Turbine blade cooling structure and engine adapted to integrated printing

Abstract

A turbine blade cooling structure and engine adapted to integrated printing and forming, the turbine blade cooling structure adapted to integrated printing and forming comprises the leading edge, trailing edge, pressure surface and suction surface of the turbine blade; a first cooling zone, a second cooling zone and a third cooling zone are sequentially defined along the direction from the leading edge to the trailing edge: the first cooling zone comprises: an air film hole, which is arranged on the leading edge of the first cooling zone; a closed impact cooling plate, which is arranged inside the first cooling zone, and the impact cooling hole is arranged on the impact cooling plate; the second cooling zone comprises: two sets of inclined matrix ribs and a matrix rib support plate; the third cooling zone comprises: a slit groove. The present invention adopts a cooling structure combining three cooling zones, which improves the cooling effect while meeting the requirements of integrated printing and forming.

Description

Technical Field

[0001] The present invention relates to the field of turbine blade structure design and preparation, and in particular to a turbine blade cooling structure and an engine suitable for integrated printing molding. Background Art

[0002] With the increase of turbine inlet temperature, the efficiency and power of modern gas turbines have increased. The turbine blades and vanes are exposed to high temperatures, which exceed the melting point of metal compounds. Therefore, internal cooling structures are required. For turbine blade cooling structures, it is important to use appropriate boundary conditions and perform reasonable mechanical design to avoid excessive temperature gradients. Because excessive temperature gradients will increase thermal stress and reduce component life.

[0003] Internal cooling and external cooling are two important methods of cooling turbine blades. The cooling air is drawn out from the compressor, and the size of the flow rate affects the turbine in the following ways: 1. If the turbine uses too much cooling air flow, the air volume at the head of the combustion chamber will be reduced, and the nitrogen oxide pollution in the combustion chamber will increase at the same power. 2. If the turbine uses too much cooling air flow, the trailing edge of the turbine blade will be thickened, resulting in a large wake area, which reduces the aerodynamic efficiency. 3. If the cooling air flow is not enough to cool the turbine, the life of the components will be reduced.

[0004] Therefore, designing a suitable turbine cooling structure to keep the cooling air flow within the appropriate range is beneficial to the entire gas turbine design and requires a closed-loop process of "design-calculation-test-design-..." Testing and trial production are the last link in the R&D process, which ultimately enables the mass production of turbine blades and requires cooperation between the R&D team and the processing team.

[0005] General design scheme of gas turbine primary conductor:

[0006] Usually, the blade is divided into three sections along the height direction: blade root, blade middle, and blade tip. Cooling air enters the cooling passage from the blade root. The blade middle is the main place for cooling air heat exchange. When designing the blade tip, attention should be paid to whether cooling air enters and aerodynamic efficiency.

[0007] Turbine cooling blades are usually divided into zones along the blade chord length, where short blades are divided into two zones and long blades are divided into three zones (I, II, and III zones, such as Figure 1 According to the possible bad points in the manufacturing process or problems in the operation of each zone, the impact on the life of the entire blade is evaluated to determine the different machining accuracy requirements for the three zones.

[0008] Each design company designs the cooling structure according to the design requirements of the turbine (combustion chamber outlet gas velocity, gas pressure, mainstream gas turbulence, cold air flow range, cold air temperature, cold air pressure, etc.) and the accumulated empirical formulas, and fine-tunes the specific dimensions of each cooling unit to complete the conceptual design. After the preliminary design scheme is iterated by CFD (computational fluid dynamics), design experiments such as heat exchange tests are carried out to form a preliminary detailed design, and the shape is determined by blade tests, and the cooling effect is determined by cooling tests using thermal paint, etc. The thermal shock resistance of the system is determined by thermal shock tests and the cause of the damage point is determined. This series of design iterations and tests requires rapid modeling and processing of turbine blades, and the design cycle is about one year. If traditional casting is used, it will take at least another year, and the product is expensive. If the blades after the test are modified again, another cycle will be required. Using advanced 3D printing as a processing method, design problems can be quickly fed back and modified, and the molding cycle is short. At the same time, the price of the first piece of printed trial production is cheaper than casting. Therefore, the use of printing for turbine blade design can meet the needs of shortening cycle time and reducing costs.

