Design method of gas turbine blade with tip slot and winglet composite structure

Abstract

The application discloses a design method of a gas turbine working blade with a tip slot and a winglet composite structure, which comprises the following steps: firstly, determining a preliminary design scheme of a three-dimensional blade; then, carrying out multi-state calculation and three-dimensional numerical simulation iteration operation to realize iteration optimization of two-dimensional blade type design parameters, and obtaining a benchmark design scheme; and finally, carrying out iteration optimization of the tip slot and the winglet composite structure. The tip slot and the winglet composite structure change the surface speed distribution on both sides of the rotor tip, reduce the pressure difference on both sides of the rotor tip, achieve the purpose of controlling the rotor tip leakage flow, and make the airflow form flow separation at two places of the pressure and suction surface ribs of the winglet, thereby forming two blockages to the leakage jet, and the complex flow structures such as the scraping vortex in the slot and the wall angle vortex enhance the mixing of the leakage flow in the gap, reduce the leakage jet coefficient, and reduce the mixing loss of the leakage flow and the main flow, so that the working performance of the gas turbine is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas turbine working blade design, in particular, to a gas turbine working blade design method with a tip slot and a winglet composite structure. BACKGROUND

[0002] The turbine is one of the key components of an aero turbine engine, and its performance directly affects whether the engine can operate efficiently. Inside the turbine passage, due to the radial gap between the rotor and the stationary casing, part of the flow on the pressure side of the rotor tip is driven by the tip load to form a leakage flow, which inevitably mixes with the main flow, causing tip leakage loss and mixing loss, which may account for 1 / 3 of the total loss inside the rotor passage. Tip clearance leakage flow has a great influence on the flow and loss inside the rotor passage, mainly in the following four aspects: 1) the work of the rotor tip flow is reduced, the direction of the part of the flow entering the rotor tip gap is twisted without the action of the blade, and the part of the flow produces zero rim work in the rotor passage; 2) the flow loss inside the passage increases, and the increased flow loss mainly includes the loss inside the tip clearance and the mixing loss of the leakage flow and the main flow inside the rotor passage; 3) the effective flow area inside the passage is reduced, and the generation of the leakage vortex causes a certain blockage to the main flow, so that the effective flow area is smaller than the theoretical value; 4) the aerodynamic conditions at the inlet of the downstream blade row are deteriorated, and the tip leakage flow makes the aerodynamic parameter distribution at the outlet of the rotor passage more uneven, resulting in the operation of the downstream blade row far from the design condition. Therefore, controlling the rotor tip leakage loss is of great significance to the efficient operation of the turbine component and the entire power device.

[0003] At present, the method for controlling the rotor tip leakage loss mainly adopts reducing the tip clearance (i.e. adopting a flat tip design scheme), which can directly reduce the flow area and the leakage amount of the leakage flow, and reduce the leakage loss and the mixing loss with the main flow. However, reducing the tip clearance will cause the rotor tip to rub against the stationary casing due to thermal expansion and centrifugal force, which will seriously endanger the safety of the engine. SUMMARY

[0004] The present application provides a gas turbine working blade design method with a tip slot and a winglet composite structure to solve the technical problem of large tip leakage loss of the existing gas turbine working blade.

[0005] According to one aspect of the present application, a gas turbine working blade design method with a tip slot and a winglet composite structure is provided, which includes the following contents:

[0006] Different radial heights are constructed according to the profile design of the gas turbine working blade, and the corresponding stacking law is selected according to the profile design to stack each two-dimensional profile along the radial direction to form a preliminary design scheme of a three-dimensional blade.

[0007] Carrying out multi-state calculation based on the preliminary design scheme of three-dimensional blade;

[0008] Carrying out three-dimensional numerical simulation according to the multi-state calculation result, adjusting and optimizing the design parameters of the two-dimensional blade profile according to the three-dimensional numerical simulation result, carrying out multi-state calculation based on the redesigned three-dimensional blade, and continuously iterating and optimizing until the performance of the gas turbine meets the design requirements, thereby obtaining the baseline design scheme of the gas turbine working blade;

[0009] Designing the tip slot and small wing composite structure based on the baseline design scheme of the gas turbine working blade, and carrying out multi-state calculation, comparing the multi-state calculation results of the blade design scheme with the tip slot and small wing composite structure with the multi-state calculation results of the baseline design scheme, if the improvement range of the performance of the gas turbine meets the design requirements, the design is completed, if it does not meet the design requirements, the geometric design parameters of the tip slot and the small wing are adjusted and redesigned, and the iteration is continuously carried out until the improvement range of the performance of the gas turbine meets the design requirements.

[0010] Further, when the blade profile of the gas turbine working blade is designed as a single-section straight blade or a two-section non-straight blade, a linear stacking law is selected, and when the blade profile of the gas turbine working blade is designed as a three-section non-straight blade, a parabolic stacking law is selected.

[0011] Further, the design parameters of the two-dimensional blade profile include radius, axial chord length, number of blades, leading edge small circle diameter, trailing edge small circle diameter, inlet configuration angle, outlet configuration angle, leading edge wedge angle, trailing edge wedge angle, installation angle, bending angle and effective flow angle.

[0012] Further, the process of carrying out multi-state calculation based on the preliminary design scheme of the three-dimensional blade includes the following contents:

[0013] Structuring the grid division of the two rows of working blades of the two-stage gas turbine, wherein the main flow channel grid adopts H-type topology structure, and the grid around the blade and in the internal area of the gap adopts O-type topology structure;

[0014] Selecting the k-ε model as the turbulence model for three-dimensional calculation of the two-stage gas turbine;

[0015] Processing the three-dimensional calculation results to obtain the upstream and downstream flow conditions of the multi-state gas turbine working blade and the loss distribution of the blade itself.

