Turbine vane endwall structure with z-shaped mounting gap

Abstract

The application provides a turbine guide vane end wall structure with Z-shaped installation gap. Z-shaped structures with the same shape are arranged on opposite pressure surface side edges and suction surface side edges of the end wall at the installation gap between two adjacent turbine guide vane end walls, and the Z-shaped structures comprise two parallel straight edge sections and a corner section, and the corner section is located at a cascade passage throat. The Z-shaped structures on the pressure surface side edges and the suction surface side edges are staggered along the main flow direction and extend in parallel at opposite positions, so that the Z-shaped installation gap is formed. The installation gap part formed by the corner section of the Z-shaped structure can block the cold air coming flow sucked into the installation gap groove. Due to the presence of the Z-shaped corner section, the cold air sucked into the installation gap groove upstream overflows after impacting the wall surface of the corner section, a strong counter vortex pair is formed on the end wall surface, and thus the generation of a high-temperature area at the cascade passage throat can be effectively avoided, and the film cooling efficiency of the end wall surface is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of turbine end wall cooling of gas turbine, and particularly relates to a turbine guide vane end wall structure with Z-shaped installation gap. BACKGROUND

[0002] Turbine inlet gas temperature is an important indicator for increasing the thrust-to-weight ratio of an aero-engine. The turbine inlet gas temperature of current advanced aero-engines has reached above 2000K, and the hot end components such as turbine end walls need to be effectively cooled. As a typical high-temperature part of the turbine guide vane, the end wall is gradually damaged by heat corrosion due to the gradually reduced amount of cooling air and the significantly strengthened heat exchange in the end wall area by the complex secondary flow structure. Therefore, how to achieve high-efficiency film cooling effect on the end wall surface under limited cooling flow is a major problem in the cooling design of the end wall. The research on the film cooling characteristics of the turbine end wall is one of the hotspots in the cooling technology research of high-temperature components of gas turbines in recent years, and the research on the installation gap structure design of the end wall has gradually become the focus of researchers.

[0003] The installation gap is inevitably present in the end wall of the guide vane. The turbine end wall bears a large thermal stress due to the high-temperature gas in front of the turbine, thereby generating thermal deformation. In order to reduce the damage of the thermal deformation to the end wall structure, the turbine blades are installed on the turbine disc one by one or in stages, and the installation allowance is reserved on the end walls of adjacent blades to allow the thermal expansion during the operation of the engine. This design causes the installation gap to exist in the end wall of the guide vane. Due to the existence of the installation gap, a high-temperature area that is not cooled will be formed on the end wall surface.

[0004] In recent years, the research on the end wall installation gap mainly focuses 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 gas jet of the film hole at some positions on the end wall surface to be sucked into the gap, thereby causing the spanwise expansion effect of the cold gas jet to decrease. Moreover, the fluid in the groove formed by the sealing piece at the gap and the edge of the end wall changes the coverage range of the original structure of the cold gas jet to a certain extent, thereby causing the high-temperature area on the end wall surface to be not cooled. However, there is little research on the cooling of the installation gap. In the document "Numerical Simulation Research on Aerodynamic Characteristics of Leakage Flow of Turbine Guide Vane End Wall Installation Gap", Zeng Fei of China Aero-engine Research and Manufacturing Group Hunan Institute of Power Machinery researched the influence of factors such as whether there is a gap in the guide vane end wall and the size of the gap on the turbine flow field and performance. The research results show that with the increase of the gap width, the main flow invasion phenomenon tends to increase, which inevitably causes the side surface of the end wall to face a large thermal load. Although this research studies the influence of the geometric parameters of the installation gap on the temperature distribution of the end wall, it still focuses on the turbine flow field and performance research, and does not propose a solution to the cooling of the high-temperature area of the end wall caused by the installation gap. SUMMARY

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

[0006] To achieve the above objectives, the technical solutions provided by the present invention are:

[0007] A turbine guide vane end wall structure with a Z-shaped installation gap is provided. An installation gap exists between two adjacent turbine guide vane end walls. A sealing piece is provided in the installation gap to prevent 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 walls are provided with a Z-shaped structure of the same shape at the opposite pressure side edge and suction 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 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 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 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 clearance groove is 1.2-1.4 mm.

