A double impingement film cooling structure with inclined impingement hole web

Abstract

The application discloses a double-impingement air film cooling structure with an inclined impingement hole web plate, which comprises a cold-side flat plate, a hot-side flat plate and an inclined impingement web plate connecting the two flat plates. A plurality of primary impingement holes are formed in the cold-side flat plate, and a plurality of secondary impingement holes are formed in the inclined impingement web plate. The cold-side flat plate, the hot-side flat plate and the inclined impingement web plate jointly form a primary impingement cavity and a secondary impingement cavity which are arranged in sequence along the direction of a cooling airflow. A plurality of air film holes are formed in the hot-side flat plate. The cooling airflow enters the primary impingement cavity through the primary impingement holes and impinges on the hot-side flat plate, then enters the secondary impingement cavity through the secondary impingement holes and impinges on the hot-side flat plate again, and finally flows out through the air film holes to form an air film on the outer surface of the hot-side flat plate. The application constructs two types of closed impingement cavities through the inclined impingement web plate, realizes the synergistic effect of twice impingement reinforced heat exchange and external air film protection, effectively reduces the outflow speed of the cooling air, and improves the utilization efficiency of the cooling air and the cooling effect.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine technology, specifically relating to a double-impact film cooling structure with a web plate featuring oblique impact holes. Background Technology

[0002] With the continuous improvement of the thrust-to-weight ratio of aero engines, the turbine inlet temperature has far exceeded the temperature resistance limit of existing high-temperature alloy materials. Therefore, it is necessary to adopt efficient cooling technologies to provide thermal protection for high-temperature components such as combustion chambers, turbine blades, and nozzles. The double-wall cooling structure combining impact cooling and film cooling is one of the mainstream cooling solutions for high-temperature components in advanced engines.

[0003] However, in areas with high pressure ratios between cold and combustion gases, such as the nozzle expansion section, traditional impact-film cooling structures suffer from the following problems: Firstly, the excessively high pressure ratio causes the cooling airflow to be ejected at high speed from the film orifice, making it difficult to adhere to the hot side wall, resulting in a blow-off phenomenon and reducing the film coverage effect. Secondly, increasing the amount of cold air used to ensure cooling performance reduces the mainstream gas flow of the engine, affecting overall engine performance. Furthermore, existing cooling structures often only consider heat exchange efficiency when considering internal flow, neglecting the structural load-bearing capacity itself.

[0004] Therefore, there is an urgent need for a new type of cooling structure that can adapt to high pressure conditions and has both efficient cooling and structural reinforcement functions. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a double-impact air film cooling structure with a web of oblique impact holes. This structure aims to solve the problems of high cold air outflow velocity, poor air film adhesion, and low cold air utilization in the high pressure ratio region, while enhancing the overall rigidity of the cooling structure and achieving synergistic optimization of efficient cooling and structural enhancement.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A dual-impact film cooling structure with an oblique impact hole web includes: a cold-side plate, a hot-side plate, and an oblique impact web connecting the cold-side plate and the hot-side plate; the cold-side plate has multiple primary impact holes; the oblique impact web has multiple secondary impact holes; the cold-side plate, the hot-side plate, and the oblique impact web together form a primary impact chamber and a secondary impact chamber arranged sequentially along the cooling airflow direction; the hot-side plate has multiple film cooling holes; the cooling airflow enters the primary impact chamber through the primary impact holes and impacts the hot-side plate, then enters the secondary impact chamber through the secondary impact holes and impacts the hot-side plate again, and finally flows out through the film cooling holes, forming a film cooling gas on the outer surface of the hot-side plate.

[0008] Furthermore, the inclination angle of the oblique impact web relative to the hot side plate is 30° to 60°.

[0009] Furthermore, the cross-section formed by two adjacent oblique impact webs, the cold-side plate, and the hot-side plate is trapezoidal. Furthermore, the air film hole is an oblong air film hole, and the angle between its axis and the hot side plate is less than 45°.

