Turbine guide vane end wall structure with bilateral equal-curvature arc-shaped wall surface assembly clearance

Abstract

The invention discloses a turbine guide vane end wall structure of a bilateral equal-curvature arc-shaped wall surface assembly clearance, and belongs to the field of gas turbine end wall cooling. The structure comprises two adjacent turbine guide vane end walls and an assembly gap between the two adjacent turbine guide vane end walls, and a sealing piece is arranged in the gap. According to the improvement, two opposite wall surfaces forming the assembling gap are arc-shaped wall surfaces with equal curvature and extend in the axial direction of the end wall, one side wall surface is concave, and the other side wall surface is convex; meanwhile, a leakage hole is formed in the sealing piece and used for guiding cooling airflow into the assembling gap. According to the structure, leakage flow is guided through the arc-shaped wall face, normal momentum is reduced, attachment is enhanced, main flow invasion can be effectively resisted, internal temperature distribution of the gap is improved, and the air film cooling efficiency and the overall thermal protection capacity of the downstream surface of the end wall are remarkably improved through coupling superposition of the leakage flow and cold air of the air film holes of the end wall. The technical problems that downstream gas film coverage is insufficient and local thermal load is high due to a traditional assembly gap are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of turbine endwall cooling of gas turbine, and particularly relates to a turbine vane endwall structure with double-side equal-curvature arc-shaped wall surface assembly gap. BACKGROUND

[0002] The continuous increase of turbine inlet gas temperature puts forward higher requirements for turbine endwall cooling technology. As a key area in turbine high-temperature components, the endwall surface often forms a local high heat transfer area due to the existence of complex three-dimensional secondary flow vortex system, resulting in concentrated heat load and great difficulty in cooling. In actual assembly, assembly gaps inevitably exist between adjacent turbine vane endwalls. Although the gap is a space reserved for thermal expansion, it will cause gap leakage flow, which significantly changes the flow field and temperature field distribution near the endwall. Specifically, the leakage flow will destroy the gas film coverage integrity of the endwall surface, especially in the downstream region, not only leading to the decline of gas film cooling efficiency and the expansion of local low cooling efficiency area, but also exacerbating the adverse effects of secondary flow structures such as passage vortex, and causing additional mixing loss.

[0003] At present, the research on assembly gap mainly focuses on the flow characteristics of gap leakage flow and its influence on aerodynamic loss, and there is still a lack of systematic and effective structure design scheme for improving endwall gas film cooling coverage, inhibiting mainstream invasion and improving overall cooling efficiency under limited cooling gas conditions. SUMMARY

[0004] The purpose of the present application is to solve the problems of poor gas film coverage, low cooling efficiency and high local heat load of the endwall surface caused by leakage flow in the assembly gap of the turbine endwall in the prior art, and to provide a turbine vane endwall structure for optimizing the gap flow and enhancing the coupling effect of leakage flow and gas film by double-side equal-curvature arc-shaped wall surface modeling.

[0005] The conventional technical idea in the art is that, in view of the destructive effect of assembly gap leakage flow on endwall surface gas film coverage and the increase of aerodynamic loss, the structure design usually focuses on perfecting the sealing to inhibit or eliminate leakage as much as possible, and will not actively open leakage holes on the sealing piece to introduce or enhance leakage flow. The inventors of the present application have overcome the technical prejudice that "leakage flow is necessarily harmful" and creatively proposed that by designing specific double-side equal-curvature arc-shaped wall surface to reconstruct the geometric shape of the assembly gap, the flow pattern of the leakage flow can be actively guided and reshaped, so that the originally adverse leakage flow is transformed into an effective secondary cooling gas source that can strengthen the gas film cooling of the downstream endwall. The core of this invention concept is to combine gap modeling design with active use of leakage flow, and to change harm into benefit through structural innovation, so as to significantly improve the overall cooling effect and thermal protection performance of the turbine vane endwall, especially in the downstream region, under the condition of limited cooling gas flow.

