Cylindrical gas film hole structure with side ribs suitable for cooling of engine hot end components

Abstract

The application discloses a cylindrical gas film hole structure with side ribs suitable for cooling of engine hot end components, and the engine hot end components can be engine turbine guide vanes, moving vanes, combustion chambers and the like, and is used for realizing efficient cooling of different requirements. The application aims at the technical problem that the existing cylindrical gas film hole is easy to form kidney-shaped vortex on the wall surface to be cooled, and the kidney-shaped vortex lifts the cooling gas and deteriorates the cooling effect. The application directly sets the elongated strip-shaped side rib structure extending along the center line on the two sides of the cylindrical gas film hole, reconstructs the jet flow structure in the hole through the side rib, and induces the airflow on the two sides to accelerate to form accelerated flow, so that the formation of the kidney-shaped vortex on the wall surface to be cooled is inhibited, the purpose of enhancing the gas film adhesion is achieved, and the application has the advantages of simple structure and wide applicability.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine turbine blade cooling technology, and relates to a film cooling hole structure. Specifically, it relates to a cylindrical film cooling hole structure with side ribs suitable for cooling hot-end components of an engine. This structure facilitates the rapid formation of an anti-kidney vortex on the wall surface to be cooled, inhibits the formation of kidney vortex, enhances the adhesion ability of the film cooling system, and does not significantly increase aerodynamic losses. Background Technology

[0002] The inlet temperature of advanced civilian high-bypass turbofan engines has exceeded 2000K, far exceeding the maximum temperature that turbine blade materials can withstand (typically, the maximum temperature a turbine blade can withstand is between 1500K and 1700K. Different materials have different maximum withstand temperatures; for example, cast nickel-based alloys can generally withstand a maximum temperature of 1300K to 1500K, while wrought nickel-based alloys can reach 1600K to 1700K). Turbine blade cooling is a crucial technology that ensures stable turbine operation and a long service life under high temperature and high pressure environments. Film cooling is a common method for turbine blade cooling. Film cooling technology protects turbine blades to operate normally at high temperatures, preventing creep or damage caused by high temperatures. Film cooling efficiency is influenced not only by flow parameters such as air-to-air ratio, density ratio, and mainstream Reynolds number, but also by the geometry of the film cooling orifice. Different orifice shapes affect cooling efficiency; for example, generally, circular orifices have higher cooling efficiency than square orifices because they offer better gas injection characteristics and create a more uniform cooling gas flow field. Furthermore, the orifice diameter, layout, inclination angle, and depth all influence cooling efficiency. In conclusion, the geometry of the film cooling orifice is a crucial design parameter for turbine blade film cooling and requires comprehensive consideration during design and operation.

[0003] Currently, researchers have conducted extensive studies on the geometry of film cooling orifices, including composite-angle orifices and irregularly shaped orifices. Results show that improving the orifice shape can effectively enhance film cooling performance compared to traditional cylindrical orifices. This is mainly because during the mixing of the jet and the mainstream in a cylindrical orifice, the temperature and velocity difference between the jet and the mainstream creates a kidney-shaped vortex, forcing the low-temperature cooling jet to detach from the wall, while the high-temperature mainstream combustion jet re-attaches to the wall, resulting in a reduced film cooling area and decreased film cooling effect. Improving the orifice shape, to some extent, increases the outlet area, reduces the jet outlet velocity, and weakens the influence of the kidney-shaped vortex, thereby improving the film cooling effect. However, irregularly shaped orifices and other film cooling orifice structures are complex, difficult to manufacture, and costly. Furthermore, they can negatively impact the mainstream aerodynamic performance of the turbine blade surface and increase aerodynamic losses. Summary of the Invention

[0004] (I) Purpose of the Invention

[0005] To address the aforementioned deficiencies and shortcomings of existing technologies, the present invention aims to propose a cylindrical film cooling orifice structure with side ribs suitable for cooling engine hot-end components, such as turbine guide vanes, moving blades, and combustion chambers, to achieve efficient cooling for different needs. This structure addresses the technical problem of existing cylindrical film cooling orifices easily forming kidney-shaped vortices on the wall to be cooled, thus lifting the cooled air and worsening the cooling effect. By directly setting rib structures on both sides inside the cylindrical film cooling orifice, the jet flow structure inside the orifice is reconstructed through the side ribs, and the airflow on both sides is induced to accelerate, thereby suppressing the formation of kidney-shaped vortices on the wall to be cooled and achieving the purpose of enhancing film adhesion. It has the advantages of simple structure and wide applicability.