[0009] 3D printing is formed by stacking layers, and its processing advantages are particularly evident in complex structures such as holes and curved surfaces. However, traditional turbine designs, especially internal cooling structures, are not designed for 3D printing and cannot take advantage of this processing method. If the suspended angle of the printed structure exceeds the material allowable value, the surface roughness of the molded part will increase, or collapse during the printing process will cause printing failure. On the other hand, if we excessively pursue the printing of complex structures without starting from the requirements of turbine blade cooling design to design practical and efficient products, it is undoubtedly putting the cart before the horse. Summary of the invention

[0010] In view of this, the main purpose of the present invention is to provide a turbine blade cooling structure and an engine suitable for integrated printing, so as to at least partially solve at least one of the above-mentioned technical problems.

[0011] The technical solution of the present invention:

[0012] As one aspect of the present invention, a turbine blade cooling structure suitable for integrated printing is provided, comprising a leading edge, a trailing edge, a pressure surface and a suction surface of the turbine blade; a first cooling zone, a second cooling zone and a third cooling zone are sequentially defined from the leading edge to the trailing edge:

[0013] The first cooling zone comprises:

[0014] Air film holes, arranged on the leading edge of the first cooling zone;

[0015] A closed impingement cooling plate is disposed inside the first cooling zone, and impingement cooling holes are disposed on the impingement cooling plate;

[0016] The second cooling zone comprises:

[0017] Two sets of inclined matrix ribs, the two sets of inclined matrix ribs are respectively arranged close to one side of the pressure surface and one side of the suction surface;

[0018] A matrix rib support plate is disposed between the two sets of inclined matrix ribs, and one end of the matrix rib support plate is connected to the impingement cooling plate, and the other end of the matrix rib support plate extends to the inner wall close to the trailing edge;

[0019] The third cooling zone includes:

[0020] A split groove extending in a chord length direction, one end of the split groove being connected to the second cooling zone, and the other end of the split groove penetrating the pressure surface;

[0021] Wherein, a partition is arranged between the first cooling zone and the second cooling zone, and a partition through hole is arranged on the partition.

[0022] As another aspect of the present invention, an engine is also provided, which includes a turbine blade, and the turbine blade includes the turbine blade cooling structure adapted for integrated printing as described above.

[0023] Based on the above technical solution, the present invention has at least one or part of the following beneficial effects compared with the prior art:

[0024] 1. The cooling structure of turbine blades suitable for integrated printing and forming proposed by the present invention adopts the method of impingement cooling for the inner layer and air film cooling for the outer layer in the first cooling zone; the method of matrix rib cooling is adopted in the second cooling zone; the method of slit groove cooling is adopted in the third cooling zone; the three cooling zones adopt different cooling methods for different positions, and the three cooling zones are combined through interval through holes, which not only meets the actual internal cooling needs, but also adapts to the SLM (integrated selective laser melting) printing processing method;

[0025] 2. The inner impact cooling plate is in a diamond or teardrop shape, and one end of the diamond is connected to the front edge to prevent the impact cooling plate from being suspended in the air during printing;

[0026] 3. In the second cooling zone, the pressure surface and the suction surface have two layers of inclined matrix ribs respectively. The two sets of inclined matrix ribs are separated by a matrix rib support plate. The height of the inclined matrix ribs is continuously reduced along the chord length direction. The angle between the inclined matrix ribs and the connected matrix rib support plate, pressure surface or suction surface is 10° to 40° to avoid the structure from hanging in the printing. There is a guide structure at the inlet of the inclined matrix ribs. The two ends and the middle of the inclined matrix ribs along the blade height direction are closed surfaces, so that the airflow inside the inclined matrix ribs is folded to another layer on the closed surface to increase the flow length;