[0006] To achieve the above objectives, the technical solution provided by this invention is:

[0007] A turbine guide vane endwall structure with a double-sided equal curvature arc-shaped wall assembly gap is provided, comprising two adjacent turbine guide vane endwalls forming an assembly gap between them. A sealing plate is disposed within the assembly gap to prevent combustion gas in the blade passage from entering the cold air chamber.

[0008] The opposing walls forming the assembly gap on the end walls of the two turbine guide vanes are arc-shaped walls with equal curvature. The arc-shaped walls extend along the axial direction of the turbine guide vane end walls and the cross-sectional configurations in the extension direction are consistent.

[0009] The arc-shaped wall is constructed such that, under the condition that the three-dimensional position of the assembly gap on the turbine guide vane end wall surface is fixed, the arc-shaped wall on the pressure side is recessed towards the turbine guide vane end wall entity to which it belongs, and the arc-shaped wall on the suction side is protruded away from the turbine guide vane end wall entity to which it belongs.

[0010] The emission angle at the top edge of the curved wall is 5°~40°;

[0011] The sealing plate has leakage holes to guide the sealing cold air into the assembly gap, so as to resist the intrusion of the upstream mainstream gas, improve the temperature distribution inside the gap, and achieve secondary cooling of the downstream end wall surface.

[0012] Furthermore, the tangents at the bottom edges of the arcuate walls on both sides of the turbine guide vane endwall are perpendicular to the surface of the turbine guide vane endwall.

[0013] Furthermore, the emission angle of the top edge of the curved wall is 5°~30°.

[0014] Furthermore, the width of the assembly gap is 1.0~2.0 mm and the depth is 1.0~1.5 mm.

[0015] Furthermore, multiple leakage holes are opened downstream of the sealing plate and are arranged at intervals along the axial direction of the sealing plate.

[0016] Furthermore, there are 5 leakage holes, which are evenly distributed along the axial direction.

[0017] Furthermore, the axial distance between the leakage hole closest to the downstream outlet of the assembly gap and the downstream edge of the turbine guide vane endwall is 0.03 to 0.1 times the axial length of the turbine guide vane endwall.

[0018] Furthermore, the axial distance between two adjacent leakage holes is 0.03 to 0.1 times the axial length of the turbine guide vane endwall.

[0019] Furthermore, the diameter of the leakage hole is 0.7~1.0 mm.

[0020] The advantages of this invention are:

[0021] 1. The turbine guide vane endwall structure provided by this invention significantly improves the cooling performance and flow field distribution of the turbine guide vane endwall by employing an assembly gap formed by double-sided equal-curvature arc-shaped walls and combining it with leakage holes in the downstream region of the sealing plate. This structure allows the cooling airflow introduced from the leakage holes to adhere more smoothly to the arc-shaped walls, effectively suppressing mainstream intrusion, improving the temperature distribution inside the gap, and utilizing the leakage flow to achieve secondary cooling of the downstream region of the endwall. Simultaneously, the smaller exit angle at the top edge of the arc-shaped walls reduces the normal momentum of the leakage flow, enhancing its coupling with the upstream film cooling jet, forming a film cooling superposition effect, thereby significantly improving the film cooling coverage efficiency of the downstream endwall surface, especially in the localized low-efficiency zone easily caused by traditional assembly gaps, where the cooling effect is significantly improved. Furthermore, this structure also helps reduce the mixing loss between the leakage flow and the mainstream, suppressing the adverse effects of secondary flow structures such as channel vortices, achieving more uniform and efficient full film thermal protection of the endwall surface under limited cold air flow conditions.

[0022] 2. According to the numerical simulation results, the structure of the present invention can increase the air film cooling efficiency in the gap by up to about 125.7% under typical working conditions, and increase the net heat flux reduction in the main affected area downstream of the end wall by up to about 80.4%, thereby substantially enhancing the overall cooling performance and thermal protection effect. Attached Figure Description

[0023] The above and / or other features and advantages of the present invention will become more readily understood from the following description with reference to the accompanying drawings, which are not drawn to scale and some features are enlarged or reduced to show details of specific parts.

[0024] Figure 1 These are comparative diagrams of the distribution of film cooling efficiency on the endwall surface of turbine guide vanes; where (a) is a schematic diagram of a structure without assembly gaps, and (b) is a schematic diagram of a structure with assembly gaps on a traditional straight wall surface.

