side of the outer peripheral diaphragm 5. It may be formed by inserting a partition plate inclined in the rotor rotation direction toward.

  Next, the operation and effect of the present embodiment will be described with reference to FIGS. 2, 4 to 6. FIG. 4 is a diagram schematically illustrating the flow of the working fluid in the axial turbine according to the first embodiment of the present invention. FIG. 5 is a diagram schematically showing the relationship among the stationary blade outflow velocity V, the moving blade circumferential velocity U, and the moving blade relative inflow velocity W when the circumferential velocity of the moving blade is high. FIG. 6 is a diagram schematically illustrating an effect of suppressing an increase in the moving blade relative inflow velocity W of the axial turbine according to the first embodiment of the present invention.

  As shown in FIG. 4, the annular flow path 16 communicates with the exhaust chamber 9 via a wide slit 17 having a small pressure loss, so that the pressure P16 in the annular flow path 16 is equal to the pressure P1 of the exhaust chamber 9. Can be considered. Therefore, as shown in FIG. 2, since the pressure P16 in the annular flow path 16 is smaller than the pressure P13 on the outer peripheral side 13 between the stationary and moving blades, it is induced by the pressure difference P13-P16, and FIG. As shown in FIG. 3, a suction flow 24 of the working fluid is induced in the vent hole 12 from the inner peripheral side of the outer peripheral side diaphragm toward the outer peripheral side. Further, as shown in FIG. 4, the flow 25 of the working fluid attracted from the working fluid flow path 4 to the annular flow path 16 through the vent hole 12 flows through the slit 17 to the exhaust chamber 9 at a small flow rate.

  As shown in FIG. 2, the pressure difference P13−P16 between the static pressure P13 on the outer peripheral side between the static and moving blades in the working fluid flow path 4 and the pressure P16 of the annular flow path 16 communicating with the exhaust chamber 9 is obtained. When the working fluid discharged from the outer peripheral portion 13 of the stationary blade is attracted to the annular flow path 16 through the vent hole 12, a suction flow 24 is induced, but the vent hole 12 is inclined in the rotational direction of the turbine rotor 1. Therefore, a turning speed in the same direction as the rotation direction 20 is induced on the outer peripheral side 13 between the stationary and moving blades.

  FIG. 5 is a schematic diagram of a general velocity triangle between the stationary and moving blades. The working fluid 26 having a high pressure P0 is accelerated by passing between the stationary blades 3a and 3b adjacent in the circumferential direction, and is turned into a flow of velocity V (static blade outflow velocity V). When the flow of the stationary blade outflow velocity V is viewed in the relative coordinate system rotating together with the moving blade 2, the moving blade 2 rotates at the peripheral speed U in the rotation direction 20, and therefore, as shown in FIG. And the vector U are combined, the moving blade relative inflow velocity becomes a flow of velocity W. A triangle composed of the vector V, the vector U, and the vector W is called a velocity triangle. As is apparent from the velocity triangle shown in FIG. 5, when the moving blade circumferential speed U increases, the relative flow velocity W flowing into the moving blade increases. In order to reduce the moving blade relative inflow velocity W, it is necessary to increase the stationary blade outflow velocity V. However, when the state quantity of the working fluid at the paragraph inlet is fixed, in order to increase the stationary blade outflow velocity V, the static pressure P13 between the stationary and moving blades is decreased and the pressure ratio P13 / P0 is decreased. However, the static pressure P13 becomes larger toward the outer peripheral side due to the swirl speed field at the stationary blade outlet, and as the blade length becomes longer, the influence of the swirl speed field becomes stronger, and it becomes difficult to reduce P13. That is, it is difficult to increase the stationary blade outflow speed V.

