Turbine guide vane end wall cascade-like channel type assembly clearance structure based on transverse pressure gradient

Abstract

The invention discloses a turbine guide vane end wall cascade-like channel type assembly clearance structure based on a transverse pressure gradient, and belongs to the field of gas turbine end wall cooling. The assembly gap is of a cascade-like channel type structure with the consistent cross section configuration in the axial direction, the pressure side wall face is similar to a blade pressure surface molded line, the suction side wall face is similar to a blade suction surface molded line, and a flow channel capable of generating a stable transverse pressure gradient is jointly formed. And a leakage hole is formed in the sealing sheet. The transverse pressure gradient is utilized to actively regulate and control sealing cold air entering the gap from the leakage hole, so that the sealing cold air is orderly migrated from the pressure side to the suction side and flows close to the wall surface, and the adiabatic temperature distribution in the gap and the air film coverage of the suction side wall surface are remarkably improved. And meanwhile, the leakage flow and the cold air of the air film holes in the end wall have a synergistic effect, so that the cooling effect and uniformity of the downstream surface of the end wall are enhanced, the net heat flux reduction amount is remarkably increased, the mixing loss is reduced to a certain extent, and good balance between efficient and uniform cooling and low pneumatic loss is realized.

Description

Technical Field

[0001] This invention belongs to the field of gas turbine endwall cooling technology, specifically relating to a turbine guide vane endwall cascade-type assembly gap structure based on lateral pressure gradient. Background Technology

[0002] The turbine inlet gas temperature directly affects the thrust-to-weight ratio and thermal efficiency of aero-engines. Currently, it exceeds 2400K, far surpassing the temperature resistance limit of high-temperature materials, making turbine endwall cooling technology crucial. In the high-pressure turbine blade passageway, the endwall region not only bears extremely high thermal loads but is also strongly influenced by secondary flow structures such as horseshoe vortices and channel vortices, making it prone to thermal failure. In actual assembly, an assembly gap must be provided between the endwalls of adjacent blades to accommodate thermal expansion; however, this gap can lead to leakage jets of the sealing cooling gas. The interaction of the leakage flow with the mainstream and secondary flows disrupts the gas film coverage on the endwall surface, creating localized low-cooling-efficiency zones and increasing mixing losses.

[0003] Traditional cooling research is largely based on ideal, gapless conditions, failing to fully consider the complexity of actual gap flow. Although recent studies have attempted to improve the leakage flow direction by optimizing gap design, a systematic analysis of the interaction mechanism between the leakage flow and the cooling gas in discrete film cooling orifices is still lacking. Furthermore, it has not been able to achieve coordinated control of the flow within the gap and the end-wall film cooling under limited cooling gas conditions. Therefore, effectively suppressing the damage of leakage flow to the film cooling system, improving cooling uniformity, and controlling aerodynamic losses have become critical technical challenges that need to be addressed in turbine end-wall cooling design. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that the existing turbine guide vane endwall assembly gap structure is damaged by leakage flow, resulting in reduced cooling efficiency and increased heat load. The invention proposes a blade-like channel-type assembly gap structure that actively regulates the flow within the gap by utilizing the lateral pressure gradient, thereby improving the uniformity of endwall cooling and the effect of air film coverage.

[0005] In this field, conventional approaches to addressing the destructive effects of assembly gap leakage flow on end-wall cooling primarily focus on optimizing the sealing structure to minimize leakage flow or compensating for the heat load caused by leakage flow through localized enhanced cooling. These methods essentially treat leakage flow as an unavoidable harmful flow. This common perception has led to the technical bias that "assembly gap leakage flow inevitably has a negative impact on end-wall cooling." This invention breaks through this bias, not simply pursuing the minimization of leakage, but actively shaping the flow characteristics of the leakage flow itself through an innovative cascade-like channel structure. It transforms the leakage flow from a "harmful jet" that needs to be resisted into a "secondary source of cooling air" that can be precisely guided and efficiently utilized. Under the regulation of the lateral pressure gradient, this leakage flow not only no longer damages the original air film, but also synergistically couples with the cooling air in the end-wall air film vents, becoming an effective component in strengthening downstream end-wall air film coverage and improving overall cooling efficiency.