[0025] Figure 2 This is an isometric view of the turbine guide vane endwall structure with assembly gaps on both sides of the same curvature arc-shaped wall surface according to the present invention.

[0026] Figure 3 yes Figure 2 An enlarged view of region A shows the assembly structure of the sealing strip;

[0027] Figure 4 This is a top view of the structure of the present invention;

[0028] Figure 5This is an isometric view of the sealing sheet in this invention;

[0029] Figure 6 These are schematic diagrams of sealed cold air flow, where (a) is a schematic diagram of a structure with a conventional straight wall assembly gap, and (b) is a schematic diagram of a structure with a double-sided equal curvature arc-shaped wall assembly gap of the present invention.

[0030] Figure 7 This is a comparison diagram of the distribution of gas film cooling efficiency on the end wall surface of the conventional structure and the structure of the present invention under different leakage flow mass flow ratios.

[0031] Figure 8 This is a comparison diagram of the temperature distribution of the insulating wall in the assembly gap between the traditional structure and the structure of the present invention under different leakage flow mass flow ratios.

[0032] Figure 9 This is a comparison diagram of the cold gas ejection velocity and streamline distribution in the leakage hole of the traditional structure and the structure of the present invention under different leakage flow mass flow ratios.

[0033] Figure 10 This is a comparison diagram of the convective heat transfer coefficient distribution on the end wall surface of the conventional structure and the structure of the present invention under different leakage flow mass flow ratios.

[0034] Figure 11 This is a comparison diagram of the convective heat transfer coefficient distribution on the end wall surface of the traditional structure and the structure of the present invention under conditions of no cold air flow.

[0035] Figure 12 This is a comparison chart showing the distribution of the reduction in net heat flux on the end wall surface of the conventional structure and the structure of the present invention under different leakage flow mass flow ratios.

[0036] In the figure: 1-Turbine guide vane end wall; 2-Film gas hole; 3-Assembly clearance; 4-Turbine guide vane; 5-Sealing plate; 6-Sealing cavity wall; 7-Leakage hole; 8-Cold air cavity. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments thereof. It should be noted that the following detailed description of the present invention is for illustrative purposes only and is not intended to limit the scope of the invention.

[0038] This invention provides a turbine guide vane endwall structure with a double-sided equal curvature arc-shaped wall assembly gap, which mainly addresses the problems of insufficient air film coverage on the endwall surface, especially in the downstream region, and the local low cooling efficiency zone induced by traditional assembly gaps.

[0039] To clearly reflect the impact of assembly clearance on the film cooling efficiency of the end wall surface, a comparative analysis was first conducted using numerical simulation. For example... Figure 1As shown, (a) illustrates the ideal end-wall surface film cooling efficiency distribution without assembly gaps, while (b) illustrates the distribution with conventional straight wall assembly gaps (i.e., the exit angle of the top edge of the gap wall). The distribution of film cooling efficiency on the endwall surface (90°) is shown. A comparison reveals that the presence of a gap in the assembly of a conventional straight wall causes the cold air jet exiting from the film cooling holes on the upstream pressure side of the endwall to be entrained into the gap. This portion of the cold air moves downstream along the mainstream direction within the gap and then overflows, leading to a further expansion of Region 1, the area without film cooling coverage at the front of the endwall blade passage. However, the overflowing cold air in the throat region of the blade passage somewhat compensates for the film cooling coverage in Region 2, resulting in an overall decreasing trend in film cooling efficiency. When the cold air jet exiting the film cooling orifice in the middle section of the pressure side crosses the gap, some of the cold air is entrained by the gap due to its blocking effect. This causes a slight "misalignment" of the film cooling trajectory on the endwall surfaces on both sides of the gap. Furthermore, the flow momentum of some of the cold air that crosses the gap decreases, resulting in a reduction in the spanwise expansion effect of the cold air jet. This prevents it from forming a film cooling superposition effect with the downstream cold air. It can be seen that the film cooling efficiency of the cold air in the downstream film cooling orifice of the endwall is significantly lower than that of the endwall without the assembly gap. In addition, the momentum loss caused by the upstream cold air crossing the gap alters the coverage area of ​​the original structure's cold air jet to some extent, creating a new low-efficiency region (Region 3) on the downstream surface of the endwall, dominated by a wake shedding vortex. This reveals the mechanism by which traditional structures disrupt film cooling coverage, leading to a decrease in cooling efficiency.