[0016] Further, the process of processing the three-dimensional calculation results to obtain the upstream and downstream flow conditions of the multi-state gas turbine working blade and the loss distribution of the blade itself includes the following contents:

[0017] The flow, expansion ratio, efficiency and power of each stage of turbine are calculated, and compared with the overall technical index; the inlet and outlet flow angles of each row of working blades are obtained, and the inlet attack angle loss is evaluated; the energy loss system of each row of blades is obtained and distributed along the span direction, and the area with larger loss is determined; the surface load of each row of blades at different span heights is obtained, and the loading mode is determined; and the flow field of each stage of turbine at different span heights is obtained, and the loss source in the passage is qualitatively analyzed.

[0018] Further, the geometric design parameters of the tip slot and the winglet composite structure include the shape and depth of the tip slot, the thickness of the rib, the top width / height / forward angle of the pressure side rib, and the top width / height / back sweep angle of the suction side rib.

[0019] Further, the shape of the tip slot is the same as the blade profile, the depth of the tip slot, the height of the pressure side rib, and the height of the suction side rib are 1-3 times the flat tip gap, the thickness of the rib, the top width of the pressure side rib, and the top width of the suction side rib are greater than or equal to 0.5 mm and less than the maximum thickness of the tip, and the forward angle of the pressure side rib and the back sweep angle of the suction side rib are between 30° and 60°.

[0020] Further, the design process of the tip slot includes the following contents:

[0021] The suction and pressure surface profiles of the two-dimensional blade profile are biased inward by a certain distance, and the leading edge small circle and the trailing edge small circle with a certain radius are used to cut the biased suction and pressure surface profiles, so as to determine the shape of the tip slot, and three-dimensional calculation and analysis of various slot depths are carried out according to the determined slot shape to determine the slot depth.

[0022] Further, the design process of the pressure side rib includes the following contents:

[0023] Based on the forward inclination of the pressure side rib of the tip slot, the inclined surface is a circular arc surface, and is tangent to the main body surface of the blade at the position where the inclination starts, and the distance from the tangent point to the tip is the height of the pressure side rib, so as to ensure smooth transition of the inclined blade surface and the main body surface of the blade, and the inclination angle gradually transitions to 0° near the leading edge and trailing edge of the blade.

[0024] Further, the design process of the suction side rib includes the following contents:

[0025] Based on the back sweep of the suction side rib of the tip slot, the inclined surface is a circular arc surface, and is tangent to the main body surface of the blade at the position where the inclination starts, and the distance from the tangent point to the tip is the height of the suction side rib, so as to ensure smooth transition of the inclined blade surface and the main body surface of the blade, and the inclination angle gradually transitions to 0° near the leading edge and trailing edge of the blade.

[0026] The present application has the following effects:

[0027] The gas turbine working blade design method with the tip slot and winglet composite structure of the present application firstly determines a preliminary design scheme of a three-dimensional blade, then performs an iterative operation of multi-state calculation and three-dimensional numerical simulation on the preliminary design scheme to realize iterative optimization of two-dimensional blade profile design parameters, so as to obtain a reference design scheme of the gas turbine working blade, and ensure that the efficiency, power, flow, strength, vibration, life and other performances of the gas turbine meet the basic design requirements. Finally, iterative optimization of the tip slot and winglet composite structure is performed on the basis of the reference design scheme. The tip slot and winglet composite structure changes the surface velocity distribution, i.e. load distribution, on both sides of the rotor tip, reduces the pressure difference on both sides of the rotor tip, achieves the purpose of controlling the rotor tip leakage flow, and makes the airflow form flow separation at both the pressure surface rib and the suction surface rib of the winglet, thereby blocking the leakage jet twice, and the complex flow structures such as the groove internal scraping vortex and wall angle vortex enhance the mixing of the leakage flow inside the gap, reduce the leakage jet coefficient, and reduce the mixing loss of the leakage flow and the main flow, thereby greatly improving the working performance of the gas turbine.

[0028] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, illustrate preferred embodiments of the present application, and assist in the explanation of the present application. In the drawings:

[0030] Figure 1 is a flowchart of the gas turbine working blade design method with the tip slot and winglet composite structure of the preferred embodiment of the present application.

[0031] Figure 2 is a schematic diagram of the angle and size definition of the two-dimensional blade profile in the preferred embodiment of the present application.

[0032] Figure 3 is Figure 1 is a sub-flowchart of step S2 in

[0033] Figure 4 is a schematic diagram of the calculation domain for three-dimensional calculation of the gas turbine in the preferred embodiment of the present application.

[0034] Figure 5 is a schematic diagram of the cross section of the blade with the tip slot structure in the preferred embodiment of the present application.

[0035] Figure 6 is a schematic diagram of the cross section of the blade with the tip slot and winglet composite structure in the preferred embodiment of the present application.

[0036] Figure 7 is a schematic diagram of the geometric control parameters of the tip slot design in the preferred embodiment of the present application.

[0037] Figure 8 is a schematic diagram of the radial distribution of the energy loss coefficient calculated by the reference design scheme, the tip slot design scheme and the compound structure of the tip slot and the winglet of the first stage blade in the preferred embodiment of the present application.