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

[0007] A turbine guide vane endwall assembly gap structure based on a lateral pressure gradient is provided, comprising adjacent turbine guide vane endwalls, on which turbine guide vanes are mounted, and an assembly gap is formed between two adjacent turbine guide vane endwalls. A sealing plate is provided within the assembly gap to prevent combustion gas in the blade passage from entering the cold air chamber. Wherein:

[0008] The assembly gap is a cascade-like channel type assembly gap, and has a consistent cross-sectional configuration along the axial extension direction of the end wall;

[0009] In the cross-sectional configuration, the assembly gap is similar to the blade pressure surface profile on one side wall of the pressure side and similar to the blade suction surface profile on one side wall of the suction side. The two side walls together form a flow channel that can generate a stable lateral pressure gradient.

[0010] The sealing plate has a leakage hole to guide the sealing cold air into the assembly gap. The stabilizing lateral pressure gradient can guide the introduced sealing cold air to migrate from the pressure side wall to the suction side wall and adhere to it, thereby resisting the intrusion of the mainstream combustion gas, improving the insulation temperature distribution inside the gap, and achieving secondary cooling of the end wall.

[0011] Furthermore, the curvature of the arc on the pressure side wall gradually increases from the bottom to the top of the gap; the first half of the arc on the suction side wall from the bottom to the top of the gap is an acceleration segment with increasing curvature, and the second half is a diffusion segment with a gradual change in curvature.

[0012] Furthermore, the angle of attack of the sealed cold air entering the cascade-like assembly gap is between the direction of the cold air flow and the tangent direction of the bottom profile of its pressure side wall. The range is 35° to 65°.

[0013] Furthermore, the width of the gap in the cascade-like assembly is 1.0~2.0 mm, and the depth is 1.0~1.5 mm.

[0014] Furthermore, five leakage holes are opened downstream of the sealing plate and are arranged at equal intervals along the axial direction of the sealing plate.

[0015] Furthermore, the axial distance between the leakage hole closest to the downstream outlet of the cascade-type assembly clearance and the downstream edge of the turbine guide vane endwall. satisfy: ,in, This is the axial length of the turbine guide vane endwall.

[0016] Furthermore, the axial distance between two adjacent leak holes Axial length of turbine guide vane endwall satisfy: .

[0017] Furthermore, the diameter of the leakage hole is 0.7~1.0 mm.

[0018] Furthermore, the axial length of the turbine guide vane endwall It is 80~100 mm.

[0019] The advantages of this invention are:

[0020] This invention utilizes an assembly gap with a cascade-like cross-sectional configuration between the endwalls of adjacent turbine guide vanes, along with a sealing plate featuring leakage holes. By leveraging the stable lateral pressure gradient formed by the profiles of the gap's two side walls, it actively guides and controls the leakage flow of the sealing cold gas. Under the influence of the pressure gradient, the leaking cold gas migrates orderly from the pressure side to the suction side, enhancing the wall-adhering flow characteristics within the gap, significantly improving the adiabatic temperature distribution in the gap region, and effectively suppressing the intrusion of mainstream combustion gases. Simultaneously, the controlled leakage flow and the outflow from the film cooling holes on the endwall surface create a film cooling superposition effect. On one hand, this superposition of momentum disperses the downstream vortex structure, expanding the film cooling coverage area; on the other hand, it promotes tighter adhesion of the cold gas to the suction side wall, significantly improving the uniformity and coverage efficiency of film cooling on the endwall surface, especially on the suction side. Furthermore, this structure improves cooling performance while also considering aerodynamic performance, reducing mixing losses between the traditional gap leakage flow and the mainstream flow to a certain extent. At low mass flow ratios, its aerodynamic losses are lower than those of traditional gap structures, increasing only slightly at high flow ratios, thus achieving an optimized balance between cooling efficiency and aerodynamic losses. This invention provides an effective solution for achieving efficient and uniform full-coverage cooling of the turbine endwall under real assembly conditions. Attached Figure Description

[0021] 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.