[0040] To address the aforementioned problems, this invention proposes an innovative end-wall cooling structure. Now referring to... Figures 2 to 6 The structure and its arrangement on the endwall of the turbine guide vane are described in detail.

[0041] A turbine guide vane typically includes multiple turbine guide vanes 4, each mounted on a turbine guide vane endwall 1, and multiple film cooling holes 2 are arranged on the surface of the turbine guide vane endwall 1. Figure 2 , Figure 4 As shown, an elongated assembly gap 3 inevitably exists between two adjacent turbine guide vane endwalls 1. In this invention, the configuration of this assembly gap 3 is redesigned: the two opposing walls forming the assembly gap 3, namely the pressure side edge wall and the suction side edge wall of the adjacent endwalls respectively, are arc-shaped walls with equal curvature. These double-sided arc-shaped walls with equal curvature extend along the axial direction of the turbine guide vane endwall 1 (i.e., approximately the direction of mainstream gas flow) and have the same cross-sectional configuration in the extension direction, constituting the double-sided walls of the assembly gap 3.

[0042] like Figure 3 , Figure 5 and Figure 6As shown in (b), a sealing plate 5 is provided within the assembly gap 3, which serves to block the high-temperature combustion gas in the turbine blade passage from entering the cooling chamber 8. The sealing plate 5 is placed in the assembly groove formed by the sealing chamber wall 6. A key improvement of this invention is that multiple leakage holes 7 are provided on the sealing plate 5. It should be noted that the location of the leakage holes 7 in this invention is based on in-depth flow field analysis and experimental verification. Although theoretically, orifices can be opened at different axial positions on the sealing plate 5, the applicant found that under the action of high-pressure mainstream combustion gas in the turbine blade passage, orifices opened in the upstream region of the sealing plate often cannot allow the sealing cooling gas to flow out effectively due to excessive back pressure. Therefore, the leakage holes 7 that can actually take effect, provide stable outflow, and achieve the cooling effect of this invention are actually located in the downstream region of the sealing plate 5. The local pressure conditions here allow the sealing cooling gas to be ejected smoothly and enter the gap channel formed by the arc-shaped wall. The effective cooling airflow of this invention originates from the sealing cold air ejected from the downstream leakage hole 7, constituting a practical air source that improves gap flow, resists mainstream intrusion, and achieves secondary cooling of the downstream end wall. Part of the sealing cold air from the cold air chamber 8 forces the sealing plate 5 to move towards the outer surface of the end wall, thereby achieving a tight seal against the bottom edge of the assembly gap 3. The other part is ejected from the downstream leakage hole 7 and enters the gap channel formed by the double-sided equally curved arc-shaped walls.

[0043] The operating principle of this structure is as follows: The cooling airflow ejected from the leakage hole 7 first impacts the arc-shaped wall surface of the assembly gap 3. Because the wall surface is an arc-shaped guide surface, it effectively reduces the normal momentum of the cooling air jet, allowing it to flow more smoothly and closely along the wall surface towards the gap outlet. Figure 6 As shown in (b), the cold air forms a local vortex structure within the gap and then flows out smoothly. This flow characteristic enables the cooling airflow to effectively resist the intrusion of the upstream mainstream combustion gas, significantly improves the temperature distribution of the insulating wall inside the assembly gap 3, and forms a secondary cooling air source for the downstream end wall surface. Figure 6 The conventional vertical wall shown in (a) is ( In the 90° gap, the cold air is injected almost vertically upwards, with a large normal momentum, and mixes violently with the mainstream. This not only fails to effectively improve the temperature within the gap, but also contributes little to the gas film coverage of the downstream end wall.

