JP2019173616A - Film cooling structure - Google Patents

Abstract

To suppress peeling of cooling gas from a surface of a high-temperature member, to improve film cooling performance.SOLUTION: In a film cooling structure that forms a film cooling film on a surface 2 of a high-temperature member 1 facing a high-temperature flow passage through which high-temperature gas 10 flows, at least one recess 30 is provided on the high-temperature surface 2 so as to correspond to an ejection port 5 of a film cooling hole 4 opened on the high-temperature surface 2; and the recess 30 is arranged upstream of the ejection port 5 in the flow direction of the high-temperature gas 10, and is formed symmetrically with respect to a center line C2 of the ejection port 5 extending in the flow direction of the high-temperature gas 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a film cooling structure or the like that forms a film cooling film on the surface of a high-temperature member of a gas turbine such as a turbine blade that faces a high-temperature channel through which high-temperature gas flows.

  In film cooling of a member exposed to a high-temperature gas, cooling gas is ejected from film cooling holes (pores) provided on the surface of the member, and the surface of the member is covered with this cooling gas, so that heat input from the high-temperature gas to the member can be achieved. Suppress. Therefore, it is important to improve the film cooling performance that the jetted cooling gas flows along the surface of the member. Therefore, a pair of protrusions are provided on the upstream side of the film cooling holes to give vertical vortices to the high temperature gas, and the cooling gas ejected from the film cooling holes is pressed by the swirling high temperature gas, so that the film cooling air from the member surface It has been proposed to suppress peeling (see Patent Document 1).

JP 2014-214632 A

  However, forming a protrusion on the surface of a high-temperature component as in Patent Document 1 has manufacturing difficulties. Moreover, there is a possibility that the protrusions may disappear while being exposed to the high-temperature and high-speed gas, and there is a problem in terms of practicality.

  An object of this invention is to provide the practical film cooling structure etc. which can suppress peeling of the cooling gas from the surface of a high temperature member, and can improve a film cooling performance.

  In order to achieve the above object, the present invention extends in the direction of hot gas flow so that the film cooling hole opened on the surface of the hot member is positioned upstream of the film cooling hole in the hot gas flow direction. At least one recess formed symmetrically with respect to the center line of the jet port of the film cooling hole is disposed on the surface of the high temperature member.

  According to this invention, peeling of the cooling gas from the surface of a high temperature member can be suppressed and film cooling performance can be improved.

The perspective view of the film cooling structure which concerns on 1st Embodiment of this invention. A plan view of the film cooling structure of FIG. Cross-sectional view taken along line AA in FIG. Cross-sectional view taken along line B-B in FIG. Cross-sectional view taken along line CC in FIG. The top view of the film cooling structure which concerns on 2nd Embodiment of this invention. The top view of the film cooling structure which concerns on 3rd Embodiment of this invention. The top view of the film cooling structure which concerns on 4th Embodiment of this invention. Partial sectional drawing of the gas turbine which is one application object of the film cooling structure of this invention The figure which shows the application example 1 of the film cooling structure of this invention The figure which shows the example 2 of application of the film cooling structure of this invention The figure which shows the example 3 of application of the film cooling structure of this invention Plan view of film cooling structure according to comparative example FIG. 13 is a cross-sectional view taken along line C'-C 'in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
-Film cooling structure-
1 is a perspective view of a film cooling structure according to a first embodiment of the present invention, FIG. 2 is a plan view of the film cooling structure of FIG. 1 as viewed from a high-temperature flow path, and FIG. 3 is an arrow along line AA in FIG. FIG. 4 is a sectional view taken along the line BB in FIG. 2. In these drawings, the vicinity of the film cooling structure of the high temperature member 1 is extracted and partially shown. The illustrated film cooling structure is a structure for forming a film cooling film on the surface of the high temperature member 1 facing the high temperature flow path through which the high temperature gas 10 flows in the direction of the arrow, and includes a film cooling hole 4 and a recess 30. Hereinafter, when simply described as “upstream side” and “downstream side”, it means the upstream side and the downstream side in the flow direction of the hot gas 10.

