Turbine blade turbulent flow column and annular pit combined cooling enhancing structure and application thereof

Abstract

The invention belongs to the technical field of internal cooling of turbine blades of aero-engines, and particularly discloses a turbine blade turbulent flow column and annular pit combined cooling enhancement structure and application thereof.The turbine blade turbulent flow column and annular pit combined cooling enhancement structure comprises two structure bodies arranged in a spaced mode, and a cylindrical turbulent flow column with a dish-shaped protruding part is connected between the two structure bodies; annular pits are formed in the positions, connected with the turbulent flow columns, of the two structure bodies, the longitudinal cutting section shapes of the annular pits are the same as half of the dish-shaped protruding parts, and the volumes are complementary. The cooling channel body comprises a pressure side wall face and a suction side wall face, the two ends of the cylindrical turbulent flow column are connected with the two side wall faces respectively, heat exchange blocks are arranged on the wall faces, and the annular pits are located in the heat exchange blocks. According to the structure, the heat exchange area is increased, the heat exchange effect of the near wall surface is enhanced, and secondary flow and vortex system mixing is combined, so that the cooling performance is remarkably improved. The cooling enhancing structure is particularly suitable for the tail edge of a turbine blade and other areas with narrow internal spaces, the cooling efficiency can be improved on the premise that the weight is not increased, and meanwhile the structural strength and stability are both considered.

Description

Technical Field

[0001] The invention relates to the technical field of internal cooling of aero-engine turbine blades, and in particular to a turbine blade spoiler column and annular pit combined cooling enhancement structure and application thereof. Background Art

[0002] As aviation demand continues to grow, the requirements for aircraft engine performance are also gradually increasing. Studies have shown that for every 100K increase in the temperature before the turbine, the thrust of the aircraft engine can be increased by about 10%. However, the current allowable temperature of aircraft engine turbine blade materials is only about 1300K, which is still a huge gap compared to the 2000K turbine inlet temperature of high-performance engines. Therefore, in order to ensure that the turbine blades, as key components, have a long service life, they must be cooled.

[0003] The turbine blades of aircraft engines are mainly composed of three parts: the leading edge, the mid-chord and the trailing edge. Its cooling technology is mainly divided into internal cooling and external cooling. Among them, the trailing edge is limited by the blade shape, the overall thickness is low and the internal space is small, and the air film holes cannot be arranged. Therefore, the thermal load is high, and it is one of the key areas of thermal failure of the blade. As an important cooling enhancement structure, the spoiler column can increase the heat exchange area, enhance the local vortex system and improve the overall structural strength. It is a commonly used cooling enhancement method for the trailing edge. In recent years, the annular pit cooling structure has gradually attracted attention as an emerging cooling enhancement structure. It has a low pressure loss, can increase the secondary flow intensity, and then strengthen the heat exchange and improve the cooling effect. Therefore, how to combine the existing spoiler column structure with the annular pit structure to meet the needs of efficient cooling of aircraft engine turbine blades has become a technical problem that technicians in this field need to solve urgently. Summary of the invention

[0004] The purpose of the present invention is to provide a turbine blade spoiler column and annular pit combined cooling enhancement structure and its application. On the basis of the existing turbine blade internal cooling technology, the traditional spoiler column structure is optimized and modified, and combined with the annular pit structure, so as to further enhance the heat exchange effect to meet the needs of efficient cooling of aircraft engine turbine blades.

[0005] To achieve the above-mentioned purpose, in one aspect, the present invention provides a turbine blade spoiler column and annular pit combined cooling enhancement structure, comprising two structural bodies arranged at intervals, a cylindrical spoiler column being connected between the two structural bodies, the cylindrical spoiler column comprising a spoiler column body and a dish-shaped protrusion located on the circumference of the spoiler column body, the dish-shaped protrusion being arranged in the middle of the spoiler column body, and its longitudinal cross-section shape is elliptical, annular pits are provided around the circumference of the cylindrical spoiler column at the positions where the two structural bodies connect the cylindrical spoiler columns, the annular pits are concentric with the spoiler column body, and the longitudinal cross-section shapes of the two annular pits are identical and symmetrical.

[0006] In some alternative embodiments of the present invention, the longitudinal cross-sectional shape of the annular pit is the same as half of the longitudinal cross-sectional shape of the dish-shaped protrusion, and the volumes of the two annular pits are complementary to the volume of the dish-shaped protrusion.

