Cooling structure and airfoil

Abstract

A cooling structure and an airfoil are used for improving the situation that cross flow weakens the impact jet flow heat exchange effect. The cooling structure is used for the airfoil and comprises a targeting wall and an impingement wall; the targeting wall is used for being impacted by cooling gas; the impact wall is located in the opposite direction of the targeting wall and provided with at least one convex hull, the convex hulls protrude towards the targeting wall, and the top end of each convex hull is provided with an impact hole for cooling gas to impact the targeting wall through the impact holes.

Description

Technical Field

[0001] The utility model relates to cooling technology, in particular to a cooling structure and an airfoil. Background Art

[0002] To improve the overall performance of aircraft engines, the temperature before the turbine needs to be increased, which means that the turbine blades must withstand higher gas temperatures. In modern aircraft engine design technology, in addition to developing new materials and processes, it is necessary to design blade cooling structures with high cooling efficiency to ensure that turbine blades can operate normally in high-temperature gas. For the guide vanes of aircraft engine high-pressure turbines, a common blade cooling design solution is to arrange air film holes on the blade surface, drawing cooling air out of the air film holes. As the cooling air flows through the holes, it removes heat from the blades and forms a cooling air film on the blade surface, reducing direct contact between the blades and the high-temperature gas. In addition, the blade is divided into several chambers, and cooling solutions such as jet impingement are used in each chamber to enhance the scouring of the cooling air on the inner wall and strengthen internal heat exchange. To achieve jet impingement cooling, a common solution is to insert an impingement bushing into the blade chamber and open impingement holes on the bushing as needed, so that the cooling air is throttled at the impingement holes, forming a jet under the action of the internal and external pressure difference. The use of film cooling technology can effectively reduce the temperature of turbine blades, but if too much cold air is consumed for cooling, the efficiency of the turbine will be reduced, especially the cold air flowing out of the film holes behind the guide vane throat, which has poor work capacity and is detrimental to the performance of the turbine. In order to balance the contradiction between cooling and performance, film holes are generally not set behind the throat position of the blade suction surface, such as Figure 1 As shown in the figure, this poses certain challenges to the blade cooling design, which requires relying solely on the cold air flowing out of the film holes on the front side of the suction throat and the efficient internal jet impact to reduce the temperature of the rear area of ​​the suction throat. In the rear area of ​​the suction throat, after the impact jet washes the inner wall of the blade, there is no film hole to divert the cold air. In order to maximize the jet impact heat transfer effect, the target surface spacing of the jet (the distance from the impact hole outlet to the target surface) is often designed to be very small, resulting in a narrow channel cross-section and high cross-flow velocity when the cross-flow flows toward the trailing edge. In an array composed of multiple rows of impact holes, along the chord direction, as the impact hole rows accumulate, the cross-flow flow rate gradually increases, the flow velocity gradually increases, and the weakening of the downstream impact jet heat transfer becomes more and more obvious, resulting in poor cooling effect. Utility Model Content

[0003] The purpose of the utility model is to provide a cooling structure and an airfoil, which are used to improve the situation in which the cross flow weakens the heat exchange effect of the impinging jet.

[0004] In the first aspect, the present invention provides a cooling structure. According to an embodiment of the present invention, the cooling structure is used for an airfoil and includes a targeting wall and an impact wall; the targeting wall is used to be impacted by cooling gas; the impact wall is located opposite to the targeting wall and is provided with at least one bulge, the bulge protruding toward the targeting wall, and an impact hole is provided at the top of each bulge for cooling gas to impact the targeting wall through the impact hole.

[0005] In one or more embodiments, the convex hull is a solid of revolution with a cosine curve as its outline.

[0006] In one or more embodiments, the convex hull is tangent to the impact wall at a root.

[0007] In one or more embodiments, the central axis of each impact hole coincides with the central axis of the convex hull where it is located.

[0008] In one or more embodiments, the diameter of the convex hull is D, the diameter of the impact hole is d, and D / d≥2.

[0009] In one or more embodiments, the distance from the outlet of the impact hole to the wall surface of the targeting wall is j, the diameter of the impact hole is d, and 0.5≤j / d≤3.

[0010] In one or more embodiments, the plurality of impact holes and the plurality of convex hulls in which they are located are arranged in columns along the radial direction and in rows along the chord direction, the radial spacing between two radially adjacent impact holes is Pr, the chordal spacing between two chordally adjacent impact holes is Pc, the diameter of each convex hull is D, the diameter of each impact hole is d, 3≤Pr / d≤10, Pr / D≥1, 3≤Pc / d≤10, Pc / D≥1.