  The high temperature member 1 separates a low temperature channel through which a low temperature gas having a low temperature relative to the high temperature gas 10 and a high temperature channel through which the high temperature gas 10 flows. Hereinafter, the surface facing the high-temperature channel of the high-temperature member 1 is referred to as a high-temperature surface 2, and the surface facing the low-temperature channel is referred to as a low-temperature surface 3. The high temperature surface 2 and the low temperature surface 3 are in a front-back relationship. The film cooling hole 4 penetrates the high temperature member 1, and one end opens to the low temperature surface 3 as the inlet 6 of the cooling gas 20, and the other end opens to the high temperature surface 2 as the outlet 5 of the cooling gas 20. . The high-pressure cooling gas 20 flowing through the low-temperature channel flows into the film cooling hole 4 through the inflow port 6 and is ejected from the ejection port 5 to the high-temperature channel. By covering the high temperature surface 2 with a film cooling film formed by the cooling gas 20 ejected from the ejection port 5, heat input from the high temperature gas 10 to the high temperature surface 2 is suppressed. The film cooling holes 4 are inclined in the flow direction of the high temperature gas 10 from the low temperature surface 3 toward the high temperature surface 2 so that the cooling gas 20 is ejected into the high temperature flow path along the high temperature surface 2 as much as possible. The angle α (FIG. 2) formed by the center line C1 (straight line) of the film cooling hole 4 and the high temperature surface 2 is set as small as possible in production (for example, about 30 °). Since the film cooling hole 4 is a circular hole (cylindrical hole) whose cross section orthogonal to its own center line C1 is circular, both the inlet 6 and the outlet 5 have their long axes extending in the flow direction of the hot gas 10. It has an oval shape. Note that the angle α is an angle in a cross section perpendicular to the high temperature surface 2 including the center line C2 of the jet nozzle 5 extending in the flow direction of the high temperature gas 10.

-Depression-
The depression 30 is provided on the high temperature surface 2 corresponding to the jet outlet 5 of the film cooling hole 4. In the present embodiment, the film cooling hole 4 and the depression 30 are in a one-to-one relationship. 1 to 4 partially show the film cooling structure, only one film cooling hole 4 is shown. Actually, however, a plurality of film cooling holes 4 are provided in the high temperature member 1, and the film cooling hole 4 is shown in FIG. There are as many depressions 30 as the number of cooling holes 4. The recess 30 is located upstream of the jet port 5 and has a symmetrical shape with respect to the center line C2 of the jet port 5 when viewed from the high-temperature channel. The depression 30 can be formed at the casting stage of the high temperature member 1.

  The depression 30 is a depression provided on the high temperature surface 2 side of the high temperature member 1, and the inner wall surface is formed with a curved surface without corners except for an elliptical edge that is a boundary with the high temperature surface 2 and a portion on the center line C <b> 2. Has been. The inner wall surface of the recess 30 is within the thickness of the high temperature member 1 and is located on the low temperature surface 3 side (the opposite side to the high temperature flow path) from the high temperature surface 2. The recess 30 includes a pair of recesses 30a and 30b each having a short axis and a long axis. The inner wall surfaces of the recesses 30a and 30b are curved surfaces such as a part of the surface of the spheroid, and the boundary with the high temperature surface 2 is elliptical so that the distance between the major axes increases toward the downstream side. Is arranged. In the present embodiment, the upstream portions of the recesses 30a and 30b overlap on the center line C2, and the recess 30 has a V-shape symmetrical with respect to the center line C2 when viewed from the high temperature channel.

  The major axes of the recesses 30a and 30b are inclined at an angle θ with respect to a plane (cross section taken along the line AA) perpendicular to the high temperature surface 2 through the center line C2. θ is 45 degrees or less (θ ≦ 45 °). This is because if θ> 45 °, the rotation direction of the pair of vertical vortices formed by the recesses 30a and 30b may be opposite to the intended direction. The width taken in the minor axis direction of the recesses 30a and 30b (the length of the minor axis of the recesses 30a and 30b) W is naturally shorter than the length taken in the major axis direction (the length of the major axis of the recess 30). (L> W). The width W of the recesses 30a and 30b is set to be equal to or smaller than the diameter (hole diameter) D of the film cooling hole 4 which is a circular hole. The depth of the depression 30 (the amount of depression from the high temperature surface 2) H is half of the width W of the depression 30 (W ≦ D). Moreover, since the distance (interval on the center line C2) X taken in the flow direction of the hot gas 10 between the jet outlet 5 and the depression 30 of the film cooling hole 4 cannot be expected to be effective, the effect of the film cooling hole 4 It should be set to 4 times or less of the diameter D (X ≦ 4D). In this embodiment, as shown in FIG. 3 and FIG. 4, the positions of the recess 30 and the film cooling hole 4 overlap in the flow direction of the hot gas 10 (the downstream edge of the recess 30 is the inlet 6. Located on the downstream side of the upstream edge).