[0038] Figure 9 is a schematic diagram of the radial distribution of the energy loss coefficient calculated by the reference design scheme, the tip slot design scheme and the compound structure of the tip slot and the winglet of the second stage blade in the preferred embodiment of the present application.

[0039] Figure 10 is a schematic diagram of the axial distribution of the blade surface Mach number at 97.5% blade height calculated by the reference design scheme, the tip slot design scheme and the compound structure of the tip slot and the winglet of the first stage blade in the preferred embodiment of the present application.

[0040] Figure 11 is a schematic diagram of the axial distribution of the blade surface Mach number at 97.5% blade height calculated by the reference design scheme, the tip slot design scheme and the compound structure of the tip slot and the winglet of the second stage blade in the preferred embodiment of the present application.

[0041] Figure 12 (a) in is a schematic diagram of the Mach number distribution at 50% streamwise section of the first stage blade with the compound structure of the tip slot and the winglet in the preferred embodiment of the present application.

[0042] Figure 12 (b) in is a schematic diagram of the Mach number distribution at 50% streamwise section of the second stage blade with the compound structure of the tip slot and the winglet in the preferred embodiment of the present application.

[0043] Figure 12 (c) in is a schematic diagram of the velocity vector distribution at 50% streamwise section of the first stage blade with the compound structure of the tip slot and the winglet in the preferred embodiment of the present application.

[0044] Figure 12 (d) in is a schematic diagram of the velocity vector distribution at 50% streamwise section of the second stage blade with the compound structure of the tip slot and the winglet in the preferred embodiment of the present application.

[0045] Figure 13 (a) in is a schematic diagram of the tip end area flow loss of the first stage blade with the compound structure of the tip slot and the winglet in the preferred embodiment of the present application.

[0046] Figure 13(b) is a schematic diagram of the tip region loss of the secondary working blade with the blade tip groove and winglet composite structure in the preferred embodiment of the present invention.

[0047] Figure 14 This is a schematic diagram comparing the turbine stage efficiency of a single-stage turbine working blade with different tip groove depth designs and with a flat tip design in a preferred embodiment of the present invention.

[0048] Figure 15 This is a schematic diagram comparing the total leakage at the clearance outlet of a single-stage turbine working blade with different blade tip groove depth designs and with a flat blade tip design in a preferred embodiment of the present invention.

[0049] Figure 16 This is a schematic diagram comparing the turbine stage efficiency of a single-stage turbine working blade with a composite design of grooves and ribs with different pressure surface inclination angles in a preferred embodiment of the present invention, compared with that of a flat blade tip and a conventional grooved blade tip.

[0050] Figure 17 This is a schematic diagram comparing the total leakage at the clearance outlet of a single-stage turbine working blade with a composite design of grooves and ribs with different pressure surface inclination angles in a preferred embodiment of the present invention, and with flat blade tips and ordinary grooved blade tips.

[0051] Figure 18 This is a schematic diagram comparing the turbine stage efficiency of a single-stage turbine working blade with a composite design of groove + pressure surface rib forward inclination + different suction surface rib sweep angles in a preferred embodiment of the present invention, and a composite design of flat blade tip and groove + pressure surface rib forward inclination + suction surface rib not swept back.

[0052] Figure 19 This is a schematic diagram comparing the total leakage at the clearance outlet of a single-stage turbine working blade in a preferred embodiment of the present invention, which uses a composite design of groove + pressure surface rib forward inclination + different suction surface rib sweep angles, with a flat blade tip and a composite design of groove + pressure surface rib forward inclination + suction surface rib not sweeping. Detailed Implementation

[0053] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0054] like Figure 1 As shown, a preferred embodiment of the present invention provides a design method for a gas turbine blade with a composite structure of blade tip groove and airfoil, comprising the following:

[0055] Step S1: Construct two-dimensional blade profiles at different radial heights based on the blade profile design of the gas turbine working blades, and select the corresponding stacking rule according to the blade profile design to stack each two-dimensional blade profile radially to form a preliminary design scheme for three-dimensional blades.

[0056] Step S2: multi-state calculation based on the preliminary design of three-dimensional blades;

[0057] Step S3: three-dimensional numerical simulation according to the multi-state calculation results, optimization and adjustment of the design parameters of the two-dimensional blade profile, multi-state calculation based on the redesigned three-dimensional blades, continuous iteration and optimization until the gas turbine performance meets the design requirements, and the baseline design of the gas turbine working blade is obtained;

[0058] Step S4: design of the tip slot and small wing composite structure based on the baseline design of the gas turbine working blade, and carry out multi-state calculation, compare the multi-state calculation results of the blade design scheme with tip slot and small wing composite structure with the multi-state calculation results of the baseline design scheme, if the improvement range of the gas turbine performance meets the design requirements, the design is completed, if it does not meet the design requirements, the geometric design parameters of the tip slot and the small wing are adjusted, and the iteration is continuously carried out until the improvement range of the gas turbine performance meets the design requirements.