[0011] In one or more embodiments, the plurality of impact holes and the plurality of convex hulls in which they are located are arranged into a first row and a second row along the chord direction, the first row and the second row are alternately distributed along the radial direction, the impact holes in different first rows are arranged into columns along the radial direction, and the impact holes in different second rows are arranged into columns along the radial direction, each impact hole in the second row is located at the chord-wise middle position between two chord-wise adjacent impact holes in the first row, the chord-wise spacing between two chord-wise adjacent impact holes in the first row and the second row is Pc, the radial spacing between the impact holes in the first row and the radially adjacent impact holes in the second row is Pr, the chord-wise spacing between the impact holes in the first row and the radially adjacent impact holes in the second row is Ph, the diameter of each convex hull is D, the diameter of each impact hole is d, 3≤Pc / d=2Ph / d≤10, Pc / D≥1, 2.6≤Pr / d≤8.7, and Pr / D≥0.87.

[0012] In one or more embodiments, the cosine curve is based on the protrusion height of the impact wall being h, the diameter of the convex hull being D, the central axis of the impact hole coinciding with the central axis of the convex hull, the central axis of the impact hole being the y-axis, and the straight line on the surface of the impact wall being the x-axis. The equation of the cosine curve is: Among them, 1≤D / h≤2.5.

[0013] In one or more embodiments, the targeting wall is not provided with air film holes.

[0014] In a second aspect, the present invention provides an airfoil. According to an embodiment of the present invention, the airfoil includes the above-mentioned cooling structure.

[0015] In one or more embodiments, the targeting wall provides a suction side wall behind the throat of the airfoil. The airfoil further includes an impingement bushing and a trailing edge split. The impingement wall is provided by the impingement bushing, and the cooling cavity where the impingement wall is located is connected to the trailing edge split.

[0016] The embodiments of the present invention have at least the following beneficial effects:

[0017] The impact wall adjacent to the convex hull increases the flow cross section of the cross flow, reduces the flow velocity of the cross flow, reduces the deflection effect of the cross flow on the jet, and reduces the weakening effect of the cross flow on the jet impact heat transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:

[0019] Figure 1 is a cross-sectional view of an airfoil;

[0020] Figure 2 is an oblique view of the impact bushing;

[0021] Figure 3 is a side view of the impact bushing;

[0022] Figure 4 It is a partial cross-sectional view of an airfoil;

[0023] Figure 5 A partial cross-sectional view of a targeting wall and an impact wall with a convex hull;

[0024] Figure 6 A partial front view of an impact wall with sequentially arranged convex hulls;

[0025] Figure 7 A partial front view of an impact wall with a staggered array of convex hulls;

[0026] Figure 8 is a cross-sectional view of the convex hull.

[0027] Reference numerals:

[0028] 1- airfoil;

[0029] 2- Impact bushing;

[0030] 3-Cooling chamber;

[0031] 4- caudal edge split;

[0032] 5- Impact hole;

[0033] 6- Cooling air;

[0034] 7-jet;

[0035] 8-Targeting wall;

[0036] 9-air film hole;

[0037] 10-throat;

[0038] 11-cross flow;

[0039] 12- Spacing between the targeting wall and the impact bushing;

[0040] 13- Impact wall;

[0041] 14-convex hull;

[0042] 15-cross flow channel;

[0043] 16- Cosine curve as the contour of the convex hull

[0044] 17-first row;

[0045] 18-Second row. DETAILED DESCRIPTION

[0046] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided to explain the present invention, not to limit the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the present invention. For example, features shown or described as part of one embodiment can be used together with another embodiment to produce yet another embodiment. Therefore, the present invention is intended to cover such modifications and variations as fall within the scope of the appended claims and their equivalents.

[0047] It should be noted that these and other subsequent drawings are only examples and are not drawn to scale, and should not be used to limit the actual scope of protection required by the present invention.

[0048] The terms "first," "second," and the like may be used interchangeably to distinguish one feature from another and are not intended to imply that each feature must be located as shown in each embodiment.

[0049] Figure 1 and Figure 4 The cross-sectional structure of the airfoil 1 is shown, where the cross-sectional view is perpendicular to the radial direction of the airfoil 1 , where the radial direction of the airfoil 1 is the direction from the blade root to the blade tip of the airfoil 1 . Figure 5 and Figure 8 The cross-sectional structure of the airfoil 1 is shown, where the cross-sectional plane is perpendicular to the chord direction of the airfoil 1, where the chord direction of the airfoil 1 is the leading edge-trailing edge direction of the airfoil 1. The transverse direction is perpendicular to the radial direction and the chord direction.