[0022] Figure 1 This is an isometric view of the turbine guide vane endwall blade-like cascade channel assembly clearance structure based on the lateral pressure gradient of the present invention;

[0023] Figure 2 yes Figure 1 An enlarged view of region A shows the assembly structure of the sealing strip;

[0024] Figure 3 This is an isometric view of the sealing sheet of the turbine guide vane endwall blade-like cascade channel assembly gap structure of the present invention;

[0025] Figure 4 This is a top view of the turbine guide vane endwall cascade-type assembly clearance structure of the present invention;

[0026] Figure 5 These are schematic diagrams of the sealed cold gas fluid domain in the simulation experiment, where (a) is a schematic diagram of the traditional assembly gap structure; and (b) is a schematic diagram of the blade-like channel assembly gap structure of the present invention.

[0027] Figure 6 This is a schematic diagram of the mainstream streamlines within the endwall blade passage under actual engine operating conditions, influenced by the lateral pressure gradient.

[0028] Figure 7 The cloud map shows the distribution of film cooling efficiency on the endwall surface of a turbine guide vane with conventional assembly gaps / the blade-like channel assembly gap of the present invention under different leakage flow mass flow ratios.

[0029] Figure 8 The distribution of SS surface film cooling efficiency and cross-sectional cloud diagram of adiabatic temperature within the gap are shown in different leakage flow mass flow ratios with conventional assembly gaps / the present invention's cascade-type assembly gap.

[0030] Figure 9 The cold gas ejection velocity distribution and streamline diagram of the leakage hole in the cascade-type assembly gap of the present invention with different leakage flow mass flow ratios;

[0031] Figure 10 The heat transfer coefficient distribution cloud map of the turbine guide vane endwall surface with conventional assembly gap / the blade-like channel type assembly gap of the present invention under different leakage flow mass flow ratios;

[0032] Figure 11 It is a cloud map of the heat transfer coefficient distribution on the endwall surface of a turbine guide vane with conventional assembly gaps / the blade-like channel type assembly gap of the present invention under no cooling air flow;

[0033] Figure 12 This is a cloud map showing the reduction in net heat flux on the endwall surface of a turbine guide vane with conventional assembly clearance / the blade-like channel assembly clearance of the present invention under different leakage flow mass flow ratios.

[0034] Figure 13 This is a cloud map showing the pressure loss coefficient distribution of the turbine guide vane endwall cascade passage section with conventional assembly clearance / the cascade passage type assembly clearance of this invention under different leakage flow mass flow ratios.

[0035] In the figure: 1-Turbine guide vane end wall; 2-Film gas hole; 3-Blade cascade type assembly clearance; 4-Turbine guide vane; 5-Sealing plate; 6-Sealing cavity wall surface; 7-Clearance PS surface; 8-Clearance SS surface; 9-Leakage hole; 10-Cold air cavity. Detailed Implementation

[0036] 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.

[0037] This invention provides a turbine guide vane endwall cascade-like assembly gap structure based on lateral pressure gradient, and proposes a solution to the problems of insufficient gas film coverage on the downstream surface of the endwall, local low cooling efficiency zone induced by traditional assembly gaps, and internal cooling of the gap that has been neglected in the past based on ideal assembly conditions.