[0010] Furthermore, the primary impact hole, the secondary impact hole, and the air film hole are arranged alternately in the flow direction.

[0011] Furthermore, the axis of the primary impact hole is perpendicular to the cold-side plate.

[0012] Furthermore, the diameter of the primary impact hole is equal to the diameter of the secondary impact hole.

[0013] Furthermore, the distance H between the cold-side plate and the hot-side plate is 3 to 10 times the diameter of the primary impact hole.

[0014] Furthermore, the inclined impact web forms a support structure between the cold-side plate and the hot-side plate to improve the overall rigidity of the cooling structure.

[0015] Furthermore, the cooling structure is applied to the nozzle expansion section of an aero-engine, wherein the cold-side plate and the outer wall of the nozzle form a cold air passage, and the hot-side plate forms the inner wall surface of the nozzle.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention divides the double-layer plate into a primary impact chamber and a secondary impact chamber by obliquely impacting the web plate. This organizes the cooling airflow to continuously impact the hot-side plate twice, fully utilizing the high heat transfer coefficient of impact to significantly enhance internal heat transfer and improve cooling efficiency. The two impact processes achieve a stepped pressure reduction, effectively reducing the pressure and velocity of the cooling airflow exiting the film cooling holes. This avoids the "blowing away" phenomenon under high-pressure conditions, allowing the cold air to adhere to the surface of the hot-side plate and form a stable film, thus saving 14.9% of the cold air consumption while achieving the same cooling effect.

[0017] 2. The inclined impact web used in this invention also serves as a support member connecting the cold side plate and the hot side plate, forming a stable triangular support structure, which significantly improves the overall rigidity and deformation resistance of the cooling structure, and is suitable for harsh working environments with high temperature and high pressure.

[0018] 3. The present invention adopts an elongated oval air film hole and sets an inclination angle of less than 45°, which further improves the longitudinal coverage width and adhesion of the air film, and realizes the synergistic effect of internal enhanced heat exchange and external air film protection. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a double-impact film cooling structure with an oblique impact hole web according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the airflow in the cooling structure of an embodiment of the present invention; Figure 3 This is a schematic diagram of the airflow in a conventional impingement film cooling structure. Figure 4 This is a schematic diagram showing the characteristic dimensions of the cooling structure according to an embodiment of the present invention; Figure 5 This is a diagram of the elongated film pore structure used in an embodiment of the present invention; Figure 6 This is a schematic diagram illustrating the application of the present invention in the nozzle expansion section; Figure 7 The curve shows a comparison of the spanwise average overall cooling efficiency between the embodiments of the present invention and conventional impact film cooling structures.

[0021] Explanation of reference numerals in the attached figures: 1-Cold side plate; 2-Hot side plate; 3-Slanted impact web; 4-Primary impact chamber; 5-Secondary impact chamber; 6-Primary impact hole; 7-Secondary impact hole; 8-Film gas hole; A-Main flow gas; B-Cooling airflow; C-Primary impact airflow; D-Secondary impact airflow; E-Cooling film gas; H-Plate spacing; L-Length of rectangular segment of oblong film gas hole; α-Inclination angle of web; β-Inclination angle of film gas hole; θ-Angle of impact hole; δ-Plate thickness. Detailed Implementation

[0022] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0023] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] Example 1 This embodiment provides a dual-impact film cooling structure with a web featuring oblique impact holes, which is applied to the heat shield cooling of the expansion section of a two-dimensional nozzle in an aero-engine.

[0025] like Figure 1 and Figure 4 As shown, the cooling structure includes: a cold-side plate 1, a hot-side plate 2, and an inclined impact web 3 connecting the two plates. The cold-side plate 1 has multiple primary impact holes 6, the axes of which are perpendicular to the cold-side plate 1. The inclined impact web 3 has multiple secondary impact holes 7. The cold-side plate 1, the hot-side plate 2, and the inclined impact web 3 together form a primary impact chamber 4 and a secondary impact chamber 5 arranged sequentially along the cooling airflow direction. The hot-side plate 2 has multiple elongated film cooling holes 8.