[0044] The specific geometric features of the double-sided constant curvature arc-shaped wall have a significant impact on performance. First, the double-sided constant curvature arc-shaped wall has a specific curvature direction to optimize the guidance of cooling airflow. Specifically, the curvature direction of the double-sided constant curvature arc-shaped wall is configured such that, in the cross-section of the assembly gap perpendicular to the mainstream gas flow direction, both sides of the arc-shaped wall bend inwards into the gap and are arranged asymmetrically about the gap centerline. More specifically, the arc-shaped wall is configured such that, while ensuring the three-dimensional position of the assembly gap on the turbine guide vane endwall surface is fixed, the arc-shaped wall on the pressure side is concave towards the turbine guide vane endwall entity, while the arc-shaped wall on the suction side bulges away from the turbine guide vane endwall entity. This asymmetrical relative curvature configuration, in conjunction with the downstream leakage hole 7, forms an optimized flow channel that can efficiently convert the vertically incident cold gas flow into a tangential component along the downstream endwall surface and promote adhering flow of the airflow.

[0045] Furthermore, to ensure that the sealing gas ejected from the leakage hole 7 can smoothly enter the gap and have sufficient initial momentum, the arc-shaped wall surface has been structurally optimized. Specifically, the tangent of the bottom edge of the arc-shaped wall surface (i.e., the side closest to the sealing plate) is perpendicular to the surface of the turbine guide vane end wall 1, that is, parallel to the axis of the leakage hole 7. Figure 6 As shown in (b), this design ensures that the incident direction of the sealed cold air is perpendicular to the bottom inlet of the gap, reducing the flow loss and impact when the cold air enters, and laying the foundation for effective flow guidance in the arc-shaped channel.

[0046] The angle of emission from the top edge of the curved wall It is a validated key parameter. Numerical simulation studies (such as...) Figure 7 , Figure 8 As shown in the figure, it was found that when the exit angle At a 45° angle, its cooling effect may even be inferior to that of a traditional 90° vertical wall, which will be described in detail below. This is because the 45° angle causes the leakage flow to still have a large normal momentum, making it unable to fully adhere to the end wall surface. At the same time, due to insufficient radial momentum, it is difficult to effectively resist the mainstream intrusion after disturbance within the gap, ultimately resulting in poor gas film coverage. Conversely, when the exit angle is... Reducing the angle to below 45°, particularly preferably within the range of 5° to 40°, and more preferably within the range of 5° to 30° (e.g., 15°), yields a significant improvement in cooling performance. The principle is that when the exit angle... When the gap is smaller and closer to the end wall surface, on the one hand, the entrainment effect of the assembly gap 3 on the cold air ejected from the upstream film cooling hole 2 is reduced, allowing more cold air to smoothly cross the gap; on the other hand, the leakage flow flowing out of the gap outlet has a larger flow momentum component, which can uniformly adhere to the downstream end wall surface with lower kinetic energy loss. This allows the leakage flow to better couple with the cold air passing through the upstream film cooling hole and the cold air ejected from the downstream film cooling hole 2, forming a superimposed film covering layer, which disperses the vortex structure in the downstream region of the gap, significantly improving the cooling efficiency of the downstream end wall surface (especially the traditional low cooling efficiency zone).

[0047] The dimensions of the assembly clearance 3 need to balance thermal expansion requirements with aerodynamic performance. The axial length of a typical turbine guide vane endwall 1... The axial chord length of the guide vane midsection is 80~100 mm. The gap width is 68~88 mm. Preferably, the depth is 1.0~2.0 mm, for example 1.2 mm. The preferred clearance is 1.0 to 1.5 mm, for example, 1.4 mm. Too large a clearance may result in unacceptable aerodynamic losses, while too small a clearance may cause thermal expansion jamming.