[0007] In some alternative embodiments of the present invention, the diameter of the spoiler column body is a, the length of the minor axis of the ellipse of the longitudinal cross-section of the dish-shaped protrusion is 2b, the length of the major axis of the ellipse of the longitudinal cross-section of the dish-shaped protrusion is 2c, the diameter of the annular pit is 2c, and the depth is b.

[0008] In some alternative embodiments of the present invention, the diameter 2c of the annular pit is equal to twice the diameter a of the spoiler column body, and 2c = 2a = 8 mm; the length 2b of the minor axis of the ellipse of the longitudinal cross-section of the dish-shaped protrusion is equal to half of the diameter a of the spoiler column body, and 2b = 0.5a = 2 mm.

[0009] In some alternative embodiments of the present invention, the spoiler column body, the dish-shaped protrusion, and the two structural bodies are integrally formed.

[0010] On the other hand, the present invention also provides an internal cooling channel for a turbine blade, including a cooling channel body and a plurality of cooling structures provided in the cooling channel body, and the cooling structure is the combined cooling enhancement structure of the turbine blade spoiler column and the annular pit described in any one of the above.

[0011] In some alternative embodiments of the present invention, the cooling channel body includes a pressure side wall surface and a suction side wall surface, and two ends of the cylindrical spoiler column are connected to the pressure side wall surface and the suction side wall surface.

[0012] In some alternative embodiments of the present invention, heat exchange blocks protrude from the outer sides of the pressure side wall surface and the suction side wall surface, the annular pit is provided inside the heat exchange block, the heat exchange block is 30 mm long, 14 mm wide, and the distance between adjacent two heat exchange blocks is 2 mm.

[0013] In some alternative embodiments of the present invention, the cooling structures are arranged in 4 rows along the inlet and outlet directions of the cooling channel body, and 2 are arranged in parallel in each row.

[0014] In some alternative embodiments of the present invention, the cooling channel body includes a flow stabilizing section and a heat exchange section, the flow stabilizing section is arranged near the inlet of the cooling channel body, and a plurality of cooling structures are arranged in the heat exchange section.

[0015] Compared with the prior art, the present invention discloses at least the following beneficial effects:

[0016] By combining the disc-shaped protrusions with the annular pits, the present invention achieves volume complementarity, thus significantly increasing the heat transfer area. Meanwhile, the use of turbulator structures effectively enhances the overall structural strength. When the air flow passes through the disc-shaped protrusions, its large surface area can come into full contact with the air flow to achieve efficient heat transfer. In addition, a low-temperature region is formed in the middle of the turbulators, thereby increasing the heat flux density inside the turbulators. When the air flow passes through the disc-shaped protrusions, it also pushes the gas towards the wall, increasing the gas velocity entering the annular pits, thus enhancing the heat transfer effect of the annular pits. When the air flow passes through the annular pits, the secondary flow generated mixes with the near-wall vortex system of the turbulators to form a higher near-wall heat transfer effect.

[0017] Verified by numerical calculation, under the same channel aerodynamic parameter settings, compared with the traditional turbulator structure with the same hydraulic diameter (i.e., the same diameter), the structure of the present invention can provide at least a 17.7% increase in the Nusselt number. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a longitudinal cross-sectional view of the combined cooling enhancement structure of the turbulator and the annular pit of the turbine blade of the present invention;

[0020] Figure 2 It is a front view of the internal cooling channel of the turbine blade provided with the cooling enhancement structure of the present invention;

[0021] Figure 3 It is a side view of the internal cooling channel of the turbine blade provided with the cooling enhancement structure of the present invention;

[0022] Figure 4 It is an axonometric view of the internal cooling channel of the turbine blade provided with the cooling enhancement structure of the present invention;

[0023] Figure 5 It is a front view of the internal cooling channel of the turbine blade provided with the traditional turbulator;

[0024] Figure 6 It is a comparison diagram of the numerical calculation results of the heat transfer effects of the internal cooling channel of the turbine blade applying the cooling enhancement structure of the present invention and the internal cooling channel of the turbine blade provided with the traditional turbulator;

[0025] In the figure: 1, structural body; 2, turbulator body; 3, disc-shaped protrusion; 4, annular pit; 5, cooling channel body; 6, cooling structure; 7, inlet; 8, outlet; 9, heat exchange block; 10, traditional turbulator. Detailed implementation manner

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] To solve the problem that the current internal cooling capacity of turbine blades is insufficient and cannot meet the increasing cooling requirements, the embodiments of the present invention propose a combined cooling enhancement structure of a turbulator and an annular pit for turbine blades, which increases the heat exchange area and improves the heat exchange effect without changing the unit structural mass and hardly changing the flow resistance, so as to have better cooling performance.