-Film cooling-
FIG. 5 is a cross-sectional view taken along line CC of FIG. In the figure, the high-temperature gas 10 flows through the high-temperature flow path from the front in the direction orthogonal to the paper surface to the back. The cooling gas 20 ejected from the ejection port 5 to the high-temperature flow path also flows toward the back in the direction perpendicular to the paper surface, and a film cooling film is formed by the cooling gas 20 so as to cover the high-temperature surface 2 of the high-temperature member 1. In the present embodiment, the recess 30 formed symmetrically with respect to the center line C <b> 2 is disposed on the high-temperature surface 2 so as to be located on the upstream side of the jet nozzle 5 as described above. As a result, the hot gas 10 flowing along the high temperature surface 2 is given a swirl component in a direction to blow down toward the film cooling hole 4 when the depression 30 is exceeded. Specifically, as seen from the upstream side in the flow direction of the hot gas 10 as shown in the figure, when the hot gas 10 flowing on the right side of the center line C2 exceeds the recess 30 (recess 30a), it turns counterclockwise (counterclockwise). ) Is generated. Symmetrically across the center line C2, when the hot gas 10 flowing on the left side of the center line C2 exceeds the depression 30 (recess 30b), a vertical vortex 51 that turns clockwise (clockwise) is generated. Since these vertical vortices 50 and 51 have a swirling component that blows down from the high-temperature flow path to the high-temperature surface 2 in the vicinity of the center line C2, they face the cooling gas 20 ejected from the film cooling holes 4 on the center line C2. Thus, by giving the component facing the cooling gas 20 to the high-temperature gas 10, the cooling gas 20 ejected into the high-temperature channel is pressed toward the high-temperature surface 2 by the high-temperature gas 10. Thereby, peeling of the cooling gas 20 from the high temperature surface 2 is suppressed, and a film cooling film is effectively formed and spread along the high temperature surface 2.

-Comparative example-
13 is a plan view showing a film cooling structure according to a comparative example, and FIG. 14 is a cross-sectional view taken along line C′-C ′ of the high temperature member of FIG. 13 corresponds to FIG. 2, and FIG. 14 corresponds to FIG.

  The comparative example in the figure corresponds to a configuration in which the recess 30 is omitted from the film cooling structure according to the present embodiment. The hot gas 110 flows in the direction of the arrow, and the cooling gas 120 is ejected from the ejection port 105 of the film cooling hole 104. The film cooling holes 104 are inclined in the flow direction of the high temperature gas 110 from the low temperature surface 103 toward the high temperature surface 102 in order to improve the adhesion of the cooling gas 120 to the high temperature surface 102. When the cooling gas 120 is ejected from the film cooling holes 104, a pair of vortices 150 and 151 that entrain the hot gas 110 are generated around the cooling gas 120 as shown in FIG. As shown in the figure, when viewed from the flow direction of the hot gas 110, the vortex 150 on the right side of the cooling gas 120 is clockwise (clockwise), and the vortex 151 on the left side of the cooling gas 120 is counterclockwise (counterclockwise). Rotate to. The pair of vortices 150 and 151 draws the high-temperature gas 111 and 112 between the cooling gas 120 and the high-temperature surface 102, and promotes the peeling of the cooling gas 120 from the high-temperature surface 102, thereby reducing the film cooling performance.

-Effect-
(1) Film cooling performance In the present embodiment, as described above, a swirl component is imparted when the hot gas 10 flowing along the hot surface 2 exceeds the recess 30 and swirls in the direction to blow down toward the film cooling hole 4. A pair of longitudinal vortices 50 and 51 can be generated. The longitudinal vortices 50 and 51 rotate in the opposite direction to the vortices 150 and 151 (FIG. 14) accompanying the ejection of the cooling gas 20 and weaken the vortices 150 and 151. In combination with this action, the cooling gas 20 ejected from the film cooling holes 4 is suppressed by the high temperature gas 10 (vortices 50, 51) imparted with the swirl component by the depression 30, and the cooling gas 20 is cooled from the high temperature surface 2. The peeling of the gas 20 is suppressed and the film cooling performance is improved.