[0048] The arrangement of the leakage holes 7 has also been optimized. For example... Figure 5 As shown, in the downstream region of the sealing plate 5, multiple leakage holes 7 are opened at equal axial intervals, for example, 5 holes. The axial distance between the leakage hole closest to the downstream outlet of the assembly gap 3 and the downstream edge of the turbine guide vane endwall 1 is... Designed for the axial length of the end wall 0.03 to 0.1 times (e.g.) ). Axial distance between adjacent leak holes 7 Also designed as 0.03 to 0.1 times (e.g.) ). Orifice diameter of the leakage hole The design is 0.7~1.0 mm (e.g., 0.8 mm). This design places the leakage hole group near the critical downstream film cooling area, ensuring that the leaked cold air is effective at the location where enhanced cooling is needed. At the same time, it avoids the phenomenon of cold air not being able to flow out or even the mainstream intruding into the cold air chamber due to being too close to the upstream. This achieves efficient utilization of the limited sealing cold air and effectively controls the flow and temperature field in the gap and downstream end wall through multi-point and orderly cold air injection.

[0049] The advantages of this invention will be further illustrated below with numerical simulation results from an example. In this example, three comparative models were constructed: a traditional straight-line wall gap ( =90°) and the two types of double-sided equal curvature arc-shaped wall gaps of the present invention (selected respectively) =45° and =15°), key geometric parameters are summarized in Table 1. Gap width of all models =1.2mm, depth =1.4mm. The specific design of the double-sided equal curvature arc-shaped wall surface is achieved by ensuring consistent width and depth, and controlling the exit angle at the top edge. This is achieved at 45° and 15°. Five leakage holes are equally spaced along the axial direction downstream of the sealing plate. Their geometric dimensions and positioning parameters are selected as follows: hole diameter... =0.8mm, axial length of the end wall =90mm.

[0050]

[0051] It should be noted that in numerical simulation studies of turbine guide vane endwall assembly clearances, to accurately simulate the physical phenomenon of cold air leakage that cannot be completely avoided by the sealing structure during engine operation, the common practice in this field is to set leakage holes at the corresponding positions of the sealing plate to equivalently characterize this "leakage flow". Therefore, in the comparative simulation of this example, the traditional straight wall assembly clearance model (corresponding to...) =90°) and the double-sided equal curvature arc-shaped wall model of the present invention (corresponding to) Both 45° and 15° have leak holes of the same position and size on their sealing plates to ensure that the comparison is carried out under the same leakage flow conditions, focusing on evaluating the differential impact of the gap wall shape itself on the leakage flow characteristics and cooling effect.

[0052] In the numerical simulation, the flow parameters of the calculation model of this invention are shown in Table 2. The end-wall cold air adopts a split-chamber inlet form. During the calculation, both the main inlet and the cold air inlet are mass flow rate inlets, with the main inlet flow rate being 4.379 kg·s. -1 The temperature was 1939.3 K, and the total pressure was 1.0033 MPa; the cold air inlet flow rate on the pressure side of the end wall was 0.005087 kg·s. -1 The temperature is 639.3 K; the downstream cold air inlet flow rate is 0.01171 kg·s. -1 The temperature was 639.3 K; the cold air inlet flow rates for the leakage flow during assembly were 0.003057 / 0.006131 / 0.009196 kg·s, respectively. -1 Ensure quality flow ratio The concentrations are 0.7% / 1.4% / 2.1%, and the temperature is 639.3K; the main outlet is a pressure outlet with a pressure of 0.6919MPa.

[0053]

[0054] Numerical simulations were performed using commercial computational fluid dynamics (CFD) software. The three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations were solved, and the SST k-ω turbulence model was chosen. The SST k-ω model has been widely applied and validated in boundary layers, mixing layers, and high-velocity flows, and also covers the region of interest in this paper. A segregated implicit solver was used, with the pressure and velocity coupling employing the COUPLE algorithm. The convection term was discretized using a second-order upwind scheme. The convergence criterion for the numerical solution was that the residuals of each discretized quantity were less than 10. -6 .

[0055] Figure 7 This demonstrates different leakage flow mass flow ratios ( Under these conditions, the surface air film cooling efficiency of the three structural end walls is... The distribution cloud map. The expression for the film cooling efficiency is as follows:

[0056]

[0057] In the formula, Indicates the mainstream gas inlet temperature. This indicates the temperature of the end wall insulation under cold air conditions. This indicates the temperature at the air inlet.

