Turbine guide vane end wall structure with Z-shaped mounting gap

Abstract

The invention provides a turbine guide vane end wall structure with a Z-shaped mounting gap, which is characterized in that Z-shaped structures with the same shape are arranged at the mounting gap between two adjacent turbine guide vane end walls and at the opposite pressure surface side edge and suction surface side edge of the end walls, and each Z-shaped structure comprises two parallel straight edge sections and a corner section, and the corner section is positioned at the throat part of the cascade channel. The Z-shaped structures on the edges of the pressure surface side and the suction surface side are arranged in a staggered mode in the flowing direction of the main flow and extend in parallel at the opposite positions, so that a Z-shaped installation gap is formed. And the mounting gap part formed by the corner section of the Z-shaped structure can generate a blocking effect on the cold air incoming flow entrained and sucked into the mounting gap groove. Due to the existence of the Z-shaped corner section, the upstream cold air entrained into the mounting gap groove overflows after impacting the wall surface of the corner section, and a relatively strong contra-rotating vortex pair is formed on the surface of the end wall, so that the generation of a high-temperature area at the throat part of the cascade channel can be effectively avoided, and the air film cooling efficiency of the surface of the end wall is improved.

Description

Technical Field

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

[0002] The gas temperature before the turbine is an important indicator for increasing the thrust-to-weight ratio of aircraft engines. At present, the gas temperature before the turbine of advanced aircraft engines has reached more than 2000K, and its hot end components such as the turbine end wall need to be effectively cooled. As the typical high-temperature part of the turbine guide, the end wall has a major difficulty in its cooling design, as the amount of air used for cooling is gradually reduced, and the complex secondary flow structure significantly enhances the heat exchange in the end wall area. Therefore, how to achieve efficient film cooling effect on the end wall surface under limited cooling flow is a major problem in its cooling design. Therefore, the end wall has gradually become a component that is easily damaged by heat corrosion. The study of the film cooling characteristics of the turbine end wall has been one of the hot topics in the research of gas turbine high-temperature component cooling technology in recent years. The research on the end wall installation gap structure design has gradually become the focus of researchers.

[0003] The installation gap is an inevitable existence of the guide vane end wall. Due to the high temperature of the gas before the turbine, the turbine end wall is subjected to large thermal stress and thus thermal deformation. In order to reduce the damage of thermal deformation to the end wall structure, the turbine blades are installed on the turbine disk one by one or step by step, and the installation margin is reserved on the adjacent blade end wall to allow for thermal expansion during engine operation. This design results in the existence of the installation gap on the guide vane end wall, and the existence of the installation gap will form an uncooled high temperature area on the end wall surface.

[0004] In recent years, the research on the end wall installation gap has mainly focused on improving the turbine flow field distribution of the end wall installation gap and improving the film cooling efficiency of the end wall surface. The existence of the installation gap causes the cold air jet of the film hole at some positions on the end wall surface to be sucked into the gap, resulting in a decrease in the spanwise expansion effect of the cold air jet. In addition, due to the acceleration of the cold air jet passing through the gap by the fluid in the groove formed by the sealing sheet and the edge of the end wall at the gap, the coverage of the cold air jet of the original structure has been changed to a certain extent, resulting in the appearance of uncooled high-temperature areas on the end wall surface. However, there are currently few studies on the cooling of the installation gap. Zeng Fei from the Hunan Power Machinery Research Institute of China Aero Engine Corporation studied the influence of factors such as the presence or absence of a gap on the guide vane end wall and the size of the gap on the turbine flow field and performance in the document "Numerical Simulation of Aerodynamic Characteristics of Leakage Flow in the Installation Gap of the Turbine Guide Vane End Wall". The research results show that as the gap width increases, the mainstream intrusion phenomenon tends to increase, which inevitably makes the side of the end wall face a huge heat load. Although this study investigated the effect of the geometric parameters of the mounting gap on the end wall temperature distribution, it still focused on the turbine flow field and performance research and did not propose a solution for cooling the high temperature area of ​​the end wall caused by the mounting gap. Summary of the invention

[0005] The purpose of the present invention is to solve the problem in the prior art that the cooling of the inside of the installation gap is ignored during the design stage of the gas turbine turbine end wall cooling structure, and the existence of the installation gap changes the flow field on the end wall surface, resulting in the appearance of an uncooled high-temperature area on the end wall surface, and provides a turbine guide vane end wall structure with a Z-shaped installation gap.