  On the other hand, in the present embodiment, as shown in FIG. 6, the rotating direction 20 of the moving blade is the same direction as the tangential component VT1 of the rotating direction 20 of the outflow velocity V of the stationary blade. It has the effect of increasing V1. That is, by inducing a suction flow 24 in the rotation direction 20 to the bypass flow path 15 through the vent hole 12, VT1, which is a rotation direction component of the stationary blade outflow speed V1, is accelerated to VT2. By accelerating from VT1 to VT2, an effect of increasing the stationary blade outflow velocity V itself can be obtained, so that the relative velocity W1 flowing into the moving blade can be reduced to W2 even though the circumferential speed U is the same. it can. Therefore, if the configuration of the present embodiment is applied when there is no suction flow 24 and the blade relative inflow velocity W1 is supersonic, the suction blade 24 causes the blade relative inflow velocity W2 to be lower than the sound velocity. Therefore, it is possible to suppress the generation of a shock wave at the moving blade inlet, to avoid an increase in the loss accompanying it, to increase the output, and to improve the turbine stage efficiency. Further, this embodiment is particularly effective when the turbine stage is made longer and the annular zone area is increased beyond the limit peripheral speed, and an increase in output can be realized, and the efficiency of the turbine stage can be improved.

  In addition, as shown in FIG. 3, by making the vent hole 12 wide in the turbine axial direction, the flow exiting the stationary blade is gradually accelerated in the rotor rotation direction 20 toward the moving blade inlet by the suction flow 24. Thus, the flow direction becomes the same as the flow 23, and the relative inflow speed of the moving blade can be reduced.

  This embodiment can be applied not only to the final paragraph but also to an intermediate paragraph as long as the exhaust chamber is replaced with the downstream inlet. As an example, an example in which the present invention is applied to a bleed paragraph of an intermediate paragraph will be described in Example 3 described later.

  The effect of the present embodiment is effective regardless of the working fluid such as steam or air.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  The basic configuration of the present embodiment is the same as that of the first embodiment, and components different from those of the first embodiment will be described below with reference to FIG.

  FIG. 7 is a cross-sectional view showing the main structure of the final stage of the axial flow turbine according to the second embodiment of the present invention. The same components as those in FIG. To do. In the present embodiment, the annular flow channel 16 and an exhaust chamber (not shown) formed on the outer circumferential side of the outer flow channel wall 7 are communicated with the outer flow channel wall 7 constituting the annular flow channel 16. An exhaust passage 27 is provided. The exhaust chamber formed on the outer peripheral side of the outer peripheral flow path wall 7 passes through the diffuser flow path in the exhaust chamber formed by the outer peripheral flow path wall 7 and the inner peripheral flow path wall 8 and has recovered the static pressure. The pressure flow is lower than that of the stationary blade outlet. Accordingly, the working fluid 24 sucked into the annular flow path 16 through the vent hole 12 passes through the slit or hole-shaped exhaust flow path 27, is attracted to the space on the outer peripheral side of the paragraph, and is discharged. Therefore, according to the configuration of the present embodiment, although it is necessary to provide the hole 27 in the outer peripheral flow path wall 7 as compared with the structure for discharging to the downstream side of the paragraph according to the first embodiment, the annular flow path 16 Interference between the working fluid flow discharged from the working fluid flow and the working fluid flow exiting the rotor blade 2 can be suppressed, and the possibility of causing energy loss can be reduced.

  Therefore, by applying the configuration of the present embodiment, it is possible to suppress the moving blade relative inflow velocity, suppress the generation of shock waves at the moving blade inlet, and the loss associated therewith, as in the first embodiment. Can be avoided, the output can be increased, and the turbine stage efficiency can be improved. Further, by applying this embodiment, the interference between the working fluid flow discharged from the bypass flow path 15 and the working fluid flow exiting the rotor blade 2 is suppressed as compared with the first embodiment. This can reduce the possibility of energy loss.

  The effect of the present embodiment is effective regardless of the working fluid such as steam or air.

