WO1998025009A1

WO1998025009A1 - Turbine blade and its use in a gas turbine system

Info

Publication number: WO1998025009A1
Application number: PCT/DE1997/002702
Authority: WO
Inventors: Michael Haendler; Michael Scheurlen
Original assignee: Siemens Aktiengesellschaft
Priority date: 1996-12-02
Filing date: 1997-11-18
Publication date: 1998-06-11
Also published as: EP0954680A1; JP4027430B2; EP0954680B1; DE59706345D1; JP2001505275A

Abstract

A turbine blade (1) has a wall structure (2) around which a hot gas (18) can flow. The wall structure (2) has a cooling area (5) through which a cooling fluid (6) flows between an outer wall (3) and an inner wall (4). Each cooling area (5) has heat transfer elements (7) around which the cooling fluid (6) can flow. The heat transfer elements (7) are successively arranged in a main flow direction (12) and are thermoconductively connected to the outer wall (3).

Description

description

Turbine blade and use in a gas turbine plant

The invention relates to a turbine blade with a wall structure around which a hot gas can flow and which, at least in regions, has an outer wall around which the hot gas can flow, an inner wall and a cooling region arranged between the inner wall and the outer wall for the flow of a cooling fluid. The invention further relates to the use of such a turbine blade in a gas turbine system.

A guide vane of a gas turbine with a guide of cooling gas for cooling it is described in US Pat. No. 5,419,039. The guide vane is designed as a casting or composed of two castings. In its interior, it has a supply of cooling air from the compressor of the associated gas turbine system. In its wall structure which is exposed to the hot gas flow of the gas turbine and surrounds the air supply, cast-in cooling pockets which are open on one side are provided. The cooling pockets are arranged on the outside of the wall structure both in the flow direction of the hot gas and perpendicular to the flow direction of the hot gas along the main direction of expansion of the guide vane. Cooling air flows into the cooling bag in each cooling bag from the cooling air supply through a plurality of holes in the wall structure. This is flowed through by the cooling air in the flow direction of the hot gas and enters into the flow of the gap in a gap already formed by the casting of the guide vanes and extending over the entire width of the cooling pocket

Hot gas. As a result, film cooling is achieved to some extent on the outer surface of the wall structure. A base or unspecified bases can be provided in the cooler bag to improve the heat conduction. DE 22 41 192 B2 describes a hollow gas turbine blade with an insert. This insert serves as a partition in the cavity enclosed by the turbine blade. The insert consists of two parts that are spaced apart by spacers. The cavity of the turbine blade is divided by a longitudinal web into an inlet chamber for cooling air and an outlet chamber for cooling air. Between the insert and the blade wall, an intermediate space is formed in the inlet chamber for cooling air, in which spacers, which are also used for heat transfer, are provided which are connected to the blade wall. The two parts of the insert are made impermeable to cooling air in the inlet chamber, so that the two parts form a channel which is only open in the inflow region of the turbine blade to the inlet chamber. Cooling air therefore flows from the inflow region of the turbine blade through the channel formed by the two parts of the insert in the direction of the trailing edge of the turbine blade. In the outlet chamber for cooling air, the two parts of the insert each have a plurality of openings through which cooling air can exit into the outlet chamber. Openings for the exit of cooling air are provided both at the inflow region and at the trailing edge of the turbine blade. Film cooling on the outer surface of the blade wall is achieved through the openings in the inflow region by cooling air emerging.

In the Patents Abstracts of Japan, M-1151, August 26, 1991, vol. 15 / no. 136, relating to Japanese Patent Application Laid-Open 3-130503A, describes a method for cooling components of a gas turbine which are exposed to high temperatures, in particular a gas turbine blade, by means of water. The gas turbine blade is designed as a hollow blade and has an intermediate wall in its interior. This intermediate wall is connected to the outer wall of the turbine blade via cooling fins. In the interior enclosed by the partition wall, feeds are provided through which under pressure standing water can be radiated into the gap. The water atomized in this way collides with the intermediate wall and thereby cools it. The outer wall of the blade is also cooled via the cooling fins by cooling the intermediate wall. A large number of small holes are present both in the outer wall and in the intermediate wall.

The object of the invention is to provide a turbine blade with a coolable wall structure. Another object is to specify the use of such a turbine blade.

According to the invention, the object directed to a turbine blade with a wall structure around which hot gas can flow is achieved by such a turbine blade, which has an inflow region, an outflow region and, in between, has a pressure side and a suction side, and at least in regions, an outer wall around which the hot gas can flow Has inner wall and a cooling area arranged between the inner wall and outer wall for the flow of a cooling fluid and the cooling area has an inlet assigned to the inner wall and an outlet for cooling fluid assigned to the outer wall, wherein in the cooling area heat transfer elements around which the cooling fluid flows in a main flow direction are arranged one behind the other are thermally connected to the outer wall.

