JP2011169172A - Turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turbine which can effectively perform pressure recovery of fluid, while inhibiting occurrence of pressure loss due to peeling to exhaust the fluid, with minimum configuration. <P>SOLUTION: A gas turbine 1 includes: a rotor 2; a casing 11 forming a working fluid channel 14 through which the fluid is circulated: a turbine body 10 having a plurality of stationary blades radially provided on the inner circumferential surface of the casing 11 and a plurality of moving blades 13 radially provided on the other side of the central axis S direction of the stationary blades; and a diffuser 20 connected with the casing 11, which is formed radially expanding, gradually from one side of the central axis S direction toward the other side, with a substantially tubular shape, and forms an exhaust fluid channel 21 inside thereof, which exhausts the fluid. An open angle θ is set to 15° or above and 30° or below, and tip clearance C formed between the inner circumferential surface of the casing 11 and one of the moving blades 13, which is most adjacent to the diffuser 20, is set to 0.1% or above and 1.0% or below for the channel height H of the working fluid channel at the position of the moving blade 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a turbine that is rotationally driven by a working fluid.

  Conventional turbines include gas turbines and steam turbines. For example, a gas turbine is generated by a rotor, a compressor that generates compressed air by rotational driving of the rotor, a combustor that generates combustion gas by burning compressed air generated by the compressor, and a combustor. And a turbine main body for rotating the rotor by causing the combustion gas to flow along the central axis of the rotor as a working fluid. Further, in such a gas turbine, a diffuser that discharges the working fluid that rotates the rotor is connected to the turbine body. The diffuser is formed so as to gradually expand in diameter along the central axis direction. Thus, the circulating working fluid is decelerated by the diffuser and recovered in pressure, and then discharged to the atmosphere or reused in another facility.

  Here, the larger the channel height on the outlet side relative to the channel height at the inlet of the diffuser, that is, the larger the opening angle of the diffuser with respect to the rotor central axis, the larger the ratio of the outlet channel area to the inlet. Thus, the working fluid can be effectively decelerated. On the other hand, if the opening angle of the diffuser is large and the flow path area changes suddenly, separation occurs in the working fluid flowing along the inner peripheral surface, resulting in a pressure loss and a reduction in efficiency. By increasing the dimension along the central axis direction of the diffuser, the working fluid can be decelerated effectively by reducing the opening angle of the diffuser and increasing the flow area ratio of the outlet to the inlet, but pressure recovery can be achieved. Due to such limitations, it may be difficult to ensure a sufficient length, and an increase in loss due to long dimensions may occur. Therefore, a wall surface facing the downstream side is provided above and below the inlet of the diffuser, and a secondary jet generated by extracting from the upstream turbine stage or compressor stage is injected along the inner peripheral surface from the wall surface. It has been proposed to let Further, as a supply source of the secondary jet, not only the above-described turbine stage and compressor but also an independent booster unit and a point of using ambient air have been proposed (for example, see Patent Document 1).

JP 2004-162715 A

  However, in the diffuser in the turbine as in Patent Document 1, it is necessary to newly provide a structure for supplying the secondary jet and a structure for injecting, and there is a problem that the apparatus structure becomes complicated. Moreover, it is necessary to form a level | step difference in order to provide the wall surface for injecting a secondary jet in the entrance of a diffuser, and it may become a cause of new peeling. Furthermore, when the secondary jet is extracted by extraction from the turbine stage or the compressor stage, the working fluid is reduced, and the turbine efficiency is reduced. In addition, when a booster unit is additionally installed, a power source for the unit is required separately, which ultimately reduces the efficiency as a whole. Similarly, when ambient air is used, a means for compressing to a necessary pressure is required, and as a result, the efficiency is lowered as a whole.

  The present invention has been made in view of the above-described circumstances, and provides a turbine capable of effectively recovering the pressure of the fluid and discharging it while suppressing the occurrence of pressure loss due to separation with a minimum configuration. The challenge is to do.

In order to solve the above problems, the present invention proposes the following means.
The turbine according to the present invention has a rotor rotatable around a central axis, and a substantially cylindrical shape disposed on the outer periphery of the rotor, and a working fluid in which fluid flows from one side to the other side in the central axis direction. A turbine body having a casing forming a flow path, a plurality of vanes radially provided on an inner peripheral surface of the casing, a plurality of blades radially provided on the other side in the central axis direction of the vanes, and the turbine A diffuser that is connected to the casing of the main body, is formed in a substantially cylindrical shape so as to gradually increase in diameter from one side to the other side in the central axis direction, and forms a discharge fluid passage that discharges the fluid inside. The diffuser is disposed at the same position in the circumferential direction on the inner peripheral surface, and the inlet of the exhaust fluid passage and the height of the inlet passage from the inlet of the exhaust fluid passage to the other side along the central axis. .5 times different position The opening angle formed by the line connecting the central axis and the central axis is set to 15 degrees or more and 30 degrees or less, and among the moving blades, the one closest to the diffuser is between the inner peripheral surface of the casing. The tip clearance to be formed is set to 0.1% to 1.0% of the flow path height of the working fluid at the position of the moving blade.