  Next, a third embodiment of the present invention will be described with reference to FIGS. The present embodiment is an example in which the present invention is applied to an intermediate stage of an axial flow turbine, and in particular, an example in which the present invention is applied to an extraction stage. FIG. 8 is a meridional cross-sectional view showing a main structure of an axial turbine intermediate stage according to the third embodiment of the present invention. FIG. 9 is a cross-sectional view of the BB cross section shown in FIG. 8 as viewed from the upstream side in the turbine axial direction.

  FIG. 8 is a cross-sectional view showing the main structure of an axial turbine intermediate stage according to the third embodiment of the present invention. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 8, an extraction chamber 30 formed in an annular shape in the turbine circumferential direction is formed between the turbine casing 29 and a plurality of outer peripheral diaphragms 5 fixed to the turbine casing 29 in the turbine axial direction. Yes. A plurality of bleed pipes (not shown) are connected to the bleed chamber 30 in the circumferential direction, and a part of the main working fluid flow 19 that has passed near the outer peripheral end of the rotor blade 2 extends in the circumferential direction formed between the outer diaphragms. Then, the air is guided to the extraction chamber 30 through the slit 31 and is extracted out of the turbine casing through the extraction pipe.

  In the present embodiment, the working fluid flow path 4 and the extraction chamber 30 are arranged between the stationary blade 3 outlet and the moving blade 2 inlet of the outer peripheral diaphragm 5 constituting the extraction chamber 30 upstream of the extraction chamber 30. A bypass passage 15 is constituted by an exhaust chamber 30 provided with a communication hole 12 that communicates with the working fluid passage 4 on the downstream side of the rotor blade 2.

  As shown in FIG. 9, in this embodiment, the vent hole 12 communicates with the bleed chamber 30 and, as in the first embodiment, extends from the inner peripheral side of the outer peripheral diaphragm 5 toward the outer peripheral side. Thus, it is formed to be inclined in the rotational direction 20 of the turbine rotor 1 with respect to the turbine radial direction. In this embodiment as well, in practice, a plurality of vent holes 12 are provided over the entire circumference in the circumferential direction, spaced apart at a constant interval.

  In addition, the structure which looked at the flow-path side surface 5a of the outer peripheral side diaphragm 5 of FIG. 8 from the turbine radial direction is fundamentally the same as 1st Embodiment, and abbreviate | omits description.

  The effect of this Embodiment is demonstrated. The extraction chamber 30 communicates with the working fluid channel 4 on the downstream side of the moving blade 2 via the slit 31, and it can be considered that the extraction chamber pressure P30 is equal to the working fluid channel 4 on the downstream side of the moving blade 2. it can. Therefore, the working fluid suction flow 32 from the inner peripheral side of the outer peripheral diaphragm 5 toward the outer peripheral side is caused by the pressure difference between the static pressure P13 on the outer peripheral side between the static and moving blades in the working fluid flow path 4 and the extraction chamber pressure P30. Induced. As shown in FIG. 8, the working fluid flow 32 that has passed through the vent hole 12 is extracted outside the turbine casing together with the extraction air flow 33 extracted in the extraction chamber.

  Therefore, according to the configuration of the present embodiment, similarly to the first embodiment, in the intermediate paragraph, the moving blade relative inflow speed can be suppressed, the generation of shock waves at the moving blade inlet is suppressed, The increase of the loss accompanying it can be avoided, an output can be increased, and turbine stage efficiency can be improved.

  The effect of the present embodiment is effective regardless of the working fluid such as steam or air.

  Next, as a fourth embodiment of the present invention, an example in which the present invention is applied to a low-pressure turbine final stage of a steam turbine will be described with reference to the drawings.

  The basic structure of the present embodiment is the same as that of the first embodiment described above, and the same components are denoted by the same reference numerals and description thereof is omitted. Hereinafter, a configuration different from that of the first embodiment in the present embodiment will be described with reference to FIG. FIG. 10 is a view of the flow passage side surface of the outer peripheral diaphragm of the axial flow turbine according to the present embodiment as seen from the turbine radial direction.

