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 a wavy impingement wall; the targeting wall is used for being impacted by cooling gas; the wave-shaped impact wall is located in the opposite direction of the target wall and comprises at least one wave crest and at least one wave trough, the wave crests and the wave troughs are distributed alternately in the radial direction and extend in the chordwise direction, the distance from the wave crests to the target wall is smaller than the distance from the wave troughs to the target wall, the wave crests are provided with impact holes, and the impact holes are communicated with the wave crests. And the targeting wall is impacted by cooling gas through the impingement hole.

Description

Technical Field

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

[0002] In order to improve the comprehensive performance of aircraft engines, the temperature before the turbine needs to be increased, resulting in the turbine blades having to withstand higher gas temperatures. In modern aircraft engine design technology, in addition to developing new materials and new processes, it is necessary to design a blade cooling structure with high cooling efficiency in order to ensure that the turbine blades can work normally in high-temperature gas. For the guide blades of the high-pressure turbine of an aircraft engine, a common blade cooling design scheme is to arrange air film holes on the blade surface, draw out the cooling air from the air film holes, and the cooling air can take away the heat of the blade when flowing in the holes, and form a cooling air film on the blade surface, reducing the direct contact between the blade and the high-temperature gas. In addition, several chambers are divided inside the blade, and cooling schemes such as jet impingement are used in each chamber to enhance the scouring of the cooling air on the inner wall and strengthen the internal heat exchange. In order to construct jet impingement cooling, a common scheme is to insert an impingement bushing into the chamber of the blade, and open impingement holes on the bushing as needed, so that the cooling air is throttled at the impingement hole, and a jet is formed 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 not conducive 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 of the blade suction surface, such as Figure 1 As shown in the figure, this brings certain challenges to the blade cooling design, which requires only the cold air flowing out of the film holes on the front side of the throat of the suction surface and the efficient internal jet impact to reduce the temperature of the rear area of ​​the throat of the suction surface. In the rear area of ​​the throat of the suction surface, the impact jet has no film holes to divert the cold air after washing the inner wall of the blade, and in order to maximize the jet impact heat exchange 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, so that when the cross flow flows to the trailing edge, the channel cross section is narrow and the cross flow velocity is high. 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 impact jet heat exchange at the downstream becomes more and more obvious, resulting in poor cooling effect. Utility Model Content

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

[0004] In the first aspect, the utility model provides a cooling structure. According to an embodiment of the utility model, the cooling structure is used for an airfoil and includes a targeting wall and a wavy impact wall; the targeting wall is used to be impacted by cooling gas; the wavy impact wall is located opposite to the targeting wall, and includes at least one wave crest and at least one wave trough, the wave crests and the wave troughs are radially alternately distributed and extend along the chord direction, the distance from the wave crest to the targeting wall is smaller than the distance from the wave trough to the targeting wall, and the wave crest is provided with an impact hole for cooling gas to impact the targeting wall via the impact hole.

[0005] In one or more embodiments, the wave crest includes a first circular arc wall, and the wave trough includes a second circular arc wall.

[0006] In one or more embodiments, the wave-shaped impact wall further includes a straight wall body, the straight wall body bridges the first circular arc wall body and the second circular arc wall body, and the straight wall body is tangent to the first circular arc wall body and tangent to the second circular arc wall body.

[0007] In one or more embodiments, the central axis of each impact hole passes through the center of the first arc wall.

[0008] In one or more embodiments, the plurality of impact holes are arranged in a row along the radial direction, and the distance from the center of each of the second arc wall bodies to the central axes of two radially adjacent impact holes is the same.

[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 diameter of each impact hole is d, and the radius of the first arc wall is r. 1 , the radius of the second arc wall is r 2 , 2d≤r 1 ≤r 2 .

[0011] In one or more embodiments, the distance from the outlet of each impact hole to the wall surface of the targeting wall is j, the height difference between the wave crest and the wave trough is h, and h / j≥2.

[0012] In one or more embodiments, the plurality of impact holes are arranged in columns radially and in rows chordally, the radial spacing between two radially adjacent impact holes is Pr, the diameter of each impact hole is d, 3≤Pr / d≤10, and the chord-wise spacing between two chord-wise adjacent impact holes is Pc, 3≤Pc / d≤10.

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

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

[0015] In one or more embodiments, the targeting wall provides a suction side wall on the rear side of the throat of the airfoil, and the airfoil further includes an impact bushing and a trailing edge split, the wavy impact wall is provided by the impact bushing, and the cooling chamber where the wavy impact 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 trough increases the flow area of ​​the cross-flow channel, increases the flow cross-flow section, reduces the flow velocity of the cross-flow, reduces the deviation effect of the cross-flow on the jet, reduces the weakening effect of the cross-flow on the jet impact heat exchange, and the wave peak protruding toward the target wall shortens the target surface distance from the impact hole outlet to the inner wall surface of the target wall, thereby enhancing the impact heat exchange effect of the jet. 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 an oblique view of the impact bushing;

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

[0023] Figure 5 A schematic diagram of a jet with a wave-shaped impact wall impacting a target wall;

[0024] Figure 6 It is a partial cross-sectional view of a corrugated impact wall and a targeting wall;

[0025] Figure 7 It is a partial front view of the wavy impact wall.