  According to this configuration, the fluid flows in the central axis direction through the working fluid flow path of the turbine main body between the stationary blades and the moving blades, thereby rotating the rotor provided with the moving blades. In addition, the fluid that has flowed through the working fluid flow path flows into the exhaust fluid flow path inside the diffuser connected to the casing, and the diffuser gradually expands in diameter toward the other side in the central axis direction, thereby increasing the flow path area. Thus, the pressure is reduced and the pressure is recovered, and then discharged. Here, the opening angle is set to 15 degrees or more, so that the tip clearance of the moving blade closest to the diffuser is in the direction of the central axis of the moving blade while effectively recovering the pressure of the fluid. By setting it to 0.1% or more of the flow path height of the working fluid at the position, a leakage flow is positively introduced from the tip clearance along the inner peripheral surface of the diffuser, and from the inner peripheral surface of the fluid. Peeling can be suppressed and pressure loss due to peeling can be prevented. Further, since the opening angle is set to 30 degrees or less, it is possible to reliably prevent the fluid from peeling from the inner peripheral surface of the diffuser. Further, since the tip clearance of the moving blade closest to the diffuser is set to 1.0% or less of the flow path height of the working fluid at the position in the central axis direction of the moving blade, the leakage flow is increased. It can prevent that turbine efficiency falls. In addition, as described above, it is only necessary to adjust the opening angle and the tip clearance, so that it is possible to achieve both the pressure recovery of the fluid in the diffuser and the suppression of the occurrence of pressure loss due to the separation, with a minimum configuration. .

  In the turbine described above, the exhaust fluid flow path has a cross-section in the radial direction, has a cross-sectional blade shape, and has a maximum cross-sectional width from the inlet of the exhaust fluid flow path to the central axis. It is more preferable that the cross member is provided so as to be a position separated by 1.5 times or more of the flow path height of the inlet along the direction.

  According to this configuration, the transverse member is located at a position where the cross-sectional width is maximum, and is separated from the inlet of the exhaust fluid flow path by 1.5 times or more of the flow path height of the inlet along the central axis direction. By being provided in this way, the fluid that has flowed into the inlet of the exhaust fluid flow path flows through the side of the transverse member after being sufficiently decelerated. For this reason, the pressure loss which arises when a fluid branches by a crossing member and flows to the side can be suppressed.

  Further, in the turbine described above, a guide for guiding the fluid along the central axis direction on one side in the central axis direction with respect to the transverse member on the circumferential surface facing the exhaust fluid flow path of the diffuser. More preferably, means are provided.

  According to this configuration, the fluid that flows from the working fluid flow path of the turbine body into the exhaust fluid flow path of the diffuser with a circumferential velocity component is provided on one side of the central axis with respect to the transverse member. As a result, the air flows toward the cross member as a flow along the central axis. For this reason, it can suppress that the fluid which flows through an exhaust fluid flow path has a circumferential direction component, and collides with a crossing member, and can suppress a pressure loss to the minimum.

  Further, in the turbine described above, vortex generating means for locally generating a vortex in the fluid is provided on the other side in the central axis direction of the circumferential surface facing the discharge fluid flow path of the diffuser. More preferably, it is provided.

  According to this configuration, the vortex is locally generated by the vortex generating means in the fluid flowing through the side of the transverse member and flowing toward the other side in the central axis direction inside the discharge fluid flow path. For this reason, the fluid on the other side in the central axial direction than the cross member is suppressed from being peeled off from the inner peripheral surface of the diffuser by the vortex, and pressure loss caused by the peeling can be suppressed.

  According to the turbine of the present invention, it is possible to effectively recover the pressure of the fluid and discharge it while suppressing the pressure loss due to separation with a minimum configuration.

It is a half sectional view showing a schematic structure of a gas turbine of a 1st embodiment of the present invention. It is a principal part expanded sectional view of the gas turbine which concerns on embodiment of this invention, Comprising: The principal part I in FIG. 1 is shown. It is sectional drawing which shows the model of the gas turbine used for the analysis in Example 1 of this invention. It is a graph which shows the analysis result in Example 1 of this invention, and shows the relationship between a tip clearance / flow path height and turbine efficiency (stage efficiency). In Example 1 of this invention, the analysis result when the opening angle is 12 degrees is shown, and when the tip clearance is (a) 0.00%, (b) 0.15%, (c) 0.3% It is a stream diagram which shows the state of the flow in an exhaust gas flow path. In Example 1 of this invention, the analysis result when the opening angle is 20 degrees is shown, and when the tip clearance is (a) 0.00%, (b) 0.15%, (c) 0.3% It is a stream diagram which shows the state of the flow in an exhaust gas flow path. In Example 1 of this invention, the analysis result when the opening angle is 28 degrees is shown, and when the tip clearance is (a) 0.00%, (b) 0.15%, (c) 0.3% It is a stream diagram which shows the state of the flow in an exhaust gas flow path. It is a principal part expanded sectional view of the gas turbine which concerns on the 2nd Embodiment of this invention. It is a graph which shows the analysis result in Example 2 of this invention, and shows the relationship between a tip clearance / flow path height and turbine efficiency (stage efficiency). It is a principal part expanded sectional view of the gas turbine which concerns on the 3rd Embodiment of this invention. In the gas turbine which concerns on the modification of the 3rd Embodiment of this invention, it is detail drawing explaining the detail of a guide means. In the gas turbine which concerns on the modification of the 3rd Embodiment of this invention, it is detail drawing explaining the detail of a guide means. It is a principal part expanded sectional view of the gas turbine which concerns on the 4th Embodiment of this invention. In the gas turbine which concerns on the 4th Embodiment of this invention, it is detail drawing explaining the detail of a vortex generating means. It is a detailed view explaining the details of a vortex generating means in the gas turbine concerning the modification of the 4th embodiment of the present invention. FIG. 10 is a detailed diagram illustrating details of vortex generating means in a gas turbine according to another modification of the fourth embodiment of the present invention. It is sectional drawing which shows schematic structure of the gas turbine which concerns on the 5th Embodiment of this invention.