[0028] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0029] Embodiment 1

[0030] Referring to Figure 1 As shown, the embodiments of the present invention provide a combined cooling enhancement structure of a turbulator and an annular pit for turbine blades, including two spaced structural bodies 1. A cylindrical turbulator is connected between the two structural bodies 1. The cylindrical turbulator includes a turbulator body 2 and a disc-shaped protrusion 3 located on the circumferential side of the turbulator body 2. The turbulator body 2 is a cylindrical structure, and the longitudinal cross-sectional shape of the disc-shaped protrusion 3 is an ellipse. The above-mentioned various mechanisms are integrally formed with smooth transitions. The two structural bodies 1 are respectively connected to both ends of the cylindrical turbulator, and annular pits 4 surrounding the circumferential side of the cylindrical turbulator are provided at the positions where the two structural bodies 1 are connected to the cylindrical turbulator. The longitudinal cross-sectional shapes of the two annular pits 4 are the same as the longitudinal cross-sectional shape of the disc-shaped protrusion 3. The shape of a single-sided annular pit 4 is half of an ellipse. Therefore, the volume of the annular pits 4 on the two structural bodies 1 is complementary to the volume of the disc-shaped protrusion 3.

[0031] In a specific embodiment, the diameter of the turbulator body 2 is a, the height of the dish-shaped protrusion 3 (i.e., the length of the minor axis of the ellipse in the longitudinal cross-section of the dish-shaped protrusion 3) is 2b, the maximum outer diameter of the dish-shaped protrusion 3 (i.e., the length of the major axis of the ellipse in the longitudinal cross-section of the dish-shaped protrusion 3) is 2c, and the diameter of the annular pit 4 is 2c and the depth is b. Among them, the major axis length 2c of the ellipse = 2a = 8 mm (i.e., the semi-major axis length c is equal to the diameter a of the turbulator body 2, equal to 4 mm), the minor axis length 2b of the ellipse = 0.5a = 2 mm, the depth b of the unilateral annular pit 4 is equal to the semi-minor axis length of the ellipse, equal to 1 mm, and the diameter 2c of the annular pit 4 is equal to the major axis length of the ellipse, equal to 8 mm.

[0032] Embodiment 2

[0033] Referring to Figures 2 to 4 As shown, Embodiment 2 of the present invention further provides an internal cooling channel for a turbine blade. The internal cooling channel for the turbine blade applies the combined cooling enhancement structure of the turbulator and the annular pit of the turbine blade in Embodiment 1 of the present invention. The internal cooling channel for the turbine blade is provided in the turbine blade, and is particularly suitable for the internal cooling of the trailing edge of the turbine blade. The internal cooling channel for the turbine blade includes a cooling channel body 5. The cooling channel body 5 has an inlet 7 and an outlet 8, and the interior is a hollow gas domain. The total length g = 140 mm. A flow stabilizing section is provided at the front of the channel, and the length of the flow stabilizing section d = 60 mm. The middle is a heat exchange section, and 4 rows and 2 columns of cooling structures 6 are provided in the heat exchange section. The cooling structure 6 is the combined cooling enhancement structure of the turbulator and the annular pit of the turbine blade in Embodiment 1 of the present invention.

[0034] Specifically, the cooling channel body 5 includes a pressure side wall surface and a suction side wall surface. A cylindrical turbulator with a dish-shaped protrusion 3 is provided between the two side wall surfaces. Annular pits 4 are provided on both the pressure side wall surface and the suction side wall surface. The position of the annular pit 4 is at the root of the cylindrical turbulator and is coaxially arranged with the axis of the cylindrical turbulator.