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

[0016] The advantages of the present invention are:

[0017] The turbine guide vane end wall structure with Z-shaped installation gap of the application forms an installation gap structure with Z-shaped corner section between two adjacent turbine guide vane end walls, and the corner section is located at the throat of the cascade passage. Due to the existence of the Z-shaped corner section, the cold air sucked into the installation gap groove from the upstream will overflow after impacting the wall surface of the corner section, forming a strong counter-rotating vortex pair on the end wall surface. On the one hand, the counter-rotating vortex pair will improve the film coverage effect of the end wall surface near the Z-shaped installation gap corner section, enhance the film cooling efficiency of the region and reduce the adiabatic wall temperature of the end wall surface; on the other hand, the cold air of the end wall surface film hole near the downstream of the blade pressure surface will be forced to be sucked into the downstream gap of the Z-shaped installation gap, effectively reducing the temperature in the downstream gap of the Z-shaped installation gap and improving the distribution of the adiabatic wall temperature in the Z-shaped installation gap. Therefore, the Z-shaped installation gap realizes the high-efficiency film cooling effect of the turbine guide vane end wall surface under the limited cooling flow, and solves the problem of high-temperature area on the end wall surface caused by the installation gap. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and / or other features and advantages of the application will be more apparent from the following description taken in conjunction with the accompanying drawings, which are not drawn to scale, and in which some features can be exaggerated or minimized for the sake of clarity, in the accompanying drawings:

[0019] Figure 1 is the cold air flow trajectory of the peripheral film hole on the suction surface side of the front edge surface of the turbine guide vane end wall with a straight-line installation gap;

[0020] Figure 2 is the adiabatic wall temperature distribution cloud atlas of the turbine guide vane end wall with a straight-line installation gap;

[0021] Figure 3 is the isometric view of the turbine guide vane end wall structure with Z-shaped installation gap of the application;

[0022] Figure 4 is Figure 3 is an enlarged view of region A in FIG. 8, showing the installation structure of the sealing piece;

[0023] Figure 5 is the top view of the turbine guide vane end wall structure with Z-shaped installation gap of the application;

[0024] Figure 6 is Figure 5 is an enlarged view of region B in FIG. 8, showing the corner section of the Z-shaped installation gap;

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

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

[0027] Figure 9 is the vortex guide vane end wall structure of the application, the degree of entrainment of the upstream and downstream film jet of the vortex guide vane end wall structure and the temperature distribution of the internal wall of the gap;

[0028] Figure 10 is the vortex guide vane end wall surface film cooling efficiency distribution cloud chart of the application;

[0029] Figure 11 is the vortex guide vane end wall surface adiabatic wall temperature distribution cloud chart of the application.

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

[0031] The application will be described in detail below with reference to the accompanying drawings by means of exemplary embodiments of the application. It should be pointed out that the following detailed description of the application is for illustrative purposes only and is not limiting on the application.

[0032] The application provides a vortex guide vane end wall structure with a Z type installation gap, and proposes a solution for the cooling of the high temperature zone of the end wall caused by the existing linear type installation gap.

