A cooling structure for turbine stator blades

Abstract

The present invention discloses a cooling structure for a turbine stator blade, including a turbine stator blade and a baffle; the turbine stator blade includes an upper edge plate, a lower edge plate and a blade profile; the baffle is a thin-walled sheet metal having the same shape as the front section of the turbine stator blade, and is wrapped around the upper edge plate, the lower edge plate and the front section of the blade profile to form a slit cavity. The upper edge plate, the lower edge plate and the blade profile are respectively provided with a plurality of ribs and air holes at certain intervals in their front sections. The present invention designs a thin-walled baffle structure to form a certain slit cavity with the turbine stator blade, and the cooling airflow fully exchanges heat inside the cavity, so that the metal temperature of the front section of the blade profile and the front section of the edge plate of the stator blade is reduced, and when the gas flows out through the slit, an efficient air film can be formed on the gas side wall surface of the stator blade, thereby protecting the gas side wall surface of the stator blade and improving the utilization efficiency of the cold air. At the same time, the front section of the stator blade profile, which is the most easily damaged in the traditional design, is transferred to the thin-walled baffle, thereby protecting the stator blade itself from damage.

Description

Technical Field

[0001] The invention relates to the field of turbine blade cooling structures, in particular to a cooling structure for turbine stationary blades. Background Art

[0002] A gas engine is a type of internal combustion engine that generates power and work by burning natural gas. It can be used to propel cars and ships, or it can be used to drive generators to generate electricity after combustion. Its advantage is that it is cleaner and more environmentally friendly than diesel or gasoline engines. Gas engines can replace diesel and gasoline engines and are now widely used in public transportation, oil field power generation and other fields. From the simple circulation method of the gas turbine, it can be seen that increasing the initial temperature of the turbine inlet gas can improve the power and performance of the gas turbine, but at the same time, the temperature of the turbine blades increases and the service environment becomes more severe. The initial temperature of the gas of the F-class gas turbine is about 1400℃, which is far beyond the tolerance limit of the blade metal. Therefore, the advanced cooling structure design of the turbine blades is crucial for the safe operation of the gas turbine.

[0003] Among them, typical turbine stator blades all adopt a hollow structure, and the heat of the blades is removed by a combination of cooling methods such as impact cooling, convection cooling, and film cooling of cooling air in the blade cavity, blade body pores, and blade outer wall to achieve the effect of lowering the temperature. The front section of the stator blade profile is directly affected by the upstream gas, so the environment it is in is more severe, and it is also one of the common parts of the stator blade damage, which is mainly manifested in coating peeling, metal bulging, burn-through, and even fracture. In order to control the metal temperature of the front section of the stator blade profile within the allowable range, the common cooling structure is to draw air from the compressor into the cavity of the front section of the stator blade profile, and then flow out through the dense film holes on the wall of the front section of the blade profile. Under the action of the gas, the outer wall of the front section of the blade profile is covered to achieve film cooling, and the ceramic thermal insulation coating on the outer wall of the blade is used to achieve double protection.

[0004] For example, a Chinese invention patent with application publication number CN 114396316 A and application publication date 2022.04.26 discloses a turbine static blade and a turbine static blade, including a blade body, the blade body having a leading edge side and a trailing edge side, a first cavity and a second cavity are provided in the blade body, the first cavity and the second cavity are arranged sequentially along the direction from the leading edge side to the trailing edge side, a slit is provided on the trailing edge side of the blade body, the slit connects the second cavity with the outer side of the blade body, the blade body is provided with a plurality of film cooling holes, the film cooling holes connect the first cavity, the second cavity with the outer side of the blade body.

[0005] A turbine guide cooling blade is disclosed in a Chinese invention patent with application publication number CN 111485956 A and application publication date 2020.08.04, comprising a main body, a first baffle and a plurality of air film holes, the main body comprising a leading edge and a trailing edge; the first baffle is arranged inside the main body to form an independent first cavity and a second cavity inside the main body, the first cavity is located on the side of the main body close to the leading edge, and the second cavity is located on the side of the main body close to the trailing edge, and an air vent is arranged on the first baffle, and the first cavity and the second cavity are connected through the air vent; the plurality of air film holes are all arranged on the main body, and the plurality of air film holes are respectively connected with the first cavity and the second cavity; wherein the air film hole is a first through hole, and the air film hole forms a first gradually expanding opening from the middle of the air film hole toward the outer surface of the main body.