[0058] from Figure 7 It can be observed that in the traditional structure ( In (=90°), as As the volume increases, the film cooling efficiency actually decreases. This is because the vertically ejected leakage flow penetrates deeply into the mainstream, resulting in severe mixing and failure to form a good adhesion. However, in this invention... In a structure with a =15° angle, efficiency is significantly improved, and... At a concentration of 2.1%, full gas film coverage of the downstream surface was essentially achieved. This confirms the superiority of the small exit angle arc-shaped wall in promoting leakage flow adhesion and forming gas film superposition.

[0059] It is worth noting that in this invention The 45° structure has a lower cooling efficiency than the conventional design. The structure has a 90° exit angle. This is because the 45° exit angle results in the leaking flow still having a large normal momentum, making it impossible to form a sufficiently adherent and effective gas film on the endwall surface; at the same time, its radial momentum is insufficient to strongly resist the intrusion of the upstream mainstream after being disturbed and enhanced by the internal arc gap. These two factors together result in this structure being unable to establish a good gas film coverage and failing to protect the existing gas film layer, leading to low efficiency.

[0060] Figure 8 Showing different Insulation wall temperature in the lower assembly gap Distribution of dimensional temperature. The expression is as follows:

[0061]

[0062] In the formula, This indicates the wall temperature.

[0063] from Figure 8 It can be seen that the present invention The structure with a temperature of 15°C is most effective at reducing the adiabatic wall temperature within the gap, indicating its strongest ability to improve the internal temperature distribution of the gap. In contrast, The 45° structure has a very limited effect on improving the insulation wall temperature within the gap, compared to traditional structures ( The difference (=90°) is not significant, which is consistent with... Figure 7 This is consistent with its poor cooling efficiency. Furthermore, calculations show that, under the same conditions, the present invention… The air film cooling efficiency within a structural gap of 15° can be improved by up to approximately 125.7% compared to traditional structures.

[0064] Figure 9 The dimensionless velocity of the cold gas ejected through the leak hole The streamline diagram provides a direct comparison of the flow characteristics within the gap. The calculation formula is as follows:

[0065]

[0066] In the formula, Indicates the fluid velocity on the end wall surface. Indicates the mainstream import flow rate. This indicates the local fluid velocity.

[0067] from Figure 9 As can be seen, the traditional structure ( The streamlines in the 90° (=90°) show obvious signs of mainstream intrusion, while the structure of this invention ( The streamlines (15°) adhere more closely to the curved wall surface, resulting in a smoother and more concentrated flow, demonstrating its significantly enhanced resistance to mainstream intrusion.

[0068] Figure 10 Showing different lower end wall surface convective heat transfer coefficient Distribution cloud map, Calculate using the following formula:

[0069]

[0070] In the formula, This represents the heat flux across the end wall surface under cold airflow conditions. In the vicinity of the main area affected by the leakage flow, the traditional structure... As the flow increases, the intensity of convective heat transfer gradually rises. This is because the strong shearing effect of the leakage flow disrupts the gas film coverage, leading to the formation of a strong heat transfer zone. The present invention... The 15° structure benefits from the strong adhesion of the leakage flow, which reduces the heat transfer intensity in this area to some extent.

[0071] To obtain the reference heat transfer coefficient under no-cooling conditions (For subsequent comprehensive evaluation), the heat transfer coefficients of the end wall surfaces of each structure were calculated under no cooling air flow, and the distribution is as follows: Figure 11 As shown. The calculation is as follows:

[0072]

[0073] In the formula, This represents the heat flux across the end wall surface under conditions of no cold air flow. This indicates the end-wall insulation temperature under conditions without air conditioning.

[0074] To comprehensively evaluate the overall thermal protection effect of film cooling under real heat transfer conditions, the reduction in net heat flux was analyzed. , Calculate using the following formula:

[0075]

[0076] Figure 12 Showing different The following three structures Distribution cloud map. It can be seen that this invention... =15° structure compared to =90° and The 45° structure significantly improves the downstream surface of the end wall. Especially in the vicinity of the main area affected by the leakage flow, the present invention =15° structure Compared to =90° structure at high mass flow ratio ( The maximum improvement is approximately 80.4% at 2.1%. This core performance indicator fully demonstrates that the structure proposed in this invention can effectively compensate for the cooling defects of traditional assembly gaps in this area under real engine heat transfer conditions, and significantly improve the overall cooling performance and thermal protection capability of the end wall surface.