(2) Practicality As shown in Patent Document 3, if a protrusion is provided on the high temperature surface 2 on the upstream side of the jet outlet 5 of the film cooling hole 4, a film cooling performance equivalent to this embodiment is expected. it can. However, when exposed to the high temperature gas 10, the height of the protrusion gradually decreases due to the high temperature oxidation phenomenon, and the film cooling performance may deteriorate with time. On the other hand, since the dent 30 in this embodiment is dented from the beginning, it does not disappear, and the deterioration of the film cooling performance with time can be suppressed.

  In particular, in the present embodiment, since the recess 30 has an overlapping positional relationship in the flow direction of the film cooling hole 4 and the high temperature gas 10, it is closer to the film cooling hole 4 than the surrounding high temperature surface 2. Thereby, the temperature reduction effect of the dent 30 can be improved by the convection cooling effect by the cooling gas 20 flowing through the film cooling hole 4 as compared with the peripheral portion of the high temperature member 1, and the temporal change in the shape of the dent 30 can be suppressed. The change in cooling performance can be suppressed more effectively.

(3) Ease of manufacturing The recess 30 can be formed at the casting stage of the high-temperature member 1, and in this case, the step of finishing the recess 30 after the casting of the high-temperature member 1 can be omitted. Even if it is necessary to finish the recess 30 after casting the high temperature member 1, the surface of the recess can be easily finished by electric discharge machining using an electrode having a shape matched to the recess 30. The film cooling hole 4 may be a simple circular hole formed by electric discharge machining or the like after the high temperature member 1 is cast, and the production time and cost can be reduced. Since the shape of the film cooling hole 4 is simple, the film cooling hole 4 can be processed with high accuracy, variation in the shape of the film cooling hole 4 can be suppressed, and deterioration of the cooling performance can be suppressed. However, the film cooling hole 4 is not a simple circular hole but may be a shape hole having a complicated cross-sectional shape used for improving the film cooling performance.

(4) Others The inventors of the present application have examined the film cooling performance in several ways by changing the shape of the depressions 30 and the arrangement pattern of the depressions 30 on the upstream side of the jet outlets 5 of the film cooling holes 4. As a result, the following knowledge was obtained. First, in the present embodiment, as described above, the length L of the recess 30 is longer than the width W to have an elongated shape, and the recess 30 is arranged in a V shape that opens toward the downstream side. In the case of this structure, for example, when the recess 30 is a single circular recess, the velocity components of the longitudinal vortices 50 and 51 are strengthened compared to the case where the recesses 30a and 30b separated with the center line C2 interposed therebetween are arranged in parallel. It was found that the film cooling performance was further improved. Further, by making the width W of the recess 30 (recessed portions 30a, 30b) smaller than the diameter D of the film cooling hole 4, the strength of the longitudinal vortices 50, 51 is further increased, which is more effective in improving the film cooling performance. I also understood.

(Second Embodiment)
FIG. 6 is a plan view of the film cooling structure according to the second embodiment of the present invention as viewed from the high temperature flow path. Elements similar to those in the first embodiment are denoted by the same reference numerals as those in the above-described drawings, and description thereof will be omitted as appropriate. The present embodiment is an example in which the shape of the recess 30 is changed. In the present embodiment, the two recesses 30a and 30b constituting the recess 30 are separated. The pair of recesses 30a and 30b are symmetric with respect to the center line C2 of the jet nozzle 5, and are spaced apart by an interval S across the center line C2. The interval S is the distance between the center points of the recesses 30 a and 30 b as viewed from the direction orthogonal to the high temperature surface 2. As shown in the figure, the recesses 30a and 30b are arranged such that the distance between the major axes increases toward the downstream side in the flow direction of the hot gas 10. Other configurations are the same as those in the first embodiment, including the relationship between the width W, the length L, the angle θ, and the diameter D.

  Also in this embodiment, the vertical vortices 50 and 51 can be generated, and the same effect as in the first embodiment can be obtained.

