CN118669183A - Cooling structure and turbine blade equipped with expansion film holes - Google Patents

Abstract

The present disclosure provides a cooling structure and a turbine blade equipped with an expansion type air film hole. The cooling mechanism includes a substrate and an air film hole formed on the substrate. The air outlet of the air film hole is configured to expand to both sides along the gas span direction orthogonal to the gas flow direction of the jet passing through the air film hole to form a fan-shaped hole structure. A transition section and an expansion section are sequentially arranged between the air inlet and the air outlet of the air film hole. The expansion section is configured to gradually narrow from the transition section to the air outlet along the width direction of the air outlet and gradually widen along the length direction of the air outlet. The expansion structure weakens the strength of the kidney-shaped vortex formed near the air outlet in the flow field and induces the generation of an anti-kidney vortex pair. The turbine blade includes a blade formed by a substrate, a gas flow channel for accommodating the passage of cooling gas is arranged in the blade, and a plurality of air film holes are arranged on the substrate to communicate with the gas flow channel. Such a turbine blade has the advantages of a cooling structure and has a better cooling effect.

Description

Cooling structure and turbine blade equipped with expansion film holes

Technical Field

At least one embodiment of the present disclosure relates to the technical field of gas turbines, and more specifically, to a cooling structure and a turbine blade equipped with expansion film holes.

Background Art

Increasing the turbine inlet temperature is the most direct way to improve the efficiency of aircraft engines. At present, the inlet temperature of the turbine of a civil large bypass ratio aircraft engine has exceeded 2000K (Kelvin), which is much higher than the maximum temperature that the material used for the blades can withstand. For this reason, existing turbine blades mostly use film cooling technology to maintain the normal operation of the blades under high temperature conditions.

In the existing air film cooling technology, the commonly used discrete air film holes are mostly constructed in a cylindrical shape. However, during the application process of the air film holes constructed in a cylindrical structure, since the jet passing through the air film holes is too concentrated, it is easy to form a strong kidney-shaped vortex pair near the air outlet in the flow field, resulting in the mainstream passing through the blade surface being sucked from both sides of the kidney-shaped vortex to the bottom of the jet, which reduces the wall attachment ability of the air film, and further leads to poor cooling effect of the air film hole.

Summary of the invention

In order to solve at least one of the above and other technical problems in the prior art, the present disclosure provides a cooling structure and a turbine blade equipped with an expansion type air film hole. Through the air outlet configured as a fan-shaped hole structure and the air outlet configured as an expansion structure, the jet passing through the air film hole can be diffused in a larger area, which can weaken the strength of the formed kidney-shaped vortex and limit the development of the kidney-shaped vortex, which is conducive to increasing the wall attachment ability of the air film.

On the one hand, an embodiment of the present disclosure provides a cooling structure equipped with expansion-type air film holes, including a substrate, in which a plurality of air film holes obliquely extending along the thickness direction of the substrate are arranged; an air inlet of the air film hole is formed on the inner surface of the substrate, and an air outlet of the air film hole is formed on the outer surface of the substrate, and the air outlet is constructed as a fan-shaped hole structure that expands to both sides along an air flow direction that is orthogonal to the air flow direction of the gas passing through the air film holes; a transition section and an expansion section are sequentially arranged between the air inlet and the air outlet, and the expansion section is constructed as an expansion structure that gradually shrinks along the width direction of the air outlet and gradually widens along the length direction of the air outlet from the transition section to the air outlet, so as to weaken the strength of the kidney-shaped vortex formed near the air outlet in the flow field and induce the generation of an anti-kidney-shaped vortex pair.

In an illustrative embodiment, the air outlet is configured to be symmetrical along the center line of the air film hole.

In an illustrative embodiment, in the orthographic projection of the substrate in the thickness direction, a side of the air outlet close to the air inlet forms a first arc-shaped portion recessed toward the air inlet, and a side of the air outlet away from the air inlet forms a second arc-shaped portion having the same recessed direction as the first arc-shaped portion, and the first arc-shaped portion and the second arc-shaped portion are connected by a straight line portion.

In an illustrative embodiment, a connection portion between the first arc-shaped portion and/or the second arc-shaped portion and the straight portion is configured as a rounded structure.

In an illustrative embodiment, the transition section is configured as a cylindrical hole structure.

In an illustrative embodiment, in the orthographic projection of the substrate in the thickness direction, the length of the expansion section is configured to be 2.5 to 5 times the aperture of the transition section.