[0026] Reference numerals:

[0027] 1- airfoil;

[0028] 2- Impact bushing;

[0029] 3-Cooling chamber;

[0030] 4- caudal edge split;

[0031] 5- Impact hole;

[0032] 6- Cooling air;

[0033] 7-Jet;

[0034] 8- Targeting wall;

[0035] 9-air film hole;

[0036] 10 - larynx;

[0037] 11-cross flow;

[0038] 12- Spacing between the targeting wall and the impact bushing;

[0039] 13-Wave-shaped impact wall;

[0040] 14- crest;

[0041] 15-trough;

[0042] 16- cross flow channel;

[0043] 17-protruding tendons;

[0044] 18- first arc wall;

[0045] 19- second arc wall;

[0046] 20-straight wall;

[0047] 21-straight impact wall;

[0048] 22- Transition side wall. DETAILED DESCRIPTION

[0049] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are shown in the accompanying drawings. Each example is provided to explain the present invention, rather than to limit the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as part of one embodiment may be used together with another embodiment to produce yet another embodiment. Therefore, the present invention is intended to cover these modifications and variations that fall within the scope of the appended claims and their equivalents.

[0050] It should be noted that these and other subsequent drawings are only examples and are not drawn in proportion, and should not be used as a limitation on the actual scope of protection required by the present utility model.

[0051] The terms "first", "second", etc. may be used interchangeably to distinguish one feature from another, and are not intended to mean that each feature must be located as shown in the figures in each embodiment.

[0052] Figure 1 and Figure 4 The cross-sectional structure of the airfoil 1 is shown, where the cross-sectional plane is perpendicular to the radial direction of the airfoil 1 , and 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 6 The cross-sectional structure of the airfoil 1 is shown, and the cross-sectional plane is perpendicular to the chord direction of the airfoil 1, and 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.

[0053] like Figure 1 and Figure 4 As shown, the airfoil 1 may include an impact bushing 2, which is disposed 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 gas 6 is introduced into the hollow impact bushing 2 from the inlet of the impact bushing 2, and further combined with Figure 5 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.

[0054] 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 may 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, so as to avoid excessive consumption of cooling gas 6 and reduce the efficiency of the turbine. The throat 10 is located at the point where the flow area of ​​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 4 As shown, for the target wall 8 without the air film hole 9, the jet 7 forms a cross flow 11 after impacting the target wall 8. The cross flow 11 flows along the chord direction in 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 split 4. In order to maximize the impact heat exchange 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 chord 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 rate continues to increase, and the deflection effect on the jet 7 continues to increase, weakening the impact heat exchange effect of the jet 7, resulting in poor cooling effect, the wall temperature of the target wall 8 increases, and the pressure loss of the high-speed cross flow 11 is also large when passing through the narrow gap 12 and the trailing edge split 4.

[0055] like Figures 2 to 7As shown, in order to alleviate the problem that the cross flow 11 weakens the impact heat exchange effect of the jet 7, the impact bushing 2 can be provided with a wavy impact wall 13 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 provided and the cross flow 11 weakens the impact heat exchange of the jet 7. The wavy impact wall 13 is provided with at least one crest 14 and at least one trough 15, the distance from the crest 14 to the target wall 8 is less than the distance from the trough 15 to the target wall 8, the crest 14 protrudes toward the target wall 8, and the trough 15 is recessed away from the target wall 8. The crests 14 and the troughs 15 are radially distributed alternately, and the crests 14-troughs 15-crests 14-troughs 15... can be distributed radially. The crests 14 and the troughs 15 both extend in the chord direction, and the troughs 15 thus form a cross-flow channel 16 that is recessed away from the target wall 8 and extends in the chord direction, and the crests 14 thus form a rib 17 that protrudes toward the target wall 8 and extends in the chord direction. The impact hole 5 can be arranged on the wave crest 14, and further reference is made to Figure 5 The cooling gas 6 forms a jet 7 which is ejected at high speed through the impact hole 5 to impact the inner wall surface of the target wall 8, thereby enhancing convective heat exchange. After impacting the target wall 8, the jet 7 flows radially to both sides and enters the radially adjacent cross-flow channel 16 to converge, and forms a cross-flow 11 to flow toward the downstream trailing edge slit 4. The trough 15 increases the flow area of ​​the cross-flow channel 16, increases the flow cross section of the cross-flow 11, reduces the flow velocity of the cross-flow 11, reduces the deflection effect of the cross-flow 11 on the jet 7, reduces the weakening effect of the cross-flow 11 on the impact heat exchange of the jet 7, and the peak 14 protruding toward the target wall 8 shortens the target surface distance from the outlet of the impact hole 5 to the inner wall surface of the target wall 8, thereby enhancing the impact heat exchange effect of the jet 7. In addition, after the jet 7 impacts the targeting wall 8, the cross-flow channel 16 and the rib 17 extending along the chord direction make the flow resistance of the cross-flow 11 in the radial direction greater than the flow resistance in the chord direction, thereby guiding the cross-flow 11 to flow along the chord direction, reducing the mixing loss of the cross-flow 11 and the jet 7, and reducing the total pressure loss of the cooling gas flow.