(First embodiment)
A first embodiment according to the present invention will be described below with reference to the drawings.
FIG. 1 is a half sectional view showing a schematic configuration of a gas turbine according to a first embodiment of the present invention.
As shown in FIG. 1, the gas turbine 1 burns by burning a rotor 2 that can rotate around a central axis S, a compressor 3 that generates compressed air A, and the compressed air A generated by the compressor 3. A combustor 4 that generates gas G, a turbine body 10 that rotationally drives the rotor 2 using the combustion gas G generated by the combustor 4 as a working fluid, and a diffuser 20 that discharges the combustion gas G are provided. The rotor 2 is inserted into the compressor 3 and the turbine body 10 and is supported by bearings 7 and 8 so as to be rotatable around the central axis S on both sides of the arrangement of the compressor 3 and the turbine body 10.

  The compressor 3 is composed of a substantially cylindrical compressor casing 3 a disposed on the outer periphery of the rotor 2, and a compressor stationary blade including a plurality of compressor stationary blades 3 b provided radially on the inner peripheral surface of the compressor casing 3 a. And a compressor blade row composed of a plurality of compressor blades 3 c provided radially on the outer periphery of the rotor 2. The compressor stationary blade row and the compressor rotor blade row are alternately provided in a plurality of rows along the central axis S direction, and a compressed air flow path 3d is formed so as to pass through these blade rows. The compressor stationary blade row and the compressor rotor blade row have a multistage structure with a pair (stage) adjacent to each other in the direction of the central axis S. The compressor 3 rotates the compressor blades 3c together with the rotor 2, thereby adiabatically compressing the air taken into the compressed air flow path 3d from the upstream side to the downstream side of the compressed air flow path 3d. A is generated. The combustor 4 is disposed between the compressor 3 and the turbine body 10, and generates combustion gas G by mixing the high-pressure compressed air A compressed by the compressor 3 and burning it. To the turbine body 10.

  The turbine body 10 includes a substantially cylindrical turbine casing 11 disposed on the outer periphery of the rotor 2, a turbine stationary blade row including a plurality of turbine stationary blades 12 provided radially on the inner peripheral surface of the turbine casing 11, and a rotor A plurality of turbine blades 13 provided on the outer periphery of the turbine blades 13. The turbine stationary blade row and the turbine rotor blade row are alternately provided in a plurality of rows along the central axis S direction, and a combustion gas flow path 14 is formed so as to pass through these blade rows. The turbine stationary blade row and the turbine rotor blade row have a multistage structure in which a pair (stage) adjacent to each other in the direction of the central axis S is formed. The turbine body 10 rotates the rotor 2 via the turbine rotor blade 13 by causing the combustion gas G generated by the combustor 4 to flow downstream along the central axis S, thereby expanding the combustion gas G. The thermal energy of G is converted into rotational energy of mechanical work. Here, as shown in FIG. 2, the tip clearance C, which is a gap between the tip 13a of the turbine blade 13 at the final stage and the inner peripheral surface 11a of the turbine casing 11, is set to a predetermined size. Specifically, the tip clearance C is a combustion gas flow path height H (hereinafter simply referred to as a combustion gas flow path height H) of the combustion gas flow path 14 at a position in the direction of the central axis S where the turbine rotor blade 13 is provided. ), In other words, 0.1% or more and 1.0% or less with respect to the separation distance between the outer peripheral surface 13c of the platform 13b provided at the base end of the turbine rotor blade 13 and the inner peripheral surface 11a of the turbine casing 11. Is set to a size. The tip clearance C varies depending on operating conditions, and the above range is defined as the tip clearance C during rated operation.

  Further, as shown in FIG. 1, the diffuser 20 has a substantially cylindrical shape connected to the turbine casing 11, and an exhaust gas flow for discharging the combustion gas G flowing from the combustion gas passage 14 into the inside as the exhaust gas G <b> 1. A path 21 is formed. Specifically, the diffuser 20 has a substantially cylindrical exhaust casing 22 connected to the turbine casing 11, and a substantially cylindrical casing disposed inside the exhaust casing 22, and a protective casing 23 that accommodates the bearing 8 and the like therein. A space having an annular cross section formed between the exhaust casing 22 and the protective casing 23 is configured as the exhaust gas passage 21. The exhaust casing 22 is formed so as to gradually expand in diameter from one S1 side in the central axis S direction on the inlet 21a side of the exhaust gas passage 21 toward the other S2 side on the outlet 21b side. On the other hand, the protective casing 23 is formed to have substantially the same outer diameter from one S1 side to the other S2 side in the central axis S direction. For this reason, the exhaust gas flow path 21 formed between the exhaust casing 22 and the protective casing 23 is formed so that the cross-sectional area is enlarged by gradually increasing the flow path height from the inlet 21a toward the outlet 21b. ing.