[0059] It can be understood that the gas turbine working blade design method with tip slot and winglet composite structure of the embodiment first constructs two-dimensional blade profiles at different radial heights according to the blade profile design of the gas turbine working blade, and stacks each two-dimensional blade profile along the radial direction to form a preliminary design scheme of a three-dimensional blade according to the corresponding stacking law selected according to the blade profile design. Then, multi-state calculation is carried out based on the preliminary design scheme of the three-dimensional blade to obtain the upstream and downstream flow conditions of the multi-state gas turbine working blade and the loss distribution of the multi-state gas turbine working blade itself, and three-dimensional numerical simulation is carried out according to the obtained upstream and downstream flow conditions of the multi-state gas turbine working blade and the loss distribution of the multi-state gas turbine working blade itself, the design parameters of the two-dimensional blade profile are optimized and adjusted according to the three-dimensional numerical simulation result, and multi-state calculation is carried out based on the redesigned three-dimensional blade, and the optimization is iterated until the gas turbine performance meets the design requirements, and the baseline design scheme of the gas turbine working blade is obtained. Finally, the design of the tip slot and the winglet composite structure is carried out on the basis of the baseline design scheme of the gas turbine working blade, and multi-state calculation is carried out, and the multi-state calculation results of the blade design scheme with the tip slot and the winglet composite structure are compared with the multi-state calculation results of the baseline design scheme. If the improvement range of the gas turbine performance meets the design requirements, the design is completed, if the design requirements are not met, the geometric design parameters of the tip slot and the winglet are re-adjusted, and the iteration is continuously carried out until the improvement range of the gas turbine performance meets the design requirements. The gas turbine working blade design method with tip slot and winglet composite structure of the present application first determines the preliminary design scheme of the three-dimensional blade, and then carries out the iterative operation of multi-state calculation and three-dimensional numerical simulation on the preliminary design scheme to realize the iterative optimization of the two-dimensional blade profile design parameters, so as to obtain the baseline design scheme of the gas turbine working blade, and ensure that the efficiency, power, flow, strength, vibration, life and other performances of the gas turbine meet the basic design requirements. Finally, the tip slot and the winglet composite structure are iteratively optimized on the basis of the baseline design scheme. The tip slot and the winglet composite structure change the surface velocity distribution, i.e. the load distribution, on both sides of the rotor tip, reduce the pressure difference on both sides of the rotor tip, achieve the purpose of controlling the rotor tip leakage flow, and make the flow separation occur at the pressure surface rib and the suction surface rib of the winglet at the same time, block the leakage jet twice, and enhance the mixing of the leakage flow inside the gap by scraping the complex flow structures such as the internal groove vortex and the wall angle vortex, reduce the leakage coefficient of the gap jet, and reduce the mixing loss of the leakage flow and the main flow, thereby greatly improving the working performance of the gas turbine.

[0060] It is understood that in step S1, based on the gas turbine design requirements, two-dimensional airfoils at different radial heights are constructed using the 11-parameter method, and these two-dimensional airfoils are then stacked radially according to a certain stacking rule to form a preliminary design scheme for a three-dimensional blade. The 11-parameter method is a two-dimensional airfoil design method proposed in 1985 by L.P. Ritchard, a senior aerodynamic engineer at Williams Company in the United States. It uses 11 independent parameters for the construction design of two-dimensional airfoils. This invention improves the tangential chord length in the 11-parameter method to the installation angle and the throat top width to the effective airflow angle. Specifically, as shown... Figure 2 As shown, the design parameters of the two-dimensional airfoil in this invention include radius R and axial chord length b. x Number of blades z, diameter of leading edge minor circle r1, diameter of trailing edge minor circle r2, inlet construction angle β 1k Exit structural angle β 2k Leading edge wedge angle ω1, trailing edge wedge angle ω2, mounting angle γ, bending angle δ, and effective airflow angle β eff There are a total of 12 independent parameters, among which, throat width a = blade pitch t * effective airflow angle β eff It is understandable that by using the installation angle instead of the tangential chord length and the effective airflow angle instead of the throat top width as two-dimensional airfoil design parameters, the flow rate and expansion ratio of each stage of the turbine can be quickly adjusted, which is beneficial for the rapid and accurate iterative optimization of subsequent two-dimensional airfoil design parameters.

[0061] Furthermore, the stacking rules adopted vary depending on the blade profile design of the gas turbine blades. Specifically, when the blade profile of the gas turbine blade is a single-section straight blade or a two-section non-straight blade, a linear stacking rule is selected, while when the blade profile of the gas turbine blade is a three-section non-straight blade, a parabolic stacking rule is selected.

[0062] Understandable, such as Figure 3 As shown, step S2 specifically includes the following:

[0063] Step S21: Perform structured mesh generation on the two rows of working blades of the two-stage gas turbine. The mainstream channel mesh adopts an H-type topology, while the mesh around the blades and inside the gap adopts an O-type topology.

[0064] Step S22: Select the k-ε model as the turbulence model to perform three-dimensional calculations on the two-stage gas turbine;

[0065] Step S23: Process the three-dimensional calculation results to obtain the upstream and downstream flow conditions and the distribution of their own losses of the multi-state gas turbine working blades.

