JP2006002609A - Blade row structure for turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blade row structure for a turbine establishing a technique for cooling a blade row to cope with future temperature increase. <P>SOLUTION: In a moving blade row ring (2), a plurality of platforms (6) arranged abreast in the circumferential direction and moving blades (4) each of which is fixed to each of the plurality of the platforms (6) are formed. In upstream portions of the platforms (6), flow deflection portions (11) are formed to increase a proportion of inflow of cooling air (25), which flows out of a gap (9) between a stationary blade row ring (1) and the moving blade row ring (2) in the centrifugal direction, into the rotational direction rear sides (8) of the moving blades (4). The flow deflection portions (11) are swelled in the centrifugal direction from reference faces (12) of the platforms (6). The cooling air (25) receives resistance from the flow deflection portions (11), lowers its speed, and relatively retreats to the rotational direction with respect to the moving blades (4). As a result, the proportion of inflow of the cooling air (25) into the rotational direction rear sides (8) of the moving blades (4) is increased. This increase makes pressure distribution of the cooling air (25) more appropriate, and suppresses deterioration caused by thermal change of surfaces of the platforms (6). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a turbine cascade structure, and more particularly, to a turbine cascade structure that forms a cooling air flow.

  In response to a demand for an increase in the amount of electric power demand, there is a demand for higher temperatures in gas turbines. The high temperature of the combustion gas may deteriorate the support structure ring such as a shroud that supports the rotor blades and the stationary blades of the turbine and shorten the life thereof. The turbine structure includes a plurality of stator blade rings, a stator blade side support ring that supports the stator blade ring, a rotor blade ring that is sandwiched between the stator blade rings in the rotation axis direction, and the blade array ring. Is formed from a rotor blade side support ring (which is integrated with the hub) and other structures.

  A gap is necessarily provided between the rotating blade row ring that rotates and the stationary blade row ring that is fixed. It is known that the high-temperature gas flow that enters from the gap deteriorates the portion of the support structure that exists radially inward from the rotor blade ring. In order to prevent such deterioration, as known from Patent Document 1, a sealing mechanism such as a labyrinth seal is arranged to prevent intrusion of a high-temperature gas flow toward the inside.

  In the future, it is necessary to further increase the temperature of gas turbines. In the high-temperature gas turbine anticipated in the future, it is considered that prior measures against quality deterioration of the moving blades or stationary blades subjected to dynamic high-temperature thermal stress are necessary. The technology for cooling the cascade ring is not known.

  It is required to establish blade cascade cooling technology to cope with future high temperatures.

JP-A-11-6446

  SUMMARY OF THE INVENTION An object of the present invention is to provide a turbine cascade structure that establishes cascade cooling technology to cope with future high temperatures.

  A turbine cascade structure according to the present invention includes a stationary blade cascade ring (1) and a moving blade cascade ring (2) disposed opposite to the stationary blade cascade ring (1) and downstream of the stationary blade cascade ring (1). And other components. The moving blade row ring (2) is formed of a plurality of platforms (6) arranged side by side in the circumferential direction and a moving blade (4) fixed to each of the plurality of platforms (6). The upstream portion of the platform (6) has cooling air (25) flowing out in the centrifugal direction from the gap (9) between the stationary blade row ring (1) and the moving blade row ring (2). A flow deflection portion (11) is formed to increase the ratio of flowing into the rear side (8) in the rotation direction. The flow deflection part (11) swells in the centrifugal direction from the reference plane (12) of the platform (6).

  The cooling air (25) receives a resistance from the flow deflection portion and decreases its speed, retreats relative to the rotor blade (4) in the rotational direction, and moves backward (8) in the rotational direction of the rotor blade (4). The rate of flowing into the water increases. Such an increase optimizes the pressure distribution of the cooling air and suppresses deterioration due to thermal changes on the surface of the platform. It is more effective to provide another flow deflection part (26) in the downstream part of the platform (6). The other flow deflection part (26) swells in the centrifugal direction from the reference plane (12) of the platform (6). The flow of cooling air is deflected symmetrically, the flow is remote, and its cooling performance is made uniform from upstream to downstream.