  Here, as shown in FIG. 2, the exhaust casing 22 of the diffuser 20 is set to expand at a predetermined opening angle θ from the inlet 21 a to the outlet 21 b side of the exhaust gas passage 21. . In the present invention, the opening angle θ is the same as that of the inner circumferential surface 22a of the exhaust casing 22, and the inlet 21a of the exhaust gas passage 21 and the inlet 21a along the central axis S from the inlet 21a to the other S2 side. Is defined as an angle formed by a line L connecting a position 21b different by 1.5 times the inlet flow path height B and the central axis S. In the present embodiment, the opening angle θ is set to 15 degrees or more and 30 degrees or less.

  A bearing support member 25 is provided between the exhaust casing 22 and the protective casing 23 as a transverse member provided so as to traverse the exhaust gas passage 21 in the radial direction. The bearing support member 25 has an outer peripheral end supported by the inner peripheral surface 22a of the exhaust casing 22 and an inner peripheral end to which the bearings 7 and 8 are attached. As a result, the rotor 2 includes the bearings 7 and 8 and the bearing support member. 25 and the exhaust casing 22 are supported from the outside of the diffuser 20. Here, the bearing support member 25 constituting the transverse member has a cross-sectional wing shape (streamline shape), that is, the cross-sectional width gradually increases from the one S1 side to the other S2 side of the central axis S, and the maximum width. After that, the cross-sectional width is gradually reduced. Here, the position of such a cross member is a position where the cross-sectional width is maximum, and the inlet passage height B is 1.5 to the other side S2 from the inlet 21a of the exhaust gas passage 21 along the central axis S. It is desirable to set it at a position more than double. Further, a manhole 26 is provided on the other side S <b> 2 in the central axis S direction from the bearing support member 25. The manhole 26 is substantially cylindrical and has an outer peripheral end connected to the exhaust casing 22 and opened to the outside, and an inner peripheral end connected to the protective casing 23 and opened to the inside. For this reason, it is possible to access the bearings 7, 8 and the like inside the protective casing 23 from the outside of the diffuser 20 through the manhole 26.

Next, the operation of the gas turbine 1 of this embodiment will be described.
As shown in FIG. 1 and FIG. 2, in the gas turbine 1 of this embodiment, the combustion gas G that circulates through the combustion gas passage 14 and rotationally drives the rotor 2 is discharged to the exhaust gas passage 21 of the diffuser 20. It flows in as gas G1. The exhaust gas G1 gradually decelerates and recovers its pressure as the cross-sectional area of the exhaust gas passage 21 gradually increases. Here, by setting the opening angle θ to 15 degrees or more, the cross-sectional area of the exhaust gas passage 21 is actively expanded from the one S1 side to the other S2 side in the central axis S direction, thereby the exhaust gas G1. Can be effectively decelerated and pressure recovery can be achieved.

  On the other hand, a part of the combustion gas G flowing through the combustion gas passage 14 flows into the exhaust gas passage 21 as a leakage flow Ga from the tip clearance C of the turbine blade 13 at the final stage, and the inner periphery of the exhaust casing 22. It will flow along the surface 22a. Here, by setting the tip clearance C to 0.1% or more of the combustion gas flow path height H, the flow rate of the leakage flow Ga from the tip clearance C of the turbine blade 13 at the final stage increases, and the leakage flow Ga Is positively supplied to the diffuser 20 side. Thereby, in the vicinity of the inner peripheral surface 22a of the exhaust casing 22 of the diffuser 20, the total pressure inside the boundary layer can be increased. For this reason, as described above, even when the exhaust casing 22 of the diffuser 20 is enlarged in diameter by a larger opening angle θ than in the conventional case, the cross-sectional area is increased, the positively along the inner peripheral surface 22a of the exhaust casing 22 By introducing the leakage flow Ga, it is possible to suppress the exfoliation of the exhaust gas G1 from the inner peripheral surface 22a of the exhaust casing 22 and to suppress the generation of pressure loss due to the exfoliation. On the other hand, by setting the opening angle θ to 30 degrees or less, it is possible to reliably prevent the exhaust gas G1 from being separated from the inner peripheral surface 22a of the exhaust casing 22 of the diffuser 20, and the turbine operation at the final stage. Since the tip clearance C of the blade 13 is set to 1.0% or less, the flow rate of the leakage flow Ga is excessively increased, the flow rate of the main flow contributing to the output is reduced, and the turbine efficiency (stage efficiency) is lowered. Can be prevented.