[0026] In a preferred embodiment, the inclination angle (i.e., web inclination angle α) of the oblique impact web 3 relative to the hot-side plate 2 is 30° to 60°. Within this angle range, the cooling airflow can act on the hot-side plate 2 at the optimal impact angle, while ensuring that the oblique impact web has good structural support capabilities. In this embodiment, the web inclination angle α is preferably 45°.

[0027] Furthermore, such as Figure 1 As shown, the cross-section formed by the adjacent inclined impact webs 3, the cold-side plate 1, and the hot-side plate 2 is trapezoidal. This trapezoidal structure causes the primary impact chamber 4 and the secondary impact chamber 5 to gradually expand or contract in the flow direction, which is beneficial for the deceleration and pressurization of the cooling airflow and the directional guidance of the impact side plates, further improving heat exchange efficiency and flow uniformity. It should be noted that even if the adjacent inclined impact webs 3 are arranged in parallel (i.e., the cross-section is parallelogram), as long as their inclination angle is still within the range of 30° to 60°, the basic function of two-stage impact cooling can still be achieved, and good structural support can be provided.

[0028] In this embodiment, the primary impact hole 6, the secondary impact hole 7, and the film gas hole 8 are arranged alternately in the flow direction. Specifically, as shown... Figure 1 As shown, the primary impact hole 6 is opened on the cold side plate 1 above the primary impact chamber 4, the secondary impact hole 7 is opened on the inclined impact web 3 connecting the cold side plate 1 and the hot side plate 2, and the air film hole 8 is opened on the hot side plate 2 at the bottom of the secondary impact chamber 5.

[0029] Along the direction of cooling airflow, the primary impact chamber 4 and the secondary impact chamber 5 are arranged alternately, and the positions of the holes match this arrangement: multiple rows of primary impact holes 6 are formed on the cold-side plate 1 above each primary impact chamber 4; multiple rows of secondary impact holes 7 are formed on each inclined impact web 3, serving as channels for cooling airflow from the primary impact chamber 4 into the adjacent secondary impact chamber 5; multiple air film holes 8 are formed on the hot-side plate 2 at the bottom of each secondary impact chamber 5. The primary impact holes 6, secondary impact holes 7, and air film holes 8 are spatially staggered in the flow direction. This spatial staggered arrangement avoids the cooling airflow from the primary impact holes 6 directly passing through the secondary impact holes 7 and air film holes 8 to form a straight flow path, forcing the cooling airflow to fully diffuse within the primary impact chamber 4 and the secondary impact chamber 5, forming a uniform double impact coverage on the corresponding area of ​​the hot-side plate 2. At the same time, the cooling airflow that finally overflows from the air film holes 8 forms a continuous and uniform air film coverage layer on the outer surface of the hot-side plate 2, effectively avoiding localized uneven heat exchange or cooling blind spots.

[0030] like Figure 4 and Figure 5 As shown, in this embodiment, the plate spacing H between the cold-side plate 1 and the hot-side plate 2 is 3 mm. The diameters of the primary impact hole 6 and the secondary impact hole 7 are both 1 mm. That is, the plate spacing H is 3 times the diameter of the primary impact hole 6. It should be noted that, depending on different cooling requirements and structural strength requirements, the plate spacing H can be selected within the range of 3 to 10 times the diameter of the primary impact hole 6. When the plate spacing is small (e.g., 3 times the diameter), the impact jet can reach the surface of the hot-side plate 2 with higher momentum, obtaining a stronger local heat transfer effect; when the plate spacing is large (e.g., 10 times the diameter), the impact jet has more diffusion space before reaching the hot-side plate 2, obtaining a more uniform impact coverage area. The plate thickness δ of the cold-side plate 1, the hot-side plate 2, and the inclined impact web 3 is all 1 mm.

[0031] like Figure 4 As shown, the axis of the primary impact hole 6 is perpendicular to the cold side plate 1, and the impact hole angle θ is 90° to ensure that the impact jet has the maximum momentum flux.