[0033] In order to reflect the influence of the existing linear type installation gap on the end wall, the numerical simulation method is used to simulate the temperature distribution of the end wall surface and the internal wall of the gap. Figure 1 and Figure 2 It can be seen from the above that the existence of the installation gap causes the film cooling jet at some positions on the end wall surface to be entrained into the gap. After the part of the cooling gas moves downstream along the main flow direction in the gap, it occurs slight overflow phenomenon near the throat of the cascade passage. In addition, due to the large flow direction velocity of the cooling gas in the gap, when the cooling gas jet passes through the gap, it is accelerated by the fluid in the gap, which increases the flow direction velocity of the cooling gas jet after passing through the gap, causing the slight "misalignment" phenomenon of the adiabatic wall temperature on the end wall surface on both sides of the gap. In addition, due to the entrainment of part of the cooling gas into the gap structure, the spanwise expansion effect of the cooling gas jet is reduced. Moreover, due to the acceleration effect of the fluid in the groove on the cooling gas jet passing through the gap, the coverage range of the original structure cooling gas jet is changed to a certain extent, resulting in the occurrence of the high temperature zone on the end wall surface near the throat of the cascade passage which is not cooled.

[0034] In this regard, the applicant proposes the end wall cooling structure with a Z type installation gap of the application, in which the turning section position of the Z type installation gap is designed at the throat of the cascade passage to avoid the generation of the high temperature zone on the end wall surface.

[0035] Reference will now be made to Figures 3 to 7The application discloses a Z-shaped installation gap cooling structure for a turbine guide vane end wall and a layout position applied to the turbine guide vane end wall.

[0036] The turbine guide vane end wall structure with the Z-shaped installation gap comprises a plurality of turbine guide vanes 3 arranged on the turbine guide vane end wall 1, and a plurality of film holes 2 arranged on the surface of the turbine guide vane end wall 1.

[0037] As shown in the turbine guide vane end wall structure with the Z-shaped installation gap according to the exemplary embodiment of the application, the Z-shaped structures on the opposite pressure side edge and suction side edge of the turbine guide vane end wall are identical in shape and comprise two parallel straight edge segments and a corner segment connected between the two straight edge segments, and the corner segment is located at the throat of the cascade passage.

[0038] As shown in the turbine guide vane end wall structure with the Z-shaped installation gap according to the exemplary embodiment of the application, the Z-shaped structures on the opposite pressure side edge and suction side edge of the turbine guide vane end wall are identical in shape and comprise two parallel straight edge segments and a corner segment connected between the two straight edge segments, and the corner segment is located at the throat of the cascade passage. Figure 6 The angle θ between the corner segment and the straight edge segment can be 10°-150°, preferably 25°-65°, and more preferably 35°-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 installation gap between the adjacent turbine guide vane end walls 1. Figure 5The two Z-shaped structures are staggered in the main flow direction, that is, the corner sections of the two Z-shaped structures are staggered in the main flow direction instead of being directly opposite to each other, and the corner sections of the two Z-shaped structures are spaced apart in the main flow direction, so that the gap width at the Z-shaped corner section is greater than the gap width at other sections. The two Z-shaped structures extend in parallel at opposite positions, so that a Z-shaped installation gap 4 is formed, in which the Z-shaped corner section is located at the throat of the cascade passage. The seal piece 6 forms a Z-shaped installation gap groove with the corresponding edge surface of the adjacent two turbine vane end walls under the action of the sealing cold air, and 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, thereby slowing down the speed of the upstream cold air flowing in the installation gap.

[0040] According to the present application, 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 vane end wall. In other words, a Z-shaped structure is shown in the figure, which is Z-shaped when viewed from the bottom of the turbine vane, but can also be a structure that is Z-shaped when viewed from the top of the turbine vane.

[0041] With the turbine 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 film hole 2 into the end wall cooling structure with a Z-shaped installation gap, and the cooling air flow entering the end wall surface film hole 2 sprays a cooling air film covering the surface of the turbine vane end wall 1. Since the seal piece 6 causes no leakage flow of cold air in the installation gap, but the upstream cold air flowing through the film hole 2 is affected by the horseshoe vortex in the cascade passage and is sucked into the Z-shaped installation gap groove and impinges on the corner section wall to produce overflow, forming a strong counter-rotating vortex pair on the turbine vane end wall 1. On the one hand, the counter-rotating vortex pair has a strong deceleration effect on the overflow cold air, enhancing the effect of the turbine vane end wall 1 surface film cooling, effectively reducing the adiabatic wall temperature in this area; on the other hand, the spanwise width of the counter-rotating vortex pair is large, which forces the cold air of the turbine vane 3 pressure surface downstream near the end wall surface film hole to be sucked into the downstream gap of the Z-shaped installation gap 4, enhancing the heat exchange between the cold air flow and the inside of the Z-shaped installation gap 4, improving the adiabatic wall temperature distribution of the installation gap, thereby avoiding the formation of a high temperature zone on the end wall surface.