Next, examples of the gas turbine 1 of this embodiment will be described.
In the present embodiment, in the model as shown in FIG. 3, the turbine efficiency (in each of the plurality of embodiments in which the tip clearance C and the opening angle θ are changed within the above range and the plurality of comparative examples outside the above range are respectively shown. Stage efficiency) was determined by CFD analysis. Specifically, as shown in FIG. 3, in this model, the bearing support member 25 is moved from the inlet 21a of the exhaust gas passage 21 to the other S2 side along the central axis S at a position where the cross-sectional width is maximum. The position is set to be 1.5 times the inlet flow path height B. Further, the position is a position of 0.2L, where L is the distance from the starting point to the outlet 21b of the exhaust gas passage 21 with the trailing edge tip 12a of the turbine stationary blade 12 at the final stage as the starting point. ing. The tip clearance C is 0.00% (comparative example), 0.15% (example), 0.3% (example), 0.45% (example) with respect to the combustion gas flow path height H. ). Further, the opening angle θ was set to 12 degrees (comparative example), 20 degrees (example), and 28 degrees (example). The inner peripheral surface 22a of the exhaust casing 22 is an intermediate position that becomes 0.08L from the inlet 21a of the exhaust gas passage 21 to a position (0.2L) that is 1.5 times the inlet passage height B. It is set to be bent and consist of two surfaces.

  FIG. 4 shows the result of obtaining the turbine efficiency (stage efficiency) in each example and comparative example, the horizontal axis is the tip clearance C / combustion gas flow path height H (%), and the vertical axis is the turbine efficiency (stage efficiency) ( %). 5, 6, and 7 show streamlines based on the analysis results when the opening angle θ is 12 degrees, 20 degrees, and 28 degrees in order, and (a), (b), (C) shows a state in which the tip clearance C is 0.00%, 0.15%, and 0.30% in order. As shown in FIG. 4, when the opening angle θ is 20 degrees and 28 degrees, a high turbine efficiency (stage efficiency) can be obtained when the tip clearance C is 0.1% or more. This is because it is possible to effectively recover the pressure of the exhaust gas G1 by setting the opening angle θ to 20 degrees or 28 degrees, and by actively introducing the leakage flow Ga, the inner circumferential surface 22a of the exhaust casing 22 This is because exfoliation of the exhaust gas G1 is suppressed and pressure loss due to exfoliation can be suppressed. In the streamline diagrams shown in FIGS. 6 (b), 6 (c), 7 (b), and 7 (c), the separation E is not recognized, or even if it is recognized, it is clear. . On the other hand, when the opening angle θ is 20 degrees and 28 degrees, the turbine efficiency (stage efficiency) is lower when the tip clearance C is 0% than when the tip clearance C is 0.15%. Recognize. As shown in FIGS. 6A and 7A, the leakage flow Ga from the chip clearance C is not supplied, so that the exhaust gas G1 is peeled along the inner peripheral surface 22a of the exhaust casing 22. This is due to the fact that pressure loss has occurred.

  Further, when the opening angle θ is 12 degrees, as shown in FIGS. 5A to 5C, even though the tip clearance C is 0.00%, the peeling occurs only slightly. As shown, the turbine efficiencies (stage efficiencies) all showed only low values compared to the cases where the opening angle θ was 20 degrees and 28 degrees. This is because the pressure recovery of the exhaust gas G1 is not sufficiently achieved in the diffuser 20 because the opening angle θ is small.

  As described above, in the gas turbine 1 of the present embodiment, the pressure loss of the exhaust gas G1 in the diffuser 20 and the pressure loss due to the separation are achieved with a minimum configuration that only adjusts the opening angle θ and the tip clearance C to the above ranges. Therefore, it is possible to improve the turbine efficiency (stage efficiency). The bearing support member 25, which is a transverse member, is provided at a position where the cross-sectional width is the maximum, at a position separated from the inlet 21a of the exhaust gas passage 21 by 1.5 times or more of the inlet passage height B. As a result, the exhaust gas G1 flowing into the inlet 21a of the exhaust gas passage 21 flows through the bearing support member 25 and the manhole 26 after being sufficiently decelerated. For this reason, it is possible to minimize the pressure loss that occurs when the exhaust gas G1 branches off at the bearing support member 25 and the manhole 26 and flows to the side, thereby further improving the turbine efficiency (stage efficiency).

(Second Embodiment)
Next, a second embodiment of the present invention will be described. 8 and 9 show a second embodiment of the present invention. In this embodiment, the same members as those used in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIG. 8, in the gas turbine 30 of this embodiment, the turbine rotor blade 31 differs from the turbine rotor blade 13 of the gas turbine 1 of the first embodiment shown in FIG. The shroud 32 is provided so as to overhang. Here, a concave portion 11b is formed in an annular shape at a position in the direction of the central axis S where the turbine rotor blade 31 is provided on the inner peripheral surface 11a of the turbine casing 11, and the shroud 32 has a predetermined side on the concave portion 11b. It is accommodated with clearance and tip clearance C. Further, the shroud 32 is disposed so that the inner peripheral surface 32a is substantially on the same curved surface as the inner peripheral surface 11a of the turbine casing 11, and in this embodiment, the combustion gas flow path height H is the outer periphery of the platform 31b. It is defined by the distance between the surface and the inner peripheral surface 32a of the shroud 32.
Moreover, the fin 33 which protrudes toward the outer peripheral surface 32b of the shroud 32 toward the internal peripheral surface of the recessed part 11b which opposes is provided. In the present embodiment, similarly, the tip clearance C is 0.1% or more and 1.0 with respect to the combustion gas flow path height H at the position in the direction of the central axis S where the turbine rotor blade 31 is provided. The size is set to be less than%. Further, the opening angle θ of the exhaust casing 22 of the diffuser 20 is set to 15 degrees or more and 30 degrees or less.