[0006] The traditional cooling structure design of the front section of the static blade and the front section of the edge plate has the following disadvantages:

[0007] First, the air film cooling effect of the front section of the stationary blade is poor. The front section of the stationary blade is under the direct scouring of high-speed gas. Due to the curvature of the front section of the blade, the air outflow from the air film holes in the front section of the blade hits the incoming gas, only covering a small area near the air film holes, or even failing to cover the wall. The air film covering effect is poor, and the effect of isolating the gas impact is not ideal, so a dense arrangement of air film holes is required.

[0008] Second, the air film holes in the front section of the stationary blades have difficulty in venting gas and even gas backflow. There is a gas stagnation area in the front section of the stationary blades. The pressure in this area is not much different from the cooling air pressure from the compressor in the stationary blade chamber, resulting in insufficient power for the cooling air to flow outward, and even gas backflow into the blade cavity. The intrusion of gas into the blade will cause the temperature of the blade base to rise, resulting in oxidation corrosion, cracks, bulging and other damages that seriously reduce the service life of the stationary blades or the safety of operation.

[0009] Third, the air film holes in the front section of the stationary blade are very densely arranged, which greatly reduces the strength of the stationary blade. Since the air film cooling effectiveness of the front section of the stationary blade is low, if you want to achieve the ideal air film cooling effect, you must reduce the arrangement spacing of the air film holes in the front section of the blade, resulting in a very dense arrangement of the air film holes in the front section of the blade, which increases the amount of material removed in the front section of the blade and reduces the strength of the blade.

[0010] Fourth, the front section of the stator blade is easily damaged during operation, and the cost of repairing and replacing the blades is high and the cycle is long. The gas temperature near the front section of the stator blade is high, while the temperature of the cooling air introduced into the inner cavity of the stator blade is much lower than the gas. The huge temperature difference between the two causes the metal thermal stress in the front section of the stator blade to be highly concentrated. This is the reason why the front section of the stator blade is extremely easy to damage, and it is difficult to repair after damage. It is more common to directly replace the entire stator blade, which is very costly.

[0011] Fifth, in order to ensure the air film coverage effect, the air film holes on the stationary blade edge plate need to be at a certain angle along the airflow direction, which makes it impossible to arrange them at the front end of the blade edge plate. The metal at the front end of the edge plate is directly heated by the fuel gas and cannot be cooled, which is prone to oxidation and corrosion. Summary of the invention

[0012] In order to overcome the problems existing in the prior art, the present invention provides a cooling structure for a turbine stator blade, in which a thin-walled sheet metal baffle structure having the same shape as the front section of the blade profile and the front section of the upper and lower edge plates is independently designed at the front section of the stator blade profile and the front section of the upper and lower edge plates, so as to form a slit cavity for cooling gas. After sufficient heat exchange of the cooling airflow inside the cavity, the metal temperature of the front section of the stator blade profile and the front section of the edge plate is reduced to an allowable range, and then when the gas flows out through the slit, an efficient air film can be formed to cover the gas side wall surface of the stator blade, thereby protecting the gas side wall surface of the stator blade and improving the utilization efficiency of the cold air.

[0013] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a cooling structure for a turbine stator blade, comprising a turbine stator blade and a baffle; the turbine stator blade comprises an upper edge plate, a lower edge plate and a blade profile; the baffle is a thin-walled sheet metal having the same shape as the front section of the turbine stator blade, wrapped around the upper edge plate, the lower edge plate and the front section of the blade profile to form a slit cavity.

[0014] By adopting the above technical scheme, the front section of the stator blade profile which is most easily damaged in the traditional design is transferred to the thin-walled baffle, thereby protecting the stator blade itself from damage. Replacing the baffle is relatively simple and cost-effective compared to the existing technology which requires repairing and replacing the entire stator blade. At the same time, the front section of the edge plate which is difficult to cool in the traditional scheme is provided with cooling protection, and an air film covering is formed through the slit.

[0015] The present invention is further configured as follows: the upper edge plate is provided with a plurality of upper edge plate ribs at a certain interval along the circumferential direction at its front section, and the upper edge plate is also provided with a plurality of upper edge plate air holes.

[0016] The present invention is further configured as follows: the lower edge plate is provided with a plurality of lower edge plate ribs at a certain interval along the circumferential direction at its front section, and the lower edge plate is also provided with a plurality of lower edge plate air holes.

[0017] The present invention is further configured as follows: a plurality of blade-shaped ribs are arranged at certain intervals along the radial direction on the outer wall surface of the front section of the blade; and a plurality of blade-shaped pores are arranged along the wall thickness direction.

[0018] The present invention is further configured as follows: an air supply chamber is also provided on the blade profile.

