WO2021259355A1

WO2021259355A1 - Corrugated air film hole provided with branch holes

Info

Publication number: WO2021259355A1
Application number: PCT/CN2021/102056
Authority: WO
Inventors: 杨晓军
Original assignee: 中国民航大学
Priority date: 2020-06-25
Filing date: 2021-06-24
Publication date: 2021-12-30
Also published as: CN111706409A; CN111706409B

Abstract

A corrugated air film hole provided with branch holes. The corrugated air film hole provided with branch holes is a double-corrugated hole, comprising a main hole (2) and two branch holes. Each branch hole consists of a branch hole front half segment (3) and a branch hole rear half segment (5). The two branch hole rear half segments (5) are disposed on the left and right sides of the front portion of the main hole (2) and have span-wise expansion and backward tilt. The two branch hole rear half segments (5) are in communication with the rear portion of the main hole (2). Compared with cylindrical holes, the corrugated air film hole provided with branch holes can greatly enhance air film cooling performance, and the cooling effect is improved and is more stable.

Description

A corrugated air film hole with branch holes

Technical field

The invention belongs to the technical field of film cooling of hot end components in a gas turbine power plant, and particularly relates to a corrugated film hole with branch holes.

Background technique

The continuous increase of the inlet temperature of the turbine stage can increase the thrust-to-weight ratio and thermal efficiency of the aeroengine. With the continuous improvement of the requirements for the thrust-to-weight ratio of aero engines, the temperature in front of the engine turbine has further increased. At present, the gas temperature before the turbine of the engine with a thrust-to-weight ratio of 10 is about 1940K. In the future, civil aviation airliners may reach a thrust-to-weight ratio of 15, and the gas temperature before the turbine is about 2150K. The thrust-to-weight ratio of the fifth-generation fighter engine will be as high as 15-20. It is 2100K～2300K. The continuous increase of the gas temperature in front of the turbine has exceeded the limit that the material can withstand. In order to make the hot end parts of the turbine work effectively for a long time, it is necessary to use advanced film cooling technology.

Film cooling is a typical external cooling technology. The cooling medium is generally introduced from the compressor, sprayed out through discrete holes on the high-temperature component, and covered on the surface of the high-temperature component, thereby separating the high-temperature gas from the wall and reducing heat exchange. At the same time, the high-temperature components are also cooled to ensure that the working temperature of the material is stable and acceptable. The effect of film cooling is affected by many factors. One of the main factors is the structural characteristics of the film pores. Different shapes of film pores will greatly affect the cohesion and cooling effect of the film. Chinese Patent Literature (CN201711202938.1) discloses a single-branch pore structure; Chinese Patent Literature (CN201910190482.4) discloses a double-branched pore optimized pore structure; Chinese Patent Literature (CN201710454453.5) A three-branch hole structure is disclosed; the branch holes can increase the total area of the air outlet, reduce the jet flow, and reduce the mixing of the cooling air flow with the main flow, thus improving the wall cohesion; with the appearance of the branch holes, good The branch hole structure can optimize the vortex structure of film cooling, making the cooling effect better. Since the branch hole needs to be processed in a relatively close area on the surface of the high-temperature component, this places high requirements on the structural strength of the hot-end component that is subjected to high temperature and high pressure. In recent years, the supporting holes are mostly integrated with the main holes, which solves the structural pressure and at the same time guarantees a good cooling effect. The disadvantage is that the structure will become complicated. At present, the cooling effect of the cat ear hole in the international advanced hole structure is particularly excellent. The cat ear hole structure (Japanese patent) borrows the double jet hole structure at the outlet end, the branch hole adopts a compound angle, and the main hole uses a cylindrical hole and is connected by an expansion section. In the two parts, experts in my country’s advanced laser drilling believe that the composite angle of the cat’s ear holes and the special lateral diversion structure of the outlet make micro-vortexes formed at the outlet, and the downstream air-conditioning can closely adhere to the wall. The stronger the blowing, the closer it is. The better the attachment, which is needed in engineering. In recent years, my country has also studied a variety of special-shaped holes with supporting holes, including ingot holes, heart-shaped holes, etc. Compared with foreign countries, the domestic research is mainly based on simulation, and the experimental verification of complex special-shaped holes is rarely carried out. The reason is The designed shape cannot be processed qualified. Experts also pointed out that one of the deep reasons why it is difficult to process is the need to achieve three-dimensional processing of superalloy composite structures. Among them, complex shaped holes with supporting holes put forward extremely high requirements for this processing, especially the need to realize complex blades. Spatial online positioning and correction, etc.