  Except for the above configuration, CFD analysis was performed in the same manner as in Example 1 using the same model as in FIG. In this example, the turbine efficiency (stage efficiency) was obtained by changing the tip clearance C at each of the plurality of opening angles θ as follows. That is, at an opening angle of 10 degrees, the tip clearance C is 0.00% (comparative example), 0.09% (comparative example), and 0.72% (comparative example) with respect to the combustion gas flow path height H. Set. Further, at an opening angle of 12 degrees, the tip clearance C was set to 0.09% (comparative example) and 0.69% (comparative example) with respect to the combustion gas flow path height H. Further, at an opening angle of 16 degrees, the tip clearance C was set to 0.09% (comparative example) and 0.68% (example) with respect to the combustion gas flow path height H. Further, at an opening angle of 20 degrees, the tip clearance C is 0.09% (comparative example), 0.22% (example), 0.43% (example) with respect to the combustion gas flow path height H, It was set to 0.67% (Example). Further, at the opening angle of 24 degrees, the tip clearance C was set to 0.09% (comparative example) and 0.66% (example) with respect to the combustion gas flow path height H.

  FIG. 9 shows the relationship between the tip clearance C / combustion gas flow path height H (%) and turbine efficiency (stage efficiency) (%) based on the analysis result. Similarly, in this embodiment, when the opening angle θ is 15 degrees or more and 30 degrees or less and the tip clearance C is 0.1% or more and 1.00% or less with respect to the combustion gas flow path height H, high efficiency is shown. . Similarly, in the turbine rotor blade 31 having the shroud 32, the tip clearance C is in the above range, so that the exhaust gas G1 is effectively separated from the inner peripheral surface 22a of the exhaust casing 22 of the diffuser 20 by the leakage flow Ga. This is because it can be suppressed.

(Third embodiment)
Next, a third embodiment of the present invention will be described. 10 and 11 show a third embodiment of the present invention. In this embodiment, the same members as those used in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 10, in the gas turbine 40 of this embodiment, the diffuser 20 is on the inner peripheral surface 22a of the exhaust casing 22, and on the one side S1 side in the central axis S direction that is upstream from the bearing support member 25 that is a transverse member. Further, guide means 41 for guiding the exhaust gas G1 along the direction of the central axis S is provided. As shown in FIG. 11, the guide means 41 is specifically an airfoil member having a blade shape in cross section, and the center line of the cross section of the exhaust gas passage 21 is located on the upstream side in the central axis S direction on the one side S1. Along the inflow direction of the exhaust gas G1 flowing into the inlet 21a with a circumferential velocity component, the curve is formed on a curve along the central axis S gradually toward the other S2 side in the central axis S direction. Yes. A plurality of airfoil members are arranged at intervals in the circumferential direction. For this reason, the exhaust gas G1 flowing in from the exhaust gas passage inlet 21a is a flow along the central axis S direction by the airfoil member in the vicinity of the inner peripheral surface 22a of the exhaust casing 22 (outer peripheral portion in the exhaust gas passage 21). After being guided in such a way, it flows on the side of the bearing support member 25. For this reason, the exhaust gas G1 flowing through the exhaust gas passage 21 is prevented from colliding with the bearing support member 25, which is a transverse member, having a circumferential component, minimizing pressure loss and turbine efficiency (stage). (Efficiency) can be further improved.

  In the above, the specific position of the guide means 41 is about 20% or more of the length of the bearing support member 25 in the direction of the central axis S relative to the front edge of the target bearing support member 25, and the central axis. It is preferable that they are separated on one side in the S direction. Further, the height (the length in the radial direction) of the guide means 41 is preferably 5% or more of the blade height of the turbine rotor blade 13. The length of the airfoil member constituting the guide means 41 in the central axis S direction is preferably 1 to 3 times the height protruding from the inner peripheral surface 22a. Further, the interval between the airfoil members is more preferably 0.5 to 1.5 times the length in the central axis S direction. In the present embodiment, the guide means 41 is provided on the inner peripheral surface of the exhaust casing 22, but may be provided on the outer peripheral surface of the protective casing 23, and may be provided on both surfaces. good.

  In the above description, the bearing support member 25 that is a transverse member and the airfoil member that is the guide means 41 are configured as separate members. However, the present invention is not limited to this, and the bearing support member 25 and The guide means may be integrally formed. That is, as shown in FIG. 12, the bearing support member 25 gradually flows into the inlet 21a of the exhaust gas passage 21 as the edge 25a on the one S1 side in the central axis S direction goes toward the one S1 side in the central axis S direction. It is provided so as to be inclined along the central axis S so as to follow the flow of the exhaust gas G1 to be guided, and the edge portion 25a constitutes the guide means 42. By doing so, the exhaust gas G1 flows through the side of the main body portion 25b of the bearing support member 25 after being guided along the central axis S direction by the edge portion 25a constituting the guide means 42. Have the same effect.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. 13 and 14 show a fourth embodiment of the present invention. In this embodiment, the same members as those used in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 13, in the gas turbine 50 of this embodiment, the diffuser 20 is the inner peripheral surface 22a of the exhaust casing 22, and the other side S2 side in the central axis S direction that is downstream from the bearing support member 25 that is a transverse member. In addition, a vortex generating means 51 for locally generating a vortex in the exhaust gas G1 is provided. FIG. 14 is a plan view in which a part of the inner peripheral surface 22a of the exhaust casing 22 is viewed in the radial direction from the inner peripheral side toward the outer peripheral side. As shown in FIGS. 13 and 14, the vortex generating means 51 is specifically a protrusion protruding from the inner peripheral surface 22a, and is formed in an elongated shape inclined from the central axis S as viewed in the radial direction. . In the present embodiment, the cross-sectional contour has a linear shape on one side and an arc shape on the other side. And the protrusion which comprises such a vortex generating means 51 is arrange | positioned in the circumferential direction at equal intervals, the same direction, and the inclination with respect to the central axis S with the same inclination angle.

