Wave-shaped installation gap structure suitable for turbine guider end wall

Abstract

The invention provides a wave-shaped installation gap structure suitable for an end wall of a turbine guider, and the end wall is provided with a wave line structure at the side edge of a pressure surface at an installation gap, and the wave line structure extends in parallel with the side edge line of a corresponding suction surface of the adjacent end wall. The sealing pieces and the corresponding edge faces of the end walls of the two adjacent turbine guiders form wavy line type installation gap grooves under the action of sealing cold air, and the wavy line structures can block and guide air entrained into the wavy line type installation gap grooves. The wavy line structure can weaken the flowing speed of gas in the groove and weaken or eliminate the overflow degree of the gas in the groove near the throat part in the cascade channel, so that a high convective heat transfer coefficient area behind a gas overflow point in the groove near the throat part of the cascade channel of an original structure is reduced or eliminated. The temperature of gas in the groove of the structure is low, so that the temperature of the side edge of the pressure surface and the side edge of the suction surface of the end wall of the turbine guider is low, and the ablation phenomenon of the edge position of the end wall can be avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of gas turbine turbine end wall cooling, and in particular relates to a wave-shaped installation gap structure suitable for a turbine guide end wall. Background Art

[0002] The turbine is one of the core components of a gas turbine, and its performance directly affects the working performance of the gas turbine. In order to meet development needs, the overall performance of the gas turbine is usually improved by increasing the inlet temperature before the turbine. With the replacement of gas turbines, the inlet temperature of advanced gas turbines can reach 2400K, and due to the development of low-pollution and low-emission combustion technology, the temperature of the inlet gas near the end wall of the turbine is closer to the mainstream temperature, resulting in high surface temperature and thermal stress of the turbine guide end wall, which is very prone to thermal deformation and high-temperature ablation.

[0003] At present, discrete hole air film cooling is usually adopted, supplemented by the upstream slot flow of the end wall to reduce the surface temperature of the turbine guide vane end wall, so as to ensure that it can operate safely and reliably for a long time under the complex and changeable working conditions of the gas turbine. At the same time, in order to reduce the damage of thermal deformation to the turbine guide vane end wall structure, the turbine guide vane usually adopts a split design, and retains the installation margin between the adjacent turbine guide vane end walls. The existence of this design makes the installation gap between the turbine guide vane end walls. The existence of this installation gap is very likely to cause the mainstream gas intrusion phenomenon, and it will also affect the coverage effect of the air film on the end wall surface.

[0004] In the papers "Effect of End Wall Channel Gap on End Wall Leakage Flow Cooling" (Propulsion Technology, 2017, Vol. 38, No. 4, pp. 719-725), "Study on the Effect of Air Film Hole Arrangement on Turbine End Wall Cooling and Aerodynamic Performance" (Journal of Xi'an Jiaotong University, 2023, Vol. 57, No. 8, pp. 22-33), and "Experimental Study on the Effect of Assembly Gap Leakage Flow on Turbine End Wall Cooling" (Journal of Xi'an Jiaotong University, 2023, Vol. 57, No. 5, pp. 1-10), the authors proposed to use the method of introducing sealing cold air into the installation gap to avoid the invasion of mainstream high-temperature gas and realize the cooling of the downstream end wall surface at the same time. However, with the development of gas turbines, the method of sealing cold air alone cannot meet the sealing requirements of gas turbines under complex and changeable working conditions. At present, most of them use the sealing plate sealing structure used in "Numerical Simulation of Aerodynamic Characteristics of Turbine Guide Vane End Wall Installation Gap Leakage Flow" (Propulsion Technology, 2024, Vol. 45, No. 10, 2312089). The installation gap between the sealing plate structure and the end wall will form a groove. After part of the cold air and high-temperature combustion gas are sucked into the groove, the flow speed along the groove flow direction is fast and overflow is likely to occur at the throat of the blade channel. Under the influence of the cross flow on the end wall surface of the turbine guide vane, the overflowing gas covers the suction side of the end wall, and the occurrence of overflow will destroy the development of the local boundary layer, causing the boundary layer downstream of the overflow point to redevelop, resulting in a high convective heat transfer coefficient at this location, and ablation is very likely to occur near the overflow point. Summary of the invention

[0005] The purpose of the present invention is to solve the problem in the prior art that the gas temperature in the installation gap groove of the end wall of the turbine guide vane of a gas turbine is too high, resulting in a high convection heat exchange zone generated after overflow near the throat of the blade channel, causing ablation of the side edge of the suction surface of the end wall, and to provide a wave-shaped installation gap structure suitable for the end wall of the turbine guide vane.