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

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

[0008] At the installation gap between two adjacent turbine guide vane end walls, the turbine guide vane end wall is provided with a Z-shaped structure of the same shape at the opposite pressure surface side edge and suction surface side edge, which includes two parallel straight edge sections and a corner section connected therebetween, and the corner section is located at the throat of the blade cascade channel;

[0009] The Z-shaped structure on the edge of the pressure surface and the Z-shaped structure on the edge of the suction surface are staggered along the mainstream flow direction and extend in parallel at opposite positions to form a Z-shaped installation gap;

[0010] Under the action of sealing cold air, the sealing plate forms a Z-shaped installation gap groove with the corresponding edge surfaces of the two adjacent turbine guide vane end walls. The installation gap part formed by the corner section of the Z-shaped structure can block the cold air flow sucked into the Z-shaped installation gap groove.

[0011] Further, the Z-shaped structure of the Z-shaped installation gap can be the following two structures: the two structures are symmetrical with respect to a plane perpendicular to the surface of the turbine guide vane end wall.

[0012] Furthermore, the width of the Z-shaped installation gap remains unchanged in the extension direction except at the corner section.

[0013] Furthermore, the width of the Z-shaped installation gap at the corner section is 3.0-4.0 mm, and the width D at other parts is 1.0-1.2 mm.

[0014] Furthermore, the depth δ of the Z-shaped installation gap groove is 1.2-1.4 mm.

[0015] Furthermore, an angle θ between the corner segment and the straight edge segment is 10° to 150°.

[0016] The advantages of the present invention are:

[0017] The turbine guide vane end wall structure with a Z-shaped installation gap of the present invention has an installation gap structure with a Z-shaped corner section formed between two adjacent turbine guide vane end walls, and the corner section is located at the throat of the blade channel. Due to the existence of the Z-shaped corner section, the cold air sucked into the installation gap groove from the upstream generates overflow after impacting the corner section wall surface, forming a strong counter-rotating vortex pair on the end wall surface. On the one hand, this pair of vortex pairs will improve the air film coverage effect of the end wall surface near the corner section of the Z-shaped installation gap, enhance the air film cooling efficiency of this area and reduce the insulating wall temperature of the end wall surface; on the other hand, it will force the cold air from the air film holes on the end wall surface near the downstream of the blade pressure surface to be sucked into the gap downstream of the Z-shaped installation gap, effectively reduce the temperature in the gap downstream of the Z-shaped installation gap, and improve the distribution of the insulating wall temperature in the Z-shaped installation gap. Therefore, the Z-shaped installation gap achieves an efficient air film cooling effect on the turbine guide vane end wall surface under limited cooling flow, and at the same time solves the problem of the installation gap causing a high temperature area on the end wall surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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:

[0019] Figure 1 The cold air flow trajectory of the peripheral air film holes on the suction side of the leading edge surface of the turbine guide vane end wall with a linear installation gap;

[0020] Figure 2 It is a cloud diagram of the adiabatic wall temperature distribution on the surface of the turbine guide vane end wall with a linear installation gap;

[0021] Figure 3 is an axonometric view of a turbine guide vane end wall structure with a Z-shaped installation gap according to the present invention;

[0022] Figure 4 yes Figure 3 The enlarged view of the middle area A shows the installation structure of the sealing piece;

[0023] Figure 5 is a top view of a turbine guide vane end wall structure with a Z-shaped installation gap according to the present invention;

[0024] Figure 6 yes Figure 5 An enlarged view of the middle area B shows the corner section of the Z-shaped installation gap;

[0025] Figure 7 is a cross-sectional view of a turbine guide vane end wall structure with a Z-shaped installation gap according to the present invention;

[0026] Figure 8 It is a schematic diagram of sealing cold air of a turbine guide vane end wall structure with a Z-shaped installation gap of the present invention;

[0027] Fig. 9 The entrainment degree of the upstream and downstream air film jets of the turbine guide vane end wall structure of the present invention and the temperature distribution of the inner wall surface of the gap;

[0028] Fig.10 It is a distribution cloud diagram of film cooling efficiency on the surface of the turbine guide vane end wall of the present invention;

[0029] Fig.11 It is a cloud diagram of the adiabatic wall temperature distribution on the surface of the turbine guide vane end wall of the present invention.