[0019] The present invention is further configured as follows: when the baffle is installed on the turbine stator blade, the upper edge plate ribs, lower edge plate ribs, and blade profile ribs are located between the baffle and the upper edge plate, lower edge plate, and blade profile, and an upper edge plate slit chamber, a lower edge plate slit chamber, and a blade profile slit chamber are formed on the turbine stator blade.

[0020] By adopting the above technical solution, the cooling air from the upper side of the front section of the upper edge plate can enter the slit chamber of the upper edge plate through the air holes of the upper edge plate. After the cooling air flows in the slit chamber, it flows out of the chamber through the slit along the flow direction of the gas and enters the mainstream gas.

[0021] The cooling air from the lower side of the front section of the lower edge plate enters the slit chamber of the lower edge plate through the air holes of the lower edge plate. After flowing in the slit chamber, the cooling air flows out of the chamber through the slit along the flow direction of the gas and enters the mainstream gas.

[0022] The cooling air from the air supply chamber enters the blade-shaped slit chamber through the blade-shaped air holes. The cooling air is divided into two directions in the chamber, flowing out of the chamber through the pressure side and suction side slits respectively, and entering the mainstream combustion gas.

[0023] The present invention is further configured as follows: the upper edge plate, the lower edge plate, the blade profile, the upper edge plate ribs, the lower edge plate ribs, and the blade profile ribs are integrally cast.

[0024] The present invention is further configured as follows: a certain thickness of TBC thermal barrier coating is sprayed on the outer wall surface of the baffle to resist the impact of high-temperature combustion gas.

[0025] With the above technical solution, the front baffle of the blade is formed by sheet metal, which ensures the original aerodynamic shape. The thin-walled sheet metal can be deformed by heat to release internal stress, avoiding the peeling of the surface TBC coating due to excessive internal stress, and extending the service life of the coating. The outer surface of the baffle is sprayed with TBC thermal insulation coating, and the impact holes and slits set on the inner surface of the blade are used for heat exchange by cold air flow, so that the coating itself is subjected to a large temperature gradient, so that the metal temperature of the baffle can be reduced to the temperature allowed by the service life of the baffle sheet metal material.

[0026] In summary, the beneficial effects of the above technical solution of the present invention are as follows:

[0027] 1. A thin-walled sheet metal baffle structure is independently designed at the front section of the turbine stator blade profile and the front sections of the upper and lower edge plates to form a cooling gas slit cavity. After the cooling airflow fully exchanges heat inside the cavity, the metal temperature of the front section of the stator blade profile and the front section of the edge plate is reduced. Then, when the gas flows out through the slit, an efficient air film can be formed to cover the gas side wall of the stator blade, thereby protecting the gas side wall of the stator blade and improving the utilization efficiency of the cold air.

[0028] 2. The formed narrow slit cavity is filled with cooling gas, so that the metal of the front section of the blade is wrapped by cold air and is not directly eroded by the gas, and the thermal stress of the metal in this area is reduced; and the front section of the blade does not need to be densely covered with pores, the number of pores is reduced, and the strength of the front section of the blade is improved. The high-temperature gas does not directly collide with the cooling airflow of the film holes in the front section of the traditional static blade, eliminating the risk of gas backflow.

[0029] 3. The stationary blade body is formed by one-piece casting, and the baffle is formed by sheet metal stamping. Two processes and two materials are used. The stationary blade body material mainly focuses on load-bearing and heat-bearing; the sheet metal material mainly meets the requirements of heat resistance and oxidation resistance, while taking load-bearing into consideration, each with its own emphasis.

[0030] 4. The present invention transfers the front section of the stationary blade profile, which is the most easily damaged in the traditional design, to the thin-walled baffle, thereby protecting the stationary blade itself from damage. Replacing the baffle is relatively simpler and less costly than repairing or replacing the entire stationary blade.

[0031] 5. The sheet metal part of the baffle at the leading edge of the stationary blade is subjected to very little air flow force and is mainly used to bear heat. The thin-walled sheet metal baffle adopted in this scheme covers this area. The gas side is sprayed with a TBC insulation layer, and the back side is combined with the efficient impingement cooling and flow heat exchange set on the blade, which can make the temperature gradient mainly concentrated on the coating, thereby protecting the metal temperature of the baffle sheet metal to meet the use requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0033] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0034] Figure 2 It is a partial cross-sectional view of the present invention;

[0035] Figure 3 for Figure 2 Sectional view at the middle AA position;

[0036] Figure 4 for Figure 2 Cross-section of the middle BB position;

[0037] Figure 5 It is a schematic diagram of the baffle structure of the present invention.