[0066] Specifically, Autogrid5 is used to perform structured meshing on the two rows of working blades, the main flow channel mesh adopts H-type topology structure, the mesh around the blade and in the internal region of the gap adopts O-type topology structure, and the O-type topology is more conducive to the display of detailed features. Then, ANSYS / CFX 17.2 is used to perform three-dimensional calculation and analysis on the two-stage gas turbine, the k-ε model is selected as the turbulence model, a single-channel model is used, the total temperature (radial distribution), total pressure (uniform at the inlet) and airflow angle (perpendicular to the inlet) are given as the inlet boundary conditions, the average static pressure is given as the outlet boundary condition, the periodic boundary condition is used on the circumferential sides of the stator and rotor channels, the mixing surface method is used for data transmission between the interfaces between the stator and the rotor, all solid walls are set as adiabatic no-slip, and the wall roughness is set as 0.02 mm. In addition, the cold gas is added in the form of a point source, and the cold source positions on the blade surface are accurately obtained by Autogrid5 in the form of a cold gas hole on the blade surface, for example, the cold source positions at the blade tip of the first-stage rotor are distributed on the mid-chord line of the blade tip, which is accurately given in UG, as shown in FIG. 8. Figure 4 Finally, the three-dimensional calculation results are processed, specifically including: calculating the flow rate, expansion ratio, efficiency and power of each stage of the turbine, and comparing them with the overall technical indicators; obtaining the inlet and outlet airflow angles of each row of working blades to evaluate the inlet attack angle loss; obtaining the energy loss system of each row of blades and distributing it along the spanwise direction to determine the region with greater loss; obtaining the surface load at different spanwise heights of each row of blades to determine the loading mode; obtaining the flow field at different spanwise heights of each stage of the turbine to qualitatively analyze the loss sources in the channel; thereby obtaining the upstream and downstream flow conditions of the multi-state gas turbine working blade and the loss distribution of the blade itself.

[0067] It can be understood that the flow rate, expansion ratio, efficiency and power of each stage of the turbine obtained after the three-dimensional calculation in the step S2 usually cannot meet the overall technical indicators, and therefore the preliminary design scheme of the three-dimensional blade needs to be optimized and adjusted. Therefore, in the step S3, three-dimensional numerical simulation is performed according to the upstream and downstream flow conditions of the multi-state gas turbine working blade and the loss distribution of the blade itself, to analyze the turbine performance parameters and the flow field detail distribution, and the design parameters of the two-dimensional blade profile are optimized and adjusted according to the three-dimensional numerical simulation results, and the multi-state calculation is performed again based on the redesigned three-dimensional blade, to check whether the efficiency, power, flow rate, strength, vibration, service life and other performances of the gas turbine can meet the basic design requirements, and the iteration and optimization are continuously performed until the performance of the gas turbine meets the basic design requirements, thereby obtaining the baseline design scheme of the gas turbine working blade.

[0068] It can be understood that in the step S4, the tip groove and the winglet composite structure are designed on the basis of the reference design scheme of the gas turbine working blade, and multi-state calculation is carried out, and the multi-state calculation process is the same as that in step S2, which will not be repeated here. In order to avoid numerical differences caused by different grid division methods, the tip groove and the winglet composite structure adopt the same topology structure as the flat tip when the grid is divided, that is, the O-type topology structure is adopted. Then, the multi-state calculation results of the blade design scheme with the tip groove and the winglet composite structure are compared with the multi-state calculation results of the reference design scheme. If the improvement range of the gas turbine performance meets the design requirements, for example, the gas turbine efficiency, power and blade loss of the blade design scheme with the tip groove and the winglet composite structure are improved compared with the reference design scheme, and the blade strength, vibration and service life meet the design requirements, then the blade design is completed. If the design requirements are not met, the geometric design parameters of the tip groove and the winglet are adjusted, and the iteration is continuously carried out until the improvement range of the gas turbine performance meets the design requirements. When adjusting the geometric design parameters of the tip groove and the winglet, the adjustment and optimization are mainly carried out according to the efficiency change of each stage of turbine, the tip leakage of two rows of working blades and the flow field distribution in the tip groove.

[0069] Optionally, the geometric design parameters of the tip groove and the winglet composite structure include the shape and depth of the tip groove, the rib thickness, the top width / height / forward angle of the pressure surface rib, and the top width / height / back sweep angle of the suction surface rib. As preferred, the shape of the tip groove is the same as the blade profile, the depth of the tip groove, the height of the pressure surface rib and the height of the suction surface rib are 1-3 times of the flat tip gap, the rib thickness, the top width of the pressure surface rib and the top width of the suction surface rib are greater than or equal to 0.5 mm and less than the maximum thickness of the tip, and the forward angle of the pressure surface rib and the back sweep angle of the suction surface rib are between 30° and 60°. Among them, the top width of the pressure surface rib and the top width of the suction surface rib are generally the same as the rib thickness.

[0070] It can be understood that, as shown in Figure 5 and Figure 6 , the design process of the tip groove and the winglet composite structure includes the following steps:

[0071] 1) Determine the shape and depth h of the tip groove: on the basis of the flat tip, select a certain spanwise height of the tip end area to be recessed downward as the depth h of the tip groove;

[0072] 2) Determine the rib thickness t, the pressure surface rib top width t1, and the suction surface rib top width t2: comprehensively consider the strength, life, vibration, thermal load, and machining of the gas turbine working blade, and determine the thickness of the rib thickness t, the pressure surface rib top width t1, and the suction surface rib top width t2 to be greater than or equal to 0.5 mm and less than the maximum thickness of the blade tip;

[0073] 3) Determine the rake angle a of the pressure surface rib and the rib height h1.

[0074] 4) Determine the back rake angle β of the suction surface rib and the rib height h2.

[0075] The design process of the blade tip groove includes the following contents:

[0076] The suction and pressure surface profiles of the two-dimensional blade profile are offset inward by a certain distance, and the suction and pressure surface profiles after offset are intercepted by a leading edge small circle and a trailing edge small circle with a certain radius, so as to determine the shape of the blade tip groove. According to the determined groove shape, three-dimensional calculation and analysis of various groove depths are carried out to determine the groove depth.