[0006] (II) Technical Solution

[0007] To achieve its inventive purpose and solve its technical problems, the technical solution adopted by this invention is as follows:

[0008] A cylindrical film cooling hole structure with side ribs, suitable for cooling hot-end components of an engine, wherein the film cooling holes are arranged in an array on a substrate of the hot-end component to be cooled. The substrate of the substrate to be cooled includes an outer wall surface and an inner wall surface disposed opposite each other. The space defined by the inner wall surface is a high-temperature zone, and the space outside the outer wall surface is a low-temperature zone. Each film cooling hole extends from the outer wall surface to the inner wall surface to spray a low-temperature cooling jet into the high-temperature zone defined by the inner wall surface, forming a cooling film covering the inner wall surface. The structure is characterized in that...

[0009] The main body of each of the air film holes is a cylindrical through hole. At least two slender strip-shaped side ribs protruding radially outward along the inner wall of the cylindrical through hole are symmetrically provided. The extension direction of the two slender strip-shaped side ribs along their length is consistent with the center line direction of the cylindrical through hole. Each slender strip-shaped side rib extends to the outer wall surface and inner wall surface of the wall surface substrate to be cooled at both ends, and remains flush with the inner and outer walls of the wall surface substrate to be cooled.

[0010] Each of the aforementioned air film holes and the two elongated side ribs provided on their inner walls are arranged in an inclined state on the substrate of the wall surface to be cooled, and the angle between the center line of the air film hole and the tangent direction of the wall surface of the substrate to be cooled is an acute angle.

[0011] Furthermore, the rib height h of the elongated strip-shaped side rib is 1 / 5 to 1 / 10 of the diameter D of the cylindrical through hole, and the rib width b of the elongated strip-shaped side rib is equivalent to its rib height h.

[0012] In a preferred embodiment of the present invention, the diameter D of the cylindrical through hole is between 2 and 10 mm, the rib height h of the slender strip-shaped side rib is between 0.1D and 0.2D, and the rib width b is between 0.15D and 0.3D.

[0013] In a preferred embodiment of the present invention, the angle between the centerline of the air film hole and the tangential direction of the wall surface of the substrate to be cooled is 20° to 60°.

[0014] In a preferred embodiment of the present invention, the spacing P between two adjacent air film holes in the array of multiple air film holes is between 3 and 20 mm.

[0015] The cylindrical film cooling hole structure with side ribs of the present invention, suitable for cooling hot-end components of an engine, works on the following principle:

[0016] In film cooling technology, a low-temperature cooling jet is ejected from a film cooling orifice, forming a cooling film covering a high-temperature surface. As the low-temperature cooling jet flows across the surface, it absorbs heat while carrying it away, thus cooling the wall surface. However, when using cylindrical film cooling orifices, during the mixing process between the cylindrical orifice jet and the mainstream, the temperature and velocity difference between the jet and the mainstream creates a downward-extending kidney-shaped vortex. This kidney-shaped vortex easily causes the film to detach from the wall surface, forcing the low-temperature cooling jet to leave the wall. This causes the high-temperature mainstream gas flow to re-attach to the wall surface, resulting in a reduction in the area of ​​the film covering the wall and a decrease in the film cooling effect.