(Third embodiment)
FIG. 7 is a plan view of the film cooling structure according to the third embodiment of the present invention as seen from the high temperature flow path. Elements similar to those in the first embodiment are denoted by the same reference numerals as those in the above-described drawings, and description thereof will be omitted as appropriate. In the first embodiment, the configuration in which one depression 30 is provided on the high temperature surface 2 of the high temperature member 1 corresponding to one ejection port 5 is illustrated, but at least one depression 30 is sufficient. A plurality of depressions 30 may be provided correspondingly. This embodiment is an example in which a plurality (two in this example) of the depressions 30 are arranged in the flow direction of the hot gas 10 on the upstream side of the jet outlet 5 of one film cooling hole 4. The two depressions 30 have the same shape and orientation as those of the depression 30 of the first embodiment that is symmetric with respect to the center line C2, and are arranged along the center line C2. In this example, the sizes of the two depressions 30 are also equal. In addition, the two recesses 30 are overlapped with each other in the flow direction of the film cooling hole 4 and the hot gas 10. Other configurations are the same as those of the first embodiment.

  Thus, by arrange | positioning the hollow 30 in multiple tandem in the flow direction of the high temperature gas 10, in this embodiment, the speed of the vertical vortex 50 and 51 can be strengthened compared with 1st Embodiment, and the high temperature of the cooling gas 20 is obtained. Separation from the surface 2 can be more effectively suppressed.

  In addition, the improvement of the film cooling performance in the case of providing two depressions 30 corresponding to one ejection port 5 is significantly higher than in the case of one. However, it was found that the film cooling performance when the number of the depressions 30 is three is similar to that when the number of the depressions 30 is three, and the effect of the film cooling performance is small even when the number of the depressions 30 is increased to three or more. The effect of improving the film cooling performance of the present embodiment was remarkable even when compared with the configuration in which the concave portions 30a and 30b were separated with the center line C2 interposed therebetween as in the second embodiment.

(Fourth embodiment)
FIG. 8 is a plan view of the film cooling structure according to the fourth embodiment of the present invention as viewed from the high temperature flow path. Elements similar to those in the first embodiment are denoted by the same reference numerals as those in the above-described drawings, and description thereof will be omitted as appropriate. This embodiment is an example in which the second embodiment and the third embodiment are combined, and the dent 30 separated by the recesses 30a and 30b as in the third embodiment is placed on the upstream side of the jet outlet 5 of the film cooling hole 4 at a high temperature. A plurality of gas 10 are arranged in the flow direction. Other configurations are the same as those in the above-described embodiment. Thus, even if the embodiments are combined, the effect of improving the film cooling performance can be obtained.

(Modification)
In the above embodiment, the case where the recesses 30a and 30b of the recess 30 are elliptical when viewed from the high-temperature flow path has been described as an example. For example, the major axis is curved so as to be convex in one of the minor axis directions. It is good also as a shape which deform | transformed the ellipse. In addition, the recesses 30a and 30b may have a shape that is asymmetric with respect to the major axis (for example, a shape in which the major axis is offset from the center in any of the minor axis directions).

(Applicable)
FIG. 9 is a partial cross-sectional view of a gas turbine which is one application target of the film cooling structure of the present invention. The gas turbine shown in this figure is driven by a compressor 100 that sucks and compresses the atmosphere a, a combustor 200 that combusts compressed air b from the compressor 100 together with fuel c, and a combustion gas d from the combustor 200. The turbine 300 is provided.

  The rotor 100A of the compressor 100 and the rotor 300A of the turbine 300 are connected coaxially. For example, a generator is connected to the rotor 100A or the rotor 300A. As a result, the generator rotates together with the rotor 300A of the turbine 300, and the rotational energy of the rotor 300A is converted into electric energy. The combustion gas e that has imparted shaft power to the rotor 300A is discharged from the gas turbine, and is led to, for example, a purification device and then released.

  The combustor 200 includes a combustor liner 201 that forms a combustion chamber for burning the fuel c and the compressed air b, a tail cylinder 202 that connects the combustion chamber 201 to the turbine 300, and a combustor liner 201 and a tail. An outer casing, a burner and the like surrounding the cylinder 202 are provided. A cylindrical air flow path is formed between the combustor liner 201 and the transition piece 202 and the outer casing.

  The turbine 300 includes a rotor 300A and a casing 315 that covers the outer side of the rotor 300A in the circumferential direction. The rotor 300A is configured by alternately stacking a plurality of turbine disks 317 and spacers 318 in the axial direction, each having a plurality of rotor blades 316 provided in the circumferential direction on the outer peripheral portion. Further, the annular blade row of the stationary blade 321 is fixed inside the casing 315 so as to face the upstream side of the moving blade 316 in each paragraph.