[0077] For example, as shown in Figure 7 The suction and pressure surface profiles of the two-dimensional blade profile are offset inward by 0.5 mm, and the suction and pressure surface profiles after offset are intercepted by a leading edge small circle with a radius of 0.5 mm and a trailing edge small circle with a radius of 0.225 mm, so that the groove shape is the same as the blade profile, wherein the distance A between the center of the groove leading edge and the leading edge of the blade profile is equal to 3.3% of the chord length, the distance C between the center of the groove trailing edge and the trailing edge of the blade profile is equal to 13% of the chord length, the diameter B of the groove leading edge is equal to 42% of the maximum thickness of the blade, and the diameter D of the groove trailing edge is equal to 33% of the maximum thickness of the blade. It can be understood that the diameters of the leading edge small circle and the trailing edge small circle used for interception can also be selected as other sizes. Then, according to the determined groove shape, three-dimensional calculation and analysis of various groove depths are carried out, and the specific three-dimensional calculation and analysis process is the same as step S2, which will not be described here. According to the three-dimensional calculation results obtained by processing, the depth h of the blade tip groove is determined, wherein the depth of the blade tip groove is 1-3 times the flat tip gap.

[0078] It can be understood that the blade tip groove design method of the present application can design the corresponding blade tip groove according to the blade profile of the gas turbine working blade. The blade tip groove can be designed according to the blade profile design. The airflow in the blade tip groove will form a complex vortex system, so as to effectively limit the effective flow area of the leakage flow and achieve the purpose of controlling the blade tip leakage flow.

[0079] It can be understood that the design process of the pressure surface rib includes the following contents:

[0080] The pressure surface side of the tip slot is inclined by an angle a, the inclined surface is a circular arc surface, and the tangent point of the inclined surface to the main body surface is at the position where the inclined surface starts, and the distance from the tangent point to the tip is the height h1 of the pressure surface rib, so as to ensure smooth transition of the inclined blade surface to the main body surface, and the inclined angle gradually transitions to 0° near the leading edge and trailing edge of the blade.

[0081] In addition, the design process of the suction surface rib includes the following contents:

[0082] The suction surface side of the tip slot is inclined by an angle β, the inclined surface is a circular arc surface, and the tangent point of the inclined surface to the main body surface is at the position where the inclined surface starts, and the distance from the tangent point to the tip is the height h2 of the suction surface rib, so as to ensure smooth transition of the inclined blade surface to the main body surface, and the inclined angle gradually transitions to 0° near the leading edge and trailing edge of the blade.

[0083] It can be understood that due to the forward inclination of the pressure surface rib and the backward inclination of the suction surface rib, the leakage flow enters the slot at a larger angle, increases the top separation of the suction surface rib and the pressure surface rib, forms two blockages of the leakage jet, increases the top width of the tip slot, makes the flow structure in the tip slot more complex, and increases the transverse size and flow direction range of the complex vortex system in the slot, further reduces the effective flow area of the leakage flow. In addition, the tip slot alone can also reduce the effective flow area of the leakage flow through the complex vortex system in the slot, thereby achieving the purpose of controlling the tip leakage flow, but the suction pressure decreases near the 60% axial position, and the local load increases, which seriously affects the efficiency of the gas turbine. The composite structure design of the tip slot + winglet in the present application not only has the advantages of the tip slot alone, but also the winglet and the tip slot can work together. The existence of the winglet not only forms two flow separations of the suction surface rib and the pressure surface rib, and two blockages of the leakage jet, but also increases the top width of the tip slot, makes the flow structure in the tip slot more complex, increases the transverse size and flow direction range of the complex vortex system in the slot, further reduces the effective flow area of the leakage flow, and increases the suction pressure near the 60% axial position, reduces the local load, and greatly improves the efficiency of the gas turbine.

[0084] It can be understood that the present application also applies the gas turbine working blade design method with the tip slot and winglet composite structure to complete the design of the first stage working blade and the second stage working blade of the gas turbine, and carries out comparative calculation and analysis with the first stage working blade and the second stage working blade designed by using the benchmark design scheme. The design parameters of the first stage working blade of the gas turbine are as follows: the slot depth h = 0.45 mm (1.5 times the flat tip tip clearance), the pressure surface rib forward angle α = 45°, the suction surface rib backward angle β = 45°, and the pressure and suction surface rib height h1 = h2 = 0.75 mm (2.5 times the flat tip tip clearance). The design parameters of the second stage working blade of the gas turbine are as follows: the slot depth h = 0.8 mm (2 times the flat tip tip clearance), the pressure surface rib forward angle α = 45°, the suction surface rib backward angle β = 45°, and the pressure and suction surface rib height h1 = h2 = 1 mm (2.5 times the flat tip tip clearance). The rib thickness and the top width of the pressure and suction surfaces are t = t1 = t2 = 0.5 mm, and the specific design parameters are shown in Table 1.