[0027] 4. One end of the split groove is on the pressure surface, and holes can be opened between each split groove to allow air flow;

[0028] 5. Compared with the traditional processing method, the design cycle of the present invention is short;

[0029] 6. The price of the test verification parts produced by printing is cheaper than that of casting by traditional processing methods, which is helpful to reduce the design cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the partitioning of turbine cooling blades along the chord length direction in the prior art;

[0031] Figure 2 A three-dimensional schematic diagram of a turbine blade cooling structure adapted for integrated printing and forming according to an embodiment of the present invention;

[0032] Figure 3 It is a front view of a turbine blade cooling structure adapted for integrated printing and forming according to an embodiment of the present invention;

[0033] Figure 4 A top view of a cold zone structure of a turbine blade adapted for integrated printing and forming according to an embodiment of the present invention;

[0034] Figure 5 for Figure 3 Middle DD section cutaway view;

[0035] Figure 6 for Figure 3 Middle EE section cutaway view;

[0036] Figure 7 for Figure 3 Middle FF section cutaway view;

[0037] Figure 8 for Figure 4 Middle GG section cutaway view;

[0038] Fig. 9 Schematic diagram of the airflow direction of the inclined matrix ribs according to an embodiment of the present invention.

[0039] In the above drawings, the meanings of the reference numerals are as follows:

[0040] 1. First cooling zone; 2. Second cooling zone; 3. Air film hole; 6. Slit groove; 7. Leading edge; 8. Trailing edge; 9. Impact cooling plate; 10. Inclined matrix ribs; 11. Matrix rib support plate; 12. Interval through hole; 13. Third cooling zone; 14. Pressure surface; 15. Suction surface; 16. Partition. DETAILED DESCRIPTION

[0041] The following technical problems exist in the design of traditional turbine blade cooling structure:

[0042] 1. The existing turbine blade design process still uses the traditional casting process, which is expensive. The designed blades need to be repeatedly modified based on the test results, and the total design cycle is extremely long.

[0043] 2. After the traditional turbine blade is designed, the first trial-made one needs to be cast, and the product price is expensive;

[0044] 3. At the same time, the existing turbine blade cooling structure is not suitable for integrated SLM (selective laser melting) printing. The traditional turbine blade cooling structure is prone to the problem of cooling structure overhang during SLM printing.

[0045] Based on this, the present invention proposes a turbine blade cooling structure that is adaptable to integrated printing and molding for a selective laser melting (SLM) processing method.

[0046] Compared with traditional processing methods, the turbine blade cooling structure proposed in the present invention is suitable for integrated selective laser melting (SLM) processing and printing, and has a short design cycle. It avoids the problem that the traditional processing method has an initial design cycle of about one year, and the use of traditional casting molding technology requires at least one year. The designed blades also need to be repeatedly iterated and modified based on the test results, resulting in an extremely long total design cycle.

[0047] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0048] In an embodiment of the present invention, a turbine blade cooling structure suitable for integrated printing is provided, such as Figure 1 As shown, the turbine blade includes a leading edge 7, a trailing edge 8, a pressure surface 14 and a suction surface 15; a first cooling zone 1, a second cooling zone 2 and a third cooling zone 13 are sequentially defined along the direction from the leading edge 7 to the trailing edge 8, wherein:

[0049] like Figure 2 , Figure 3 and Figure 4As shown, the first cooling zone 1 comprises: an air film hole 3, which is arranged on the front edge 7 of the first cooling zone 1; a closed impingement cooling plate 9, which is arranged inside the first cooling zone 1, and an impingement cooling hole is arranged on the impingement cooling plate 9;