Summary of the invention

In order to solve the above-mentioned problems, the object of the present invention is to provide a corrugated air film hole with branch holes.

In order to achieve the above-mentioned purpose, the corrugated air film hole with supporting holes provided by the present invention is a double corrugated hole including a main hole and two supporting holes; each supporting hole is composed of the front half of the supporting hole and the second half of the supporting hole; The rear half section of the supporting hole is arranged on the left and right sides of the front part of the main hole, and has a spanwise expansion and a backward inclination; the rear half section of the two supporting holes communicates with the rear part of the main hole.

The main hole and the supporting hole are both cylindrical holes, the diameter of the main hole is D, the diameter of the supporting hole ranges from 0.8D to D, the central axis length of the main hole is defined as the hole length, and the hole length L=2D to 6D, The intersection of the central axis of the support hole is located at the segment point of L'/L=0.4-0.6 on the central axis of the main hole, where L'is the distance between the intersection of the two support holes and the outlet center of the main hole.

The main hole is arranged obliquely, the inclination angle α between the central axis of the main hole and the main air flow direction is 20°-50°; the central axes of the two supporting holes are coplanar, and the central axis of the supporting hole is relative to the central The angle of the axis in the main air flow direction is the backward inclination angle γ of the branch hole, and the angle is -5°～10°; the angle β between the branch hole and the main hole in the span direction is the expansion angle, and the value is 14° ～30°.

The double corrugated holes are arranged at intervals, and their spanwise spacing P=3D～5D.

The corrugated air film hole with branch holes provided by the present invention is a single corrugated hole, which includes a main hole and two rear half sections of the branch holes; the rear half section of the two branch holes communicates with the rear part of the main hole.

The single corrugated holes are arranged at intervals, and their spanwise spacing P=3D～5D.

Compared with the prior art, the corrugated air film hole with branch holes provided by the present invention has the following beneficial effects:

1. Setting branch holes can increase the outlet area of the air film hole, reduce the momentum of the outlet air flow, and make the cooling air flow closer to the wall, so the cooling effect is better.

2. The cooling air flow behind the branch holes will produce a swirling flow that is opposite to the main flow. The airflows interfere with each other, resulting in a good vortex structure behind the air film holes. The cooling airflow affects each other before it touches the main flow, reducing the formation speed of the kidney vortex, and also weakening the degree of entrainment of the main flow, so the cooling efficiency is better than that of the branched holes.

3. At the same time, the branch hole enlarges the area of the inlet, reduces the flow loss of the inlet section, improves the airflow distribution in the hole, and makes the airflow distribution after the outlet more uniform, especially under the high blowing ratio, you can get better Air film coverage area. The single corrugated hole is lower than the double corrugated hole at a high blow ratio due to the lack of a support hole modification at the inlet end, but the difference is not much at a low blow ratio.

4. The cross-sections of the main hole and the supporting hole are circular, the structure is simple, and it is easy to process; the intersection of the central axis of the two supporting holes is the area near the midpoint of the central axis of the main hole, which is convenient for spatial positioning, and the supporting hole in the double corrugated hole It is consistent with the main hole, penetrates the flat plate, and is easy to process. The supporting hole in the single corrugated hole is processed to the main hole area. Since the supporting hole and the main hole have a certain angle, there is a certain tolerance margin in the processing depth, and the hole structure will not be damaged due to the design or the vibration of the processing direction. .