[0030] In the figure: 1-turbine guide vane end wall; 2-air film hole; 3-turbine guide vane; 4-Z-type installation gap; 5-sealing cavity wall; 6-sealing piece; 7-cooling cavity. DETAILED DESCRIPTION

[0031] 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.

[0032] The present invention provides a turbine guide vane end wall structure with a Z-shaped installation gap, and proposes a solution for cooling a high-temperature area of ​​the end wall caused by the existing linear installation gap.

[0033] In order to reflect the impact of the existing linear installation gap on the end wall, the numerical simulation method is used to Figure 1 and Figure 2 It can be seen that the existence of the installation gap causes the cold air jet from the air film hole at some positions on the end wall surface to be sucked into the gap. After this part of the cold air moves downstream along the mainstream flow direction inside the gap, a slight overflow phenomenon occurs near the throat of the blade channel. Since the flow velocity of the cold air in the gap is relatively large, when the cold air jet passes through the gap, it will be accelerated by the fluid in the gap, resulting in an increase in the flow velocity of the cold air jet after passing through the gap, causing a slight "misalignment" phenomenon in the adiabatic wall temperature of the end wall surface on both sides of the gap. In addition, since part of the cold air is sucked into the gap structure, the spanwise expansion effect of the cold air jet is reduced. Moreover, due to the acceleration of the cold air jet passing through the gap by the fluid in the groove, the coverage range of the cold air jet of the original structure is changed to a certain extent, resulting in an uncooled high-temperature area on the end wall surface near the throat of the blade channel.

[0034] In this regard, the applicant proposed the end wall cooling structure with a Z-shaped installation gap of the present invention, wherein the corner section of the Z-shaped installation gap is designed to be located at the throat of the blade channel to avoid the generation of a high temperature area on the end wall surface.

[0035] Now refer to Figures 3 to 7The invention describes the Z-type installation gap cooling structure for the turbine guide vane end wall and the application and arrangement position on the turbine guide vane end wall.

[0036] The turbine guide vane includes a plurality of turbine guide vanes 3, which are arranged on the turbine guide vane end wall 1. For example, each turbine guide vane end wall 1 is provided with a turbine guide vane, and a plurality of air film holes 2 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 formed by the sealing cavity wall surface 5 is opened at the installation gap between the adjacent turbine guide vane end walls 1. A sealing plate 6 is arranged in the sealing plate installation groove to block the gas in the blade cascade channel from entering the cold air cavity. After the sealing cold air from the cooling cavity 7 enters the sealing plate installation groove from the sealing cold air inlet, it will force the sealing plate 6 in the sealing plate installation groove to move toward the outer surface of the end wall, thereby contacting the edge surface on the pressure surface side of the end wall of the turbine guide vane end wall 1 and the edge surface on the suction surface side of the end wall, and the sealing plate forms an installation gap groove with the pressure surface side and the suction surface side of the turbine guide vane end wall.

[0037] In the turbine guide vane end wall structure with a Z-shaped installation gap as an exemplary embodiment of the present invention, at the installation gap between two adjacent turbine guide vane end walls, the turbine guide vane end wall is provided with a Z-shaped structure of the same shape at the opposite pressure surface side edge and suction surface side edge, which includes two parallel straight edge sections and a corner section connected therebetween, and the corner section is located at the throat of the blade cascade channel. It should be understood that the straight edge section of the Z-shaped structure on the pressure surface side edge and the suction surface side edge is much longer than the corner section. In addition, it should be pointed out that the Z-shaped structure on the pressure surface side edge and the suction surface side edge can be obtained by cutting off a portion of the wall surface edges on both sides of the existing single turbine guide vane end wall at a certain angle.

[0038] like Figure 6 As shown, the angle θ between the corner segment and the straight edge segment may be 10° to 150°, preferably 25° to 65°, and more preferably 35° to 45°.

