JP2014148938A - Film-cooled turbine blade for turbomachine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film-cooled turbine blade for a turbomachine.SOLUTION: A turbine blade has an outer wall 1 which delimits an inner cavity 2 of the turbine blade. Cooling fluid 4 is provided in the inner cavity 2, and a through duct 3 is formed in the outer wall 1. The cooling fluid 4 forms a cooling film 5 on an outer face 7 of the outer wall 1, and flows from the inner cavity 2 to outside of the turbine blade via the through duct 3. The through duct 3 is inclined with respect to an outer edge of the turbine blade, and a marginal portion 14 of an entrance 10 of the through duct 3 is formed on an upstream side 12 to be sharp-edged in relation to the other marginal portions of the entrance 10 of the through duct 3. A breakaway zone 16 is formed in the through duct 3 and is directed toward a downstream side 13 of the through duct 3 positioned on a side opposite to the breakaway zone 16, so as to induce a centric transverse flow 18 of the cooling fluid 4. A velocity vector of the flow 17 of the cooling fluid between vortex centers 21 generates a set of reversely-directed vortices 20 directed to the downstream side 13 of the through duct 3.

Description

  The present invention relates to a film cooled turbine blade for a turbomachine.

  Turbomachines, such as gas turbines in particular, have a turbine that functions by expanding hot gas that has been previously compressed in a compressor and heated in a combustion chamber. Due to the high mass flow of hot gas and hence the high power range of the gas turbine, the turbine is designed in an axial flow configuration and is formed by a plurality of blade rings arranged back and forth in the flow through direction Has been. The blade ring has a movable blade and a guide blade disposed around the blade ring. The movable blade is fixed to the rotor of the gas turbine, and the guide blade is fixed to the casing of the gas turbine.

  The higher the inlet temperature as hot gas enters the turbine, the higher the thermodynamic efficiency of the gas turbine. In contrast, the thermal load-bearing capacity of the turbine blade is limited. Accordingly, it would be desirable to provide a turbine blade that has sufficient mechanical strength for gas turbine operation even with the highest heat load. To achieve this goal, suitable materials and material combinations for turbine blades are utilized, but based on the prior art is unsuitable, only detracting from the possibility of increasing the thermal efficiency of the gas turbine. By further cooling the turbine blades during gas turbine operation to further increase the allowable turbine inlet temperature, the turbine blades themselves are lower than if they are not cooled due to the thermal load due to the hot gas. It is known to be exposed to heat loads.

  In order to keep the temperature of the turbine blade low, the blade is cooled, for example by film cooling. In order to achieve this object, a plurality of cooling air openings are provided on the surface of the blade, and the cooling air is transported from the inside of the blade to the surface of the turbine blade through the cooling air opening. After the cooling air passes through the cooling air opening, the cooling air flows along the surface of the turbine blade in a laminar form, so that the surface of the turbine blade can be isolated from the hot gas. Furthermore, since the layered cooling air functions as a barrier, the hot gas is prevented from being transported to the surface of the turbine blade.

  An object of the present invention is to provide a turbine blade for a turbomachine that can be efficiently cooled by film cooling.

  A turbine blade for a turbomachine in the present invention is a turbine blade for a turbomachine having an outer wall that defines an internal cavity of the turbine blade, wherein cooling fluid film cools the turbine blade. Turbine blades are disposed in the internal cavity from the internal cavity through the through duct so that at least one through duct is formed in the outer wall and the cooling fluid forms a cooling film on the outer surface of the outer wall. In which the through duct is inclined with respect to the outer edge of the turbine blade, such that the edge portion of the inlet of the through duct is at an acute angle relative to the opposite edge portion of the inlet. It is formed on the upper side, so that a separation area of the cooling fluid flow is formed in the through duct And the separation region induces a cross-center flow of cooling fluid directed toward the lower surface of the through duct located on the opposite side of the separation region, thereby cooling between the vortex centers A turbine blade that generates a set of oppositely directed vortices in a through duct with a velocity vector of fluid flow toward the bottom surface of the through duct.