[0050] like Figure 1 and Figure 4 As shown, the airfoil 1 may include an impact bushing 2, which is arranged in a cooling chamber 3 of the airfoil 1 connected to the trailing edge slit 4, and the impact bushing 2 is provided with a plurality of impact holes 5, further combined with Figure 2 The cooling air 6 is introduced into the hollow impact bushing 2 from the inlet of the impact bushing 2. Figure 4 Under the action of the pressure difference between the inside and outside of the impact bushing 2, the cooling gas 6 forms a jet 7 and is ejected from the impact hole 5 at high speed, impacting the inner wall surface of the target wall 8 of the airfoil 1, thereby enhancing convective heat transfer.

[0051] like Figure 1 As shown, some of the targeting walls 8 of the airfoil 1 are provided with air film holes 9, while some of the targeting walls 8 are not provided with air film holes 9. The airfoil 1 can be a guide blade of a high-pressure turbine of an aircraft engine. When the suction side wall behind the throat 10 of the high-pressure turbine guide blade is used as the targeting wall 8, the air film holes 9 may not be provided to avoid excessive consumption of cooling air 6 and reduce the efficiency of the turbine. The throat 10 is located at the point where the flow area of ​​the two circumferentially adjacent turbine blades is the smallest. The rear is the outflow direction when the turbine blade is working. As shown in FIG. Figure 4As shown, for a target wall 8 without film holes 9, the jet 7 impacts the target wall 8 to form a cross flow 11. The cross flow 11 flows along the chordwise direction within the gap 12 between the target wall 8 and the impact bushing 2 to the trailing edge of the airfoil 1 and enters the mainstream combustion gas through the trailing edge slit 4. To maximize the impact heat transfer effect of the jet 7, the gap 12 between the target wall 8 and the impact bushing 2 is often designed to be very small, and the flow cross section of the cross flow 11 is small. In the array composed of multiple rows of impact holes 5, along the chordwise flow direction of the cross flow 11, as the cross flow 11 gradually accumulates, the flow rate of the cross flow 11 continues to increase, the flow velocity continues to increase, and the deflection effect on the jet 7 continues to increase, weakening the impact heat transfer effect of the jet 7, resulting in poor cooling effect, increased wall temperature of the target wall 8, and large pressure loss when the high-speed cross flow 11 passes through the narrow gap 12 and the trailing edge slit 4.

[0052] like Figures 2 to 8 As shown, in order to alleviate the problem of cross flow 11 weakening the impact heat exchange effect of jet 7, on the opposite side of the target wall 8, especially on the opposite side of the target wall 8 where the air film hole 9 is not set and the cross flow 11 weakens the impact heat exchange effect of jet 7, at least one convex hull 14 is set on the impact wall 13 of the impact bushing 2. The convex hull 14 protrudes toward the target wall 8, and the distance from the convex hull 14 to the target wall 8 is less than the distance from the impact wall 13 to the target wall 8. The impact wall 13 adjacent to the convex hull 14 is recessed away from the target wall 8, thereby forming a cross flow channel 15 recessed away from the target wall 8. An impact hole 5 is set at the top of each convex hull 14. Figure 4 The cooling gas 6 forms a jet 7, which is ejected at high speed through the impact hole 5 and impacts the inner surface of the target wall 8, enhancing convective heat transfer. After impacting the target wall 8, the jet 7 flows in all directions and enters the surrounding cross-flow channels 15, converging to form a cross-flow 11 and flowing downstream toward the trailing edge slit 4. The impact wall 13 adjacent to the convex bulge 14 is recessed away from the target wall 8, thereby increasing the flow area of ​​the cross-flow channel 15, increasing the flow cross section of the cross-flow 11, reducing the flow velocity of the cross-flow 11, reducing the deflection effect of the cross-flow 11 on the jet 7, and reducing the weakening effect of the cross-flow 11 on the impact heat transfer of the jet 7. The convex bulge 14 protruding toward the target wall 8 shortens the target surface distance from the outlet of the impact hole 5 to the inner wall of the target wall 8, thereby enhancing the impact heat transfer effect of the jet 7. In addition, after the jet 7 impacts the target wall 8, the cross-flow channel 15 guides the cross-flow 11, thereby reducing the flow resistance of the cross-flow 11, minimizing the mixing loss between the cross-flow 11 and the jet 7, and reducing the total pressure loss of the cooling gas flow.