In an illustrative embodiment, the radius of the first arc-shaped portion is configured to be 4 to 6 times the aperture of the transition section.

In an illustrative embodiment, the radius of the second arc-shaped portion is configured to be 3 to 5 times the aperture of the transition section.

In an illustrative embodiment, the connection portion between the first arc-shaped portion and/or the second arc-shaped portion and the straight portion is configured such that the radius of the fillet is configured to be 0.1 to 0.3 times the aperture of the transition section.

In an illustrative embodiment, a plurality of the air film holes are arranged at intervals along the air flow direction and/or the air flow direction to form an air film hole array.

On the other hand, an embodiment of the present disclosure further provides a turbine blade, including a blade formed by a substrate, wherein a gas flow channel for accommodating the passage of cooling gas is arranged inside the blade, and a plurality of air film holes are arranged on the substrate, wherein air inlets of the air film holes are connected to the gas flow channel to accommodate the cooling gas flowing out through the air film holes, so that an air film is formed on at least a portion of the outer surface of the blade.

According to the cooling structure and turbine blades provided by the present invention, which are equipped with expansion-type air film holes, the air outlet is constructed as a fan-shaped hole structure, and the expansion section extends from the transition section to the air outlet. The jet passing through the air film hole can be diffused in a larger area, which can weaken the strength of the kidney-shaped vortex formed and limit the further development of the kidney-shaped vortex, which is beneficial to increase the wall attachment ability of the air film and improve the cooling effect on the blade.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a top view of a cooling structure provided with an expansion-type air film hole according to an exemplary embodiment of the present disclosure;

FIG2 is a cross-sectional view of the cooling structure provided with expansion-type air film holes along the thickness direction of the substrate according to the exemplary embodiment shown in FIG1 ;

FIG3 is a schematic diagram of a kidney-shaped vortex formed by a cooling structure equipped with an expansion-type air film hole according to the exemplary embodiment shown in FIG1 ; and

FIG. 4 is a schematic diagram of a kidney-shaped vortex formed in a flow field by a cooling structure using cylindrical air film holes in the prior art.

In the drawings, the meanings of the reference numerals are as follows:

1. Air film hole;

11. Air inlet;

12. Transition section;

13. Expansion section;

14. Exhaust port;

141, first arc-shaped portion;

142, second arc portion;

2. Matrix;

3. Mainstream;

4. Jet;

5. Kidney-shaped vortex; and

6. Reverse kidney-shaped vortex.

DETAILED DESCRIPTION

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

The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "include", "comprising", etc. used herein indicate the existence of the features, steps, operations and/or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

When using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, and C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and/or A, B, C, etc. When using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, or C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and/or A, B, C, etc.

In film cooling technology, the film cooling efficiency is not only affected by flow parameters such as blowing ratio, density ratio, mainstream Reynolds number, but also closely related to the geometric shape and related parameters of the film hole. The existing cylindrical film hole has the disadvantage of over-concentrating the jet, which will lead to the formation of a strong kidney-shaped vortex near the air outlet of the film hole, so that the mainstream is sucked from both sides of the kidney-shaped vortex to the bottom of the jet, thereby reducing the wall attachment ability of the film and further reducing the cooling effect of the film hole.

Therefore, based on the above-mentioned deficiencies of the prior art, how to design the air film hole so that the kidney-shaped vortex formed near the air outlet of the air film hole is suppressed to increase the wall adhesion ability of the air film has become a technical problem that needs to be solved urgently.

In view of this, the embodiments of the present disclosure provide a cooling structure and a turbine blade equipped with expansion-type air film holes based on the same inventive concept.

Fig. 1 is a top view of a cooling structure with expanded air film holes according to an exemplary embodiment of the present disclosure. Fig. 2 is a cross-sectional view of the cooling structure with expanded air film holes along the thickness direction of the substrate of the exemplary embodiment shown in Fig. 1 .

According to the cooling structure provided by the present disclosure, as shown in Figures 1 and 2, it includes a substrate 2. A plurality of air film holes 1 extending obliquely along the thickness direction of the substrate are arranged in the substrate 2. The air inlet 11 of the air film hole 1 is formed on the inner surface of the substrate 2, and the air outlet 14 of the air film hole 1 is formed on the outer surface of the substrate 2. The air outlet 14 is configured to be a fan-shaped hole structure that expands to both sides along the air flow direction orthogonal to the air flow direction of the gas passing through the air film hole 1. A transition section 12 and an expansion section 13 are sequentially arranged between the air inlet 11 and the air outlet 14. The expansion section 13 is configured to form an expansion structure that gradually contracts along the width direction of the air outlet 14 and gradually widens along the length direction of the air outlet 14 from the transition section 12 to the air outlet 14, so as to weaken the strength of the kidney-shaped vortex formed near the air outlet 14 in the flow field and induce the generation of an anti-kidney vortex pair.