[0038] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0039] 10-baffle, 20-turbine stator blade, 21-upper edge plate, 22-lower edge plate, 23-blade profile, 31-upper edge plate front section, 32-lower edge plate front section, 33-blade profile front section, 41-upper edge plate rib, 42-lower edge plate rib, 43-blade profile rib, 51 upper edge plate air hole, 52-lower edge plate air hole, 53-blade profile air hole, 60-blade profile front section air supply cavity, 61 upper edge plate slit cavity, 62-lower edge plate slit cavity, 63-blade profile slit cavity. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention. Based on the embodiments in this application, other similar embodiments obtained by ordinary technicians in this field without making creative work should all fall within the scope of protection of this application. In addition, the directional words mentioned in the following embodiments, such as "up", "down", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional words used are used to illustrate rather than limit the invention.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0042] Example:

[0043] The present invention will be further described below in conjunction with the accompanying drawings and preferred embodiments.

[0044] like Figure 1 , Figure 2 As shown, a cooling structure of a turbine stator blade includes a turbine stator blade 20, wherein the turbine stator blade 20 includes an upper edge plate 21, a lower edge plate 22 and a blade profile 23; it is characterized in that the cooling structure of the turbine stator blade 20 also includes a baffle 10; the baffle 10 is a thin-walled sheet metal with the same shape as the front section of the turbine stator blade 20, wrapped around the upper edge plate 21, the lower edge plate 22 and the front section of the blade profile 23 to form a slit cavity.

[0045] The upper edge plate 21 is provided with a plurality of upper edge plate ribs 41 at certain intervals along the circumferential direction at the front section thereof, and the upper edge plate 21 is also provided with a plurality of upper edge plate air holes 51 .

[0046] The lower edge plate 22 is provided with a plurality of lower edge plate ribs 42 at certain intervals along the circumferential direction at the front section thereof, and the lower edge plate 22 is also provided with a plurality of lower edge plate air holes 52 .

[0047] The front outer wall of the airfoil 23 is provided with a plurality of airfoil ribs 43 at certain intervals along the radial direction, and a plurality of airfoil holes 53 are provided along the wall thickness direction. The airfoil 23 is also provided with an air supply chamber 60 .

[0048] When the baffle 10 is installed on the turbine stator blade 20, the upper edge plate ribs 41, the lower edge plate ribs 42, and the blade profile ribs 43 are located between the baffle 10 and the upper edge plate 21, the lower edge plate 22, and the blade profile 23, and an upper edge plate slit chamber 61, a lower edge plate slit chamber 62, and a blade profile slit chamber 63 are formed on the turbine stator blade 20.

[0049] The upper edge plate 21, the lower edge plate 22, the blade profile 23, the upper edge plate ribs 41, the lower edge plate ribs 42, and the blade profile ribs 43 are integrally cast.

[0050] like Figure 4 As shown, the baffle 10 is a curved sheet metal structure of the upper edge plate front section 31, the lower edge plate front section 32 and the blade front section 33, and there are no cooling air holes on its wall surface. The baffle 10 is connected to the front end face and outer circular surface of the upper edge plate front section 31 and the front end face and inner circular surface of the lower edge plate front section 32 to achieve connection and fixation between itself and the stationary blade body 20.

[0051] By adopting the above technical solution, the cooling air from the upper side of the upper edge plate front section 31 can enter the upper edge plate slit chamber 61 through the upper edge plate air hole 51. After the cooling air flows in the slit chamber, it flows out of the chamber through the slit along the gas flow direction and enters the mainstream gas.

[0052] The cooling air from the lower side of the lower edge plate front section 32 enters the lower edge plate slit chamber 62 through the lower edge plate air holes 52. After flowing in the slit chamber, the cooling air flows out of the chamber through the slit along the gas flow direction and enters the mainstream gas.

[0053] like Figure 3 As shown, the cooling air from the air supply chamber 60 enters the airfoil slit chamber 63 through the airfoil pores 53. The cooling air is divided into two directions in the chamber, flowing out of the chamber through the pressure side slit and the suction side slit respectively, and entering the mainstream combustion gas.