[0056] like Figures 2 to 7 As shown, the wavy impact wall 13 may include the same plurality of crests 14 and the same plurality of troughs 15, and the crests 14 and troughs 15 are alternately distributed in the radial direction so that the wavy impact wall 13 has periodicity in the radial direction. The impact holes 5 on different crests 14 may be arranged in rows in the radial direction, and a row of impact holes 5 includes the impact holes 5 of each crest 14 distributed in the radial direction. The impact holes 5 on a single crest 14 may be arranged in rows in the chord direction, and a row of impact holes 5 includes a plurality of impact holes 5 on a rib 17 distributed in the chord direction.

[0057] like Figure 6As shown, the wave crest 14 may be the first arc wall 18, and the wave trough 15 may be the second arc wall 19. The wave-shaped impact wall 13 may also include a straight wall 20, which bridges the first arc wall 18 and the second arc wall 19, and the straight wall is tangent to the first arc wall 18 and the second arc wall 19. The wave-shaped impact wall 13 composed of the first arc wall 18, the straight wall 20 and the second arc wall 19 has a simple structure and can be obtained by processing in the form of sheet metal thin-walled parts using a mold, with a simple processing method and a high production yield.

[0058] like Figure 6 As shown, the central axis of each impact hole 5 may pass through the center of the first arc wall 18, and the central axis of each impact hole 5 may 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, which 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.

[0059] like Figure 6 As shown, the distance from the center of each second arc wall 19 to the central axis of two radially adjacent impact holes 5 can be the same, and the trough 15 is located at the radial middle position of the two radially adjacent impact holes 5, so that the two jets 7 ejected from the two impact holes 5 are evenly merged into the cross-flow channel 16 after impacting the target wall 8. The radius of each first arc wall 18 is r 1 The radius of each second arc wall 19 is r 2 , 2d≤r 1 ≤r 2 The height difference between the crest 14 and the trough 15 along the wall thickness θ direction is h, h / j≥2, which limits the minimum flow area of ​​the cross-flow channel 16 formed by the trough 15 and ensures that the cross-flow channel 16 has a deceleration effect on the cross-flow 11.

[0060] like Figure 7 As shown, 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, 3≤Pc / d≤10, which limits the density of the impact hole 5 array, avoids 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, and the stiffness of the jet 7 being reduced, which leads to insufficient impact heat exchange effect of the jet 7, and also avoids the impact holes 5 being too sparse, resulting in insufficient cooling effect.

[0061] like Figure 4As shown, in the impact bushing 2, the wavy impact wall 13 and the straight impact wall 21 can be connected at the rear through a transition side wall 22, so as to avoid stress concentration caused by direct connection between the wavy impact wall 13 and the straight impact wall 21, and facilitate the insertion of the impact bushing 2 into the cooling chamber 3 of the airfoil 1.

[0062] Although the present invention is disclosed as above by 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 wavy impact wall is located opposite to the target wall, and includes at least one wave crest and at least one wave trough. The wave crest and the wave trough are radially alternately distributed and extend along the chord direction. The distance from the wave crest to the target wall is smaller than the distance from the wave trough to the target wall. The wave crest is provided with an impact hole for cooling gas to impact the target wall via the impact hole.

2. The cooling structure according to claim 1, characterized in that: The wave crest includes a first circular arc wall, and the wave trough includes a second circular arc wall.

3. The cooling structure according to claim 2, characterized in that: The wave-shaped impact wall further includes a straight wall body, which bridges the first arc wall body and the second arc wall body, and the straight wall body is tangent to the first arc wall body and the second arc wall body.

4. The cooling structure according to claim 2, characterized in that: The central axis of each impact hole passes through the center of the first arc wall.

5. The cooling structure according to claim 2, characterized in that: The plurality of impact holes are arranged in a row along the radial direction, and the distances from the center of each of the second arc wall bodies to the central axes of two radially adjacent impact holes are the same.

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 2, characterized in that: The diameter of each impact hole is d, the radius of the first arc wall is r1, the radius of the second arc wall is r2, and 2d≤r1≤r2.

8. The cooling structure according to claim 1, characterized in that: The distance from the outlet of each impact hole to the wall surface of the targeting wall is j, the height difference between the wave crest and the wave trough is h, and h / j≥2.

9. The cooling structure according to claim 1, characterized in that: The plurality of impact holes 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 diameter of each impact hole is d, 3≤Pr / d≤10. The chord-wise spacing between two chord-wise adjacent impact holes is Pc, 3≤Pc / d≤10.

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 includes an impact bushing and a trailing edge split. The wavy impact wall is provided by the impact bushing. The cooling cavity where the wavy impact wall is located is connected to the trailing edge split.

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