  The film cooling structure according to this embodiment described above can be applied to such turbine members of a gas turbine, for example, the combustor liner 201, the tail cylinder 202, the stationary blade 321 and the moving blade 316. For example, when the combustor liner 201 and the tail tube 202 are to be applied, the inside of the combustor liner 201 and the tail tube 202 is a high-temperature channel, the outer annular channel is a low-temperature channel, and the combustor liner 201 and the tail tube 202 The wall surface corresponds to the high temperature member 1. Therefore, the air holes provided in the combustor liner 201 and the tail cylinder 202 can be used as the film cooling holes 4, and the depression 30 can be provided on the inner peripheral surface downstream of the air holes (the turbine 300 side). In the case where the stationary blade 321 and the moving blade 316 are to be applied, it can be suitably applied to the first stage where the temperature of the combustion gas d is particularly high. Next, application examples to the stationary blade 321 and the moving blade 316 will be sequentially illustrated.

(Application example 1)
FIG. 10 is a diagram showing an application example 1 of the film cooling structure of the present invention. The figure shows an example in which the film cooling structure for a high temperature member of the present invention is applied to the surface (blade surface) of a blade portion 302 of a stationary blade 321 of a gas turbine. The stationary blade 321 includes inner and outer end walls 303 and 304 and blade portions 302 supported at both ends thereof. A plurality of wing portions 302 are arranged in a ring shape in the same paragraph, but one of them is shown in the drawing. A low-temperature flow path exists in the inner and outer peripheries of the stationary blade ring and in the blade portion 302. When the combustion gas d (hot gas) of the gas turbine flows between the circumferentially adjacent stationary blades 321, the blade surfaces and the surfaces of the end walls 303 and 304 are exposed to the high-temperature combustion gas d. A film cooling structure according to any of the embodiments (the third embodiment in the figure) is provided on the ventral side surface (pressure surface) of the wing portion 302. In this example, a case where a plurality of film cooling structures are arranged in the turbine radial direction (blade height direction of the stationary blade) is illustrated. The film cooling structure is the same as the example described with reference to FIG. 7, and two rows of depressions that are most effective for improving the film cooling performance on the upstream side in the flow direction of the combustion gas d of the film cooling hole 4 on the surface of the blade portion 302. 30 is provided.

  Here, in the gas turbine system, from the viewpoint of resource saving and environmental protection, the temperature of the combustion gas is being increased to improve the thermal efficiency. Therefore, in components such as turbine blades that are exposed to high-temperature gas, it is necessary to cool the component parts below the limit temperature of the material in order to ensure soundness, and to suppress high-temperature corrosion and structural strength degradation of the component parts. is there. On the other hand, since the compressed air extracted from the compressor is generally used for cooling the high temperature member of the gas turbine, if the amount of the cooling gas increases as the temperature rises, the amount of air combusted in the combustor decreases and the output decreases. To do. Moreover, if the cooling gas after member cooling is discharge | released to the gas path of the turbine through which combustion gas flows, the temperature of combustion gas will fall and thermal efficiency will fall.

  On the other hand, since the cooling efficiency is improved by applying the characteristic film cooling structure in this example, an increase in the amount of cooling gas can be suppressed even if the temperature of the combustion gas is increased. As described above, the film cooling structure of the present invention can obtain higher cooling efficiency than the reference structure without the depression 30.

  Gas turbine blades are usually manufactured by precision casting, but the depression 30 can also be precision cast integrally with the blades, so that the manufacturing time and cost are not increased without changing the conventional manufacturing process. can do. Also, the film cooling hole 4 can be drilled by electric discharge machining or the like as described above after manufacturing a blade by precision casting, as in the prior art. Since the film cooling hole 4 may be a circular hole, it is much easier to process than a complicatedly shaped shape hole, and manufacturing time and cost can be reduced. Even in places where the electrode for electric discharge machining of the film cooling hole 4 is difficult to enter, such as near the boundary between the blade 302 and the end walls 303 and 304, or the narrow portion between the blades, such as the stationary blade 321, the circular hole may be used. For example, it can be easily manufactured because only one electric discharge machining is required.