[0038] First, refer to Figures 1 to 6 Provide a detailed description of the overall layout of the structure. For example... Figure 1 As shown, the turbine guide vane includes multiple turbine guide vanes 4 mounted on the turbine guide vane endwall 1. Multiple film cooling holes 2 are arranged on the surface of the turbine guide vane endwall 1. An assembly gap is formed between adjacent turbine guide vane endwalls 1. A special feature of this invention is that this assembly gap is designed as a blade-like channel type assembly gap 3. Figure 2 As shown, a sealing plate 5 is installed within the gap, which is mounted in the assembly groove formed by the sealing cavity wall 6, and is used to block the high-temperature combustion gas in the blade passage from entering the lower cold air cavity 10. The specific three-dimensional structure of the sealing plate 5 is shown in the figure. Figure 3 As shown, this will be described in detail later.

[0039] like Figure 4 Top view and Figure 5 As shown in the cross-sectional configuration comparison diagram, the core of this invention lies in the cross-sectional shape of the cascade-like channel assembly gap 3. This gap extends along the axial direction of the end wall (i.e., Figure 4The flow direction of the main combustion gas in the air has a completely consistent cross-sectional configuration. In the cross-section, the configuration of the gap on the pressure side (which can be called the gap PS surface 7) is similar to, and in particular identical to, the blade pressure surface profile, with its curvature gradually increasing from the bottom to the top of the gap. The configuration of the gap on the suction side (which can be called the gap SS surface 8) is similar to, and in particular identical to, the blade suction surface profile, with its curvature including an acceleration section with increasing curvature from the bottom to the top of the gap and a diffusion section with a gradual change in curvature. The two walls together form a flow channel that can generate a stable lateral pressure gradient. Figure 5 (b) clearly illustrates this flow channel shape, contrasting with the conventional rectangular cross-section clearance in (a). Axial length of typical turbine guide vane endwall 1. The axial chord length of the guide vane midsection is 80~100 mm. The gap is 68~88 mm. This gap is the width of the end wall. Designed to be 1.0~2.0 mm, depth The design diameter is 1.0~1.5 mm. The angle between the bottom edge plane of the sealed cold air vertical incident gap and the tangent direction of the flow direction of the cold air and the bottom profile of PS surface 7 is the angle of attack of the cold air. The angle of attack is designed to be within the range of 35° to 65°, preferably within the range of 40° to 60°, and more preferably within the range of 45° to 55°. Under this design angle of attack, the airflow can flow smoothly along the gap wall surface. Too large or too small an angle of attack will cause local cooling failure inside the gap or on the end wall surface.

[0040] like Figure 3 As shown, the sealing plate 5 mentioned above has multiple leakage holes 9, which are used to guide part of the sealing cooling gas into the assembly gap. The specific three-dimensional position of the sealing cavity and the sealing plate inside the gap structure changes relative to the configuration of the assembly gap, but the center of the leakage hole always remains aligned with the center of the bottom of the gap. It should be noted that the location of the leakage holes 9 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 gas in the turbine blade channel, 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 9 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 the present invention originates from the sealing cold air ejected from the leakage hole 9 in the downstream region, which constitutes a function to resist the intrusion of mainstream combustion gas, improve the internal thermal insulation temperature distribution of the gap, and achieve secondary cooling of the end wall.

[0041] Five leakage holes 9 are preferably opened downstream and arranged at equal intervals along the axial direction. The axial distance between adjacent leakage holes... And the axial distance between the leakage hole closest to the downstream outlet of the gap and the downstream edge of the end wall. All can be designed as the axial length of the end wall. 0.03 to 0.1 times. The diameter of leakage hole 9. It can be designed to be 0.7~1.0 mm. This arrangement makes the leakage hole as close as possible to the axial position of the film gas hole downstream of the end wall, which can effectively avoid the upstream mainstream pressure being too high, causing the cold air to not flow out or the mainstream to invade, and also ensure that the leaked cold air is fully utilized.