[0053] like Figures 2 to 8 As shown, the convex hull 14 can be a body of revolution with a cosine curve 16 as the outline. The convex hull 14 can be tangent to the impact wall 13 at the root and smoothly transition with the impact wall 13, which can reduce the surface loss of the cooling air flow and facilitate stamping during processing. Figure 4 、 Figure 5 and Figure 8The central axis of each impact hole 5 coincides with the central axis of the convex hull 14 in which it is located, so that the impact hole 5 is located at the center of the convex hull 14, so that the jet 7 ejected from the impact hole 5 is evenly merged into the surrounding cross-flow channels 15 after impacting the targeting wall 8. The central axis of each impact hole 5 can be perpendicular to the inner wall surface of the targeting wall 8. The distance from the outlet of each impact hole 5 to the inner wall surface of the targeting wall 8 is j, and the diameter of each impact hole 5 is d. 0.5≤j / d≤3 limits the target surface distance from the outlet of the impact hole 5 to the inner wall surface of the targeting wall 8, ensuring that the jet 7 formed by the impact hole 5 impacts the inner wall surface of the targeting wall 8 to generate a high heat transfer coefficient, thereby ensuring the impact heat transfer effect of the jet 7.

[0054] like Figure 8 As shown, the diameter of each convex hull 14 is D, D / d≥2, which limits the minimum ratio of the diameter D of the convex hull 14 to the diameter d of the impact hole 5, thereby limiting the minimum value of the flow area of ​​the cross-flow channel 15 and ensuring that the cross-flow channel 15 has a deceleration effect on the cross flow 11. Figure 8 The cosine curve 16 is based on the protruding height of the impact wall 13 being h, the central axis of the impact hole 5 coinciding with the central axis of the convex hull 14, the central axis of the impact hole 5 being the y-axis, and the straight line on the surface of the impact wall 13 being the x-axis. The equation of the cosine curve 16 is: Among them, 1≤D / h≤2.5 limits the ratio of the diameter D of the convex hull 14 and the protruding height h of the cosine curve 16 to prevent the convex hull 14 from being too steep or too flat. A too steep hull is not conducive to stamping during processing, and a too flat hull results in a small flow area of ​​the cross-flow channel 15, which cannot ensure the cross-flow channel 15's deceleration effect on the cross flow 11.

[0055] like Figure 6 In the illustrated embodiment, the multiple convex humps 14 on the impact wall 13 can be arranged sequentially, the multiple impact holes 5 and the multiple convex humps 14 on which they are located are arranged in columns along the radial direction and in rows along the chord direction, the different convex humps 14 and the impact holes 5 thereon are arranged in columns along the radial direction, a column of impact holes 5 includes the impact holes 5 on each convex hump 14 distributed along the radial direction, the different convex humps 14 and the impact holes 5 thereon are arranged in rows along the chord direction, and a row of impact holes 5 includes the impact holes 5 on each convex hump 14 distributed along the chord direction. The radial spacing between two radially adjacent impact holes 5 is Pr, and the chord-wise spacing between two chord-wise adjacent impact holes 5 is Pc. 3≤Pr / d≤10, Pr / D≥1, 3≤Pc / d≤10, Pc / D≥1. This limits the density of the impact hole 5 array to avoid the impact holes 5 being too dense, the total opening area of ​​the impact holes 5 being too large, the throttling effect being reduced, the pressure difference between the inlet and outlet of the impact holes 5 being reduced, the stiffness of the jet 7 being reduced, and the resulting insufficient impact heat exchange effect of the jet 7. It also avoids the impact holes 5 being too sparse, resulting in insufficient cooling effect.