  In general, the cooling gas ejected from the film cooling hole on the ventral side rather than the back side of the wing portion is more easily peeled off from the blade surface. Therefore, the film cooling performance can be particularly effectively improved by applying the film cooling structure according to the present invention to the ventral side of the wing 302 as in the example of FIG. However, the film cooling structure according to the present invention can be applied not only to the abdominal side but also to the back side, and the above-described effects can be achieved. The film cooling structure according to the present invention can be provided on at least one of the back side and the ventral side. Although FIG. 10 illustrates the case where one row of film cooling structures is provided, a plurality of rows can be provided.

(Application example 2)
FIG. 11 is a diagram showing an application example 2 of the film cooling structure of the present invention. The figure shows an example in which the film cooling structure according to the present invention is applied to an end wall 304 of a stationary blade 321 of a gas turbine. In this example, a configuration in which two wing portions 302 are provided on one end wall 304 is illustrated. Similar to the blade 302, the surface of the end wall 304 facing the gas path is also exposed to the high-temperature combustion gas d. Therefore, in order to ensure the soundness of the end wall 304, a plurality of film cooling holes 4 are provided in the end wall 304, and the temperature of the end wall 304 is reduced by jetting cooling gas therefrom. In this example, the film cooling hole 4 is disposed near the front edge 306 of the end wall 304, and two rows of depressions 30 are provided on the upstream side thereof. The film cooling structure is similar to the example described with reference to FIG. 6, but the film cooling structures of other embodiments are naturally applicable.

  As in the example of FIG. 10, even when the combustion temperature is raised to improve the thermal efficiency of the gas turbine, the increase in the amount of cooling gas and aerodynamic loss can be suppressed, so that the thermal efficiency of the gas turbine is effectively improved. Can do.

  Further, in the interblade 307 that is an area between adjacent wings 302, the disturbance of the combustion gas d flowing through the interblade 307 due to the horseshoe vortex generated at the wing leading edge 308 is large, and the jet outlet 5 of the film cooling hole 4 The effect of the depression 30 provided on the upstream side is reduced. On the other hand, the film cooling efficiency can be improved particularly effectively by providing the film cooling structure near the front edge 306 of the end wall 304 while avoiding the interblade 307 as shown in FIG. However, it is possible to improve the film cooling performance by providing a film cooling structure between the blades 307. Further, FIG. 11 illustrates the case where the end wall 304 is provided with a film cooling structure. However, at least one of the end walls 303 and 304 can be provided with a film cooling structure. Although the case where the film cooling structure is provided in one row is illustrated, a plurality of rows can be provided.

  Since the end walls 303 and 304 are manufactured by precision casting in the same manner as the wing portion 302, the recess 30 can be manufactured by precision casting integrally without increasing the manufacturing time and cost from the conventional manufacturing process. Manufacturability can also be ensured as in the example of FIG. In addition, it is difficult to make a hole having a complicated shape on the surfaces of the end walls 303 and 304 close to the wing portion 302. However, in the case of the film cooling hole 4, a circular hole is sufficient, so that the hole can be easily made.

(Application example 3)
FIG. 12 is a diagram showing an application example 3 of the film cooling structure of the present invention. This figure shows an example in which the film cooling structure according to the present invention is applied to a blade surface 301 of a moving blade 316 of a gas turbine. As shown in the figure, the inside of the moving blade 316 has a meandering flow path structure partitioned by a partition wall 331 into a front flow path 332 and a rear flow path 333. In this figure, the three flow paths on the front edge side and the three flow paths on the rear edge side form a set, which are serpentine flow paths connected on the root side and the tip side of the wing, respectively. There is an inlet for cooling air at the root of the blade, and a part of the compressed air from the compressor 100 is guided as a cooling gas through the turbine shaft, and film cooling provided at the blade leading edge and the ventral side Cooling gas is discharged from the holes 4 into the gas path. In this example, a case where two rows of depressions 30 are provided on the upstream side of the jet port 5 of the film cooling hole 4 on the ventral side and the back side is illustrated. The film cooling structure is the same as the example described with reference to FIG. 6, but the film cooling structures of other embodiments are naturally applicable.

