CN111578310A - Air film cooling hole structure for turboshaft engine - Google Patents
Air film cooling hole structure for turboshaft engine Download PDFInfo
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- CN111578310A CN111578310A CN202010361589.3A CN202010361589A CN111578310A CN 111578310 A CN111578310 A CN 111578310A CN 202010361589 A CN202010361589 A CN 202010361589A CN 111578310 A CN111578310 A CN 111578310A
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- film
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
- F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
- F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
- F23R3/04—Air inlet arrangements
- F23R3/06—Arrangement of apertures along the flame tube
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
- F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
- F23R3/42—Continuous combustion chambers using liquid or gaseous fuel characterised by the arrangement or form of the flame tubes or combustion chambers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
- F23R2900/00—Special features of, or arrangements for continuous combustion chambers; Combustion processes therefor
- F23R2900/03042—Film cooled combustion chamber walls or domes
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
Abstract
The invention belongs to the field of engine cooling, and particularly relates to an air film cooling hole structure for a turboshaft engine. The gas film cooling hole rotates for 360 degrees by taking the center line of the cylindrical gas film hole as a rotating center line and a parabola as a bus to obtain the inner surface of the hole, and the inner surface is in a tapered and gradually expanded shape; namely, the air film cooling hole in the tapered and divergent shape comprises an air inlet section with gradually reduced cross section and an air outlet section with gradually increased cross section. The inlet of the invention can guide more cooling airflow to enter the air film hole, and the air film hole is compressed at the gradually reducing section of the hole, thereby improving the flow speed and increasing the heat convection effect in the hole; the hole diameter of the divergent section is increased, the pressure and the speed are reduced, so that the cooling air flow can be closer to the inner wall of the flame tube, the effect of reducing the temperature of the wall surface is achieved, and the comprehensive cooling effect is superior to that of a cylindrical air film hole.
Description
Technical Field
The invention belongs to the field of engine cooling, and particularly relates to an air film cooling hole structure for a turboshaft engine.
Background
The discrete hole air film cooling technology is a high-efficiency cooling technology and is widely applied to cooling the flame tube wall and some high-temperature components of the turboshaft engine. The basic principle is that cooling air is introduced from the air compressor, flows out through the air film holes and covers the surface of the high-temperature component, so that the purpose of isolating the contact between a hot main flow and the surface of the high-temperature component is achieved, the surface temperature is reduced, and the long-time operation of equipment is ensured.
The most basic hole type of the discrete hole air film cooling is a cylindrical hole, and the cylindrical hole has the characteristics of simple processing and high structural strength, so that the discrete hole air film cooling is also most commonly applied to the field of aviation. The air film cooling efficiency of the cylindrical hole is obviously lower, and the requirement of the future developed aircraft engine cooling technology cannot be met, on one hand, the air film coverage width is small due to the small area of the cylindrical hole outlet, the momentum of the cold air outlet is large, and cold air is easy to blow off the wall surface when the blowing ratio is high; on the other hand, due to the kidney-shaped vortex caused by the shearing action of the cold air and the main flow when the cold air is sprayed out, the cold air is not easy to adhere to the wall surface, and the downstream cooling effect is poor.
Due to poor film cooling effect of the cylindrical holes, a series of new film cooling holes are developed continuously at home and abroad in recent years to improve the film cooling effect of the cylindrical holes, such as expanding holes, slit holes, double-jet holes, sister holes, groove holes and the like. The hole patterns are greatly improved in the aspect of air film cooling efficiency compared with cylindrical holes, wherein the expanding holes are successfully applied to practice, the cooling effect is far better than that of common cylindrical holes, and the expanding holes are easy to machine and realize; however, the conventional expanding holes still cannot actively generate a flow field vortex structure beneficial to film cooling.
Disclosure of Invention
The invention aims to provide an air film cooling hole structure for a turboshaft engine.
The technical solution for realizing the purpose of the invention is as follows: a film cooling hole structure for a turboshaft engine is characterized in that the film cooling hole rotates 360 degrees by taking the center line of a cylindrical film hole as a rotating center line and a parabola as a bus to obtain the inner surface of the hole, and the inner surface is in a tapered and gradually expanded shape; namely, the air film cooling hole in the tapered and divergent shape comprises an air inlet section with gradually reduced cross section and an air outlet section with gradually increased cross section.
Furthermore, the ratio of the diameter D of the outlet of the film cooling hole to the diameter D of the throat part is 1.0-2.5, and the included angle alpha between the central line of the film cooling hole and the flowing direction of the fluid is 25-40 degrees.
Furthermore, the diameter d of the throat part of the air film cooling hole is 0.4-1 mm.
Furthermore, the film cooling holes are arranged in multiple rows, each exhaust film cooling hole comprises multiple exhaust film cooling holes, and the multiple exhaust film cooling holes are arranged in a crossed mode.
Furthermore, the ratio P/d of the spanwise spacing P of the plurality of film cooling holes to the diameter d of the throat part is between 0.5 and 3, and the ratio S/d of the flow direction spacing S to the diameter d of the throat part is between 1 and 5.