  A turbine cascade structure according to the present invention includes a stationary blade cascade ring (1) and a moving blade cascade ring (2) disposed opposite to the stationary blade cascade ring (1) and downstream of the stationary blade cascade ring (1). It consists of and. The rotor blade ring (2) is formed of a plurality of platforms (6) arranged side by side in the circumferential direction, and a rotor blade (4) fixed to each of the plurality of platforms (6). The upstream portion of the platform (6) has cooling air (25) flowing out in the centrifugal direction from the gap (9) between the stationary blade row ring (1) and the moving blade row ring (2). A flow deflection portion is formed to increase the rate of flow to the rear side in the rotation direction. The flow deflection portion is formed as a curved portion (28) that smoothly guides the flow of the cooling air to the downstream side. Of the curved surface part (28), the curvature of the rear part in the rotation direction is larger than the curvature of the front part in the rotation direction of the curved part (28).

  As described above, the pressure distribution of the cooling air is optimized by the resistance of the cooling air. As described above, the flow is symmetrically smoothed by providing such a curved surface portion (31) on the downstream side.

  In the turbine cascade structure according to the present invention, the width of the gap (9 ″) corresponding to the rear portion in the rotational direction among the flow deflection portions is larger than the width of the gap (9 ′) corresponding to the front portion in the rotational direction among the flow deflection portions. It is effective that such a clearance relationship is provided on the downstream side, and the effects described above remain unchanged.

  The turbine cascade structure according to the present invention adds a cooling effect by adjusting the pressure distribution of the cooling air flow to a known sealing effect. In particular, the cooling effect has cooling uniformity.

The best mode of implementation of the turbine cascade structure according to the present invention will be described in detail with reference to the drawings. As shown in a developed view in FIG. 1, the stationary blade row ring 1 faces the moving blade row ring 2 in the rotation axis direction A. A large number of stationary blade blades (not shown) of the stationary blade row ring 1 are fitted or planted in the stationary blade side base ring 3. A large number of blades 4 of the blade row ring 2 are fitted or planted with respect to the blade-side base ring 5. More specifically, the multiple blade blades 4 are fitted into multiple platforms 6 fitted into the blade-side base ring 5 respectively. A large number of stationary blade blades and a large number of moving blade blades 4 are arranged side by side in the circumferential direction (rotation direction) B, respectively. The rotating blade front surface 7 in the rotational direction is swollen in the rotational direction with respect to the rotational surface rear surface 8 of the rotating blade blade 4, and the moving blade blade 4 exerts rotational force in the rotational direction B (lift in aerodynamics). receive. The rotation direction front surface 7 and the rotation direction rear surface 8 are formed as curved surfaces that are twisted three-dimensionally. An annular plate-like gap 9 is provided between the stationary blade side base ring 3 and the moving blade side base ring 5, and the gap extends in the centrifugal direction between the stationary blade side base ring 3 and the platform 6.

  The upstream edge region of the platform 6 forms a bulge 11 that bulges radially outward (in the centrifugal direction). The bulge 11 is integral with the platform 6 and is formed integrally with the platform 6 when a single metal is cut out or electrolytically processed. As shown in FIG. 2, the bulge 11 swells in the centrifugal direction from the reference surface 12 of the platform 6. The bulge shape curve 13 of the bulge 11 shown in FIG. 2 is shown as a line following the maximum distance in the centrifugal direction of the bulge 11 with respect to the reference plane 12. The rotational direction position of the bulge shape line 13 corresponding to the maximum value of the bulge shape line 13 is defined as a bulge peak point 14 or a bulge peak region 14.

  The mixed flow vector 15 of the high-temperature gas flow directed by the stationary blade row ring 1 has a direction and a flow velocity that are fixed with respect to the moving blade having a specified rotational speed. The mixed flow vector 15 is represented relative to the blade blade 4 rotating at the rated operation speed. The mixed flow vector 15 is defined by design in order to improve the turbine efficiency corresponding to the shape and rotational speed of the blade 4 and the mixed flow angle mainly corresponds to the blade surface shape of the stationary blade. .

  The bulge shape line 13 is asymmetric with respect to a plane that passes through the bulge peak region 14 and includes the rotation axis. The bulge peak region 14 is a base surface shape that is a shape of a base surface (coincidence with the reference surface 12) of the rotor blade blade 4 in a plane parallel to the mixed flow vector 15 and orthogonal to the reference surface (reference rotation surface) 12. It is positioned on the rear side in the rotational direction with respect to the center plane 18 which is equidistant from the two tangent planes 16 and 17 circumscribing (shaded shape in FIG. 1). The bulge shape line 13 is preferably smooth, and can be locally formed in the rotational direction as shown in FIG.