  When the invention is applied to the moving blade 316 as in this example, the same effect as in the case of FIGS. 10 and 11 can be obtained. FIG. 12 illustrates a configuration in which a plurality of rows of film cooling structures arranged in the blade span direction are provided in the cord length direction on each of the back side surface and the ventral side surface of the moving blade 316. Of course, a plurality of film cooling structures may be provided in the cord length direction.

(Other application examples)
The application examples 1-3 can be applied alone or in combination with at least one other application example. Further, the example in which the film cooling structure according to the present invention is applied to the combustor liner 201, the tail cylinder 202, the blade 302 of the stationary blade 321, the end walls 303 and 304, and the moving blade 316 has been described. However, the film cooling structure according to the present invention can be applied to various high-temperature members generally adopting film cooling, such as the platform of the rotor blade 316, the shroud, and the like, and the same effect can be obtained. It is done.

DESCRIPTION OF SYMBOLS 1 ... High temperature member, 2 ... High temperature surface (surface of high temperature member), 4 ... Film cooling hole, 5 ... Jet port, 10 ... High temperature gas, 30 ... Depression, 30a, 30b ... Recess, 100 ... Compressor, 200 ... Combustion 201: Combustor liner, 300 ... Turbine, 316 ... Rotor blade (turbine blade), 321 ... Stator blade (turbine blade), a ... Atmosphere (air), b ... Compressed air, c ... Fuel, d ... Combustion gas (High temperature gas), C1 ... center line of film cooling hole, C2 ... center line of jet outlet, D ... diameter of film cooling hole, W ... width of recess (length of minor axis of recess), X ... film cooling hole The distance taken in the direction of hot gas flow between the dent and the depression

Claims (14)

A film cooling structure for forming a film cooling film on the surface of a high temperature member facing a high temperature flow path through which a high temperature gas flows,
A film cooling hole having a jet opening opened on the surface of the high temperature member, and at least one depression provided on the surface of the high temperature member corresponding to the jet outlet,
The film is characterized in that the recess is located upstream of the jet port in the flow direction of the hot gas and is symmetrical about the center line of the jet port extending in the flow direction of the hot gas. Cooling structure.   2. The film cooling structure according to claim 1, wherein the recess includes a pair of recesses each having a minor axis and a major axis, and a distance between the major axes is widened toward the downstream side in the flow direction of the high-temperature gas. A film cooling structure in which the pair of recesses are arranged as described above.   3. The film cooling structure according to claim 2, wherein upstream portions of the pair of recesses overlap each other on a center line of the ejection port.   3. The film cooling structure according to claim 2, wherein the pair of recesses are arranged apart from each other with a center line of the jet port interposed therebetween.   3. The film cooling structure according to claim 2, wherein the length of the minor axis of the recess is equal to or less than the diameter of the film cooling hole.   The film cooling structure according to claim 1, wherein a plurality of the depressions are arranged in a flow direction of the high-temperature gas.   The film cooling structure according to claim 1, wherein the recess is formed as a curved surface having no corners except for an edge that is a boundary with the surface of the high temperature member.   2. The film cooling structure according to claim 1, wherein the film cooling hole is a circular hole having a circular cross section perpendicular to the center line.   2. The film cooling structure according to claim 1, wherein a distance taken in the flow direction of the high-temperature gas between the ejection port and the depression is not more than four times the diameter of the film cooling hole.   A turbine blade provided with the film cooling structure according to claim 1.   A combustor liner comprising the film cooling structure of claim 1. A compressor for compressing air;
A combustor for combusting fuel with compressed air from the compressor;
A gas turbine comprising the turbine blade of claim 10 and driven by combustion gas from the combustor. A compressor for compressing air;
A combustor comprising the combustor liner of claim 11 for combusting fuel with compressed air from the compressor;
A gas turbine comprising: a turbine driven by combustion gas from the combustor. A film cooling method for forming a film cooling film on the surface of a high temperature member facing a high temperature flow path through which a high temperature gas flows,
Formed symmetrically about the center line of the jet port extending in the flow direction of the hot gas so as to be located upstream of the jet port of the film cooling hole opened in the surface of the hot member in the flow direction of the hot gas Arranging at least one hollow on the surface of the high temperature member;
The swirling component in a direction to blow down toward the film cooling hole is imparted to the high temperature gas passing through the depression, and the cooling gas ejected from the film cooling hole is pressed by the swirling high temperature gas, and the cooling from the surface of the high temperature member is performed. A film cooling method characterized by suppressing gas separation.

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