In an exemplary embodiment, as shown in Fig. 2, the air film hole 1 is inclined along the thickness direction (y direction as shown in Fig. 2) of the substrate 2. In detail, the angle (θ, i.e., the angle formed by the axis of the transition section and the extension direction of the inner surface of the substrate) between the axis of the air film hole 1 and the substrate 2 includes but is not limited to being configured to be 20° to 60°.

In an exemplary embodiment, as shown in FIG2 , the air inlet 11 of the air film hole 1 forms an elliptical hole extending along the inner surface of the substrate 2 (the lower surface as shown in FIG2 ), and the transition section 12 extends along a thickness direction inclined to the substrate 2 (the y direction as shown in FIG2 ).

In an illustrative embodiment, the expansion section 13 is configured to expand toward both sides of the jet along the length direction of the air outlet 14 (the x direction as shown in FIG. 1 ). Further, the expansion section 13 is also configured to gradually contract toward the inside along the width direction of the air outlet 15 (the y direction as shown in FIG. 2 ) to form an expansion structure with a length greater than the aperture (i.e., D) of the transition section and a width less than the aperture (i.e., D) of the transition section, so that the area of the air outlet 14 is greater than the cross-sectional area of the cross section at the connection position of the transition section 12 and the expansion section 13.

According to an embodiment of the present disclosure, as shown in FIG. 1 , the air outlet 11 of the air film hole 1 is configured to be symmetrical along the center line of the air film hole 1 .

According to an embodiment of the present disclosure, as shown in FIG. 2 , the transition section 12 is configured as a cylindrical hole structure.

In an exemplary embodiment, as shown in FIG. 1 , the hole diameter (D) of the transition section 12 is configured to be 2 to 10 mm.

According to an embodiment of the present disclosure, as shown in FIG. 2 , in the orthographic projection in the thickness direction of the substrate 2 (i.e., the top view facing the paper as shown in FIG. 1 ), the length of the expansion section 13 (g as shown in FIG. 1 ) is constructed to be 2.5 to 5 times the aperture of the transition section 12 (i.e., 2.5D to 5D, where D represents the aperture of the transition section).

In the above embodiment, as shown in Figure 2, the length of the expansion section 13 is characterized by the distance from the connection position of the expansion section 13 and the transition section 12 to the midpoint of the air outlet 14 along the length direction of the substrate 2 (the z direction as shown in Figure 2) in the orthographic projection of the thickness direction of the substrate 2 (the y direction as shown in Figure 2).

In such an embodiment, the fan-shaped hole structure of the air outlet can weaken the strength of the kidney-shaped vortex formed, and can induce the formation of anti-kidney-shaped vortices on both sides of the air film hole, thereby inhibiting the development of the kidney-shaped vortex; the expansion section arranged between the transition section and the air outlet is conducive to further reducing the jet velocity. In this way, the wall attachment ability of the air film can be more effectively increased, thereby improving the cooling effect of the cooling structure.

According to an embodiment of the present disclosure, as shown in FIG1 , in the orthographic projection in the thickness direction of the base 2 (i.e., the top view facing the paper as shown in FIG1 ), a first arc-shaped portion recessed toward the air inlet 11 is formed on the side of the air outlet close to the air inlet 11, and a second arc-shaped portion having the same recessed direction as the first arc-shaped portion is formed on the side of the air outlet away from the air inlet, and the first arc-shaped portion and the second arc-shaped portion are connected by a straight line portion.

According to an embodiment of the present disclosure, as shown in FIG. 1 , the radius ( R1 ) of the first arc portion is configured to be 4 to 6 times the aperture of the transition section 12 (ie, 4D to 6D, where D represents the aperture of the transition section).

According to an embodiment of the present disclosure, as shown in FIG. 1 , the radius of the second arc portion is configured to be 3 to 5 times the aperture of the transition section 12 (ie, 3D to 5D, where D represents the aperture of the transition section).