[0050] like Figure 2 , Figure 3 and Figure 8 As shown, the second cooling zone 2 includes: two sets of inclined matrix ribs 10, which are respectively arranged near the pressure surface 14 and the suction surface 15; a matrix rib support plate 11, which is arranged between the two sets of inclined matrix ribs 10, and one end of the matrix rib support plate 11 is connected to the impingement cooling plate 9, and the other end of the matrix rib support plate 11 extends to the inner wall close to the trailing edge 8 but is not connected thereto; wherein, the design of the matrix rib support plate 11 divides the second cooling zone 2 into a pressure surface cavity and a suction surface cavity, and is also a support structure for the printing direction from the leading edge 7 to the trailing edge 8 of the blade;

[0051] Figure 2 , Figure 6 and Figure 8 As shown, the third cooling zone 13 includes: a slit groove 6 extending along the chord length direction, one end of the slit groove 6 is connected to the second cooling zone 2, and the other end of the slit groove 6 passes through the pressure surface 14;

[0052] like Figure 2 , Figure 7 and Figure 8 As shown, a partition plate 16 is arranged between the first cooling zone 1 and the second cooling zone 2 , and a partition through hole 12 is arranged on the partition plate 16 .

[0053] The turbine blade cooling structure suitable for integrated printing and forming proposed in the embodiment of the present invention adopts the method of impingement cooling for the inner layer and air film cooling for the outer layer in the first cooling zone 1; the second cooling zone 2 adopts the method of matrix rib cooling; the third cooling zone 13 (i.e., the tail cooling zone) adopts the method of slit groove cooling; the three cooling zones adopt different cooling methods for different positions, and the three cooling zones are combined through the interval through holes 12, which improves the cooling effect while meeting the requirements of printing and forming.

[0054] In an embodiment of the present invention, Figure 2 , Figure 3 and Figure 8 As shown, the partition 16 includes two, one end of the partition 16 is connected to the impingement cooling plate 9, and the other end of the partition 16 is connected to the pressure surface 14 or the suction surface 15; the impingement cooling plate 9 and the two partitions 16 separate the first cooling zone 1 into a first cooling cavity and a second cooling cavity; wherein the first cooling cavity is the internal space formed by the impingement cooling plate 9; the second cooling cavity is the space formed outside the impingement cooling plate 9, inside the blade leading edge 7 and surrounded by the partition 16;

[0055] The cooling compressed air enters the first cooling cavity from the blade top or blade root, enters the second cooling cavity along the cooling impact hole, and then enters the second cooling zone 2 for cooling through the interval through holes 12 on the partition 16.

[0056] In the embodiment of the present invention, the impingement cooling plate 9 is configured to be in a hollow rhombus shape or a water drop shape.

[0057] It is worth mentioning that the leading edge 7 , i.e. the head, is designed in a diamond or teardrop shape in order to be suitable for printing from the leading edge 7 to the trailing edge 8 of the blade.

[0058] In an embodiment of the present invention, when the impingement cooling plate 9 is diamond-shaped, one end of the impingement cooling plate 9 is connected to the inner wall of the leading edge 7 to avoid being suspended during printing, which helps printing without adding additional support.

[0059] In an embodiment of the present invention, Figure 7 and Figure 8 As shown, each set of inclined matrix ribs 10 includes two layers, and each layer of inclined matrix ribs 10 is connected to adjacent matrix rib support plates 11, pressure surfaces 14 or suction surfaces 15, and the included angle is 10° to 40°.

[0060] The most important point in adapting to the integrated printing and molding technology is to avoid the phenomenon of overhanging. Different materials have different overhanging angle requirements.

[0061] In an embodiment of the present invention, the material of the turbine blade is a nickel-based high-temperature alloy. When the angle is too large, exceeding 45°, it will cause the surface roughness of the molded part to increase, or collapse during the printing process; therefore, the angle between the inclined matrix rib 10 and the matrix rib support plate 11, the pressure surface 14 or the suction surface 15 of the embodiment of the present invention is preferably 10° to 40°.