[0039] The Z-shaped structure on the pressure side edge and the Z-shaped structure on the suction side edge are arranged along the Figure 5The mainstream flow direction shown in the figure is staggered, that is, the corner sections of the two are staggered in the mainstream flow direction, rather than facing each other. The corner sections of the two Z-shaped structures are spaced apart in the mainstream flow direction, so that the gap width at the Z-shaped corner section is greater than the gap width at other parts. And the two extend in parallel at relative positions, so as to form a Z-shaped installation gap 4, in which the Z-shaped corner section is located at the throat of the blade channel. Under the action of sealing cold air, the sealing sheet 6 forms a Z-shaped installation gap groove with the corresponding edge surfaces of the two adjacent turbine guide vane end walls. The installation gap portion formed by the corner section of the Z-shaped structure can block the cold air flow sucked into the Z-shaped installation gap groove, thereby slowing down the flow speed of the upstream cold air in the installation gap to the downstream.

[0040] According to the present invention, the Z-shaped structure of the Z-shaped installation gap can be the following two structures: the two structures are symmetrical about a plane perpendicular to the surface of the turbine guide vane end wall. In other words, the figure shows a Z-shaped structure, which is a Z-shaped structure when viewed from the bottom of the turbine guide vane, but it can also be a structure that is a Z-shaped structure when viewed from the top of the turbine guide vane.

[0041] By using the turbine guide vane end wall structure with a Z-shaped installation gap, the cooling air flows from the cold air cavity 7 through the cold flow inlet air film hole 2 into the end wall cooling structure with a Z-shaped installation gap, and the cooling airflow entering the air film hole 2 on the end wall surface is ejected to cover the surface of the turbine guide vane end wall 1 to form a cooling air film. Due to the sealing sheet 6, there is no leakage of cold air in the installation gap, but the cold air flowing through the air film hole 2 upstream is affected by the horseshoe vortex in the blade channel and is sucked into the Z-shaped installation gap groove and impacts the corner section wall to generate overflow, forming a strong counter-rotating vortex pair on the turbine guide vane end wall 1. On the one hand, the pair of vortex pairs will have a strong deceleration effect on the overflowing cold air, enhance the film cooling effect on the surface of the turbine guide vane end wall 1, and effectively reduce the insulating wall temperature in this area; on the other hand, the pair of vortex pairs has a large spanwise width, which will force the cold air from the film holes on the end wall surface near the downstream of the pressure surface of the turbine guide vane 3 to be sucked into the gap downstream of the Z-shaped installation gap 4, thereby enhancing the internal heat exchange between the cold air flow and the Z-shaped installation gap 4, improving the insulation wall temperature distribution of the installation gap, and thus avoiding the formation of high-temperature areas on the end wall surface.

[0042] In the present invention, the width of the Z-shaped installation gap except the corner section may be variable or constant in the extension direction, but preferably remains constant. Figure 6 and Figure 8As shown, in order to prevent the turbine guide vane end wall from getting stuck due to thermal expansion, the reserved installation gap is small. If it is too large, it may cause problems such as reduced aerodynamic efficiency. Therefore, the width L of the Z-shaped installation gap groove at the corner section can be designed to be 3.0-4.0 mm, and the width D at other parts can be designed to be 1.0-1.2 mm. In addition, the depth δ of the Z-shaped installation gap groove can be 1.2-1.4 mm.

[0043] Next, numerical simulation results of the turbine guide vane end wall structure with a Z-shaped installation gap provided by the present invention are described with reference to examples.

[0044] In this example, the reference linear installation gap structural parameters and the Z-type installation gap structural parameters of the present invention are shown in Table 1. The offset area operation is applied to the suction surface side of the turbine guide vane end wall of the linear installation gap along the mainstream inlet to the edge surface of the blade channel throat area by UG modeling software, and it is moved 1.0 mm in the direction close to the suction surface, that is, the width D of the Z-type installation gap is guaranteed to be 1.0 mm, and the angle θ between the corner section and the straight edge section is selected to be 35.5°. Similarly, the offset area operation is applied to the pressure surface side of the turbine guide vane end wall of the linear installation gap along the mainstream outlet to the edge surface of the blade channel throat area, and it is moved 1.0 mm in the direction close to the pressure surface. At this time, the width L of the Z-type installation gap at the corner section is guaranteed to be 3.0 mm. In this example, the depth δ of the Z-type installation gap groove is selected to be 1.2 mm.