  The high-pressure cooling air flows from the gap 9 into the hot gas flow path. In the known technology, air supplied from the inside to the gap 9 is used so that a high-temperature gas flow does not leak inside the gap 9 (inward in the radial direction) and deteriorate the internal structural members. Therefore, known air is used as sealing air, and its pressure is increased to a level that can effectively prevent high temperature gas from leaking. The cooling air according to the present invention has a function of sealing air, but additionally has a cooling function that overflows the high-temperature gas flow path and cools the surface portion of the platform 6 and the base portion of the blade blade 4. .

  FIG. 4 shows the difference in flow between the cooling air of the present invention supplied from the gap 9 and the known sealing air. The sealing air flow 22 flowing out in the centrifugal direction from a certain blowing point 21 belonging to the gap 9 is sucked into the low-pressure side high-temperature gas flow 23 that is guided by the high-temperature gas flows 23 and 24 and circulates forward in the rotational direction because there is no bulge 11. However, the cooling air flow 25 of the cooling air flowing out from the same blowing point 21 in the centrifugal direction is subjected to resistance from the bulge 11 and the speed is reduced, and the flow direction is relatively shifted to the side retreating from the platform 6, and the rear in the rotation direction. Sucked into the high-pressure side hot gas stream 24 wrapping around. Thus, since the cooling air flow of the present invention receives resistance from the bulge 11, there is a strong tendency to change the flow direction to the rear side in the rotation direction, and the deviation of the flow of the cooling air flow is corrected, and the platform 6 and the rotor blade are corrected. The cooling of the base part of the blade 4 can be made uniform. The cooling air flow forms a thin laminar flow on the surface of the platform 6 and most of the hot gas flow is unaffected by the low bulge 11 so that there is no substantial degradation in turbine efficiency. The platform 6 is uniformly cooled, the distortion of the platform 6 is small, and the bending of the blade blade 4 due to the distortion of the platform 6 is suppressed. It is meaningful to adjust the position of the bulge 11 in accordance with the temperature distribution of the platform 6. Corresponding to the distribution, it is meaningful to form a plurality of bulge peak regions 14 instead of a single one.

  In order to adjust the pressure distribution of the cooling air flow, it is meaningful to form a downstream bulge 26 on the platform 6 downstream as shown in FIG. The downstream bulge peak region 27 of the downstream bulge 26 exists on the front side in the rotational direction from the center plane 18. The bulge peak region 14 and the downstream bulge peak region 27 are arranged on the opposite side with respect to the center plane 18.

  FIG. 5 shows another preferred platform shape for the implementation of a turbine cascade structure according to the present invention. In the above-described form, the bulge is given in the centrifugal direction on the upstream side of the platform. In this form, the reverse bulge 28 is given in the centrifugal direction on the upstream side of the platform. The reverse bulge actually means that the upstream side of the rectangular body and the centrifugal direction side (called the upstream centrifugal direction side portion) of the rectangular body are scraped off, and so-called chamfering processing is performed. . In particular, the curved surface on the upstream centrifugal direction side portion of the platform 6 has a large curvature on the rear side in the rotational direction (reciprocal of the radius of curvature) and a small curvature on the rear side in the rotational direction. Here, the curvature is an average of local curvatures, and the bending method includes an elliptical arc and other curves instead of an arc. The cooling air that overflows at the point 21 shown in FIG. 4 flows toward the front surface 7 in the rotational direction as represented by the one-dot chain line when the reverse bulge 28 is not applied, but the reverse bulge 28 Is provided as a cooling air flow 29 equivalent to the cooling air flow 25 of FIG. It is meaningful to provide the downstream reverse bulge 31 on the downstream side of the platform 6. The curved surface on the downstream centrifugal direction side portion of the platform 6 has a small curvature on the rear side in the rotational direction and a large curvature on the front side in the rotational direction.

  FIG. 6 shows yet another preferred platform shape for the implementation of a turbine cascade structure according to the present invention. In this embodiment, the rear portion in the rotational direction of the upstream centrifugal direction side portion of the platform 6 in FIG. 1 is scraped off, and the gap 9 ″ in the rotational direction rear portion of the gap 9 between the platform 6 and the stationary blade side base ring 3. The gap 9 ′ at the front portion in the rotational direction of the gap 9 between the platform 6 and the stationary blade side base ring 3 is the rear portion in the rotational direction among the gap between the platform 6 and the stationary blade side base ring 3. Narrower than 9 ". Of the cooling air that overflows from the gap 9, the amount of air that overflows on the side of the gap 9 ″ with a large cross-sectional area is the amount of air that overflows on the side of the gap 9 ′ that has a small cross-sectional area among the cooling air that overflows from the gap 9. As a result, the amount of cooling air is more on the side of the rotational rear surface 8 and less on the side of the rotational front surface 7. In this way, the distribution of the cooling air pressure is adjusted. Of the downstream centrifugal direction side portion of the platform 6, the rotational direction front portion is scraped off, and among the gap 9 between the platform 6 and the stationary blade side base ring 3, a clearance 9 ″ in the rotational direction forward portion is widely formed.