[0035] Specifically, both the inlet 7 and the outlet 8 of the cooling channel body 5 are rectangular cross-sections with a cross-section of 30 mm × 10 mm. The two side wall surfaces at both ends of the cylindrical turbulator are connected. This wall surface is modeled as 4 groups of a total of 8 heat exchange blocks 9 provided on the two side wall surfaces. The wall temperature and other conditions of the actual blade are simulated by the heat exchange blocks 9. Each heat exchange block 9 has a length h = 30 mm and a width e = 14 mm. The heat exchange block 9 serves as the structural body 1 of the cooling structure 6, and an annular pit 4 is provided inside it. The interval f between each group of heat exchange blocks 9 is 2 mm. The boundary of the heat exchange section of the internal cooling channel provided with the cylindrical turbulator is determined by the heat exchange blocks 9, and must be able to completely cover structures such as the annular pit 4 provided on the wall surface.

[0036] As Figure 5 shown, Figure 5Shows the internal cooling channels of traditional turbine blades fabricated using the prior art. The internal cooling channels of the traditional turbine blades are used as a comparative example, with the same geometric parameters as the internal cooling channels of the turbine blades in Embodiment 2, and traditional turbulators 10 are provided therein. The diameter of the traditional turbulators 10 is the same as that of the cylindrical turbulators in Embodiment 2, but the disc-shaped protrusions 3 are not provided, and the annular pits 4 are not provided on the heat exchange blocks 9 connected thereto. In the internal cooling channels of the traditional turbine blades, the heat exchange blocks 9 are complete cuboids, and no other cooling structures 6 are provided.

[0037] In the present invention, the cylindrical turbulators with disc-shaped protrusions 3 are connected to the two side wall surfaces, which not only improves the overall structural strength but also increases the heat exchange area with the cooling air. When the air flow first impinges on the disc-shaped protrusions 3, heat exchange will occur with them first. At the same time, the disc-shaped protrusions 3 push the air flow towards the wall surface, increasing the air flow velocity near the wall surface and in the annular pits 4, and enhancing the heat exchange effect in the annular pits 4. Due to the large heat exchange area of the disc-shaped protrusions 3, it has a lower temperature under the same aerodynamic parameters, which can expand the temperature gradient, thereby increasing the heat flux density in the cylindrical turbulator part and enhancing the overall heat exchange. When the air flow passes through the cylindrical turbulators, strong wake flows will be generated or strong vortex systems will be generated near the wall surface. The vortex systems are mixed with the secondary flows generated by the annular pits 4 provided on the wall surface, enhancing the heat exchange effect on the inner wall surface of the annular pits 4.

[0038] As Figure 6 shown, numerical calculations are carried out using the channels shown in Figure 2 and Figure 5 . The temperature ratio TR = 0.13 is controlled as the overall temperature boundary condition, and its calculation formula is:

[0039]

[0040] wherein, is the average wall temperature of the wall surface of the heat exchange block 9 participating in heat exchange, and T in is the mainstream temperature at the inlet 7 of the internal cooling channel. The Reynolds number Re is controlled as the main aerodynamic parameter boundary condition, and the Nusselt number of the average heat exchange wall surface of the heat exchange block 9 is used as the parameter to evaluate the heat exchange effect. Under the condition that the Reynolds number ranges from 10000 to 70000, the cooling structure 6 can increase the Nusselt number by 17.7 - 21.2%.

[0041] An embodiment of the present invention proposes a combined cooling enhancement structure of a turbine blade turbulator and an annular pit and an internal cooling channel of a turbine blade including this structure, which has a relatively high convective cooling efficiency. While cooling the wall surface of the turbine blade, it can take into account the stability and strength of the overall structure of the turbine blade. This structure mainly adopts:

[0042] 1. A disc-shaped protrusion 3 is provided in the middle of the cylindrical turbulator to obtain a larger heat transfer area. The longitudinal section of the disc-shaped protrusion 3 is elliptical to reduce the influence of the flow resistance brought by the protrusion. 2. Annular pits 4 are provided on the wall surface of the cooling channel. The annular pits 4 are concentric with the turbulator body 2 of the cooling structure 6. The secondary flow generated by them is combined with the vortex system generated by the turbulator, and together with the enlarged heat transfer area of the annular pits 4, the heat transfer effect near the wall surface is enhanced. The longitudinal section of the annular pits 4 is the same ellipse as that of the disc-shaped protrusion 3.

[0043] 2. Compared with the prior art, the annular pits 4 have less requirement for the wall thickness of the turbine blade. Under the same thermal load condition, the number of turbulators arranged is reduced to reduce the weight of the turbine blade. The cylindrical turbulator cooling structure 6 with a disc-shaped protrusion 3 combined with the annular pits 4 is particularly suitable for internal cooling such as the trailing edge of the turbine blade.