[0045] Table 1

[0046]

[0047] In the numerical simulation, the flow parameters of the calculation model of the turbine guide vane end wall with a Z-type installation gap of the present invention are shown in Table 2. During the calculation, the mainstream inlet and the cold air inlet both use pressure inlets, wherein the mainstream inlet pressure is 2.876 MPa, the temperature is 2300 K, the cold air inlet pressure is 2.969 MPa, and the temperature is 973.6 K; the mainstream outlet uses a pressure outlet with a pressure of 1.432 MPa.

[0048] Table 2

[0049]

[0050] The turbulence model uses SST k-ω processing, because the SST k-ω model has been widely used and verified in boundary layers, mixing layers and high-speed flows, and also covers the areas of concern in this paper. The solver uses a separated implicit solver, the pressure and velocity coupling uses the COUPLE algorithm, the convection term is discretized using a second-order upwind scheme, and the convergence criterion of the numerical solution is that the residual of each discrete quantity is less than 10-6.

[0051] The analysis of the numerical simulation results shows that the cold air sucked into the gap from the upstream flows out after hitting the wall of the corner section, forming a strong counter-rotating vortex pair on the end wall surface, such as Fig. 9 As shown in the figure, the white solid line represents the cold air jet from the upstream film hole, and the blue solid line represents the cold air jet from the film hole on the downstream end wall surface near the pressure surface of the blade. Due to the presence of this pair of vortices, on the one hand, the flow velocity of the cold air jet from the film hole on the pressure surface across the gap is effectively slowed down, and the air film coverage effect on the rear end wall surface of the Z-type installation gap corner is improved, as shown in the figure. Fig.10 As shown in Region 1 of the air film cooling effect cloud map, a local high air film cooling efficiency area is formed on the wall near the corner section. On the other hand, the pair of vortices will force the cold air from the air film holes on the end wall surface near the downstream of the blade pressure surface to be sucked into the gap downstream of the Z-shaped installation gap, reducing the adiabatic wall temperature of the end wall surface and the installation gap, and the good air film coverage effect effectively isolates the heat load of the mainstream wall near the corner section, so no high temperature area is generated in the throat area of ​​the blade cascade channel, such as Fig.11 The results of numerical simulation verify that the turbine guide vane end wall with Z-type installation gap can effectively avoid the generation of high temperature area in the throat of the blade channel and improve the film cooling efficiency of the end wall surface to a certain extent.

[0052] 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 turbine guide vane end wall structure with a Z-shaped installation gap, wherein there is an installation gap between two adjacent turbine guide vane end walls, and a sealing sheet is arranged in the installation gap to block the gas in the blade cascade channel from entering the cold air cavity, characterized in that: At the installation gap between two adjacent turbine guide vane end walls, the turbine guide vane end walls are provided with a Z-shaped structure of the same shape at the opposite pressure surface side edge and suction surface side edge, which includes two parallel straight edge sections and a corner section connected therebetween, and the corner section is located at the throat of the blade cascade channel; The Z-shaped structure on the edge of the pressure surface and the Z-shaped structure on the edge of the suction surface are staggered along the mainstream flow direction and extend in parallel at opposite positions to form a Z-shaped installation gap; Under the action of sealing the cold air, the sealing plate forms a Z-shaped installation gap groove with the corresponding edge surfaces of the two adjacent turbine guide vane end walls. The installation gap portion formed by the corner section of the Z-shaped structure can block the flow of cold air sucked into the Z-shaped installation gap groove.

2. The turbine guide vane end wall structure with a Z-shaped installation gap according to claim 1, characterized in that: The Z-shaped structure of the Z-shaped installation gap can be the following two structures: the two structures are symmetrical with respect to a plane perpendicular to the surface of the turbine guide vane end wall.

3. The turbine guide vane end wall structure with a Z-shaped installation gap according to claim 1 or 2, characterized in that: The width of the Z-shaped installation gap remains unchanged in the extension direction except at the corner section.

4. The turbine guide vane end wall structure with a Z-shaped installation gap according to claim 3, characterized in that: The width of the Z-shaped installation gap at the corner section is 3.0-4.0 mm, and the width D at other parts is 1.0-1.2 mm.

5. The turbine guide vane end wall structure with a Z-shaped installation gap according to claim 4, characterized in that: The depth δ of the Z-shaped installation gap groove is 1.2-1.4 mm.

6. The turbine guide vane end wall structure with a Z-shaped installation gap according to claim 1 or 2, characterized in that: An angle θ between the corner segment and the straight edge segment is 10° to 150°.

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