[0042] The working principle of this structure is as follows: Part of the sealing cold air from the cold air chamber 10 forces the sealing plate 5 in the sealing plate assembly slot to move towards the outer surface of the end wall, thereby fitting and sealing against the bottom edge of the gap; the other part enters the blade-like channel assembly gap 3 through the leakage hole 9. For example... Figure 5 As shown in (b), the cold air first impacts the gap PS surface 7, reducing its momentum and forming a local vortex system, thus creating a relatively uniform initial cooling coverage on this surface. Subsequently, the stable transverse pressure gradient generated by the configuration of the gap PS surface 7 and the gap SS surface 8 begins to dominate the flow. This pressure gradient exerts a continuous "purge" effect on the cold air, guiding and driving it to accelerate its migration from the pressure side wall (PS surface) to the suction side wall (SS surface). During this process, the direction of the cold air flow is actively controlled, and its streamlines gradually adhere to and develop parallel to the surface of the gap SS surface 8, forming an orderly adhering flow. This flow process is related to... Figure 6 Under the actual engine operating conditions shown, the mainstream streamline trend within the blade passage, influenced by the lateral pressure gradient, is coordinated. The cold air eventually converges with the incoming flow from the SS surface 8 side of the gap and moves towards the outlet, closely adhering to the surface of the SS surface 8. After exiting from the top of the gap, it can spread more evenly on the downstream surface of the turbine guide vane endwall 1. This controlled leakage flow exhibits a radial "curtain-like" flow pattern. On the one hand, it can superimpose with the cold air jet from the upstream pressure-side film cooling hole 2, increasing the flow momentum and dispersing complex vortex structures such as shedding vortices near the downstream of the gap. On the other hand, its radial flow characteristics change the mainstream direction near the downstream wall, making the downstream film cooling hole outflow more biased towards the suction side, which is beneficial for retaining cold air for the next stage of cooling. This achieves coupling between the leakage flow and the cold air from the endwall film cooling hole, promoting full film coverage of the downstream surface.

[0043] To verify the superiority of the above structure, a comparative analysis was conducted between numerical simulation and the assembly gap of a traditional rectangular cross-section. The structural parameters of the two constructed computational models are shown in Table 1. Using UG modeling software, cascade-like cross-sectional sketches were drawn on the leading and trailing edges of the turbine guide vane endwall, as shown below. Figure 5 As shown in (b) in the image, the grass Figure 2Dimensional configuration ensures width =1.2mm, depth =1.4mm, and selected design for air conditioning angle of attack. The study was conducted at a 50° angle. Similarly, rectangular sections of the same width and depth were drawn on the leading and trailing edge surfaces of the turbine guide vane endwalls to represent the conventional assembly clearance. Figure 5 As shown in (a) above. Finally, using commands such as sweep, merge, and subtract, a three-dimensional model of the turbine guide vane endwall with a cascade-like assembly clearance is constructed. Similarly, the sealing plate is drawn using the same method, with the leakage hole geometry and positioning selected based on the hole diameter. =0.8mm, , ,in =90mm.

[0044]

[0045] It should be noted that in numerical simulation studies of the assembly clearance of turbine guide vane endwalls, in order 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," such as... Figure 5 As shown in (a) of the paper. Therefore, in the comparative simulation, both the traditional assembly gap model and the blade-cascade channel assembly gap model of the present invention have leakage 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.

[0046] 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.

[0047]

[0048] 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 .

[0049] like Figure 7 As shown, at different leakage flow mass flow ratios ( = 0.7%, 1.4%, 2.1%), the endwall surface air film cooling efficiency of the assembly gap using a blade-like channel type is ( The air film cooling efficiency is significantly better than that of traditional structures. Calculate according to the following formula:

[0050]

[0051] 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 inlet temperature of the cold air. As can be seen from the graph, the normal momentum of the cold air in the traditional gap is too large, resulting in intense mixing with the mainstream, leading to… The value is low and follows The pressure gradient increases and decreases; however, the structure of this invention utilizes a lateral pressure gradient to deflect and adhere cold air towards the gap SS surface, forming a good air film coverage. The value has increased significantly.