  The difference between the present embodiment and the first embodiment described above is that the working fluid 36 is steam. In a steam turbine that generates a low-pressure part by converting vapor in the vapor phase into liquid-phase water on the outlet side, the steam in the turbine stage near the outlet in the final stage or the like is a gas-liquid two-phase flow called wet steam It is in a state. Most of the liquid phase is small droplets that flow at almost the same speed as vapor in the vapor phase and contribute to the generation of rotational force, but some of the liquid phase is liquid on the blade surface and side wall surface. A film is formed, and the liquid film is released again as large droplets in the vapor. The re-released coarse droplet may hit the rotating blade and generate erosion. This erosion increases as the peripheral speed increases. Therefore, when the annular area is increased, the peripheral speed of the moving blade increases, which may be a more serious problem. In addition, the erosion not only lowers the performance by changing the shape of the moving blade, but also may be a starting point for breakage and breakage due to vibration of the rotating body. In addition, the fact that the coarse droplet re-released from the wall surface hits the moving blade means that it acts as a brake against the rotation of the moving blade, so that the obtained rotational force becomes small. In addition, the coarse water droplets re-released from the wall surface have a slower speed than the mainstream steam, so when flowing together with the mainstream steam, the kinetic energy of the mainstream is taken away, and this also reduces the rotational force obtained. . That is, coarse water droplets cause both reliability and turbine efficiency to decrease.

  However, in the present embodiment, as shown in FIG. 10, the vent hole 12 is inclined from the rear edge position of the stationary blade 3 while being inclined with respect to the turbine axial direction along the outlet direction 34 of the stationary blade. The liquid film flowing on the flow path side surface 5a of the stationary blade outer peripheral diaphragm 5 is sucked out of the working fluid flow path through the vent hole 12 together with the flow 35 for sucking vapor. Can do. The liquid film and coarse water droplets are not uniformly distributed in the circumferential direction at the stationary blade outlet, but are attached to the surface of the stationary blade. With the vent hole 12 of the embodiment, coarse water droplets can be efficiently removed, and coarse water droplets that collide with the rotor blades 2 can be reduced. Therefore, it is possible to suppress a decrease in reliability and turbine efficiency due to coarse water droplets.

  In this embodiment, the basic structure is the same as that of the first embodiment, and the suction blade flow can suppress the relative inflow speed of the moving blade, suppress the generation of the shock wave at the moving blade inlet, and the loss associated therewith. The increase can be avoided, the output can be increased, and the turbine stage efficiency can be improved. Moreover, in this Embodiment, the fall and the reliability resulting from the coarse water droplet which the vapor | steam which is a working fluid hold | maintains can be suppressed.

  Note that the present embodiment can be applied not only to the final paragraph but also to an intermediate paragraph as long as the exhaust chamber is replaced with the downstream inlet.

  Next, a fifth embodiment of the present invention will be described with reference to FIG.

  The basic configuration of the present embodiment is the same as that of the first embodiment, and components different from those of the first embodiment will be described below with reference to FIG.

  FIG. 11 is a view of the flow path side surface 5a of the outer peripheral diaphragm 5 of FIG. 1 as viewed from the turbine radial direction. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In the present embodiment, the vent hole 12 is opened in a hole shape, and a plurality of the vent holes 12 are provided away from the trailing edge portion of the stationary blade in the turbine shaft direction along the working fluid outlet direction of the stationary blade. . By making the opening into a hole shape and a cylindrical ventilation hole, the ventilation hole 12 can be easily manufactured as compared with the first embodiment.

  Therefore, by applying the configuration of the present embodiment, it is possible to suppress the moving blade relative inflow velocity, suppress the generation of shock waves at the moving blade inlet, and the loss associated therewith, as in the first embodiment. Can be avoided, the output can be increased, and the turbine stage efficiency can be improved. In addition, by applying this embodiment, the vent hole 12 can be easily manufactured as compared with the first embodiment, and the manufacturing cost can be reduced.

  Note that the air holes of the present embodiment can also be applied to the second to fourth embodiments described above.