Description of the drawings

1 is a schematic diagram of the structure of double corrugated holes in a corrugated air film hole with branch holes provided by the present invention;

Figures 2 (a) and (b) are respectively a top view and a side view of the double corrugated holes shown in Figure 1;

3 is a schematic diagram of the structure of a single corrugated hole in a corrugated air film hole with branch holes provided by the present invention;

Figures 4 (a) and (b) are respectively a bottom view and a side view of the single corrugated hole shown in Figure 3;

Figure 5 is a comparison of the cooling efficiency cloud diagrams of double corrugated holes and cylindrical holes, cat ear holes and single corrugated holes at high and low blowing ratios;

Figure 6(a) is the comparison of the spanwise cooling efficiency of double corrugated holes and cylindrical holes, cat ear holes and single corrugated holes when the blowing ratio is 0.5;

Figure 6(b) is the comparison of the spanwise cooling efficiency of double corrugated holes and cylindrical holes, cat ear holes and single corrugated holes when the blowing ratio is 1.5;

Figure 7 is a temperature and streamline diagram of double corrugated holes, cylindrical holes, cat ear holes and single corrugated holes at X/D=10 under the same blowing ratio;

Fig. 8 is a schematic diagram of the tolerance margin of a single corrugated hole in the machining direction provided by the present invention.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings.

Example 1:

As shown in Figures 1 and 2, the corrugated air film holes with supporting holes provided in this embodiment are double corrugated holes, including a main hole 2 and two supporting holes; The rear half section of the hole 5 is constituted; the rear half sections of the two supporting holes 5 are arranged on the left and right sides of the front part of the main hole 2 and have a spanwise expansion and backward inclination; the rear half section of the two supporting holes 5 and the rear of the main hole 2 The parts communicate with each other, and the air flow 4 flows along the direction indicated by the arrow toward the outlet section 1 similar to the special-shaped hole.

Example 2:

As shown in Figures 3 and 4, the corrugated air film hole with supporting holes provided in this embodiment is a single corrugated hole, including a main hole 2 and two supporting hole rear half sections 5; two supporting hole rear half sections 5 It communicates with the rear part of the main hole 2. This is the only difference between the single corrugated hole and the above double corrugated hole, mainly for processing considerations. In the case of limited processing equipment, in order to reduce the damage of the back substrate during laser processing or when the high-temperature component is a multilayer composite material, a single corrugated hole is used when the number of processing times in a specific area needs to be reduced. The inlet section 7 of the single corrugated hole is an ellipse consistent with the traditional cylindrical hole.

In the above double corrugated hole and single corrugated hole, the main hole 2 and the supporting hole are both cylindrical holes, the diameter of the main hole 2 is D, the diameter of the supporting hole ranges from 0.8D to D, and the central axis length of the main hole 2 is defined as The hole length, the hole length L=2D～6D, the intersection point 6 of the central axis of the supporting hole is located at the segment point of L′/L=0.4～0.6 on the central axis of the main hole 2, where L′ is the intersection point of the two supporting holes and the main The distance between the outlet centers of hole 2.

The main hole 2 is arranged obliquely, and the inclination angle α between the central axis of the main hole 2 and the flow direction of the main air flow 9 is 20°-50°.

The central axis of the two supporting holes are coplanar, and the angle of the central axis of the supporting hole relative to the central axis of the main hole 2 in the flow direction of the main airflow 9 is the backward inclination angle γ of the supporting hole, and the angle is -5°～10 °.

The angle β between the branch hole and the main hole 2 in the span direction is the expansion angle, and the value is 14°-30°. The selection needs to be combined with the hole spacing.

When in use, the single corrugated holes or double corrugated holes are arranged at intervals, and the spanwise spacing P=3D～5D.

In practical applications, for the case of double corrugated holes, the cooling air flow 8 flows into the front part of the main hole 2 and the front half 3 of the two branch holes through the main hole 2 on the double corrugated hole and the inlets of the two branch holes, and then in the main hole The rear part of the hole 2 and the rear half of the branch hole 5 are mixed, and finally flow out from the outlet section 1 outward.