[0052] Figure 8 This further demonstrates the efficiency of SS surface film cooling. The improvement in [the quality of the material] and the enhancement of the adiabatic temperature distribution within the gap. Among these improvements, the dimensionless temperature [is also considered]. The expression is as follows:

[0053]

[0054] In the formula, This indicates the wall surface temperature. The cloud map shows the adiabatic temperature inside the gaps in the structure of this invention. Significantly reduced. Calculations show that the film cooling efficiency of the cascade-like channel structure at the SS surface is significantly reduced. The maximum improvement is approximately 155.48%, fundamentally improving the cooling effect inside the gap and on the suction side wall. The leakage flow, propelled radially by the upstream cold air, spreads evenly across the downstream surface of the endwall. In the main area affected by the leakage flow, the endwall film cooling efficiency increases by a maximum of 43.2%, achieving superior full film coverage of the downstream surface. Furthermore, the radial flow of the leakage flow at a high mass flow ratio alters the flow direction of the downstream film orifice's cold air jet near the wall, bringing its film trajectory closer to the suction side. This allows for the retention of some cold air for cooling the next stage endwall surface, thus saving on the amount of cold air used for endwall cooling.

[0055] Figure 9 The dimensionless velocity of the cold gas ejection ( The distribution and streamline diagrams reveal the flow characteristics within the gap. Dimensionless velocity. Calculate according to the following formula:

[0056]

[0057] In the formula, Indicates the fluid velocity on the end wall surface. Indicates the mainstream import flow rate. This indicates the local fluid velocity. A comparison shows that the streamlines inside a traditional structure are dispersed; while the cold airflow lines inside the structure of this invention are more concentrated and approach the SS surface under the influence of the lateral pressure gradient, resulting in more orderly flow and more concentrated cold airflow lines, thus enhancing its ability to resist mainstream intrusion.

[0058] Figure 10 Showing different Below, the heat transfer coefficient of the end wall surface under cold air conditions ( )distributed. Calculate using the following formula:

[0059]

[0060] In the formula, This represents the heat flux across the endwall surface under cold air flow conditions. It can be observed that in conventional structures, strong shearing disrupts the air film in the main area affected by leakage flow, leading to localized... The temperature rises, creating an unfavorable strong heat transfer zone; however, the structure of this invention benefits from the good adhesion of the leakage flow, which reduces the heat transfer coefficient in this region to a certain extent. .

[0061] To obtain a baseline without air conditioning, Figure 11 The heat transfer coefficient of the end wall surface under no-cooling-air flow condition is shown. )distributed. The calculation is as follows:

[0062]

[0063] In the formula, This represents the heat flux across the end wall surface under conditions of no cold air flow. This figure represents the end-wall adiabatic temperature under conditions without air conditioning. It provides a benchmark for evaluating the true benefits of a cooling structure.

[0064] To comprehensively evaluate the overall thermal protection effect under real heat transfer conditions, the reduction in net heat flux was analyzed. The distribution, such as Figure 12 As shown. Calculate according to the following formula:

[0065]

[0066] As can be seen, the structure of this invention significantly improves the downstream surface of the end wall, especially the area mainly affected by leakage flow. It achieves a maximum improvement of approximately 107.75% at a high mass flow ratio, effectively compensating for the cooling deficiencies of traditional gaps in this region and demonstrating its excellent performance under real engine heat transfer conditions.

[0067] Finally, to evaluate the impact of active cooling adjustment on aerodynamic losses in cascade-type assembly clearances, a total pressure loss coefficient is introduced. To indicate different The aerodynamic loss values ​​are as follows: Figure 13 As shown. The calculation formula is as follows:

[0068]

[0069] In the formula, This is a reference value for the total pressure of film cooling. The local total pressure of the blade passage. Mainstream export static pressure, The main imported total pressure, This refers to the total pressure at the air inlet. The mainstream imported quality flow rate, This represents the mass flow rate of the cold air inlet. It can be seen that changing the gap configuration did not significantly alter the pressure loss distribution within the channel. At a small mass flow rate ratio, the structure of this invention... Even lower than traditional structures; only slightly higher at large mass flow ratios, but the resulting huge The benefits are considerable in engineering applications, demonstrating that the blade-like channel-type assembly gap cooling structure has the potential to achieve full cooling coverage of the turbine endwall.