  As described above in each embodiment, the present invention relates to the turbine radial direction from the inner peripheral side toward the outer peripheral side, which communicates with the stage outlet, between the stationary blade and outer blades of the stationary blade outer peripheral diaphragm. By providing the vent hole inclined in the rotational direction, it is possible to suppress the occurrence of shock wave loss due to the supersonic inflow of the moving blades even in the stage where the peripheral speed is large, and to improve the turbine stage efficiency.

  The effect of reducing the relative inflow speed of the moving blade and reducing the shock wave loss according to the present invention is effective regardless of the working fluid such as steam and air.

DESCRIPTION OF SYMBOLS 1 Turbine rotor 2 Moving blade 3 Stator blade 5 Outer peripheral side diaphragm 6 Inner peripheral side diaphragm 7 Outer peripheral side flow path wall 9 Exhaust chamber 12 Vent hole 15 Bypass flow path 16 Annular flow path 17 Slit 29 Turbine casing 30 Extraction chamber

Claims (8)

An axial flow turbine comprising a turbine stage that is configured with a stationary blade fixed to an outer peripheral diaphragm and a moving blade fixed to a turbine rotor and provided in a working fluid flow path,
Part of the working fluid discharged from the stationary blade is attracted to the outer peripheral side of the outer peripheral diaphragm and in a direction inclined in the turbine rotor rotation direction with respect to the turbine radial direction, and downstream of the moving blade in the working fluid flow direction An axial flow turbine comprising: a working fluid attracting means for flowing down to the side. An axial turbine according to claim 1,
The working fluid attracting means is
The outer periphery having a plurality of air holes communicating with the working fluid flow path and inclined in the turbine rotor rotation direction with respect to the turbine radial direction, spaced between the stationary blade and the moving blade and in the turbine circumferential direction Side diaphragm,
It is formed in an annular shape on the outer peripheral side of the outer peripheral diaphragm, and is configured by a bypass flow path that is connected to the vent hole and communicates with the working fluid flow path on the downstream side in the working fluid flow direction of the moving blade. An axial flow turbine. An axial flow turbine comprising a turbine stage that is configured with a stationary blade fixed to an outer peripheral diaphragm and a moving blade fixed to a turbine rotor and provided in a working fluid flow path,
The outer periphery having a plurality of air holes communicating with the working fluid flow path and inclined in the turbine rotor rotation direction with respect to the turbine radial direction, spaced between the stationary blade and the moving blade and in the turbine circumferential direction Side diaphragm,
A shaft formed annularly on the outer periphery of the outer peripheral diaphragm, connected to the vent hole, and provided with a bypass flow channel communicating with the working fluid flow channel on the downstream side in the working fluid flow direction of the moving blade. Flow turbine. The axial turbine according to claim 2 or 3,
The working fluid flowing down the working fluid channel is steam,
The axial flow turbine according to claim 1, wherein the air vent extends from the downstream of the rear edge of the stationary blade toward the moving blade inlet along a working fluid outlet direction of the stationary blade. The axial turbine according to claim 2 or 3,
The axial-flow turbine is characterized in that the vent hole is configured by a plurality of cylindrical holes that are provided apart from each other in the turbine axial direction. The axial turbine according to claim 2 or 3,
The axial flow turbine characterized in that the bypass passage communicates with an exhaust passage provided on an outer peripheral side of the bypass passage. The axial turbine according to claim 2 or 3,
The turbine paragraph is an intermediate paragraph;
2. The axial flow turbine according to claim 1, wherein the bypass passage is an annular bleed chamber formed between the outer peripheral diaphragm and a turbine casing that fixes the outer peripheral diaphragm. The axial turbine according to claim 2 or 3,
The turbine paragraph is a final paragraph;
The bypass flow path is formed between an outer peripheral diaphragm and an outer peripheral flow path wall constituting an exhaust chamber, and communicates with the working fluid flow path at the exhaust chamber inlet portion. Axial flow turbine.

Images