[0017] This invention utilizes two symmetrically arranged, elongated, protruding side ribs on the inner wall of a cylindrical film gas orifice. As the airflow passes over these ribs, it induces an accelerated flow. This accelerated flow alters the fluid's ability to reconstruct the jet structure within the cylindrical film gas orifice, weakening the formation of the kidney-shaped vortex at the outlet. This is because the accelerated flow generates strong shear forces upstream of the ribs, causing intense turbulence near the ribs. This turbulence consumes energy and momentum, thus reducing the formation of the kidney-shaped vortex. Specifically, when gas passes through the circular film gas orifice, a large kidney-shaped vortex forms at the orifice opening due to its slower velocity. This vortex extends into the orifice until it encounters the ribs. As the gas flows over the ribs, the presence of the ribs generates strong shear forces upstream of them, causing intense turbulence near the ribs. This turbulence consumes kinetic energy and momentum, thus weakening the formation of the vortex. Therefore, by setting ribs on the inner wall of the circular film cooling hole, accelerated flow can be induced, thereby weakening the formation of the outlet kidney vortex and improving the efficiency of film cooling.

[0018] It is worth noting that the geometry and number of ribs have a significant impact on the efficiency of film cooling technology. Experiments show that the taller and narrower the ribs, the greater the shear force and turbulence intensity they generate, resulting in better vortex suppression. By adjusting the rib height h and rib width b, the intensity of the accelerated flow can be adjusted, thereby controlling the film coverage and cooling effect. Furthermore, the number of ribs must be appropriate; too many ribs will increase airflow resistance and pressure loss, reducing the cooling efficiency of the film cooling system.

[0019] In a preferred embodiment of the present invention, the intensity of the accelerated flow is adjusted by adjusting the rib height h and rib width b of the elongated strip-shaped side ribs, thereby controlling the air film coverage and cooling effect.

[0020] Another objective of this invention is to provide a cooling structure for a hot-end component of an engine, comprising a hot-end component of an engine, characterized in that an array of air film cooling holes are provided on the substrate of the wall surface to be cooled of the hot-end component of the engine, wherein the air film cooling holes adopt the cylindrical air film hole structure with side ribs described above in this invention.

[0021] (III) Technical Effects

[0022] Compared with the prior art, the cylindrical film cooling hole structure with side ribs provided by the present invention, suitable for cooling hot-end components of an engine, has the following characteristics and significant technical advantages:

[0023] (1) Simple structure: The cylindrical air film hole with side ribs of the present invention directly adds two symmetrically arranged slender strip side ribs to the cylindrical air film hole, which is simple in structure and easy to process.

[0024] (2) Good adjustability: The cylindrical air film hole with side ribs of the present invention can directly change the flow intensity by adjusting the rib height and rib width of the side ribs, and control the development of the kidney vortex on the wall to be cooled, so as to obtain good cooling effect on different applications.

[0025] (3) Wide range of applications: The cylindrical film cooling hole structure with side ribs of the present invention can be used for hot end components of aero engines such as turbine guide vanes, moving blades, and combustion chambers to achieve efficient cooling for different needs.

[0026] (4) Significant improvement in cooling effect: The cylindrical air film pore structure with side ribs of the present invention suppresses the negative effect of the kidney vortex from the root, and the cooling effect is significantly improved. Attached Figure Description

[0027] Figure 1 This is a top view of the cylindrical film cooling hole structure with side ribs for cooling engine hot-end components according to the present invention.

[0028] Figure 2 This is a cross-sectional view of the cylindrical air film hole with side ribs of the present invention.

[0029] Figure 3 This is a schematic diagram of a kidney-shaped vortex structure formed by an existing cylindrical air film aperture.