[0056] like Figure 7In the illustrated embodiment, the multiple convex hulls 14 on the impact wall 13 can be arranged crosswise. In the coordinate system in the figure, u represents the chord direction, v represents the radial direction, and the multiple impact holes 5 and the multiple convex hulls 14 in which they are located are arranged into a first row 17 and a second row 18 along the chord direction. Different convex hulls 14 and the impact holes 5 thereon are arranged in rows along the chord direction. The first row 17 and the second row 18 both include the impact holes 5 on each convex hull 14 distributed along the chord direction. The first row 17 and the second row 18 are alternately distributed along the radial direction. The impact holes 5 in different first rows 17 are arranged in rows along the radial direction. A row of impact holes 5 includes the impact holes 5 on the convex hull 14 belonging to the first row 17 distributed along the radial direction. The impact holes 5 in different second rows 18 are arranged in rows along the radial direction. A row of impact holes 5 includes the impact holes 5 on the convex hull 14 belonging to the second row 18 distributed along the radial direction. Each impact hole 5 in the second row 18 is positioned at At the chordally middle position of two chordally adjacent impact holes 5 in the first row 17 and the second row 18, the chordally spacing between the two chordally adjacent impact holes 5 is Pc, the radial spacing between the impact holes 5 in the first row 17 and the impact holes 5 in the radially adjacent second row 18 is Pr, and the chordally spacing between the impact holes 5 in the first row 17 and the impact holes 5 in the radially adjacent second row 18 is Ph. 3≤Pc / d=2Ph / d≤10, Pc / D≥1, 2.6≤Pr / d≤8.7, and Pr / D≥0.87. This limits the density of the array of impact holes 5, avoids the impact holes 5 being too dense, the total opening area of ​​the impact holes 5 being too large, and the throttling effect being reduced, reduces the pressure difference between the inlet and outlet of the impact holes 5, reduces the stiffness of the jet 7, and causes insufficient impact heat exchange effect of the jet 7, and also avoids the impact holes 5 being too sparse, resulting in insufficient cooling effect.

[0057] Although the present invention is disclosed above with reference to the embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention.

Claims

1. A cooling structure for an airfoil, characterized in that include: a targeting wall for being struck by cooling gas; as well as The impact wall is located opposite to the targeting wall and is provided with at least one convex bulge, the convex bulge protrudes toward the targeting wall, and an impact hole is provided at the top of each convex bulge for cooling gas to impact the targeting wall through the impact hole.

2. The cooling structure according to claim 1, characterized in that: The convex hull is a body of revolution with a cosine curve as its outline.

3. The cooling structure according to claim 2, characterized in that: The convex hull is tangent to the impact wall at a root.

4. The cooling structure according to claim 2, characterized in that: The central axis of each impact hole coincides with the central axis of the convex hull where it is located.

5. The cooling structure according to claim 3, characterized in that: The diameter of the convex hull is D, the diameter of the impact hole is d, and D / d≥2.

6. The cooling structure according to claim 1, characterized in that: The distance from the outlet of the impact hole to the wall surface of the targeting wall is j, the diameter of the impact hole is d, and 0.5≤j / d≤3.

7. The cooling structure according to claim 3, characterized in that: The multiple impact holes and the multiple convex hulls in which they are located are arranged in columns along the radial direction and in rows along the chord direction. The radial spacing between two radially adjacent impact holes is Pr, and the chord-wise spacing between two chord-wise adjacent impact holes is Pc. The diameter of each convex hull is D, and the diameter of each impact hole is d. 3≤Pr / d≤10, Pr / D≥1, 3≤Pc / d≤10, and Pc / D≥1.

8. The cooling structure according to claim 3, characterized in that: The plurality of impact holes and the plurality of convex hulls in which they are located are arranged into a first row and a second row along the chord direction, the first row and the second row are alternately distributed along the radial direction, the impact holes in different first rows are arranged into rows along the radial direction, and the impact holes in different second rows are arranged into rows along the radial direction, each of the impact holes in the second row is located at a chord-wise middle position between two chord-wise adjacent impact holes in the first row, the chord-wise spacing between two chord-wise adjacent impact holes in the first row and the second row is Pc, the radial spacing between the impact holes in the first row and the radially adjacent impact holes in the second row is Pr, the chord-wise spacing between the impact holes in the first row and the radially adjacent impact holes in the second row is Ph, the diameter of each convex hull is D, the diameter of each impact hole is d, 3≤Pc / d=2Ph / d≤10, Pc / D≥1, 2.6≤Pr / d≤8.7, Pr / D≥0.

87.

9. The cooling structure according to claim 3, characterized in that: The cosine curve is based on the protrusion height of the impact wall being h, the diameter of the convex hull being D, the central axis of the impact hole coinciding with the central axis of the convex hull, the central axis of the impact hole being the y-axis, and the straight line on the surface of the impact wall being the x-axis. The equation of the cosine curve is: Among them, 1≤D / h≤2.

5.

10. The cooling structure according to claim 1, characterized in that: The targeting wall is not provided with air film holes.

11. An airfoil, characterized in that: The airfoil comprises a cooling structure according to any one of claims 1 to 10.

12. The airfoil according to claim 11, characterized in that: The targeting wall provides a suction side wall at the rear side of the throat of the airfoil. The airfoil further comprises an impingement bushing and a trailing edge split. The impingement wall is provided by the impingement bushing. The cooling cavity where the impingement wall is located is connected to the trailing edge split.

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