The cooling area is preferably designed as a cooling chamber which is enclosed by the outer wall and the inner wall. The formation of an enclosed cooling chamber increases the flexibility in the manufacture of the inlet and outlet and gives the possibility of also subsequently changing the inlet and the outlet of cooling fluid, in particular cooling air, in accordance with the requirements of the turbine blade. The outlet is preferably made through one or more holes. These bores or funnel-shaped openings are preferably opposite the main flow direction inclined, in particular by an angle less than 45 °, preferably 20 ° to 30 °. The inclination is preferably selected such that an acute angle of, for example, 45 ° is also formed in relation to a flow of hot gas flowing around the turbine blade. Such an acute angle favors the formation of a cooling film on the surface of the outer wall. The direction of the bores or funnel-shaped openings can also point out of a plane perpendicular to the main axis of the turbine blade at an angle of this type.

Effective heating of the cooling fluid in the cooling area over a long distance is made possible by heat transfer elements which are thermally connected to the outer wall and are arranged one behind the other in a main flow direction of the cooling fluid. The thermal connection of the heat transfer elements to the outer wall ensures effective heat transfer from the outer wall to the cooling fluid. This leads to an effective and efficient cooling of the outer wall. Furthermore, the conceptual division of the wall structure into an outer wall and into an inner wall allows the functional properties of the wall structure to be decoupled, with less demands being placed on the mechanical stability on the outer wall than on the inner wall. The inner wall can therefore, since it is not directly exposed to a hot gas flow, be made with a larger wall thickness than the outer wall and essentially takes over the mechanical supporting function for the turbine blade. The outer wall, on the other hand, can be designed with a smaller wall thickness, as a result of which it can be cooled particularly effectively via the heat transfer elements. The inner wall is preferably thicker by a factor of about 1.5 or more than the outer wall. The cross section of the cooling area between the inner wall and the outer wall is preferably of a small design to form a high speed of the cooling fluid, and is in particular in the area of the wall thickness of the outer wall. With a slight flowed cross section of the cooling area and a high speed of the cooling fluid thus formed, very high heat transfer coefficients are achieved. In addition, the cooling air emerging from the cooling area on the outer wall forms a cooling film on the surface of the outer wall which can be exposed to the hot gas (film cooling).

A plurality of heat transfer elements are preferably arranged in a row along a line, the line being inclined relative to the main flow direction, preferably at an angle of 90 °. The main flow direction is preferably essentially perpendicular to a main axis of the turbine blade, along which the turbine blade is directed. In the case of a turbine blade which is used as a guide blade, the main flow direction therefore corresponds to the flow direction of a hot gas flowing around the turbine blade or is just opposite. The heat transfer elements are preferably arranged equally spaced along the line. The heat transfer elements are preferably column-like or platform-like and extend from the outer wall to the inner wall. They can also be firmly connected to the inner wall. The cross section of the heat transfer elements can be adapted to the heat transfer and flow requirements, for example circular, polygonal or in the manner of a flow profile.

The heat transfer elements directly adjacent to one another in the main flow direction are preferably offset from one another, in particular by half the distance between two heat transfer elements arranged along the line. The main result of this is that the partial flows of the cooling fluid flowing between two adjacent heat transfer elements along the line come essentially completely into contact with a heat transfer element arranged downstream in the main flow direction for the exchange of thermal energy. The outlet can also be designed as a funnel-shaped opening that widens towards the outer surface of the outer wall. The subsequent introduction of such a funnel-shaped opening can be carried out, for example, by eroding or working out using laser beams. The funnel-shaped opening has a cross section, which can be, for example, circular, rectangular or have another simple geometric shape and, if appropriate, also changes over the diameter of the outer wall. A particularly good film cooling of the outer wall can be achieved through a funnel-shaped opening.

The inlet is preferably directed along an axis which is inclined with respect to the outer wall, in particular is perpendicular to the outer wall. Cooling fluid flowing in through the inlet therefore impacts the outer wall, as a result of which additional impingement cooling of the outer wall is achieved, at least in the region of the inlet.

The outlet of a cooling area, in particular on the suction side, is preferably arranged between the inlet for cooling air and the inflow area of the turbine blade. This ensures a so-called counterflow cooling, in which the cooling fluid within the cooling region is directed against the flow direction of the hot gas flow flowing around the turbine blade. This leads to improved film cooling, in particular in the case of a turbine blade used as a guide blade.