  When the hot gas from the combustion chamber of the turbomachine collides with the cooling fluid jet flowing out of the through duct outside the turbine blade, the hot gas flow is dispersed around the jet of the cooling fluid, and the jet boundary As a result of the drag effect of the hot gas in, a chimney vortex with two vortex arms is formed. Each of the two vortex arms is formed by a vortex, and the velocity vector of the hot gas on the inner surface of the two vortex arms is directed away from the outer wall. Thereby, the hot gas is transported toward the outside of the turbine blade. The two vortex arms of the outlet vortex have a set of opposite cooling fluid vortices, each of which overlaps and is directed in the opposite direction. Accordingly, the exit side vortex is weakened and hot gases transported outside the turbine blade are reduced, resulting in more efficient film cooling. Accordingly, the amount of cooling fluid required to cool the turbine blade is less than the amount of cooling fluid that would be required to cool the turbine blade according to the prior art. This is achieved by the higher efficiency of the turbomachine. In addition, the density of through ducts to be selected in the turbine blade can be relatively low. As a result, overall, the number of through ducts required for the turbine blade in the present invention can be further reduced, and the structural vulnerability of the turbine blade in the present invention can be further reduced.

  Preferably, the inner surface of the region of the outer wall where the through-duct is disposed is provided with a thick portion having an upper front surface on which an inlet is formed, the front surface being the inlet of the through-duct Is inclined with respect to the axis of the through-duct so that the edge portion is formed on the upper side as an edge portion formed at an acute angle with respect to the opposite edge portion of the inlet. Preferably, the front surface of the thick wall portion is arranged in a state of being substantially perpendicular to the inner surface of the outer wall or inclined with respect to the rear edge of the turbine blade. On the inclined front surface of the thick-walled portion, an edge portion formed particularly at an acute angle is provided on the upper side of the through duct. As a result, a set of oppositely directed vortices is predominantly formed.

  Preferably, if the thickness of the thick part is a manufacturing error that always occurs during molding, the through duct is statically placed in the thick part and the inlet is above the thick part. It is a dimension formed by the front surface. Preferably, the rear surface of the thick portion facing the opposite direction of the upper front surface of the thick portion is substantially parallel to the through duct. Preferably, the thick portion is a cooling rib of the turbine blade. The provision of cooling ribs increases the area of the inner surface of the turbine blade, and as a result, the turbine blade is advantageously cooled efficiently from the inside by convection of the cooling fluid. Alternatively, it is desirable for the thickened portion to be a support web that extends from the pressure side to the suction side of the turbine blade. Advantageously, the strength of the turbine blade is increased by the support web. Each cooling duct of the turbine blade is formed inside the turbine blade by a support web.

  Preferably, the thick portion is a movable body that is movable within the internal cavity of the turbine blade. The flow rate of the cooling fluid within the internal cavity can be increased by the movable body to cool the turbine blades. As a result, convection due to the cooling fluid in the internal cavity is enhanced. This advantageously also allows the turbine blades to be efficiently cooled from the inside.

  Alternatively, the inner surface of the region of the outer wall in which the through duct is disposed is disposed substantially parallel to the outer surface, and the edge portion of the inlet of the through duct is formed at an obtuse angle than the opposite edge portion of the inlet. Thus, it is desirable that the bead is integrally formed at the edge portion of the entrance of the through duct on the lower side. Such a shape of the turbine blade can be easily molded. If manufacturing errors occur during the molding of the turbine blade, the most distal position of the bead cannot be accurately predicted from the initial stage. In this case, the position of the bead can be subsequently determined by using the X-ray method. Based on this determined position, the through duct is manufactured in the correct position with respect to the beat, for example by drilling, from the outside of the turbine blade.

  Preferably, a gap having a lower rear surface on which an inlet is formed is provided on the inner surface of the region of the outer wall where the through duct is disposed, and the lower rear surface is an inlet of the through duct Is inclined with respect to the axis of the through duct so that the edge portion is formed on the upper side as an acute edge portion with respect to the opposite edge portion of the inlet. The formation of the gap can reduce the requirements for materials for manufacturing the turbine blade. Preferably, the rear surface of the gap is arranged in a state substantially perpendicular to the inner surface of the outer wall or inclined with respect to the trailing edge of the turbine blade. Advantageously, the inclined rear face forms an edge portion which is formed at a particularly acute angle on the upper side of the through duct. Preferably, the gap is rounded at the edge of the inlet so that the cooling fluid flows into the gap without peeling.