[0042] In the present application, the width of the Z-shaped installation gap at the corner section can be varied or constant in the extension direction, but is preferably constant. For example, Figure 6 and Figure 8As shown, in order to prevent the turbine guide vane end wall from being stuck due to thermal expansion, the reserved installation gap is small, and if it is too large, it may cause problems such as aerodynamic efficiency decline, 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, the numerical simulation results of the turbine guide vane end wall structure with the Z-shaped installation gap provided by the present application are described in combination with examples.

[0044] In this example, the reference straight-line installation gap structure parameters and the Z-shaped installation gap structure parameters of the present application are shown in Table 1, the straight-line installation gap turbine guide vane end wall suction surface side along the main flow inlet to the edge surface of the throat region of the cascade passage is applied with a bias region operation by UG modeling software, and is moved 1.0 mm towards the suction surface direction, that is, the width D of the Z-shaped installation gap is ensured to be 1.0 mm, and the angle θ of the corner section and the straight section is selected to be 35.5°. Similarly, the straight-line installation gap turbine guide vane end wall pressure surface side along the main flow outlet to the edge surface of the throat region of the cascade passage is applied with a bias region operation, and is moved 1.0 mm towards the pressure surface direction, at this time, the width L of the Z-shaped installation gap at the corner section is ensured to be 3.0 mm. In this example, the depth δ of the Z-shaped installation gap groove is selected to be 1.2 mm.

[0045] Table 1

[0046]

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

[0048] Table 2

[0049]

[0050] The turbulence model is selected to be SST k-ω, which has been widely applied and verified in boundary layers, mixing layers and high-speed flows, and also covers the areas concerned in this paper. The solver uses a separated implicit solver, the COUPLE algorithm is used for pressure and velocity coupling, the second-order upwind format is used for discretization of the convection term, and the convergence criterion for 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 Figure 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 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. Figure 10 As shown in Region 1 of the film cooling efficiency cloud map, a local high film cooling efficiency area is formed on the wall near the corner section. On the other hand, this pair of vortices will force the cold air from the 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 between the end wall surface and the installation gap. In addition, the good film coverage effect effectively isolates the heat load of the mainstream wall surface near the corner section, so no high temperature area is generated in the throat area of ​​the blade channel, as shown in Figure 2. Figure 11 The results of numerical simulations verify that the turbine guide vane endwall with a Z-shaped installation gap can effectively avoid the formation of a high-temperature zone at the throat of the cascade channel and improve the film cooling efficiency of the endwall surface to a certain extent.

[0052] Finally, it should be noted that the features mentioned and / or illustrated in the above description of the exemplary embodiments of the present invention may be incorporated into one or more other embodiments in the same or similar manner, combined with features in other embodiments, or substituted for corresponding features in other implementations. The technical solutions obtained by such combination or substitution shall also be deemed to be included in the scope of protection of the present invention.

Claims

1. A turbine guide vane end wall structure with a Z-shaped installation gap, wherein an installation gap exists between two adjacent turbine guide vane end walls, and a sealing piece is provided in the installation gap to prevent the gas in the 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 identically shaped Z-shaped structures at the opposite pressure side edges and suction side edges, which include two parallel straight edge sections and a corner section connected therebetween, wherein the corner section is located at the throat of the 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 part 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 side segment is 10° to 150°.

Images