  In the gas turbine 50 of the present embodiment, the exhaust gas G1 flowing through the exhaust gas passage 21 of the diffuser 20 flows from the side of the bearing support member 25 toward the center axis S and the other side S2, and then the inner periphery of the exhaust casing 22 Of the flow along the surface 22a, the vortex G2 is formed for the flow that the projection that becomes the vortex generating means 51 collides with. Here, as described above, since the protrusions are arranged at equal intervals in the circumferential direction, in the same direction, and inclined at the same inclination angle with respect to the central axis S, in the vicinity of the inner peripheral surface of the exhaust casing 22. Thus, the vortex G2 flowing in the same direction at substantially the same interval is formed, and the vortex G2 can prevent the exhaust gas G1 flowing in the vicinity of the inner peripheral surface of the exhaust casing 22 from being separated from the inner peripheral surface. Further, it is possible to further improve the turbine efficiency (stage efficiency) by suppressing the pressure loss caused by the separation.

  The position where the vortex generating means 51 is provided is preferably set in association with a position where separation can occur on the other side in the central axis S direction of the bearing support member 25 which is a transverse member. Specifically, it is preferable to perform a CFD analysis to calculate a friction coefficient Cf on the inner peripheral surface 22a, and set the Cf to a position where it is 0.002 or less. In addition, the height of the protrusion that is the vortex generating means 51 is preferably set to about 0.5 to 1.5 times the thickness of the boundary layer by obtaining the thickness of the boundary layer of the exhaust gas G1 by CFD analysis. . Further, the length of the projection in the direction of the central axis S is preferably 1 to 3 times the height, and the distance between the projections is preferably 0.5 to 3 times the length.

  Further, the vortex generating means 51 is not limited to the inner peripheral surface of the exhaust casing 22, but may be provided on the outer peripheral surface of the protective casing 23, or may be provided on both surfaces. Further, the protrusions constituting the vortex generating means 51 are not limited to the above. FIG. 15 shows a modification of the vortex generating means 51, and is a plan view in which a part of the inner peripheral surface 22a of the exhaust casing 22 is viewed in the radial direction from the inner peripheral side toward the outer peripheral side as in FIG. That is, for example, as shown in FIG. 15, two protrusions constituting the vortex generating means 51 may be paired and arranged so as to be inclined so as to face each other with the central axis S as a symmetry line. By doing in this way, the vortex G2 from which direction differs is formed alternately, and this can suppress peeling effectively.

  Further, the shape of the protrusion is not limited to the shape shown in FIGS. As shown in FIG. 16, various shapes can be selected. For example, the vortex generating means 52 in FIG. 16A includes a main body portion 52a that has a cross-sectional wing shape when viewed in the circumferential direction and a support column 52b that supports the main body portion 52a apart from the peripheral surface. Yes. Further, like the vortex generating means 53 shown in FIG. 16B, a triangular pyramid is formed so that the flow colliding from the upstream side branches off toward the downstream side, as shown in FIG. 16C. Like the vortex generating means 54, a slope 54a is formed, which is similarly triangular pyramid and is guided so that the flow colliding from the upstream side is separated from the peripheral surface toward the downstream side, and the flow flowing in the lateral direction It is good also as what is formed so that may join downstream. Further, like the vortex generating means 55 shown in FIG. 16 (e), the triangular plate may be formed so as to gradually protrude from the peripheral surface toward the downstream side which is the upstream side. Further, like the vortex generating means 56, 57, and 58 shown in FIGS. 16D, 16F, and 16G, the flow separated from the peripheral surface is the peripheral surface. May be formed such that the flow along the circumferential surface is guided laterally below the inclined surfaces 56a, 57a, 58a.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. FIG. 17 shows a fifth embodiment of the present invention. In this embodiment, the same members as those used in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 17, in the gas turbine 60 of this embodiment, a rotor 61, a turbine casing 63 provided on the outer peripheral side of the rotor 61, and a turbine runner 64 attached to the rotor 61 inside the turbine casing 63 And a substantially cylindrical diffuser 65 connected to the turbine casing 63 in a direction along the central axis S of the rotor 61.

  The turbine casing 63 is formed with a first flow path 63a that is annular and communicates with the radially outer peripheral side and the inner peripheral side, and forms a part of the combustion gas flow path. The first flow path 63a has a radial shape. Turbine stationary blades 66 are provided. A suction casing 67 is provided on the outer peripheral side of the turbine casing 63, and a suction flow path 67 a in the suction casing 67 communicates with an outer peripheral side of the first flow path 63 a, and the first flow path 63 a has a radial direction. It is possible to supply the combustion gas G as a working fluid from the outer peripheral side toward the inner peripheral side.