[0044] In the present invention, the cylindrical turbulator with a disc-shaped protrusion 3 is connected to both wall surfaces of the internal cooling channel. Its disc-shaped protrusion 3 further increases the heat transfer area, longitudinally divides the air flow, and produces the effect of pushing part of the air flow close to the wall surface. The near-wall vortex system generated by the cylindrical turbulator structure is combined with the cooling of the annular pits 4 to enhance the heat transfer effect of the wall surface.

[0045] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0046] The embodiments described above are only for describing the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A turbine blade spoiler column and annular pit combined cooling enhancement structure, characterized in that: The invention comprises two structural bodies (1) arranged at intervals, wherein a cylindrical spoiler column is connected between the two structural bodies (1), wherein the cylindrical spoiler column comprises a spoiler column body (2) and a disc-shaped protrusion (3) located on the circumference of the spoiler column body (2), wherein the disc-shaped protrusion (3) is arranged in the middle of the spoiler column body (2), and its longitudinal section shape is an ellipse, and an annular pit (4) is arranged around the circumference of the cylindrical spoiler column at the position where the two structural bodies (1) connect the cylindrical spoiler columns, wherein the annular pit (4) is concentric with the spoiler column body (2), and the longitudinal section shapes of the two annular pits (4) are the same and symmetrical.

2. The turbine blade spoiler column and annular pit combined cooling enhancement structure according to claim 1 is characterized in that: The longitudinal cross-sectional shape of the annular pit (4) is the same as half of the longitudinal cross-sectional shape of the disc-shaped protrusion (3), and the volume of the two annular pits (4) is complementary to the volume of the disc-shaped protrusion (3).

3. The turbine blade spoiler column and annular pit combined cooling enhancement structure according to claim 1, characterized in that: The diameter of the spoiler column body (2) is a, the length of the ellipse minor axis of the longitudinal section of the dish-shaped protrusion (3) is 2b, the length of the ellipse major axis of the longitudinal section of the dish-shaped protrusion (3) is 2c, and the diameter of the annular pit (4) is 2c and the depth is b.

4. The turbine blade spoiler column and annular pit combined cooling enhancement structure according to claim 1, characterized in that: The diameter 2c of the annular pit (4) is equal to twice the diameter a of the spoiler column body (2), and 2c=2a=8mm; the length 2b of the elliptical minor axis of the longitudinal section of the dish-shaped protrusion (3) is equal to half the diameter a of the spoiler column body (2), and 2b=0.5a=2mm.

5. The turbine blade spoiler column and annular pit combined cooling enhancement structure according to claim 1, characterized in that: The spoiler column body (2), the disc-shaped protrusion (3) and the two structural bodies (1) are integrally formed.

6. A turbine blade internal cooling channel, characterized in that: It comprises a cooling channel body (5) and a plurality of cooling structures (6) arranged in the cooling channel body (5), wherein the cooling structure (6) is a cooling enhancement structure combined with a turbine blade spoiler column and annular pit as claimed in any one of claims 1 to 5.

7. The turbine blade internal cooling passage according to claim 6, characterized in that: The cooling channel body (5) comprises a pressure side wall surface and a suction side wall surface, and two ends of the cylindrical spoiler column are connected to the pressure side wall surface and the suction side wall surface.

8. The turbine blade internal cooling passage according to claim 7, characterized in that: The outer sides of the pressure side wall and the suction side wall are protruded with heat exchange blocks (9), the annular recess (4) is arranged inside the heat exchange block (9), the heat exchange block (9) is 30 mm long and 14 mm wide, and the interval between two adjacent heat exchange blocks (9) is 2 mm.

9. The turbine blade internal cooling passage according to claim 6, characterized in that: The cooling structures (6) are arranged in four rows along the inlet (7) and outlet (8) directions of the cooling channel body (5), with two cooling structures arranged in parallel in each row.

10. The turbine blade internal cooling passage according to claim 9, characterized in that: The cooling channel body (5) comprises a flow stabilizing section and a heat exchange section, the flow stabilizing section is arranged close to an inlet (7) of the cooling channel body (5), and a plurality of cooling structures (6) are arranged in the heat exchange section.

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