[0006] To achieve the above purpose, the technical solution provided by the present invention is:

[0007] A wave-shaped installation gap structure suitable for the end wall of a turbine guide vane is provided. There is an installation gap between two adjacent turbine guide vane end walls. A sealing sheet is provided in the installation gap to prevent the gas in the blade cascade channel from entering the cold air cavity. The special features of the structure are:

[0008] The turbine guide vane end wall is provided with a wavy line structure on the edge of the pressure surface side at the installation gap. The wavy line structure extends parallel to the corresponding suction surface side edge line of the adjacent turbine guide vane end wall. Under the action of sealing the cold air, the sealing sheet forms a wavy line installation gap groove with the corresponding edge surfaces of the two adjacent turbine guide vane end walls. The wavy line structure can block and guide the gas sucked into the wavy line installation gap groove.

[0009] Furthermore, the groove width D of the wave-shaped installation gap groove is 0.5-1.5 mm, and the groove depth δ is 0.5D-2D.

[0010] Furthermore, the crest curvature radius r1 and the trough curvature radius r2 of the wave line structure are equal or unequal.

[0011] Furthermore, the crest curvature radius r1 and the trough curvature radius r2 of the wave line structure are 1-4 mm.

[0012] Furthermore, the ratio of the wavelength p of the wave line structure to the radius of curvature is between 1-4.

[0013] The advantages of the present invention are:

[0014] 1. The wave-shaped installation gap structure suitable for the turbine guide vane end wall of the present invention processes the side edge of the pressure surface of the turbine guide vane end wall into a wave-shaped shape at the installation gap. Under the action of the sealing cold air, the sealing sheet and the edges of the two turbine guide vane end walls will form a new type of wave-shaped installation gap groove. The wave-shaped structure can weaken the flow velocity of the gas in the groove, and at the same time weaken or eliminate the overflow degree of the gas in the groove near the throat of the blade channel, thereby reducing or eliminating the high convection heat transfer coefficient area after the overflow point of the gas in the groove near the throat of the blade channel in the original structure.

[0015] 2. The gas temperature in the structural groove is relatively low, so that the temperature of the pressure side edge and the suction side edge of the turbine guide vane end wall is relatively low, which can avoid the occurrence of ablation at the edge of the end wall.

[0016] 3. When the cold air jet from the air film hole on the pressure side surface of the end wall passes over the groove, the mainstream in the groove has an entrainment and acceleration effect on the cold air passing over the groove, which can improve the cooling effect of the end wall surface downstream of the overflow point and the blade channel outlet, and avoid the occurrence of ablation at this location. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or other features and advantages of the present invention will become more easily understood through the following description with reference to the accompanying drawings, which are not drawn to scale and some features are exaggerated or reduced to show details of specific components. In the accompanying drawings:

[0018] Figure 1 It is an isometric view of a wave-shaped installation gap structure applicable to a turbine guide vane end wall of the present invention;

[0019] Figure 2 yes Figure 1 An enlarged view of area A in the middle shows the installation structure of the sealing sheet;

[0020] Figure 3 It is a top view of the wave-shaped installation gap structure applicable to the end wall of the turbine guide vane of the present invention;

[0021] Figure 4 yes Figure 3 The enlarged view of the middle area B shows the wavy line structure at the installation gap;

[0022] Figure 5 It is a side view of the wave-shaped installation gap structure applicable to the end wall of the turbine guide vane of the present invention;

[0023] Figure 6 It is a working schematic diagram of the wave-shaped installation gap structure applicable to the end wall of the turbine guide vane of the present invention;

[0024] Figure 7 1. The comparison of the film cooling efficiency distribution in the area near the overflow point between the installation gap structure of the present invention and the existing structure, (a) is the existing structure, (b) is the structure of the present invention;

[0025] Figure 8 The comparison of the spanwise average air film cooling efficiency between the installation gap structure of the present invention and the existing structure;

[0026] Fig. 9 The figure is a comparison of the distribution of convective heat transfer coefficients in the area near the overflow point between the installation gap structure of the present invention and the existing structure, (a) is the existing structure, and (b) is the structure of the present invention.

[0027] In the figure: 1-turbine guide vane end wall; 2-guide vane; 3-air film hole; 4-sealing plate mounting groove; 5-end wall pressure surface side; 6-end wall suction surface side; 7-sealing plate; 8-seal the cold air inlet. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to the accompanying drawings by means of exemplary embodiments of the present invention. It should be noted that the following detailed description of the present invention is only for the purpose of illustration, and is not intended to limit the present invention.