[0070] In summary, this invention constructs a blade-like channel-like cross-sectional configuration at the assembly gap and rationally sets leakage holes, utilizing the generated lateral pressure gradient to actively regulate the flow of leakage flow. This allows the cool air to more effectively cover the suction sidewall, strengthening its resistance to the mainstream flow, and forming a synergistic effect with the cool air from the endwall film cooling holes. This improves the overall cooling efficiency of the endwall, achieves more uniform film coverage, and reduces the mixing loss between the traditional gap leakage flow and the mainstream flow to a certain extent, providing an effective solution for efficient turbine endwall cooling design based on real assembly conditions.

[0071] 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 cascade-type assembly gap structure based on a lateral pressure gradient, comprising adjacent turbine guide vane endwalls, on which turbine guide vanes are mounted, and an assembly gap is formed between two adjacent turbine guide vane endwalls, wherein a sealing plate is provided within the assembly gap to block the entry of combustion gas in the cascade channel into the cooling chamber, characterized in that: The assembly gap is a cascade-like channel assembly gap, and has a consistent cross-sectional configuration along the axial extension direction of the end wall; In the cross-sectional configuration, the assembly gap has a side wall similar to the blade pressure surface profile on the pressure side and a side wall similar to the blade suction surface profile on the suction side. The two side walls together form a flow channel that can generate a stable lateral pressure gradient. The sealing plate has a leakage hole for introducing sealing cold air into the assembly gap. The stable lateral pressure gradient can guide the introduced sealing cold air to migrate from the pressure side wall to the suction side wall and adhere to it, thereby resisting the intrusion of mainstream combustion gas, improving the insulation temperature distribution inside the gap, and achieving secondary cooling of the end wall.

2. The turbine guide vane endwall cascade-type assembly clearance structure according to claim 1, characterized in that: The curvature of the arc on the pressure side wall gradually increases from the bottom to the top of the gap; the first half of the arc on the suction side wall from the bottom to the top of the gap is an acceleration section with increasing curvature, and the second half is a diffusion section with a gradual change in curvature.

3. The turbine guide vane endwall cascade-type assembly clearance structure according to claim 1 or 2, characterized in that: The angle of attack of the sealed cold air entering the gap of the cascade-like assembly is between the direction of the cold air flow and the tangent direction of the bottom profile of its pressure side wall. The range is 35° to 65°.

4. The turbine guide vane endwall cascade-type assembly clearance structure according to claim 1 or 2, characterized in that: The width of the cascade-like channel assembly gap is 1.0~2.0 mm, and the depth is 1.0~1.5 mm.

5. The turbine guide vane endwall cascade-type assembly clearance structure according to claim 1, characterized in that: Five leakage holes are provided downstream of the sealing plate and are arranged at equal intervals along the axial direction of the sealing plate.

6. The turbine guide vane endwall cascade-type assembly clearance structure according to claim 5, characterized in that: The axial distance between the leakage hole closest to the downstream outlet of the blade-like channel assembly clearance and the downstream edge of the turbine guide vane endwall. satisfy: ,in, This is the axial length of the turbine guide vane endwall.

7. The turbine guide vane endwall cascade-type assembly clearance structure according to claim 5 or 6, characterized in that: Axial distance between two adjacent leak holes Axial length of turbine guide vane endwall satisfy: .

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

9. The turbine guide vane endwall cascade-type assembly clearance structure according to claim 1 or 2, characterized in that: axial length of the turbine guide vane endwall It is 80~100 mm.

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