[0077] In summary, the turbine guide vane endwall structure of the present invention, featuring a double-sided, uniformly curved arc-shaped wall assembly gap, combines a specific arc-shaped wall design with a sealing plate containing leakage holes downstream to form a synergistic and efficient cooling solution. This solution utilizes the arc-shaped wall to guide the leakage flow, enhancing its adhesion and resistance to mainstream intrusion, and improving the temperature field within the gap. Furthermore, it effectively couples the leakage flow with the cold air from the endwall's film cooling holes, forming a superimposed, fully covered film layer downstream. Thus, under limited cooling flow, it successfully solves the key technical challenges of insufficient film coverage on the downstream surface of the endwall and the localized low-cooling-efficiency zone induced by traditional assembly gaps.

[0078] Finally, it should be noted that the features mentioned and / or shown in the above description of exemplary embodiments of the present invention can be combined in the same or similar manner with one or more other embodiments, combined with or substituted for corresponding features in other embodiments. These combined or substituted technical solutions should also be considered to be included within the scope of protection of the present invention.

Claims

1. A turbine guide vane endwall structure with a double-sided equal curvature arc-shaped wall assembly gap, comprising two adjacent turbine guide vane endwalls, with an assembly gap formed between the two turbine guide vane endwalls, and a sealing plate for blocking the entry of combustion gas in the blade passage into the cooling chamber disposed within the assembly gap, characterized in that: The opposing walls forming the assembly gap on the two turbine guide vane endwalls are arc-shaped walls with equal curvature, and the arc-shaped walls extend along the axial direction of the turbine guide vane endwalls and have the same cross-sectional configuration in the extension direction. The arc-shaped wall is configured such that, under the condition that the three-dimensional position of the assembly gap on the turbine guide vane end wall surface is fixed, the arc-shaped wall on the pressure side is recessed towards the turbine guide vane end wall entity to which it belongs, and the arc-shaped wall on the suction side is protruded away from the turbine guide vane end wall entity to which it belongs. The emission angle of the top edge of the arc-shaped wall is 5°~40°; The sealing plate has a leakage hole for introducing sealing cold air into the assembly gap to resist the intrusion of upstream mainstream gas, improve the temperature distribution inside the gap, and achieve secondary cooling of the downstream end wall surface.

2. The turbine guide vane endwall structure according to claim 1, characterized in that: The tangents at the bottom edges of the arc-shaped walls on both sides of the turbine guide vane endwall are perpendicular to the surface of the turbine guide vane endwall.

3. The turbine guide vane endwall structure according to claim 1 or 2, characterized in that: The emission angle of the top edge of the arc-shaped wall is 5°~30°.

4. The turbine guide vane endwall structure according to claim 1, characterized in that: The width of the assembly gap is 1.0~2.0 mm and the depth is 1.0~1.5 mm.

5. The turbine guide vane endwall structure according to claim 1, characterized in that: Multiple leakage holes are opened downstream of the sealing plate and are arranged at intervals along the axial direction of the sealing plate.

6. The turbine guide vane endwall structure according to claim 5, characterized in that: The number of leakage holes is 5, and they are evenly distributed along the axial direction.

7. The turbine guide vane endwall structure according to claim 5 or 6, characterized in that: The axial distance between the leakage hole closest to the downstream outlet of the assembly gap and the downstream edge of the turbine guide vane endwall is 0.03 to 0.1 times the axial length of the turbine guide vane endwall.

8. The turbine guide vane endwall structure according to claim 5 or 6, characterized in that: The axial distance between two adjacent leakage holes is 0.03 to 0.1 times the axial length of the turbine guide vane endwall.

9. The turbine guide vane endwall structure according to claim 5 or 6, characterized in that: The diameter of the leakage hole is 0.7~1.0 mm.

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