The cooling area with counterflow is preferably on the

Suction side in the vicinity of the outflow area arranged so that the associated outlet for cooling fluid with respect to the flow of hot gas is upstream of the area with the lowest pressure level of the hot gas flowing along the suction side. This is particularly advantageous aerodynamically, the flow of the hot gas in the outflow region being largely unaffected by the emerging cooling fluid. The turbine blade with the wall structure comprising at least one cooling area, which is arranged between an outer wall and an inner wall, can be produced as a whole by casting in one work step. Of course, the turbine blade can also contain two or more cast parts, which are firmly connected to one another after casting by suitable methods (joining processes). Preferably the inlet is also made by casting. The turbine blade preferably has a plurality of cooling areas both along its main axis and in a plane perpendicular to the main axis. A guide vane of a stationary gas turbine can have three times three cooling chambers both on the suction side and on the pressure side and, depending on the heat transfer to be achieved, also have more or fewer cooling chambers. A geometrically more complex rotor blade preferably has fewer cooling chambers on the suction side and pressure side than a comparable guide blade.

The object aimed at using the turbine blade is achieved in that the turbine blade is used as a moving blade or guide blade in a gas turbine installation, in particular in the gas turbine, in which temperatures of well over 1000 ° C. of the hot gas flowing around the turbine blade occur.

The turbine blade is explained in more detail with the aid of the exemplary embodiments shown in the drawing. They show schematically depicting the constructive and functional features used for the explanation

1 shows a guide vane of a gas turbine in a cross section,

2 shows an enlarged view of the wall structure according to FIG. 1 and 3 shows a section through the wall structure according to FIG. 2.

1 shows a turbine blade 1, a guide blade of a gas turbine, which is directed along a main axis 19. This has a wall structure 2 with an inflow region 8, an outflow region 9 and a pressure side 10 and a suction side 11, which are arranged opposite one another. In the wall structure 2, three hollow cooling areas 5, 5a designed as cooling chambers 20 are provided on both the suction side 11 and the pressure side 10. These cooling areas 5, 5a are arranged in the wall structure 2 between an outer wall 3 and an inner wall 4. During operation of the gas turbine, not shown, a hot gas 18 (see FIG. 2) acts on the outer wall 3. The turbine blade 1 is designed as a hollow blade, so that a cooling air supply 21 enclosed by the inner wall 4 is formed. The cooling areas 5, 5a have a length that is significantly larger, for example 10 times larger than their cross section. The outer wall 3 has a significantly smaller wall thickness than the inner wall 4, for example the wall thickness of the outer wall 3 is 1.0 mm and the wall thickness of the inner wall 4 is 1.5 mm. The cross section of the cooling areas 5, 5a lies in the area of the wall thickness of the outer wall 3 and is, for example, approximately 1.0 mm. A plurality, preferably over five, heat transfer elements 7 are arranged over the length of each cooling region 5, 5a. A respective inlet 15 leads from the cooling air supply 21 into each cooling area 5, 5a, which inlet is preferably designed or cast as a bore or a plurality of bores and is adapted to the required cooling capacity. The inlet 15 is directed along an axis 22 which is substantially perpendicular to the outer wall 3. This results in an additional impact cooling of the outer wall 3 in the area of the inlet 15. From each cooling area 5, 5a, a respective outlet 16 leads to the outer surface of the wall structure 2. The outlet 16 is likewise preferably through a bore 17 or more rere bores 17, depending on the cooling performance requirements. The outlet 16 can also be produced, for example, by erosion or machining with a laser beam and can expand in a funnel shape towards the flow of the hot gas 18. The bores 17 are inclined at an acute angle with respect to the direction of flow of the hot gas 18 flowing past the turbine blade 1, as a result of which a cooling air film can form on the outer surface of the wall structure 2 in a particularly favorable manner. In particular on the suction side 11, the outlet 16 is arranged closer to the inflow region 8 than the inlet 15 assigned to the same cooling chamber 20. As a result, cooling air 6 is guided in counterflow to the flow of the hot gas 18 in the cooling chamber 20.