  The shape of the turbine blade in the present invention is suitable for the molding process, and as a result, the turbine blade can be molded without requiring any adapter. Preferably, the through duct can be manufactured by drilling such as laser drilling or erosion. Usually, drilling is performed from the outside of the turbine blade.

  Preferably, the gap is a groove in which a plurality of through ducts communicate with each other. In this case, advantageously, it becomes easier to find the groove at the same time as forming the edge part during the drilling process.

  A preferred embodiment of a turbine blade in the present invention will be described below with reference to the accompanying schematic drawings.

2 is a detailed longitudinal cross-sectional view of the outer wall of a turbine blade having a through duct and a thick wall portion. FIG. 2 is a detailed longitudinal cross-sectional view of the outer wall of a turbine blade having a through duct and a thick wall portion. FIG. 2 is a detailed longitudinal cross-sectional view of an outer wall of a turbine blade with a through duct and a support web. FIG. 2 is a detailed longitudinal cross-sectional view of an outer wall of a turbine blade with a through duct and a bead. FIG. 2 is a detailed longitudinal cross-sectional view of an outer wall of a turbine blade with a through duct and a gap. FIG. 2 is a detailed longitudinal cross-sectional view of an outer wall of a turbine blade with a through duct and a gap. FIG.

  1 to 6 represent a part of the outer wall 1 of a turbine blade of a turbomachine. The outer wall 1 forms the boundary of the inner cavity 2 and has an outer surface 7 and an inner surface 8. When the turbomachine is operating, the hot gas flow 34 with the hot gas main flow direction 9 parallel to the outer surface 7 directed toward the trailing edge (not shown) of the turbine blade. Occurs on the outer surface 7. The through duct 3 having a circular cross section 19 is guided toward the inside of the outer wall 1, is inclined with respect to the trailing edge of the turbine blade in the direction of flow from the inside to the outside, and is acute with the outer surface 7. The inclination angle 6 is formed.

  The through duct 3 shown in FIGS. 1 to 6 has an inlet 10 inside thereof and an outlet 11 outside thereof. Further, the through duct 3 has an axis 26, an upper flow surface 12, and a lower flow surface 13. The inlet 10 of the through duct 3 has an upper edge portion 14 on the upper flow surface 12 and a lower edge portion 15 on the lower flow surface 13. When the turbomachine is operating, the internal cavity 2 contains the cooling fluid 4, which flows into the through duct 3 via the inlet 10 and again through the outlet duct 3 via the outlet 11. Spill from. Since the inclination angle 6 is selected to be an acute angle, after the cooling fluid 4 flows out of the through duct 3, the cooling film 5 is formed on the outer surface 7.

  FIG. 1 represents an embodiment of a turbine blade having a thick wall portion 23. The thick portion 23 is disposed on the inner side in the region of the outer wall 1 where the through duct 3 is disposed. The thick portion 23 has a lower rear surface 28 of the thick portion extending in parallel to the through duct 3 and an upper front surface 27 of the thick portion where the inlet 10 is disposed. Yes. The thick-walled upper front surface 27 is disposed substantially perpendicular to the inner surface 8 of the outer wall 1, and the upper edge portion 14 is an edge portion that is sharper than the lower edge portion 15.

  The flow state in the turbine blade will be described below with reference to FIG. The lower edge portion 15 is formed at an obtuse angle so that the cooling fluid flow 17 can follow the lower edge portion 15 so as not to peel off. The upper edge portion 14 is formed at an acute angle so that the cooling fluid flow 17 cannot follow the upper edge portion 14. Thus, a separation region 16 of the cooling fluid flow 17 is formed on the upper flow surface 12 in the through duct 3. The separation region 16 induces a cross-center flow 18 that is directed from the upper flow surface 12 to the lower flow surface 13 in the through duct 3. The cross-center flow 18 generates a set of oppositely directed vortices 20 with vortex centers 21 in the through duct 3. At this time, the velocity vector between the two vortex centers 21 faces the lower flow surface 13 of the through duct 3.