[0085] Table 1, Parameter design table of the two-stage working blades of the gas turbine with the tip slot and winglet composite structure

[0086] Parameter Parameter Applicable Range Primary Working Blade Secondary Working Blade Groove Depth h 1.0 ~ 3.0 times flat tip gap 0.45 mm 0.8 mm Rib Thickness t ≥ 0.5 mm, < maximum thickness of tip 0.5 mm 0.5 mm Pressure Surface Rib Inclination Angle α 30° ~ 60° 45o 45o Pressure Surface Rib Height h1 1.0 ~ 3.0 times flat tip gap 0.75 mm 1 mm Pressure Surface Rib Width t1 ≥ 0.5 mm, < maximum thickness of tip 0.5 mm 0.5 mm Suction Surface Rib Inclination Angle β 30° ~ 60° 45o 45o Suction Surface Rib Height h2 1.0 ~ 3.0 times flat tip gap 0.75 mm 1 mm Suction Surface Rib Width t2 ≥ 0.5 mm, < maximum thickness of tip 0.5 mm 0.5 mm

[0087] The calculation results show that, compared with the flat tip of the benchmark design scheme, the first stage efficiency of the gas turbine is increased by 0.8 pt, the second stage efficiency is increased by 0.3 pt, and the total efficiency is increased by 0.6 pt by using the tip slot + winglet composite structure of the present application. As shown in Figure 8 and Figure 9 It can be seen that, compared with the flat tip design of the benchmark design scheme, the energy loss coefficient is significantly reduced at 40% and 50% blade height by using the tip slot and winglet composite structure design of the first stage working blade and the second stage working blade. The reason for the reduction of the energy loss coefficient is that the tip slot and winglet composite structure changes the surface velocity distribution, i.e. the load distribution, on both sides of the rotor tip, reduces the pressure difference on both sides of the rotor tip, and achieves the purpose of controlling the rotor tip leakage flow, as shown in Figure 10 and Figure 11 At the same time, the tip slot + winglet composite structure causes the flow to form flow separation at the pressure surface rib and the suction surface rib at the same time, forms two blockages to the leakage jet, and enhances the mixing of the leakage flow inside the gap by scraping the complex flow structures such as the internal gap vortex and the wall corner vortex, thereby reducing the coefficient of the gap jet and the mixing loss of the leakage flow and the main flow, as shown in Figure 12 and Figure 13 . Among them, Figure 8 , Figure 9 , Figure 10 , Figure 11The curve ori in the figure represents a reference design scheme, and the curve cav represents a design scheme of the tip slot + winglet composite structure of the application.

[0088] In addition, taking a single-stage turbine working blade as an example, four tip slots with groove depths of h = 1.0τ, 1.5τ, 2.0τ and 2.5τ (τ is the clearance height of the flat tip) are designed, and the aerodynamic performance is compared and analyzed with the flat tip, as shown in Figure 14 and Figure 15 It can be seen that, compared with the flat tip, with the increase of the groove depth, the total leakage at the clearance outlet is continuously reduced, thereby reducing the tip leakage loss of the moving blade and increasing the turbine stage efficiency, and it can be seen that, with the increase of the groove depth, the trend of the increase of the total leakage at the clearance outlet and the turbine stage efficiency gradually flattens out. Among them, Figure 14 and Figure 15 ori in the figure represents a flat tip design scheme (i.e. the reference design scheme of the application), case1, case2, case3 and case4 represent tip slot design schemes with groove depths of 1.0τ, 1.5τ, 2.0τ and 2.5τ, respectively.

[0089] In addition, on the basis of the groove depth of 2.0τ, three tip slots of the groove + winglet with the pressure surface rib forward inclination angle α = 30°, 40° and 45° are designed, and the aerodynamic performance is compared and analyzed with the flat tip and the ordinary tip slot, as shown in Figure 16 and Figure 17 It can be seen that, compared with the ordinary tip slot, the tip slot + winglet with the pressure surface rib forward inclination significantly enhances the control effect on the leakage flow, reduces the total leakage at the clearance outlet, and significantly increases the turbine stage efficiency, and it can be seen that, with the increase of the pressure surface rib forward inclination angle, the trend of the increase of the total leakage at the clearance outlet and the turbine stage efficiency gradually flattens out. Among them, Figure 16 and Figure 17 ori in the figure represents a flat tip design scheme (i.e. the reference design scheme of the application), base represents an ordinary tip slot design scheme, and case1, case2 and case3 represent tip slot design schemes with the pressure surface rib forward inclination angle of 30°, 40° and 45° on the basis of the groove depth of 2.0τ.

[0090] Further, on the basis of the groove depth of 2.0τ and the pressure surface rib forward inclination angle of 45°, three tip slots of the groove + winglet with the suction surface rib backward inclination angle β = 30°, 40° and 45° are designed, and the aerodynamic performance is compared and analyzed with the flat tip and the tip slot + winglet with the pressure surface rib forward inclination, as shown in Figure 18 and Figure 19It can be seen that compared with the concave+small wing tip with no suction surface rib aft-sweep, the concave+small wing tip with suction surface rib aft-sweep significantly enhances the control effect on the leakage flow, reduces the total leakage at the gap outlet, and makes the turbine stage efficiency increase significantly, and it can be seen that with the increase of the suction surface rib aft-sweep angle, the total leakage at the gap outlet first decreases and then increases, and the trend of turbine stage efficiency increase gradually flattens. Among them, Figure 18 and Figure 19 The ori in the above formula represents the flat tip design scheme (i.e. the reference design scheme of the present application), case1 represents the concave+small wing tip design scheme with pressure surface rib forward sweep, and case2, case3, case4 respectively represent the tip design schemes with the concave depth of 2.0τ and the pressure surface rib forward sweep angle of 45°, and the suction surface rib aft-sweep angle β=30°, 40°, 45°.