[0062] In the embodiment of the present invention, the height of the inclined matrix ribs 10 gradually decreases along the chord length direction. The purpose of designing the inclined matrix ribs 10 to gradually decrease in height along the chord length direction is to ensure that the flow area remains approximately unchanged and that a large amount of pressure loss is not generated.

[0063] In an embodiment of the present invention, Figure 5 , Figure 6 and Fig. 9 As shown, the inclined matrix rib 10 is provided with an inclined matrix rib inlet on one side close to the partition 16, and the inclined matrix rib 10 is provided with a flow guide structure at the inclined matrix rib inlet. The flow guide structure is a curved shape with a guide circle at the inclined matrix rib inlet. The flow guide structure is also helpful for printing without support.

[0064] In an embodiment of the present invention, Figure 5 , Figure 6 and Fig. 9 As shown, closed surfaces are provided at both ends and in the middle of the inclined matrix ribs 10 in the height direction of the turbine blades, so as to allow the internal airflow of one layer of inclined matrix ribs 10 to be deflected on the closed surfaces to another layer of inclined matrix ribs 10, thereby increasing the flow length and effectively utilizing the cold air by the turning.

[0065] In the embodiment of the present invention, a plurality of slit grooves 6 are provided, and through holes for air flow are provided between each slit groove 6 .

[0066] In the embodiment of the present invention, the aperture of the air film hole 3 is 0.5 mm; the aperture of the interval through hole 12 is greater than 1 mm; and the aperture of the impact cooling hole is 1 mm.

[0067] It is worth mentioning that the design of the turbine blade cooling structure adapted to integrated printing molding of the present invention not only needs to pay attention to the problem of suspension, but also the size of the aperture, which should not be too small or too large. If it is too small, firstly, it is not good for the resistance coefficient (Cd), resulting in an increase in the pressure loss through the hole and a decrease in the cold air flow; secondly, it is not conducive to the removal of impurities and the blowing of powder during the printing process. If it is too large, it will lead to excessive cold air flow.

[0068] Therefore, the appropriate aperture of the air film hole is 0.5 mm; the aperture of the interval through hole is greater than 1 mm; and the aperture of the impact cooling hole is 1 mm.

[0069] As another aspect of the present invention, an engine is also provided, the engine comprising a turbine blade, the turbine blade comprising the turbine blade cooling structure adapted for integrated printing as described above.

[0070] More specifically, the turbine blade cooling structure adapted for integrated printing molding in an embodiment of the present invention is a 3D printed gas turbine cooling blade, which is suitable for the first-stage guide vanes of a 50MW gas turbine. Under the ISO (International Organization for Standardization) operating condition of the gas turbine, the turbine front inlet temperature is 1500K, and the TCLA (cooling and leakage air) flow rate is less than 15%.

[0071] Example 1

[0072] A turbine blade cooling structure suitable for integrated printing is a 3D printed gas turbine cooling blade suitable for the first-stage guide vane of a 50MW gas turbine. Under ISO conditions, the turbine front inlet temperature is 1500K and the TCLA flow rate is less than 15%.

[0073] The turbine blade cooling structure adapted for integrated printing molding of the present invention has a diameter of the air film hole 3 of 0.5 mm;

[0074] The impingement cooling plate 9 is in a water drop shape, and the diameter of the impingement cooling holes on the impingement cooling plate 9 is 1 mm;

[0075] The pressure surface 14 and the suction surface 15 of the second cooling zone 2 are respectively independent double-layer inclined matrix ribs 10, and a matrix rib support plate 11 is added between the two sets of inclined matrix ribs 10; the single rib width of the inclined matrix rib 10 is 1.5mm, the rib spacing is 3.5mm, and the rib height continuously decreases along the chord length direction; the angle between the inclined matrix rib 10 and the adjacent matrix rib support plate 11, pressure surface 14 or suction surface 15 is 10°~40°.