Furthermore, the thickness of the cooling wall surface is between 2 mm and 5 mm.
Compared with the prior art, the invention has the remarkable advantages that:
(1) the structure of the air film cooling hole can effectively improve the flow field condition at the inlet and the outlet of the air film hole and improve the heat convection capacity in the hole;
(2) the tapered section of the air film cooling hole can improve the flowing speed of air flow in the hole and improve the cooling effect at low blowing ratio;
(3) the outlet area of the air film cooling hole is large, the covering width of the air film is improved, and the cooling gas can be attached to the wall surface better.
Drawings
FIG. 1a is a top view of a basic form of film hole cooling structure of the present invention.
FIG. 1b is a cross-sectional view of the basic form of the film hole cooling structure of the present invention.
FIG. 2a is a schematic view of the spanwise spacing, flow direction spacing and three cross-sectional arrangements of the film hole cooling structure of the present invention.
FIG. 2b is a schematic view of a plurality of holes of the film hole cooling structure according to the present invention.
FIG. 3a is a schematic diagram showing the distribution of three generatrices on the leading edge, the side edge and the trailing edge of the film hole in the film hole cooling structure of the present invention.
Fig. 3b is a graph of the local convective heat transfer coefficient on three generatrices of a conventional cylindrical film hole with a blowing ratio M of 1.5 and an inclination angle α of 30 °.
Fig. 3c is a graph of the local convective heat transfer coefficient on three generatrices of the inventive film hole at a blowing ratio M of 1.5 and an inclination angle α of 30 °.
Fig. 4 is a graph comparing the cooling efficiency on the hot side wall surface of the conventional cylindrical film hole structure and the novel film hole structure of the present invention when the blowing ratio M is 1.5 and the inclination angle α is 30 °.
FIG. 5a is a comparison contour plot of film cooling efficiency at various cross-sections downstream of the exit of a conventional cylindrical film hole structure (D4 mm).
FIG. 5b is a comparison of contour plots of film cooling efficiency at various sections downstream of the exit of the film hole structure of the present invention (D6 mm);
FIG. 5c is a comparison of contour plots of film cooling efficiency at various sections downstream of the exit of the film hole structure of the present invention (D8 mm);
FIG. 5D is a comparison plot of film cooling efficiency contour lines (D10 mm) for sections downstream of the exit of the film hole structure of the present invention.
Detailed Description
The present invention is described in further detail below with reference to the attached drawing figures.
Fig. 1a and 1b are plan and front views of a film cooling structure of the present invention, which is formed by contracting a sectional area of an inlet section and expanding a sectional area of an outlet section on a conventional cylindrical film hole structure. The throat diameter of the holes is denoted by D, the diameter of the inlet and outlet of the holes by D, the angle between the centerline of the holes and the main flow direction by α, and the wall thickness of the liner by α. The spanwise pitch of fig. 2a is denoted by P and the streamwise pitch by S.
Diameter D of the inlet and outlet of the hole: the change of the diameters of the inlet and the outlet of the hole is an important characteristic of the invention, and the contraction structure can improve the flow velocity of fluid in the hole and increase the cooling effect at low blowing ratio; the expansion structure greatly increases the area of the air film hole outlet, reduces the speed of the air cooling outlet perpendicular to the wall surface, and the air cooling can be well pressed on the wall surface by the main flow, thereby further improving the air film coverage rate of the whole downstream and the transverse average air film cooling efficiency. The ratio D/D of D to D is usually between 1.0 and 2.5, and the throat diameter D of the hole is 0.4-1.0 mm.
In practical application, a certain number of film holes are usually arranged according to requirements, and a certain distance must exist between the film holes, as shown in fig. 2 b. Span-wise spacing P and flow direction spacing S mainly influence the film hole efflux, and then influence the cooling effect on the hot side wall. Usually, the ratio P/d of the span-wise spacing P to the aperture d is between 0.5 and 3, and the ratio S/d of the flow-wise spacing S to the aperture d is between 1 and 5.
The angle between the centerline of the hole and the main flow direction is represented by α: when α is small, the expansion effect is good, but too small α causes difficulty in processing. The effect of the expansion structure and cooling efficiency will decrease when α is larger. In view of the realizability and cooling effect, α should be in the range of 20 to 50 degrees, preferably between 25 ° and 40 °.
The thickness of the cooling wall surface is expressed by general expression and is usually between 2 and 5 mm; the width and length of the flame tube depend on the actual assembly situation.
As shown in fig. 3a, three bus bars are taken on the inner surface of the hole for analysis for the sake of explanation. Fig. 3b and 3c are profiles of heat transfer coefficients of the inner surface of the hole at a blow-off ratio M of 1.5 for the conventional film hole and the novel film hole structure of the present invention, respectively. It can be seen from the figure that the novel gas film hole structure can obviously improve the convection heat exchange condition in the hole, and further reduce the temperature of the inner wall surface.