In the case of a single corrugated hole, the cooling air flow 8 flows into the front of the main hole 2 through the inlet of the main hole 2 on the single corrugated hole, and then flows into the rear of the main hole 2 and the rear half of the branch hole 5 along the axial direction of the main hole 2 Inside, and finally flow out from the outlet section 1.

Table 1 shows the simulated structure parameters of the double corrugated hole and the single corrugated hole provided in the above-mentioned Examples 1 and 2. The contrast hole type is the traditional cylindrical hole and the internationally advanced but complex cat ear hole. Wherein, number 10 is the double corrugated hole provided in

embodiment

1, 11 is a cylindrical hole, 12 is a cat ear hole, and 13 is a single corrugated hole provided in embodiment 2. It can be seen from Table 1 that the relevant simulation structure parameters of the four pass types are all consistent, and in order to be consistent with the traditional pass, no back dip angle is added.

Table 1. Simulation structure parameters of double corrugated holes, cylindrical holes, cat ear holes and single corrugated holes;

Figure 5 is a comparison of the cooling efficiency cloud diagrams of the above four kinds of holes at high and low blowing ratios. It can be clearly seen that when the blowing ratio M is 0.5, both single corrugated holes and cat ear holes show good film coverage, especially the center height In the area of cooling efficiency (red), the three types of holes are better than cylindrical holes, and the single corrugated hole has a larger coverage width in the area of high cooling efficiency. When the blowing ratio M is 1.5, the cylindrical hole has almost no cooling effect on the plane, and it is difficult for the cat ear hole to ensure a good cooling effect at the far end of the cooling hole. However, the single corrugated hole and the double corrugated hole provided by the present invention have no cooling effect. It has a good cooling effect, especially the double corrugated holes cover a longer area on the center line of the main airflow, the coverage area is more balanced, and the advantage is greater.

Figure 6 is a comparison of the spanwise cooling efficiency of the above four kinds of holes after simulation. Figure 6(a) compares the spanwise cooling efficiency of the four kinds of holes when M=0.5 is selected. It can be seen that the single corrugated hole and the double corrugated hole provided by the present invention The spanwise cooling efficiency of corrugated holes is basically the same and is much higher than that of cat ear holes and cylindrical holes. The spanwise cooling efficiency of double corrugated holes in the test area is up to 111.72% higher than that of cylindrical holes and 32.11% higher than cat ear holes. Figure 6(b) is a comparison of the spanwise cooling efficiency of the four holes when the blowing ratio is 1.5. It can be clearly seen that the spanwise cooling efficiency of the single corrugated hole and the double corrugated hole provided by the present invention is shown in the cooling area after the hole More prominent, higher than cat ear holes and cylindrical holes. Among them, the spanwise cooling efficiency of the double corrugated hole is higher than that of the single corrugated hole, and it is more stable. Its spanwise cooling efficiency is up to 634.7% of the cylindrical hole and 624.67% of the cat ear hole. The single corrugated hole drops more in the middle. The return of the cooling efficiency in the spanwise direction at the far end is basically the same as that of the double corrugated holes.

Fig. 7 is a cross-sectional dimensionless cooling temperature cloud diagram and streamline diagram at X/D=10, in which the range of the temperature cloud diagram is set to be 0 to 1. When the cooling efficiency approaches 1, it proves that the cooling effect is better. Since the section is far away from the cooling hole, the color change is not obvious, so the color characterization of the streamline diagram is also a dimensionless temperature, and the range is set to 0~0.5. It can be clearly seen that the kidney-shaped vortex of the cylindrical hole is very obvious and lifted away from the wall surface. High, the color of the center streamline can be seen, the dimensionless temperature is much lower than 0.5, and the cooling effect is not good. The vortex centers in the single corrugated holes are far apart, and because they are closer to the wall, the entrainment effect is caused, and the cooling effect of the bottom surface is not good. In comparison, the single corrugated hole and the double corrugated hole provided by the present invention are slightly lower At the vortex center of the cat’s ear hole, the cooling airflow in the center is better connected to the wall surface, especially the double corrugated holes. The branch holes in the inlet section cause the two vortexes to expand more evenly, so the coverage effect with the bottom surface is also the best.