[0091] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of designing a gas turbine working blade with a tip slot and a winglet composite structure, characterized in that, The method comprises the following steps: Different radial heights are configured according to the profile design of the gas turbine working blade, and the corresponding stacking rules are selected according to the profile design to stack the two-dimensional profiles along the radial direction to form a preliminary design scheme of the three-dimensional blade; Multi-state calculation is carried out based on the preliminary design scheme of the three-dimensional blade; According to the multi-state calculation results, three-dimensional numerical simulation is carried out, the design parameters of the two-dimensional profile are optimized and adjusted according to the three-dimensional numerical simulation results, and multi-state calculation is carried out based on the redesigned three-dimensional blade, which is iteratively optimized until the performance of the gas turbine meets the design requirements, and a reference design scheme of the gas turbine working blade is obtained; On the basis of the reference design scheme of the gas turbine working blade, the design of the tip slot and the small wing composite structure is carried out, and multi-state calculation is carried out, and the multi-state calculation results of the blade design scheme with the tip slot and the small wing composite structure are compared with the multi-state calculation results of the reference design scheme, if the improvement range of the performance of the gas turbine meets the design requirements, the design is completed, if it does not meet the design requirements, the geometric design parameters of the tip slot and the small wing are adjusted, and the iteration is carried out until the improvement range of the performance of the gas turbine meets the design requirements.

2. The gas turbine working blade design method with a tip slot and a winglet composite structure as set forth in claim 1, characterized by, When the profile design of the gas turbine working blade is a single-section straight blade or a two-section non-straight blade, a linear stacking rule is selected, and when the profile design of the gas turbine working blade is a three-section non-straight blade, a parabolic stacking rule is selected.

3. The gas turbine working blade design method with a tip slot and a winglet composite structure of claim 1, wherein, The design parameters of the two-dimensional profile include radius, axial chord length, number of blades, leading edge small circle diameter, trailing edge small circle diameter, inlet configuration angle, outlet configuration angle, leading edge wedge angle, trailing edge wedge angle, installation angle, bending angle and effective airflow angle.

4. The gas turbine working blade design method with a tip slot and a winglet composite structure of claim 1, wherein, The process of carrying out multi-state calculation based on the preliminary design scheme of the three-dimensional blade comprises the following steps: The two rows of working blades of the two-stage gas turbine are structurally meshed, wherein the main flow channel mesh adopts H-type topology structure, and the mesh around the blade and in the internal area of the gap adopts O-type topology structure; The k-ε model is selected as the turbulence model for three-dimensional calculation of the two-stage gas turbine; The three-dimensional calculation results are processed to obtain the upstream and downstream flow conditions of the multi-state gas turbine working blade and its own loss distribution.

5. The gas turbine working blade design method with a tip slot and a winglet composite structure as claimed in claim 4, characterized by, The process of processing the three-dimensional calculation results to obtain the upstream and downstream flow conditions of the multi-state gas turbine working blade and its own loss distribution comprises the following steps: The flow rate, expansion ratio, efficiency and power of each stage of turbine are calculated and compared with the overall technical index; the inlet and outlet airflow angles of each row of working blades are obtained to evaluate the inlet attack angle loss; the energy loss coefficient of each row of blades is obtained and distributed along the span to determine the area with larger loss; the surface load of each row of blades at different span heights is obtained to determine the loading mode; and the flow field at different span heights of each stage of turbine is obtained to qualitatively analyze the loss source in the channel.

6. The gas turbine blade design method with a tip slot and a winglet composite structure of claim 1, wherein, The geometric design parameters of the tip slot and the small wing composite structure include the shape and depth of the tip slot, the thickness of the rib, the top width, height and forward angle of the pressure surface rib, and the top width, height and backward angle of the suction surface rib.

7. The gas turbine working blade design method with a tip slot and a winglet composite structure of claim 6, wherein, The shape of the tip groove is the same as the blade profile, the depth of the tip groove, the height of the pressure surface rib, and the height of the suction surface rib are 1-3 times the flat tip gap, the rib thickness, the top width of the pressure surface rib, and the top width of the suction surface rib are greater than or equal to 0.5 mm and less than the maximum thickness of the tip, and the forward angle of the pressure surface rib and the backward angle of the suction surface rib are between 30° and 60°.

8. The gas turbine working blade design method with a tip slot and a winglet composite structure of claim 6, wherein, The design process of the tip groove includes the following contents: The suction and pressure surface profiles of the two-dimensional blade profile are biased inward by a preset distance, and the leading edge small circle and the trailing edge small circle with a preset radius are used to cut the biased suction and pressure surface profiles, so as to determine the shape of the tip groove, and three-dimensional calculation and analysis of various groove depths are carried out according to the determined groove shape to determine the groove depth.

9. The gas turbine working blade design method with a tip slot and a winglet composite structure of claim 8, wherein, The design process of the pressure surface rib includes the following contents: Based on the forward inclination of the blade pressure surface side of the tip groove, the inclined surface is a circular arc surface, and is tangent to the blade main surface at the position where the inclination starts, and the distance from the tangent point to the tip is the height of the pressure surface rib, so as to ensure smooth transition of the inclined blade surface and the blade main surface, and the inclination angle gradually transitions to 0° near the leading and trailing edges of the blade.

10. The gas turbine working blade design method with a tip slot and a winglet composite structure of claim 8, wherein, The design process of the suction surface rib includes the following contents: Based on the backward inclination of the blade suction surface side of the tip groove, the inclined surface is a circular arc surface, and is tangent to the blade main surface at the position where the inclination starts, and the distance from the tangent point to the tip is the height of the suction surface rib, so as to ensure smooth transition of the inclined blade surface and the blade main surface, and the inclination angle gradually transitions to 0° near the leading and trailing edges of the blade.

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