[0029] It should be pointed out that, in the context of the present invention, the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "inside", "outside", "clockwise" and "counterclockwise" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0030] In addition, terms such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0031] The present invention is based on the problem that the edge of the turbine guide vane end wall is very susceptible to high-temperature ablation due to the failure to fully consider the installation gap structure and the gas flow state in the installation gap groove on the heat exchange characteristics of the end wall surface when designing the cooling structure of the turbine guide vane end wall surface. The present invention provides a wavy installation gap structure suitable for the turbine guide vane end wall. The structure is formed by processing the pressure surface side edge of a single-unit / multi-unit turbine guide vane end wall structure into a wavy line structure while keeping the suction surface side structure of the turbine end wall unchanged, which can effectively reduce the gas temperature in the end wall installation gap groove.

[0032] Reference Figures 1 to 6 The turbine guide vane includes a single or multiple guide vanes 2, and the guide vanes 2 are arranged on the turbine guide vane end wall 1. For example, each turbine guide vane end wall 1 is provided with a guide vane, and a plurality of air film holes 3 are arranged on the surface of the turbine guide vane end wall 1. There is an installation gap between two adjacent turbine guide vane end walls 1, and a sealing plate installation groove 4 is opened between adjacent turbine guide vane end walls 1 at the installation gap. A sealing plate 7 is arranged in the sealing plate installation groove 4 to prevent the gas in the blade cascade channel from entering the cold air cavity. After the sealed cold air enters the sealing plate installation groove 4 from the sealed cold air inlet 8, it will force the sealing plate 7 in the sealing plate installation groove 4 to move toward the outer surface of the end wall, thereby contacting the edge surface of the end wall pressure surface side 5 and the edge surface of the end wall suction surface side 6 of the turbine guide vane end wall, and the sealing plate 7 forms an installation gap groove with the pressure surface side 5 and the suction surface side 6 of the turbine guide vane end wall.

[0033] In the wave-shaped installation gap structure suitable for the turbine guide end wall as an exemplary embodiment of the present invention, a wave line structure is provided on the pressure surface side edge of the turbine guide end wall at the installation gap, and the wave line structure extends parallel to the corresponding suction surface side edge line of the adjacent turbine guide end wall. As a result, the sealing sheet 7 forms a new type of wave-line installation gap groove with the corresponding edge surfaces of the two adjacent turbine guide end walls under the action of sealing the cold air, and the wave line structure can block and guide the gas sucked into the wave-line installation gap groove.

[0034] Specifically, the cold air from the mainstream inflow and the outflow of the end wall air film hole 3 will be sucked into the wave-line installation gap groove, and then move downstream along the extension direction of the groove. The wave structure on the end wall pressure surface side 5 will block and guide the gas in the groove, thereby reducing the flow velocity of the fluid in the groove, and at the same time weaken or eliminate the overflow degree of the cold air in the groove to the suction surface side 6 of the turbine end wall to a certain extent, thereby reducing or eliminating the high convective heat transfer coefficient area after the overflow point of the gas in the groove near the throat of the blade channel of the original structure; the wave-shaped installation gap structure weakens the flow velocity of the cold air in the groove, the amount of cold air gathered in the groove is relatively large, and the gas temperature in the groove is relatively low, so that the temperature of the end wall pressure surface side 5 and the end wall suction surface side 6 of the turbine guide vane edge is relatively low, thereby avoiding the occurrence of ablation at this location. In addition, when the cold air jet from the air film holes on the pressure side of the end wall passes over the groove, the mainstream in the groove has an entrainment and acceleration effect on the cold air passing over the groove, which can improve the air film coverage effect on the suction side 6 of the end wall downstream of the overflow point and at the outlet of the blade channel, avoiding the occurrence of ablation there.

[0035] In some embodiments of the present invention, Figure 6 As shown, in order to prevent the turbine guide vane end wall from getting stuck due to thermal expansion, the reserved installation clearance is small. If it is too large, it may lead to problems such as decreased aerodynamic efficiency. Therefore, the groove width D of the wave-shaped installation clearance groove, that is, the groove width at the crest and trough, can be designed to be in the range of 0.5-1.5mm, and the groove depth δ is 0.5D-2D.

[0036] According to the present invention, Figure 4 As shown, the crest curvature radius r1 and the trough curvature radius r2 of the wavy line structure may be equal or unequal, but preferably equal. In addition, the crest curvature radius r1 and the trough curvature radius r2 of the wavy line structure are 1-4 mm. In a specific embodiment, the ratio of the wavelength p of the wavy line structure to the curvature radius is between 1-4.

[0037] Next, the numerical simulation results of the wave-shaped installation gap structure applicable to the turbine guide vane end wall provided by the present invention are described with reference to examples.