[0032] In this embodiment, the aperture of the primary impact hole 6 is equal to that of the secondary impact hole 7, both being 1 mm. This equal aperture design ensures that the two impact jets have similar momentum flux, so that the heat transfer intensity of the two impacts matches, avoiding excessive primary impact or insufficient secondary impact due to aperture differences, thereby ensuring the heat transfer uniformity of the hot-side plate 2 along the flow direction.

[0033] like Figure 5 As shown, the cross-sectional area of ​​the oblong air film hole 8 is equal to that of the impact hole, and the angle β (i.e., the inclination angle of the air film hole) between its axis and the hot side plate 2 is less than 45°. In this embodiment, the angle β is preferably 30°. The length L of the rectangular segment of the oblong air film hole is 1.2 mm, and the diameter / width of the arc segment is 0.5 mm.

[0034] In this embodiment, as Figure 6 As shown, the cooling structure is applied to the expansion section of an aero-engine nozzle. The cold-side plate 1 and the outer wall of the nozzle form a cold air channel, within which the cooling airflow B from the engine's outer bypass duct flows. The hot-side plate 2 forms the inner wall of the nozzle, directly contacting the high-temperature mainstream combustion gas A inside the nozzle. By arranging the cooling structure in the expansion section of the nozzle, the gradual decrease in mainstream combustion gas pressure along the flow direction is utilized, matching the stepped pressure reduction effect of the two impacts within the cooling structure. These two impacts enhance internal heat transfer, reduce the outflow velocity from the film gas holes, and create a good film coverage for the expansion section, thereby improving cooling efficiency and saving cooling gas volume.

[0035] like Figure 2 As shown, the working process of the cooling structure described in this embodiment of the invention is as follows: After the high-pressure cooling airflow B from the outer bypass duct enters the cold air channel, it first enters the primary impact chamber 4 through the primary impact hole 6 on the cold-side plate 1, forming a primary impact airflow C, which forms the first impact cooling on the inner surface of the hot-side plate 2. Subsequently, the cooling airflow enters the secondary impact chamber 5 through the secondary impact hole 7 on the inclined impact web 3, forming a secondary impact airflow D, which forms the second impact cooling on the inner surface of the hot-side plate 2. After two impact heat exchanges, the pressure of the cooling airflow has been significantly reduced, and finally it flows out through the elongated gas film hole 8 on the hot-side plate 2, forming a cooling gas film E attached to the outer surface of the hot-side plate 2, which isolates the high-temperature mainstream combustion gas A from the wall surface.

[0036] Comparative experiment To verify the technical effect of the present invention, this embodiment is compared with conventional impact film cooling structures (such as...). Figure 3 Numerical simulations were performed for comparison (as shown). The computational domain used periodic boundary conditions, the mesh type was polyhedral, the turbulence model was k-ωSST, the main flow inlet temperature was 1900K, and the cooling air inlet temperature was 500K. The overall cooling efficiency was... φ Defined as:

[0037] In the formula, T g Mainstream imported temperature, T w The wall temperature, T c This refers to the inlet temperature of the cold air.

[0038] The calculation results are shown in Table 1: Table 1

[0039] As can be seen from Table 1, the cooling structure described in this invention saves 14.9% of the cooling air consumption, while still improving the overall cooling efficiency by 1.6% compared to the conventional structure, resulting in high cooling air utilization.

[0040] like Figure 7 As shown, the horizontal axis represents the dimensionless flow distance from the outlet of the film cooling hole, and the vertical axis represents the spanwise average integrated cooling efficiency. φ In the figure, 1 represents the overall cooling efficiency curve of the cooling structure described in this invention, and 2 represents... Figure 3 The figure shows the overall cooling efficiency curve of the conventional structure. As can be seen from the figure, the overall cooling efficiency curve of the cooling structure of the present invention exhibits a wavy distribution, and the high-efficiency region is significantly expanded, demonstrating the significant advantages of the cooling structure of the present invention in terms of cold air utilization efficiency and cooling effect.