[0076] It is worth mentioning that the specific embodiment of the present invention is mainly aimed at the existing turbine blade shape, the blade shape remains unchanged, and the internal cooling channel is designed for the middle part of the blade. Therefore, the other two parts, namely the blade top and the blade root, are not marked in the attached figure, and can be added when the turbine blade is actually printed.

[0077] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A turbine blade cooling structure adapted for integrated printing, comprising a leading edge, a trailing edge, a pressure surface and a suction surface of the turbine blade; characterized in that: The first cooling zone, the second cooling zone and the third cooling zone are defined in sequence from the leading edge to the trailing edge: The first cooling zone comprises: Air film holes, arranged on the leading edge of the first cooling zone; A closed impingement cooling plate is disposed inside the first cooling zone, and impingement cooling holes are disposed on the impingement cooling plate; The second cooling zone comprises: Two sets of inclined matrix ribs, the two sets of inclined matrix ribs are respectively arranged close to one side of the pressure surface and one side of the suction surface; A matrix rib support plate is disposed between the two sets of inclined matrix ribs, and one end of the matrix rib support plate is connected to the impingement cooling plate, and the other end of the matrix rib support plate extends to the inner wall close to the trailing edge; The third cooling zone includes: A split groove extending in a chord length direction, one end of the split groove being connected to the second cooling zone, and the other end of the split groove penetrating the pressure surface; Wherein, a partition is arranged between the first cooling zone and the second cooling zone, and a partition through hole is arranged on the partition; Wherein, each set of inclined matrix ribs includes two layers, and the inclined matrix ribs of each layer are connected to the adjacent matrix rib support plate, pressure surface or suction surface; The inclined matrix ribs are provided with closed surfaces at both ends and in the middle along the height direction of the turbine blades, so as to deflect the internal airflow of one layer of inclined matrix ribs to the inclined matrix ribs of another layer on the closed surface, thereby increasing the flow length.

2. The turbine blade cooling structure adapted for integrated printing molding according to claim 1, characterized in that: The partition includes two, one end of the partition is connected to the impingement cooling plate, and the other end of the partition is connected to the pressure surface or the suction surface; the impingement cooling plate and the two partitions separate the first cooling zone into a first cooling cavity and a second cooling cavity; The cooling compressed air introduced into the first cooling cavity enters the second cooling cavity along the cooling impact hole, and then enters the second cooling zone through the interval through holes on the partition for cooling.

3. The turbine blade cooling structure adapted for integrated printing molding according to claim 1, characterized in that: The impingement cooling plate is configured to be in a hollow rhombus shape or a water drop shape.

4. The turbine blade cooling structure adapted for integrated printing as claimed in claim 3, characterized in that: When the impact cooling plate is in a diamond shape, one end of the impact cooling plate is connected to the inner wall of the front edge to avoid being suspended during printing.

5. The turbine blade cooling structure adapted for integrated printing as claimed in claim 1, characterized in that: The angle between the inclined matrix ribs of each layer and the adjacent matrix rib support plate, pressure surface or suction surface is 10°~40°; The height of the inclined matrix ribs gradually decreases along the chord length direction.

6. The turbine blade cooling structure adapted for integrated printing as claimed in claim 5, characterized in that: The inclined matrix ribs are provided with an inclined matrix rib inlet at a side close to the partition plate, and the inclined matrix ribs are provided with a flow guide structure at the inclined matrix rib inlet.

7. The turbine blade cooling structure adapted for integrated printing as claimed in claim 1, characterized in that: A plurality of slit grooves are provided, and through holes for air flow are provided between each slit groove.

8. The turbine blade cooling structure adapted for integrated printing as claimed in claim 1, characterized in that: The aperture of the air film hole is 0.5 mm; The diameter of the interval through hole is greater than 1 mm; The diameter of the impact cooling hole is 1 mm.

9. An engine comprising a turbine blade, characterized in that: The turbine blade comprises a turbine blade cooling structure adapted for integrated printing and forming as described in any one of claims 1 to 8.

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