[0030] Figure 4 This is a schematic diagram of the kidney-shaped vortex and accelerated flow structure formed by the cylindrical air film aperture with side ribs of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1-The wall substrate to be cooled, 2-A cylindrical film cooling hole with side ribs, 3-Side ribs, 4-Inlet end, 5-Outlet end, 6-Main stream, 7-Jet, 8-Kidney-shaped vortex formed by existing cylindrical film cooling holes, 9-Kidney-shaped vortex formed by cylindrical film cooling holes with side ribs, 10-Accelerated flow formed by cylindrical film cooling holes with side ribs, D-Diameter of cylindrical through-hole, b-Width of side ribs, h-Height of side ribs, P-Spacing between adjacent film cooling holes, θ-Angle between the centerline of the film cooling hole and the tangent direction of the wall surface of the wall substrate to be cooled, m1-Height dimension of the kidney-shaped vortex formed by existing cylindrical film cooling holes, m2-Height dimension of the kidney-shaped vortex formed by cylindrical film cooling holes with side ribs, m3-Height dimension of the accelerated flow, n1-Width dimension of the kidney-shaped vortex formed by existing cylindrical film cooling holes, n2-Width dimension of the kidney-shaped vortex formed by cylindrical film cooling holes with side ribs, n3-Width dimension of the accelerated flow. Detailed Implementation

[0033] To better understand the present invention, the following embodiments further illustrate the content of the invention, so that the advantages and features of the invention can be more easily understood by those skilled in the art. It should be noted that the following descriptions are merely preferred embodiments of the present invention, but the content of the invention is not limited to the following embodiments. In fact, various modifications and variations can be made to the present invention without departing from the scope or spirit of the invention, which will be apparent to those skilled in the art. For example, features shown or described as part of one embodiment can be used with another embodiment to produce yet another embodiment. Therefore, it is intended that such modifications and variations be included within the scope of the appended claims and their equivalents.

[0034] like Figures 1-2As shown, the present invention provides a cylindrical film cooling hole structure with side ribs suitable for cooling engine hot-end components. The film cooling holes 2 are arranged in an array on the cooling wall substrate 1 of the engine hot-end component. The cooling wall substrate 1 includes an outer wall and an inner wall that are arranged opposite to each other. The space defined by the inner wall is a high-temperature zone, and the space outside the outer wall is a low-temperature zone. Each film cooling hole 2 extends from the outer wall to the inner wall to spray a low-temperature cooling jet into the high-temperature zone defined by the inner wall and form a cooling film covering the inner wall. Each air film hole 2 has a cylindrical through hole as its main body. At least two slender strip-shaped side ribs 3 protruding radially outward along the inner wall of the cylindrical through hole are symmetrically provided. The extension direction of the two slender strip-shaped side ribs 3 along their length is consistent with the direction of the center line of the cylindrical through hole. Each slender strip-shaped side rib 3 extends to the outer and inner wall surfaces of the wall surface substrate 1 to be cooled at its two ends (air inlet 4 and air outlet 5) respectively, and is flush with the inner and outer wall surfaces of the wall surface substrate 1 at both ends. Each air film hole 2 and the two slender strip-shaped side ribs 3 provided on its inner wall are provided in an inclined state on the wall surface substrate 1 to be cooled. The angle θ between the center line of the air film hole 2 and the tangent direction of the wall surface substrate 1 to be cooled is an acute angle. The rib height h of the slender strip-shaped side rib 3 is 1 / 5 to 1 / 10 of the diameter D of the cylindrical through hole, and the rib width b of the slender strip-shaped side rib 3 is equivalent to its rib height h.

[0035] Figure 1 The image shown is a top view (xz plane) of the cylindrical film cooling hole structure with side ribs, applicable to the cooling of hot-end components of an engine according to the present invention. The dashed lines represent the internal structure of the film cooling hole. It can be seen that this structure directly adds side ribs to both sides inside the cylindrical film cooling hole. The diameter of the cylindrical film cooling hole is D, which is between 2 and 10 mm; the rib height of the side rib is h, which is between 0.2 and 2 mm; the rib width of the side rib is b, which is between 0.3 and 3 mm; multiple rows of cylindrical film cooling holes with side ribs can be arranged on the substrate, with a hole spacing of P between each row, where P is between 3 and 20 mm. Figure 2 The figure shows a cross-sectional view (yz section) of a cylindrical air film hole with side ribs. The center line of the cylindrical air film hole with side ribs makes an angle θ (20-60°) with the horizontal direction. Figure 3 The kidney-shaped vortex 8 formed by the existing cylindrical air film jet 7 and the mainstream 6 on the xy section is very easy to cause the air film to detach from the wall, weakening the cooling effect. Figure 4 The kidney-shaped vortex 9 and the accelerating flow 10 are formed by cylindrical air film holes with side ribs.