[0041] In this embodiment of the invention, the inclined impact web 3 also serves as a supporting member connecting the cold-side plate 1 and the hot-side plate 2, forming a stable triangular support structure, which effectively improves the overall stiffness and deformation resistance of the cooling structure. Numerical simulation results show that, under the same thermal and pressure load conditions, the maximum deformation of the cooling structure described in this embodiment of the invention is reduced by about 25% compared with the conventional double-wall structure, significantly improving the structural reliability under high temperature and high pressure environments.

[0042] In summary, the cooling structure described in this embodiment of the invention constructs two closed impact chambers through an oblique impact web, achieving a synergistic effect of enhanced heat transfer through internal double impacts and external gas film protection. At the same time, the supporting effect of the oblique impact web enhances the structural rigidity, resulting in a comprehensive and beneficial effect of reduced cooling gas consumption, improved cooling efficiency, and enhanced structural reliability. It is suitable for efficient cooling in areas with a high pressure ratio between cooling gas and combustion gas, such as the expansion section of the nozzle of an aero-engine.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A double-impact film cooling structure with a web featuring oblique impact holes, characterized in that, include: Cold side plate (1), hot side plate (2) and oblique impact web (3) connecting the cold side plate (1) and the hot side plate (2); The cold side plate (1) is provided with multiple primary impact holes (6). The oblique impact web (3) is provided with multiple secondary impact holes (7); The cold side plate (1), the hot side plate (2) and the inclined impact web (3) together form a primary impact chamber (4) and a secondary impact chamber (5) arranged sequentially along the cooling airflow direction. The hot-side plate (2) has multiple air film holes (8); The cooling airflow enters the primary impact chamber (4) through the primary impact hole (6) and impacts the hot side plate (2). Then it enters the secondary impact chamber (5) through the secondary impact hole (7) and impacts the hot side plate (2) again. Finally, it flows out through the air film hole (8) and forms an air film on the outer surface of the hot side plate (2).

2. The double-impact film cooling structure with an oblique impact hole web according to claim 1, characterized in that, The inclined angle of the oblique impact web (3) relative to the hot side plate (2) is 30° to 60°.

3. A double-impact film cooling structure with an oblique impact hole web as described in claim 1 or 2, characterized in that, The cross section formed by the two adjacent oblique impact webs (3), the cold side plate (1), and the hot side plate (2) is trapezoidal.

4. The double-impact film cooling structure with an oblique impact hole web according to claim 1, characterized in that, The air film hole (8) is an oblong air film hole, and the angle between its axis and the hot side plate (2) is less than 45°.

5. The double-impact film cooling structure with an oblique impact hole web according to claim 1, characterized in that, The primary impact hole (6), the secondary impact hole (7), and the air film hole (8) are arranged alternately in the flow direction.

6. The double-impact film cooling structure with an oblique impact hole web according to claim 1, characterized in that, The axis of the primary impact hole (6) is perpendicular to the cold side plate (1).

7. The double-impact film cooling structure with an oblique impact hole web according to claim 1, characterized in that, The diameter of the primary impact hole (6) is equal to the diameter of the secondary impact hole (7).

8. The double-impact film cooling structure with an oblique impact hole web according to claim 1, characterized in that, The distance H between the cold side plate (1) and the hot side plate (2) is 3 to 10 times the diameter of the primary impact hole (6).

9. A double-impact film cooling structure with an oblique impact hole web according to claim 1, characterized in that, The oblique impact web (3) forms a support structure between the cold side plate (1) and the hot side plate (2) to improve the overall rigidity of the cooling structure.

10. A double-impact film cooling structure with an oblique impact hole web according to claim 1, characterized in that, The cooling structure is applied to the nozzle expansion section of the aero-engine. The cold side plate (1) and the outer wall of the nozzle form a cold air passage, and the hot side plate (2) forms the inner wall surface of the nozzle.

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