[0038] In this example, CFD software is used to calculate the air film cooling characteristics of the turbine guide end wall surface cooling structure using the existing structure (the pressure surface side edge and the suction surface side edge of the adjacent turbine guide end wall are both straight edges) and the wave-shaped installation gap structure of the present invention. The structural parameters of the existing structure and the wave-shaped installation gap of the present invention used in the calculation and the calculation boundary conditions are shown in Table 1 and Table 2, respectively, wherein the groove width D of the existing structure and the wave-shaped installation gap structure at the wave crest is 1mm, the groove depth δ is 2mm, and the groove width of the wave-shaped installation gap structure at the wave trough is 1.5mm, the curvature radius r1 and r2 at the wave crest and wave trough of the wave-shaped installation gap structure are 2mm, and the wavelength p is 5mm. During the calculation, the mainstream inlet and the cold air inlet both use pressure inlets, wherein the mainstream inlet pressure is 9.50bar, the temperature is 1569K, the cold air inlet pressure is 9.68bar, and the temperature is 669K; the mainstream outlet uses a pressure outlet with a pressure of 5.91bar.

[0039] Table 1

[0040]

[0041] Table 2

[0042]

[0043] When analyzing the calculation results, we focus on the film cooling coverage in the area near the fluid overflow point in the groove, and calculate the spanwise average, as shown in the figure below: Figure 7 and Figure 8 As shown, Figure 8 In the figure, the red line represents the existing structure, and the black line represents the structure of the present invention. Combining the air film cooling efficiency distribution cloud diagram and the wall limit streamline distribution, it can be found that when the air film hole cooling jet on the pressure surface side of the end wall flows through the installation gap groove, a part of the cold air will directly pass through the installation groove to cool the area above the overflow point on the other side of the end wall; the remaining cold air moves downstream under the influence of the fluid in the groove to cool the area downstream of the overflow point. Compared with the existing structure, the wave-line installation gap groove structure of the present invention improves the air film cooling effect of the end wall edge near the overflow point and the area downstream of the overflow point, and at the same time, it also reduces the area of ​​the uncooled high-temperature zone on the end wall surface in this area.

[0044] In order to further highlight the advantages of the wave-shaped installation gap groove structure, the distribution of the convective heat transfer coefficient on the end wall surface of the turbine guide vane with the existing structure and the wave-shaped installation gap structure of the present invention is also compared. During the calculation, the boundary conditions of the mainstream inlet and outlet remain unchanged, the end wall surface and the installation gap surface are constant temperature wall surfaces, and the wall temperature is 3000K. The calculation results are as follows: Fig. 9As shown in the figure, it can be seen that the wave-shaped installation gap groove of the present invention significantly reduces the area of ​​the high convection heat transfer zone caused by the overflow of the fluid in the groove near the overflow point, and at the same time reduces the convection heat transfer coefficient on the surface of the overflow area of ​​the fluid in the groove. Under the comprehensive influence, the installation gap structure proposed by the present invention reduces the risk of high-temperature ablation at the edge of the end wall of the turbine guide vane, which is conducive to helping it to operate safely and stably for a long time.

[0045] Finally, it should be noted that the features mentioned and / or shown in the above description of the exemplary embodiments of the present invention may be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or substituted for the corresponding features in other implementations. The technical solutions obtained by these combinations or substitutions shall also be deemed to be included in the protection scope of the present invention.

Claims

1. A wave-shaped installation gap structure suitable for the end wall of a turbine guide vane, wherein an installation gap exists between two adjacent end walls of the turbine guide vane, and a sealing sheet is provided in the installation gap to prevent the gas in the blade cascade channel from entering the cold air cavity, characterized in that: The turbine guide vane end wall is provided with a wavy line structure on the pressure surface side edge at the installation gap, and the wavy line structure extends parallel to the corresponding suction surface side edge line of the adjacent turbine guide vane end wall. The sealing sheet forms a wavy line installation gap groove with the corresponding edge surfaces of the two adjacent turbine guide vane end walls under the action of sealing the cold air. The wavy line structure can block and guide the gas sucked into the wavy line installation gap groove.

2. The wave-shaped installation gap structure suitable for the end wall of the turbine guide vane according to claim 1, characterized in that: The groove width D of the wave-shaped installation gap groove is 0.5-1.5 mm, and the groove depth δ is 0.5D-2D.

3. The wave-shaped installation gap structure suitable for the end wall of the turbine guide vane according to claim 1 or 2, characterized in that: The crest curvature radius r1 and the trough curvature radius r2 of the wave line structure are equal or unequal.

4. The wave-shaped installation gap structure suitable for the end wall of the turbine guide vane according to claim 3, characterized in that: The crest curvature radius r1 and the trough curvature radius r2 of the wave line structure are 1-4 mm.

5. The wave-shaped installation gap structure suitable for the end wall of the turbine guide vane according to claim 3, characterized in that: The ratio of the wavelength p of the wavy line structure to the radius of curvature is between 1-4.

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