[0036] The present invention relates to a cylindrical film cooling hole structure with side ribs suitable for cooling hot-end components of an engine. Its working principle is as follows: In film cooling technology, a low-temperature cooling jet is ejected from the film cooling hole, forming a cooling film covering the high-temperature surface. When the low-temperature cooling jet flows over the surface, it absorbs heat while carrying it away, thus cooling the wall surface. However, when using a cylindrical film cooling hole, during the mixing process of the cylindrical film cooling jet 7 and the mainstream 6, the temperature and velocity difference between the jet and the mainstream will form a downward-extending kidney-shaped vortex. This kidney-shaped vortex easily causes the film to detach from the wall surface, forcing the low-temperature cooling jet to detach from the wall surface, causing the high-temperature main combustion flow to re-attach to the wall surface. This results in a reduction in the area of ​​the film covering the wall surface, and a decrease in the film cooling effect.

[0037] This invention, by setting outwardly protruding elongated strip-shaped side ribs 3 on the inner wall of the cylindrical film orifice 2, induces an accelerated flow 10 in the jet 7 as it passes through the elongated strip-shaped side ribs 3. This accelerated flow 10 alters the fluid and reconstructs the jet structure within the cylindrical film orifice 2, weakening the formation of the kidney-shaped vortex 9 at the outlet. This is because the accelerated flow generates a strong shear force upstream of the side ribs 3, causing strong turbulence in the airflow near the side ribs 3. Turbulence consumes energy and momentum, thereby weakening the formation of the kidney-shaped vortex 9. Specifically, when gas passes through the circular film orifice 2, a large kidney-shaped vortex 9 forms at the orifice due to the slower gas velocity at the orifice opening. This vortex extends into the orifice until it encounters the side ribs 3. As the gas flows through the side ribs 3, the presence of the side ribs generates a strong shear force upstream of the side ribs 3, causing strong turbulence in the airflow near the side ribs 3. Turbulence consumes kinetic energy and momentum, thereby weakening the formation of the kidney-shaped vortex 9. Therefore, by setting side ribs 3 on the inner wall of the circular air film hole 2, accelerated flow can be induced, thereby weakening the formation of the outlet kidney vortex 9 and improving the efficiency of air film cooling.

[0038] It should be added that the geometry and number of side ribs 3 have a significant impact on the efficiency of film cooling technology. Experiments show that the higher and narrower the side ribs, the greater the shear force and turbulence intensity they generate, thus resulting in better vortex suppression. By adjusting the rib height h and rib width b of side ribs 3, the intensity of the accelerated flow can be adjusted, thereby controlling the film cooling coverage and cooling effect. In addition, the number of side ribs 3 also needs to be appropriate; too many side ribs will increase airflow resistance and pressure loss, reducing the cooling efficiency of the film cooling system.

[0039] It can be seen that the improved cylindrical air film hole structure with side ribs proposed in this invention has several significant technical advantages over the existing cylindrical air film hole structure without side ribs: (1) The present invention can reconstruct the jet structure in the air film hole by setting slender strip-shaped side ribs on the inner wall of the cylindrical air film hole. The slender strip-shaped side ribs induce an accelerated flow at the outlet of the air film hole. The existence of the accelerated flow weakens the kidney vortex at the outlet; (2) After adding slender strip-shaped side ribs to the inner wall of the cylindrical air film hole, the size of the kidney vortex, whether it is the height m2 or the width n2, is significantly reduced under the action of the accelerated flow (height m3 and width n3 of the accelerated flow) compared with the height m1 and width n1 of the kidney vortex formed by the existing cylindrical air film hole without side ribs. The air film adhesion ability is improved, which is conducive to obtaining a better cooling effect; 3. The intensity of the accelerated flow can be adjusted by adjusting the rib height h and rib width b, thereby controlling the air film coverage and cooling effect.