FIG. 2 and FIG. 3 show an enlarged illustration of the wall structure 2 in the area of a cooling chamber 20. Cooling fluid 6, in particular cooling air, flows through the cooling chamber 20 along a main flow direction 12. The main flow direction 12 is essentially perpendicular to the main axis 19 of the turbine blade 1. The bores 17 of the outlet 16 can be directed out of a plane perpendicular to the main axis 19. The heat transfer elements 7 are designed as columns with a circular cross section and a diameter d _x . They are thermally connected to both the inner wall 4 and the outer wall 3. Several heat transfer elements 7 are each arranged along a line 14 which is perpendicular to the main flow direction 12. A plurality of rows 13a, 13b are provided along the main flow direction 12. The distance d ₂ between two adjacent rows 13a, 13b is approximately the same or slightly less than the distance d ₃ between adjacent heat transfer elements 7 of a row 13a, 13b. The diameter d _{x of} a heat transfer element 7 is, for example, 1.0 mm, the distance d _{2 between} two rows 13a, 13b is approximately between 1.5 mm and 1.75 mm and the distance d ₃ between two heat transfer elements 7 is approximately 1.75 mm . The diameter d- _L and the distances d ₂ , d ₃ can vary from line 14 to line 14 vary according to the desired heat transfer. The heat transfer elements 7 of immediately adjacent rows 13a, 13b are offset from one another by approximately half the distance d ₃ along the respective line 14. As a result, cooling air 6, which flows between two heat transfer elements 7 adjacent along the line 14, is brought substantially completely into contact with a heat transfer element 7 of the row 13 following in the flow direction. The alternating arrangement of the heat transfer elements 7 thus increases the contact time for heat transfer between the cooling air 6 and the heat transfer element 7 connected to the outer wall 3, so that particularly high heat transfer and thus cooling of the outer wall 3 takes place. The effectiveness of the cooling is further enhanced by the fact that the outer wall 3 is designed with a small wall thickness. Furthermore, the supporting inner wall 4, which is not directly exposed to the hot gas 18, is also cooled.

The invention is characterized by a turbine blade with a wall structure in which the cooling function is essentially divided into an outer wall and the supporting function is essentially divided into an inner wall. By forming a cooling chamber between the inner and outer wall with a small cross-section and therefore high flow velocity for cooling air and heat transfer elements arranged in the cooling chamber, effective cooling of the outer wall and consequently the entire turbine blade is ensured.

Claims

claims

1. Turbine blade (1) with a wall structure (2) around which a hot gas (18) can flow, which has an inflow region (8), an outflow region (9) and an intermediate pressure side (10) and a suction side (11) and at least in areas has an outer wall (3) around which the hot gas (18) can flow, an inner wall (4) and a cooling area (5) arranged between the inner wall (4) and outer wall (3) for the flow of a cooling fluid (6), and each Cooling area (5) has an inlet (15) penetrating the inner wall (4) and an outlet (16) for cooling fluid (6) penetrating the outer wall (3), characterized in that in the cooling area (5) from the cooling fluid (6) in In a main flow direction (12) flowable heat transfer elements (7) are arranged one behind the other, which are thermally connected to the outer wall (3) and the cooling area (5) as one of the outer wall (3) and inner wall (4) closed cooling chamber (20) is formed.

2. Turbine blade (1) according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the outlet (16) is made through a bore (17) or several bores (17).

3. Turbine blade (1) according to claim 1 or 2, characterized in that a plurality of heat transfer elements (7) are arranged in a row (13) along a line (14), the line (14) relative to the main flow direction (12), is preferably inclined at an angle of 90 °.

4. turbine blade (1) according to claim 3, characterized in that several rows (13) are arranged one behind the other, and the heat Transmission elements (7) of immediately adjacent rows (13a, 13b) along the line (14) are offset from one another.

5. Turbine blade (1) according to one of the preceding claims, that a d u r c h g e k e n n z e i c h n e t that the

Inner wall (4), in particular thicker, e.g. by a factor of 1.5 than the outside wall.

6. Turbine blade (1) according to one of the preceding claims, that a d u r c h g e k e n n z e i c h n e t that the

Outlet (16) has a cross section which widens from the cooling chamber (20) to the surface of the outer wall (3) around which the hot gas (18) can flow.

7. Turbine blade (1) according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the inlet (15) is directed along an axis (22) which is inclined relative to the outer wall (3), in particular by an angle of approximately 90 °.

8. Turbine blade (1) according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the outlet (16) between the inlet (15) and the inflow region (8) is arranged at least in a cooling region (5 a).

9. Turbine blade (1) according to claim 8, characterized in that the cooling area (5a) on the suction side (11) in the vicinity of the outflow area (9) is arranged so that the outlet (16) between see an area with the lowest pressure level when hot gas (18) flows around and the inflow area (8).

10. Turbine blade (1) according to one of the preceding claims, characterized in that the outer wall (3), inner wall (4) and heat transfer elements (7) are produced by casting in one step.

11. Turbine blade (1) according to one of the preceding claims, which is a rotor blade (la) or a guide blade (lb) for a gas turbine.

12. Use of a turbine blade (1) according to claim 9 in a gas turbine system.