In such an embodiment, the air outlet 14 is configured to be limited by the area surrounded by the first arc portion 141, the second arc portion 142 and the straight portion, so that the jet passing through the air film hole can be diffused in a larger area, reducing the outflow in the central area of the air film hole and increasing the outflow from both sides of the air film hole, which is beneficial to inhibiting the formation of kidney-shaped vortex to increase the wall attachment ability of the air film.

According to an embodiment of the present disclosure, as shown in FIG. 1 , a connection portion between the first arc-shaped portion and/or the second arc-shaped portion and the straight portion is configured as a rounded structure.

According to an embodiment of the present disclosure, as shown in Figure 1, the connecting part of the first arc portion and/or the second arc portion and the straight portion is configured such that the radius of the fillet is configured to be 0.1 to 0.3 times the aperture of the transition section 12 (i.e., 0.1D to 0.3D, where D represents the aperture of the transition section).

In an exemplary embodiment, as shown in FIG1 , the included angle (γ) of the fan-shaped area formed by the first arc-shaped portion and the second arc-shaped portion is configured to include but not limited to 38° to 62°.

In such an embodiment, the connection position between the straight portion and the first arc-shaped portion 141 and the second arc-shaped portion is inverted into an arc structure, which can reduce the collision between the jet 4 and the inner edge of the air outlet 14 of the air film hole 1. In this way, it is beneficial to increase the coverage area of the air film along the air flow direction and can effectively reduce the flow resistance to the jet. It should be understood that the embodiments of the present disclosure are not limited to this.

For example, the radius of the fillet formed by the first arc-shaped portion, the second arc-shaped portion and the straight portion can be set according to the cooling efficiency and flow resistance required to be provided by the air film hole to meet the cooling effect on the blade.

According to an embodiment of the present disclosure, as shown in FIG. 1 , a plurality of air film holes 1 are arranged at intervals along the air flow direction and/or the air flow direction to form an air film hole array.

In an exemplary embodiment, as shown in FIG1 , a plurality of air film holes 1 are evenly spaced along the air flow direction of the mainstream 3 (the x direction as shown in FIG1 ). In detail, the spacing (P) between two adjacent air film holes 1 is configured to include but not limited to 3D to 6D (D represents the aperture of the transition section). It should be understood that the embodiments of the present disclosure are not limited thereto.

For example, two adjacent exhaust film holes 1 can be staggered along the airflow direction (z direction as shown in FIG. 1 ). (Not shown in the figure)

For another example, two adjacent rows of air film holes 1 can be evenly spaced along the airflow direction (z direction as shown in FIG. 1 ). (Not shown in the figure)

For example, the film hole arrays are arranged in other row/column forms, and the specific arrangement of the film hole arrays should meet the cooling requirements of the blades.

A turbine blade with a cooling structure provided in accordance with the present disclosure, as shown in FIG1 , comprises a blade formed by a substrate 2, wherein a gas flow channel for accommodating the passage of cooling gas (including but not limited to gas at a temperature lower than the operating temperature of the turbine) is provided inside the blade, and a plurality of air film holes 1 are provided on the substrate 2, wherein an air inlet 11 of the air film hole 1 is connected to the gas flow channel to accommodate the cooling gas flowing out through the air film hole 1, so that an air film is formed on at least a portion of the outer surface of the blade.

In an exemplary embodiment, the base 2 includes but is not limited to a blade integrally formed with a plate-like structure. Specifically, the base 2 integrally forms at least a portion of the leading edge, back, basin and trailing edge of the blade according to the design requirements of the blade.

In a schematic embodiment, as shown in FIG1 , a plurality of film holes 1 are evenly spaced along the airflow direction of the mainstream 3 (the x direction as shown in FIG1 , where the x direction can represent the blade height direction of the blade) to form an air film hole array in the form of a row array.

Fig. 3 is a schematic diagram of a kidney-shaped vortex formed by a cooling structure equipped with an expansion-type air film hole according to the exemplary embodiment shown in Fig. 1. Fig. 4 is a schematic diagram of a kidney-shaped vortex formed in a flow field by a cooling structure using a cylindrical air film hole in the prior art.

In an illustrative embodiment, a comparative test is conducted based on the structure and parameters of the cooling structure film hole of the above embodiment and a cylindrical film hole with a diameter D of the transition section of the cooling structure film hole of the above embodiment as the diameter.