Figure 8 is a schematic diagram of the machining allowance. When the supporting hole is processed in the direction of the arrow, due to the expansion angle β angle, in the supporting hole direction, when one end of the machining contacts the main hole 2, the other end is still with the main hole 2 There is a certain distance between the edges, as shown in Figure 14, this is the processing margin of a single corrugated hole. A good processing margin can further reduce the processing difficulty of the corrugated air film hole structure with supporting holes provided by the present invention. Provide convenience for the landing of high-efficiency cooling technology.

The above-mentioned embodiments only describe the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications made by those of ordinary skill in the art to the technical solution of the present invention All improvements and improvements shall fall within the protection scope determined by the claims of the present invention.

Claims

A corrugated air film hole with branch holes, characterized in that: the corrugated air film hole with branch holes is a double corrugated hole, including a main hole (2) and two branch holes; each branch hole is composed of The front half section of the support hole (3) and the second half section (5) of the support hole are composed; the two rear half sections (5) of the support hole are arranged on the left and right sides of the front part of the main hole (2), and have spanwise expansion and backward inclination ; The rear half of the two branch holes (5) and the rear of the main hole (2) are connected to each other.
The corrugated air film hole with supporting holes according to claim 1, characterized in that: the main hole (2) and the supporting hole are both cylindrical holes, the diameter of the main hole (2) is D, and the diameter of the supporting hole is D. The aperture range is 0.8D～D, the central axis length of the main hole (2) is defined as the length of the hole, the hole length L=2D～6D, the intersection point (6) of the central axis of the supporting hole is located on the central axis of the main hole (2) L′ /L=0.4-0.6 segment point, where L'is the distance between the intersection of the two branch holes and the outlet center of the main hole (2).
The corrugated air film hole with branch holes according to claim 1, characterized in that: the main hole (2) is arranged obliquely, and the central axis of the main hole (2) is between the flow direction of the main air flow (9) The inclination angle α is 20°～50°; the central axes of the two supporting holes are coplanar, and the angle of the central axis of the supporting holes relative to the central axis of the main hole (2) in the flow direction of the main airflow (9) is the back of the supporting hole The inclination angle γ is -5°-10°; the angle β between the branch hole and the main hole (2) in the span direction is the expansion angle, and the value is 14°-30°.
The corrugated air film holes with supporting holes according to claim 1, wherein the double corrugated holes are arranged at intervals, and the spanwise spacing P=3D～5D.
A corrugated air film hole with branch holes, characterized in that: the corrugated air film hole with branch holes is a single corrugated hole, including a main hole (2) and a second half (5) of two branch holes ; The rear half of the two branch holes (5) and the rear of the main hole (2) are connected to each other.
The corrugated air film hole with supporting holes according to claim 5, characterized in that: the main hole (2) and the supporting hole are both cylindrical holes, the diameter of the main hole (2) is D, and the diameter of the supporting hole is D. The aperture range is 0.8D～D, the central axis length of the main hole (2) is defined as the length of the hole, the hole length L=2D～6D, the intersection point (6) of the central axis of the branch hole is located on the central axis of the main hole (2) L′ /L=0.4-0.6 segment point, where L'is the distance between the intersection of the two branch holes and the outlet center of the main hole (2).
The corrugated air film hole with branch holes according to claim 5, characterized in that: the main hole (2) is arranged obliquely, and the central axis of the main hole (2) is between the flow direction of the main air flow (9) The inclination angle α is 20°～50°; the central axes of the two supporting holes are coplanar, and the angle of the central axis of the supporting holes relative to the central axis of the main hole (2) in the flow direction of the main airflow (9) is the back of the supporting hole The inclination angle γ is -5°-10°; the angle β between the branch hole and the main hole (2) in the span direction is the expansion angle, and the value is 14°-30°.
The corrugated air film holes with supporting holes according to claim 5, wherein the single corrugated holes are arranged at intervals, and the spanwise pitch P=3D～5D.