  As is clear from FIG. 1, the velocity vector of the cooling fluid flow 17 between the vortex centers 21 is directed toward the outer wall 1 immediately after flowing out of the through duct 3. The hot gas stream 34 flows around a new jet of cooling air having a set of oppositely directed vortices 20, resulting in the formation of an outlet vortex 33 by the hot gas. The outlet-side vortex 33 has two vortex arms located on either side of a set of oppositely directed vortices 20. Each vortex arm is formed by a vortex, and the velocity vector of the hot gas flow 34 between the vortex centers 21 of the vortex arms is directed toward the outer wall 1. Thereby, the hot gas is transported onto the outer surface 7 of the outer wall 1. Immediately after flowing out of the through duct 3, the vortex arms have a set of oppositely directed vortices 20 that overlap each other and have their vortices rotated in the opposite direction. Accordingly, the vortex 33 on the outlet side is weakened and the hot gas transported onto the outer surface 7 of the outer wall 1 is reduced. As a result, heat conduction to the outer wall 1 of the turbine blade is eliminated.

  The upper front surface 27 of the thick wall portion is inclined with respect to the rear edge of the turbine blade. In this case, it is also assumed that the upper edge portion 14 is formed at an acute angle with respect to the upper edge portion of FIG. Is done.

  FIG. 2 represents the thick portion 23 of FIG. The thick portion 23 has two significant manufacturing errors, each indicated by a dashed line. If there is a first manufacturing error, the thick portion 23 is offset parallel to the outer wall 1, and if there is a second manufacturing error, the thick portion 23 is on the upper front surface 27. Is offset parallel to When both the first manufacturing error and the second manufacturing error exist, the through duct 3 is disposed in the thick portion 23 and the inlet 10 is disposed on the upper front surface 27 of the thick portion 23. ing.

  The turbine blade embodiment depicted in FIG. 3 has a support web 24 that extends from the pressure side to the suction side of the turbine blade. The through duct 3 partially extends into the support web 24, and the inlet 10 is disposed on the upper front surface 35 of the support web 24.

  As is apparent from FIG. 4, the bead 22 is integrally formed on the inner surface 8 of the outer wall 1 directly adjacent to the lower edge portion 15, and as a result, the lower edge portion 15 is formed at an obtuse angle. ing. The bead 22 has a convex region on the side facing inward. It is assumed that the convex region extends to the lower edge portion 15 and / or inside the through duct 3. In this case, the separation region is eliminated particularly efficiently at the lower flow surface 13 of the through duct 3. It is assumed that the bead 22 has a rectangular cross section. Furthermore, it is assumed that the beads 22 are also configured as cooling ribs.

  5 and 6, a cap-shaped gap 25 having an upper front surface 29 and a lower rear surface 30 is formed in the outer wall 1. An inlet 10 is formed in the lower rear surface 30. The gap 25 has a rounded-shaped inlet edge portion 31 to avoid separation of the cooling fluid stream 17 when the cooling fluid stream 17 flows into the gap 25. In contrast to the embodiment depicted in FIG. 5, the gap 25 in the embodiment depicted in FIG. 6 is inclined with respect to the trailing edge of the turbine blade, and the upper edge portion 14 is formed with a particularly acute angle. Furthermore, it is assumed that the gap 25 is configured as a groove in which a plurality of through ducts 3 communicate with each other.

  Although the invention has been described in detail with reference to preferred exemplary embodiments, the invention is not limited to the disclosed embodiments and those skilled in the art will envision other modifications from the disclosed embodiments. Such changes are also within the protection scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Outer wall (of turbine blade) 2 Internal cavity 3 Through duct 4 Cooling fluid 5 Cooling film 6 Inclination angle 7 Outer surface 8 Inner surface 9 Main flow direction of hot gas 10 Inlet 11 Outlet 12 Upper flow surface 13 Lower flow surface 14 Upper edge portion DESCRIPTION OF SYMBOLS 15 Lower edge part 16 Separation area | region 17 Flow of cooling fluid 18 Center cross flow 19 Circular cross section 20 Vortex 21 Vortex center 22 Bead 23 Thick part 24 Support web 25 Gap 27 (Upper part 23) Upper front surface 28 Lower rear surface (of the thick portion 23) 29 Upper front surface (of the gap 25) 30 Lower rear surface (of the gap 25) 31 Inlet edge portion (of the gap 25) 33 Vortex on the outlet side 34 Hot gas flow

Claims (13)