In detail, as shown in Figure 3, at the outlet end of the air film hole as disclosed in the above embodiment, a kidney-shaped vortex (pair) with a longitudinal length (i.e., the y direction shown in Figure 3) of m2 and a lateral length of n2 is formed, as well as an anti-kidney-shaped vortex 6 (pair) with a longitudinal length of m3 and a lateral length of n3.

Further, as shown in FIG. 4 , a kidney-shaped vortex 5 having a longitudinal length (ie, the y direction shown in FIG. 4 ) of m1 and a transverse length of n1 is formed at the outlet end of the cylindrical air film hole.

Based on the above comparative test, m2 and m3 are both smaller than m1, and n2 and n3 are both smaller than n1. It can be seen that the above cooling structure and the turbine blade with the above cooling structure can significantly suppress the strength of the kidney-shaped vortex compared to the cooling structure and the turbine blade with cylindrical air film holes, thereby increasing the wall attachment ability of the air film, so that the cooling structure has a better cooling effect.

Furthermore, based on the analysis of typical working conditions, it is found that the cooling efficiency of the turbine blade with the above cooling structure is improved by 17% compared with the cooling structure and turbine blade with cylindrical air film holes. Therefore, the technical effect of improving the cooling efficiency is achieved.

It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure.

The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims (11)

1. A cooling structure equipped with expansion-type air film holes, characterized in that it comprises a substrate (2), wherein a plurality of air film holes (1) extending obliquely along the thickness direction of the substrate are arranged in the substrate (2); The air inlet (11) of the air film hole (1) is formed on the inner surface of the substrate (2), and the air outlet (14) of the air film hole (1) is formed on the outer surface of the substrate (2), and the air outlet (14) is configured to be a fan-shaped hole structure that expands to both sides along an air flow direction that is orthogonal to the air flow direction of the gas passing through the air film hole (1); A transition section (12) and an expansion section (13) are arranged in sequence between the air inlet (11) and the air outlet (14); the expansion section (13) is configured to form an expansion structure from the transition section (12) to the air outlet (14), which gradually contracts along the width direction of the air outlet (14) and gradually widens along the length direction of the air outlet (14), so as to weaken the strength of a kidney-shaped vortex formed near the air outlet (14) in the flow field and induce the generation of an anti-kidney-shaped vortex pair. 2. The cooling structure according to claim 1, characterized in that the air outlet (11) is configured to be symmetrical along the center line of the air film hole (1). 3. The cooling structure according to claim 1 is characterized in that, in the orthographic projection in the thickness direction of the substrate (2), a first arc-shaped portion recessed toward the air inlet (11) is formed on a side of the air outlet close to the air inlet (11), and a second arc-shaped portion having the same recessed direction as the first arc-shaped portion is formed on a side of the air outlet away from the air inlet, and the first arc-shaped portion and the second arc-shaped portion are connected by a straight line portion. 4 . The cooling structure according to claim 3 , wherein a connecting portion between the first arc-shaped portion and/or the second arc-shaped portion and the straight portion is configured as a rounded structure. 5. The cooling structure according to claim 4, characterized in that the transition section (12) is configured as a cylindrical hole structure. 6. The cooling structure according to claim 5, characterized in that, in the orthographic projection in the thickness direction of the base body (2), the length of the expansion section (13) is configured to be 2.5 to 5 times the aperture of the transition section (12). 7. The cooling structure according to claim 5, characterized in that the radius of the first arc-shaped portion is configured to be 4 to 6 times the hole diameter of the transition section (12). 8. The cooling structure according to claim 5, characterized in that the radius of the second arc-shaped portion is configured to be 3 to 5 times the hole diameter of the transition section (12). 9. The cooling structure according to claim 5, characterized in that the connecting portion of the first arc-shaped portion and/or the second arc-shaped portion and the straight portion is configured such that the radius of the fillet is configured to be 0.1 to 0.3 times the aperture of the transition section (12). 10. The cooling structure according to any one of claims 1 to 9, characterized in that a plurality of the air film holes (1) are arranged at intervals along the air flow direction and/or the air flow span direction to form an air film hole array. 11. A turbine blade having a cooling structure as described in any one of claims 1 to 10, characterized in that it comprises a blade formed by a substrate (2), wherein a gas flow channel for accommodating the passage of cooling gas is arranged inside the blade, and a plurality of air film holes (1) are arranged on the substrate (2), and an air inlet (11) of the air film hole (1) is connected to the gas flow channel to accommodate the cooling gas flowing out through the air film hole (1), so that an air film is formed on at least a portion of the outer surface of the blade.