  In the form of FIG. 5, forming the reverse bulge portion having a large curvature into the bulge portion having a large curvature can further adjust the aforementioned pressure distribution more meaningfully. In the form of FIG. 6, forming the bulge or the reverse bulge having a large curvature in the wide gap region can adjust the pressure distribution described above more meaningfully. In the form of FIG. 1, it is meaningful to give a large curvature at the rear portion in the rotational direction of the bulge 11.

FIG. 1 is an exploded plan view showing a preferred embodiment of a turbine cascade structure according to the present invention. FIG. 2 is a left side sectional view of FIG. FIG. 3 is a side cross-sectional view showing another form of bulge. FIG. 4 is a flow analysis diagram. FIG. 5 is an oblique projection showing another preferred embodiment of the turbine cascade structure according to the present invention. FIG. 6 is an oblique projection showing another preferred embodiment of the turbine cascade structure according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Stator blade ring 2 ... Rotor blade ring 4 ... Rotor blade 6 ... Platform 7 ... Forward direction surface 8 ... Rotation direction rear side 9 ... Gap 9 '... Gap 9 "... Gap 11 ... Flow deflection part 12 ... Reference | standard Surface 25 ... Cooling air 26 ... Other flow deflection part 28 ... Curved part 31 ... Curved part

Claims (6)

The stator blade ring,
A moving blade row ring facing the stationary blade row ring and disposed downstream of the stationary blade row ring,
The moving blade ring is
A plurality of platforms arranged side by side in the circumferential direction;
A rotor blade fixed to each of the plurality of platforms,
The upstream portion of the platform has a flow deflection for increasing the ratio of cooling air flowing in the centrifugal direction from the gap between the stationary blade row ring and the moving blade row ring to the rear side in the rotational direction of the blade. With parts,
The flow deflection portion is swollen in a centrifugal direction from a reference plane of the platform. The downstream part of the platform comprises another flow deflection part;
2. The turbine cascade structure according to claim 1, wherein the other flow deflection portion swells in a centrifugal direction from the reference surface of the platform. 3. The stator blade ring,
A moving blade row ring facing the stationary blade row ring and disposed downstream of the stationary blade row ring,
The moving blade ring is
A plurality of platforms arranged side by side in the circumferential direction;
A rotor blade fixed to each of the plurality of platforms,
The upstream portion of the platform has a flow deflection for increasing the ratio of cooling air flowing in the centrifugal direction from the gap between the stationary blade row ring and the moving blade row ring to the rear side in the rotational direction of the blade. With parts,
The flow deflection portion is formed as a curved portion that smoothly guides the flow of the cooling air to the downstream side, and the curvature of the rear portion in the rotation direction of the curved portion is larger than the curvature of the front portion in the rotation direction of the curved portion. Turbine cascade structure. The downstream part of the platform comprises another flow deflection part;
The other flow deflection portion is formed as another curved portion that smoothly guides the flow of the cooling air further downstream, and the curvature of the front portion in the rotation direction of the other curved portion is the other curved portion. The turbine blade cascade structure according to claim 3, wherein the turbine blade cascade structure is larger than the curvature of the rear portion in the rotational direction. The stator blade ring,
A moving blade row ring facing the stationary blade row ring and disposed downstream of the stationary blade row ring,
The moving blade ring is
A plurality of platforms arranged side by side in the circumferential direction;
A rotor blade fixed to each of the plurality of platforms,
The upstream portion of the platform has a flow deflection for increasing the ratio of cooling air flowing in the centrifugal direction from the gap between the stationary blade row ring and the moving blade row ring to the rear side in the rotational direction of the blade. With parts,
The turbine blade cascade structure in which the width of the gap corresponding to the rear portion in the rotational direction among the flow deflection portions is wider than the width of the gap corresponding to the forward portion in the rotational direction among the flow deflection portions. The downstream part of the platform comprises another flow deflection part;
The turbine blade cascade structure in which the width of the gap corresponding to the front portion in the rotation direction among the other flow deflection portions is wider than the width of the gap corresponding to the rear portion in the rotation direction among the other flow deflection portions.

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