  The turbine runner 64 includes a disk 70 attached to the rotor 61 and a turbine rotor blade 71 attached to the disk 70. The outer peripheral surface 70a to which the turbine rotor blade 71 of the disk 70 is attached runs along the radial direction on the outer peripheral side, and gradually goes from one S1 side to the other S2 side in the central axis S direction as it goes from the outer peripheral side to the inner peripheral side. The inner peripheral surface 63b of the turbine casing 63 that faces the disk 70 also has a corresponding curved shape.

  The turbine rotor blade 71 has an inner peripheral surface 63b of the turbine casing 63 and a predetermined tip clearance C. The space formed between the disk 70 and the turbine casing 63 and in which the turbine rotor blades 71 are disposed is the first flow path on the outer peripheral side as the second flow path 64a that constitutes the combustion gas flow path together with the first flow path 63a. The combustible gas G communicates with 63a in the radial direction and flows in from the outer peripheral side toward the inner peripheral side, and the combustion gas G is guided along the central axis S direction toward the other S2 side in the central axis S direction. Exhaust as exhaust gas G1. The diffuser 65 communicates with the second flow path 64a with the inside as an exhaust gas flow path 65a, and discharges the exhaust gas G1 discharged from the second flow path 64a from one side S1 to the other side S2 in the central axis S direction. Let it drain.

  And also in the radial flow gas turbine like the gas turbine 60 of the present embodiment, the opening angle θ increases from 15 degrees to 30 degrees from the inlet 65b of the exhaust gas passage 65a toward the outlet 65c. Is set to The definition of the opening angle θ is the same as in the first embodiment, and the inlet 65b of the exhaust gas passage 65a and the inlet passage of the inlet 65b from the inlet 65b to the other S2 side along the central axis S. It is defined as an angle formed by a line connecting a position different by 1.5 times the height B and the central axis S. The tip clearance C is also 0.1% or more with respect to the combustion gas flow path height H of the second flow path 64a of the combustion gas flow path at the position of the trailing edge of the turbine rotor blade 71 as in the first embodiment. The size is set to 1.0% or less.

  The configuration of the gas turbine 60 of the present embodiment has been described above. In the radial flow gas turbine as in the present embodiment, the first implementation is performed by setting the opening angle θ and the tip clearance C as described above. There is an effect similar to the form. Further, as in the second and third embodiments, a cross member may be provided in the exhaust gas flow path 65a, and a guide means and a vortex generating means may be provided.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  In each of the above-described embodiments, the bearing support member 25 has been described as a transverse member, but the manhole 26 may be similarly applied with a guide means or a vortex generating means as a transverse member.

1, 30, 40, 50, 60 Gas turbine (turbine)
2, 61 Rotor 10 Turbine body 11, 63 Turbine casing (casing)
12, 66 Turbine stationary blade (static blade)
13, 31, 71 Turbine blade (roof blade)
14, 63a, 64a Combustion gas flow path (working fluid flow path)
20, 65 Diffuser 21, 65a Exhaust fluid flow path 41, 42 Guide means 51, 52, 53, 53, 56, 57 Vortex generating means C Tip clearance S Central axis θ Open angle

Claims (4)

A rotor rotatable around a central axis;
A casing that is substantially cylindrical disposed on the outer periphery of the rotor and that forms a working fluid flow path through which fluid flows from one side to the other side in the central axis direction, and a plurality of casings provided on the inner peripheral surface of the casing And a turbine body having a plurality of moving blades provided on the other side in the central axis direction of the stationary blades;
A diffuser that is connected to the casing of the turbine main body and is formed in a substantially cylindrical shape so as to gradually increase in diameter from one side to the other side in the central axis direction, and forms a discharge fluid passage that discharges the fluid inside. And
The diffuser is arranged at the same position in the circumferential direction on the inner peripheral surface, and the inlet of the exhaust fluid passage and the inlet height of the inlet from the inlet of the exhaust fluid passage to the other side along the central axis is 1.5. The opening angle formed by the line connecting the positions different from each other and the central axis is set to 15 degrees or more and 30 degrees or less,
Among the moving blades, the one closest to the diffuser has a tip clearance formed between the inner peripheral surface of the casing and 0.1% or more of the flow path height of the working fluid at the position of the moving blade. A turbine characterized by being set to 1.0% or less. The turbine according to claim 1,
The discharge fluid flow path has a cross-section in the radial direction and has a cross-sectional wing shape, and the position where the cross-sectional width is maximum is from the inlet of the discharge fluid flow path along the central axis direction of the inlet. A turbine characterized in that a transverse member is provided so as to be at a position separated by 1.5 times or more of the flow path height. The turbine according to claim 2,
Guiding means for guiding the fluid along the central axis direction is provided on the circumferential surface facing the exhaust fluid flow path of the diffuser on one side in the central axis direction with respect to the transverse member. Turbine characterized by The turbine according to claim 2 or claim 3,
Vortex generating means for locally generating a vortex in the fluid is provided on the other side in the central axis direction of the peripheral surface of the diffuser facing the exhaust fluid flow path with respect to the transverse member. Turbine.

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