Fig. 4 is a graph comparing the cooling efficiency on the hot side wall of a conventional cylindrical film hole structure (i.e., D0.4 mm) and the novel film hole structure of the present invention when the blowing ratio M is 1.5 and the inclination angle α is 30 °. It is apparent that the novel film hole structure of the present invention can effectively increase the cooling effect of the downstream wall surface.
FIGS. 5a, 5b, 5c, 5d are contour line plots of film cooling efficiency at sections downstream of the exit of the novel film hole structure of the present invention. It can be seen from the figure that the novel air film hole structure of the invention can improve the coverage rate of the air film on the wall surface of the hot side, thereby realizing the function of cooling the wall surface.
The basic form of the air film hole cooling structure is that on the basis of a common cylindrical hole, the sectional area of an air inlet section of the small hole is gradually reduced, and then the sectional area of an air outlet section of the large hole is gradually increased, and the contraction structure can improve the flow rate of fluid in the hole and increase the cooling effect at low blowing ratio; the expansion structure greatly increases the area of the air film hole outlet, reduces the speed of the air conditioning outlet vertical wall surface, and air conditioning can be well pressed on the wall surface by main flow, so that the transverse coverage rate of the air conditioning can be improved. Thereby further improving the film coverage of the whole downstream and the transverse average film cooling efficiency.
Claims (6)
1. The film cooling hole structure for the turboshaft engine is characterized in that the film cooling hole rotates for 360 degrees by taking the center line of a cylindrical film hole as a rotating center line and a parabola as a bus to obtain the inner surface of the hole, and the inner surface is in a tapered and gradually expanded shape; namely, the air film cooling hole in the tapered and divergent shape comprises an air inlet section with gradually reduced cross section and an air outlet section with gradually increased cross section.
2. The film-cooling hole structure according to claim 1, wherein the throat diameter d of the film-cooling hole is 0.4-1 mm.
3. The film cooling hole structure according to claim 2, wherein the ratio of the diameter D of the outlet of the film cooling hole to the diameter D of the throat part is 1.0-2.5, and the included angle alpha between the center line of the film cooling hole and the fluid flowing direction is 25-40 degrees.
4. The film-cooling hole structure of claim 3, wherein the film-cooling holes are distributed in a plurality, and adjacent film-cooling holes are arranged in a crossing manner.
5. The film-cooling hole structure of claim 4, wherein the ratio P/d of the spanwise pitch P to the throat diameter d of the film-cooling holes is 0.5-3, and the ratio S/d of the flow-direction pitch S to the throat diameter d is 1-5.
6. The film-cooling hole structure according to claim 5, wherein the thickness of the cooling wall surface is 2-5 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010361589.3A CN111578310A (en) | 2020-04-30 | 2020-04-30 | Air film cooling hole structure for turboshaft engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010361589.3A CN111578310A (en) | 2020-04-30 | 2020-04-30 | Air film cooling hole structure for turboshaft engine |
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| CN111578310A true CN111578310A (en) | 2020-08-25 |
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| CN202010361589.3A Pending CN111578310A (en) | 2020-04-30 | 2020-04-30 | Air film cooling hole structure for turboshaft engine |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112555900A (en) * | 2020-12-09 | 2021-03-26 | 南京航空航天大学 | Full-coverage air film cooling structure for wall surface of combustion chamber of micro turbojet engine |
| CN112607040A (en) * | 2020-12-31 | 2021-04-06 | 西北工业大学 | Wall surface staggered inclined hole jet cooling technology for high-temperature part of aircraft |
| CN113356932A (en) * | 2021-07-07 | 2021-09-07 | 西安交通大学 | Air film cooling composite hole structure for turbine blade and turbine blade |
| CN115898554A (en) * | 2023-03-09 | 2023-04-04 | 中国航发四川燃气涡轮研究院 | Film hole structure of turbine blade |
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| GB0312265D0 (en) * | 2002-06-13 | 2003-07-02 | Snecma Propulsion Solide | A combustion chamber sealing ring and a combustion chamber including such a ring |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112555900A (en) * | 2020-12-09 | 2021-03-26 | 南京航空航天大学 | Full-coverage air film cooling structure for wall surface of combustion chamber of micro turbojet engine |
| CN112607040A (en) * | 2020-12-31 | 2021-04-06 | 西北工业大学 | Wall surface staggered inclined hole jet cooling technology for high-temperature part of aircraft |
| CN113356932A (en) * | 2021-07-07 | 2021-09-07 | 西安交通大学 | Air film cooling composite hole structure for turbine blade and turbine blade |
| CN113356932B (en) * | 2021-07-07 | 2023-04-28 | 西安交通大学 | Air film cooling composite hole structure for turbine blade and turbine blade |
| CN115898554A (en) * | 2023-03-09 | 2023-04-04 | 中国航发四川燃气涡轮研究院 | Film hole structure of turbine blade |
| CN115898554B (en) * | 2023-03-09 | 2023-06-30 | 中国航发四川燃气涡轮研究院 | Air film hole structure of turbine blade |
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Application publication date: 20200825 |
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| RJ01 | Rejection of invention patent application after publication |