[0054] like Figure 5 As shown, the baffle 10 combined with the TBC ceramic coating covering its outer wall can resist the direct erosion of high-temperature combustion gas, so that the front section of the static blade profile and the front section of the edge plate are isolated from the combustion gas, which greatly reduces the heat transfer effect of the combustion gas on the metal in this area and reduces the thermal stress;

[0055] A chamber with a certain impact spacing is formed between the inner wall of the baffle 10 and the outer wall of the turbine stator blade 20, so that both the inner and outer sides of the front section 33 of the blade are in the cooling gas, which greatly reduces the thermal stress concentration caused by the huge temperature difference in the front section 33 of the blade in the traditional design. The sheet metal part of the baffle 10 is subjected to very little air flow force and is mainly used to bear heat. The thin-walled sheet metal baffle 10 used in this solution covers this area, and its gas side is sprayed with a TBC insulation layer. The back side cooperates with the efficient impact cooling and flow heat exchange set on the blade, which can make the temperature gradient mainly concentrated on the coating, thereby protecting the metal temperature of the baffle sheet metal to meet the use requirements.

[0056] In summary, the present invention independently designs a conformal thin-walled sheet metal baffle 10 structure at the front section of the turbine stator blade 20 to form a cooling gas slit cavity. After sufficient heat exchange in the cavity by the cooling airflow, the metal temperature of the stator blade front section 33 and the upper edge plate front section 31 and the lower edge plate front section 32 is reduced to an allowable range. The cooling gas after convective heat exchange in the cavity between the baffle 10 and the main body of the turbine stator blade 20 fully takes away the heat of the baffle 10 and the stator blade and heats up, and then flows out of the cavity through the slit. The cooling gas outflow direction is consistent with the gas flow direction. It flows out through the conformal slit and can well cover the blade wall to form an effective air film. The temperature difference between the air film cold air and the mainstream gas is relatively reduced, thereby reducing the mixing loss between the two, and achieving the efficient covering and protection of the gas side wall of the turbine stator blade by the cooling gas.

[0057] And the formed slit cavity is filled with cooling gas, so that the metal of the front section 33 of the blade is wrapped by cold air and is not directly eroded by the gas, and the thermal stress of the metal in this area is greatly reduced; and the front section 33 of the blade does not need to be densely covered with pores, so the number of pores is greatly reduced, which greatly improves the strength of the area of ​​the front section 33 of the blade, and the high-temperature gas does not directly collide with the cooling airflow of the air film holes of the front section 33 of the traditional stator blade, eliminating the risk of gas backflow; the baffle structure is used to transfer the front section 33 of the stator blade, which is the most easily damaged in the traditional design, to the thin-walled baffle 10, thereby protecting the stator itself from damage. If it is damaged and needs to be replaced, the baffle 10 can be directly replaced while the stator body is retained, thereby greatly reducing the replacement and maintenance cycle and cost.

[0058] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A cooling structure for a turbine stator blade, comprising a turbine stator blade, wherein the turbine stator blade comprises an upper edge plate, a lower edge plate and a blade profile; characterized in that: The cooling structure of a turbine stator blade further comprises a baffle; the baffle is a thin-walled sheet metal having the same shape as the front section of the turbine stator blade, and is wrapped around the upper edge plate, the lower edge plate and the front section of the blade profile to form a slit cavity; the upper edge plate is provided with a plurality of upper edge plate ribs at a certain interval along the circumferential direction at the front section thereof, and the lower edge plate is provided with a plurality of lower edge plate ribs at a certain interval along the circumferential direction at the front section thereof; a plurality of blade profile ribs are provided at a certain interval along the radial direction on the outer wall surface of the front section of the blade profile; When the baffle is installed on the turbine stator blade, the upper edge plate ribs, lower edge plate ribs, and blade profile ribs are located between the baffle and the upper edge plate, lower edge plate, and blade profile, forming an upper edge plate slit chamber, a lower edge plate slit chamber, and a blade profile slit chamber on the turbine stator blade.

2. A cooling structure for a turbine stator blade according to claim 1, characterized in that: The upper edge plate is also provided with a plurality of upper edge plate air holes.

3. The cooling structure of a turbine stator blade according to claim 1, characterized in that: The lower edge plate is also provided with a plurality of lower edge plate air holes.

4. The cooling structure of a turbine stator blade according to claim 1, characterized in that: The blade is also provided with a plurality of blade-shaped air holes.

5. The cooling structure of a turbine stator blade according to claim 1, characterized in that: The blade profile is also provided with an air supply chamber.

6. The cooling structure of a turbine stator blade according to claim 1, characterized in that: The upper edge plate, the lower edge plate, the blade profile, the upper edge plate ribs, the lower edge plate ribs and the blade profile ribs are integrally cast.

7. The cooling structure of a turbine stator blade according to claim 1, characterized in that: The outer wall surface of the baffle is sprayed with a certain thickness of TBC thermal barrier coating to resist the impact of high-temperature combustion gas.

Images