[0040] The cylindrical film cooling structure with side ribs of this invention has been verified through numerical simulation of film cooling characteristics under different parameters. Compared with a simple cylindrical film cooling hole, the kidney-shaped vortex is significantly suppressed, and the film adhesion ability is greatly improved. Typical operating condition analysis shows that the cooling efficiency is improved by an average of 10%. At the same time, this structure is simple, has wide applicability, and is a promising new cooling structure.

[0041] The objectives of this invention have been fully and effectively achieved through the above embodiments. All equivalent or simple variations made to the structures, features, and principles described in this patent concept are included within the protection scope of this patent. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the structure of this invention or exceed the scope defined in these claims, all of which should fall within the protection scope of this invention.

Claims

1. A cylindrical film cooling hole structure with side ribs suitable for cooling hot-end components of an engine, wherein the film cooling holes are arranged in an array on a substrate of a wall surface to be cooled of the hot-end component of the engine, the substrate of the wall surface to be cooled includes an outer wall surface and an inner wall surface disposed opposite to each other, the space defined by the inner wall surface is a high-temperature zone, and the space outside the outer wall surface is a low-temperature zone, each of the film cooling holes extending from the outer wall surface to the inner wall surface, for injecting a low-temperature cooling jet into the high-temperature zone defined by the inner wall surface, and forming a cooling film covering the inner wall surface, characterized in that... The main body of each air film hole is a cylindrical through hole. Two slender strip-shaped side ribs protruding radially outward along the inner wall of the cylindrical through hole are symmetrically provided. The extension direction of the two slender strip-shaped side ribs along their length is consistent with the center line direction of the cylindrical through hole. Each slender strip-shaped side rib extends to the outer wall surface and inner wall surface of the wall surface substrate to be cooled at both ends, and remains flush with the inner and outer walls of the wall surface substrate to be cooled. Each of the aforementioned air film holes and the two elongated side ribs provided on their inner walls are arranged in an inclined state on the substrate of the wall surface to be cooled, and the angle between the center line of the air film hole and the tangent direction of the wall surface of the substrate to be cooled is an acute angle. Furthermore, the rib height h of the elongated strip-shaped side rib is 1 / 5 to 1 / 10 of the diameter D of the cylindrical through hole, and the rib width b of the elongated strip-shaped side rib is equivalent to its rib height h.

2. The cylindrical film cooling hole structure with side ribs suitable for cooling hot-end components of an engine according to claim 1, characterized in that, The angle between the centerline of the air film hole and the tangent direction of the wall surface of the substrate to be cooled is 20~60°.

3. The cylindrical film cooling hole structure with side ribs suitable for cooling hot-end components of an engine according to claim 1, characterized in that, In the array of multiple air film holes, the hole spacing P between two adjacent air film holes is between 1.5D and 5D.

4. The cylindrical film cooling hole structure with side ribs suitable for cooling hot-end components of an engine according to claim 1, characterized in that, The intensity of the accelerated flow can be adjusted by adjusting the rib height h and rib width b of the slender strip-shaped side ribs, thereby controlling the air film coverage and cooling effect.

5. The cylindrical film cooling hole structure with side ribs suitable for cooling hot-end components of an engine according to claim 1, characterized in that, The engine hot-end components include engine turbine guide vanes, turbine moving blades, and / or combustion chambers.

6. A cooling structure for a hot-end component of an engine, comprising a hot-end component of the engine, characterized in that, The engine hot end component has an array of air film cooling holes on the substrate of the wall to be cooled, and the air film cooling holes adopt the cylindrical air film hole structure with side ribs as described in any one of claims 1 to 5.

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