Said turbine blade for a turbomachine comprising an outer wall (1) defining the boundary of an internal cavity (2) of the turbine blade,
A cooling fluid (4) is disposed in the internal cavity (2) for film cooling the turbine blade, and at least one through duct (3) is formed in the outer wall (1). The cooling fluid (4) forms a cooling film (5) on the outer surface (7) of the outer wall (1) through the through duct (3) from the inner cavity (2) to the turbine blade. The turbine blade, wherein the through duct (3) is inclined with respect to an outer edge of the turbine blade,
The edge portion (14) of the inlet (10) of the through duct (3) is formed on the upper side surface (12) so as to have an acute angle with respect to the opposite edge portion of the inlet (10). A separation region (16) of the cooling fluid flow (17) is formed in the through duct (3),
Center crossing of the cooling fluid (4), wherein the peeling region (16) is directed towards the lower side (13) of the through duct (3) located on the opposite side of the peeling region (16) Inducing a flow (18), whereby the velocity vector of the cooling fluid flow (17) between the vortex centers (21) is towards the lower side (13) of the through duct (3), A turbine blade characterized in that a set of oppositely directed vortices (20) are generated in the through duct.   A thick part (23) is provided on the inner surface (8) of the region of the outer wall (1) where the through duct (3) is arranged, the inlet (10) is formed and the penetration It has an upper front surface (27) that is inclined with respect to the axis (26) of the duct (3), whereby the edge portion (14) of the inlet (10) of the through duct (3). The turbine blade according to claim 1, characterized in that is formed on the upper side surface (12) so as to be at an acute angle with respect to the opposite edge portion (15) of the inlet (10).   The upper front surface (27) of the thick wall portion (23) is substantially perpendicular to the inner surface (8) of the outer wall (1) or inclined with respect to the trailing edge of the turbine blade. The turbine blade according to claim 2, wherein the turbine blade is arranged in a closed state.   When the thickness of the thick part (23) is a manufacturing error that always occurs during molding, the through duct (3) is statically arranged in the thick part (23), A turbine blade according to claim 2 or 3, characterized in that the inlet (10) is dimensioned by the upper front surface (27) of the thick part (23).   The rear surface (28) of the thick portion (23) facing the opposite direction of the upper front surface (27) of the thick portion (23) is substantially parallel to the through duct (3). The turbine blade according to claim 2, wherein the turbine blade is a turbine blade.   The turbine blade according to any one of claims 2 to 5, wherein the thick portion (23) is a cooling rib of the turbine blade.   The said thick part (23) is made into the support web (24) extended from the pressure surface of the said turbine blade to the suction surface, The one according to any one of Claims 2-5 characterized by the above-mentioned. The turbine blade described. The thick portion (23) is a movable body that is movable within the internal cavity (2) of the turbine blade;
By means of the movable body, the flow rate of the cooling fluid (4) is increased to cool the turbine blade, and as a result, the convection by the cooling fluid (4) in the internal cavity (2) is increased. The turbine blade according to any one of claims 2 to 7, wherein: The inner surface (8) of the region of the outer wall (1) where the through duct (3) is disposed is disposed substantially parallel to the outer surface (7),
A bead (22) is formed integrally with the opposite edge portion (15) of the inlet (10) of the through duct (3) on the lower side surface (13), whereby the opposite edge The turbine blade according to claim 1, wherein the portion (15) is formed at an obtuse angle with respect to the edge portion (14) of the inlet (10).   A gap (25) is provided in the inner surface (8) of the region of the outer wall (1) where the through duct (3) is arranged, the inlet (10) is formed and the through duct ( 3) having a lower rear surface (30) that is inclined with respect to the axis (26) of 3), whereby the edge portion (14) of the inlet (10) of the through duct (3) 2. The turbine blade according to claim 1, wherein the turbine blade is arranged on the upper side surface (12) so as to be formed at an acute angle with respect to the opposite edge portion (15) of the inlet (10).   The rear surface (30) of the gap (25) is substantially perpendicular to the inner surface (8) of the outer wall (1) or inclined with respect to the trailing edge of the turbine blade. The turbine blade according to claim 10, wherein   The gap (25) is rounded at the inlet edge (31) of the gap (25), so that the cooling fluid (4) does not peel and flows into the gap (25). The turbine blade according to claim 10, wherein the turbine blade can be used.   The turbine blade according to any one of claims 10 to 12, wherein the gap (25) is a groove through which the through duct (3) communicates.

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