A method for designing a blade end wall fusion with a circumferentially monotonic end wall

Abstract

The present application relates to a kind of end wall circumferential monotone blade end wall fusion design method, belong to aero-engine design field.First according to maximum fusion thickness, position and front trailing edge fusion scale determine blade fusion shape, then according to the flow characteristics of transverse secondary flow determine end wall monotone slope angle and position, finally according to the constraint of each axial position passage area invariable, determine end wall and blade geometry, realize end wall circumferential monotone blade end wall fusion design.This method strengthens the control ability of the angle area dihedral angle distribution formed by end wall and blade, can control the fusion shape of suction surface and leading edge, trailing edge simultaneously, root blade element section and end wall are included in aerodynamic design space, ensure that the passage area of each axial section is invariable, avoid the mass flow variation caused by metal blockage area change and working condition deviation, more have engineering application value.End wall modeling uses circumferential monotone curve structure, while controlling transverse secondary flow, ensure good working condition adaptability.

Description

A blade endwall fusion design method with monotonic endwall circumference Technical Field

[0001] This invention relates to a blade endwall fusion design method with monotonous endwall circumference, and more particularly to a blade endwall fusion design method applicable to rotating components of turbomachinery, characterized by monotonous endwall circumference, belonging to the field of aero-engine design technology. Background Technology

[0002] The aerodynamic design of an aircraft engine has a significant impact on its performance. Among them, the aerodynamic design challenges of core components such as the compressor and turbine are mainly concentrated in the end region. Numerous studies have shown that aerodynamic losses in the end region can account for more than 30% of the total aerodynamic losses of the compressor.

[0003] Currently, various passive control technologies have emerged to address the complex flow problems in the end region caused by lateral pressure differentials and axial adverse pressure gradients within the blade passage. Among them, the sidewall-blade fusion technology, aimed at solving boundary layer convergence problems, can increase the dihedral angle by altering the root element cross-section and improve separation in the three-dimensional corner region. However, the sidewall-blade fusion technology still has its limitations:

[0004] (1) The influence of dihedral angle distribution on boundary layer intersection should be given special attention, but the sidewall blade fusion shaping method only adjusts the basic section and does not consider the design space for the hub face to control the dihedral angle.

[0005] (2) The original sidewall blade integration lacks the ability to control the lateral secondary flow, but directly combining it with non-axisymmetric endwall technology can easily cause problems such as inconsistent parameter space and poor adaptability to operating conditions, making it impossible to fully control corner separation.

[0006] (3) The extension of the blades in the sidewall blade fusion shape will inevitably lead to an increase in the local metal blockage area, which in turn will cause the risk of flow change and operating condition deviation. Compensating for the metal blockage area by directly pressing down the end wall will cause certain damage to the geometric continuity of the entire end wall.

[0007] Therefore, for complex flows in the fan / compressor end region, how to further enhance the flexibility of dihedral angle adjustment in the corner region, effectively control the convergence and development of boundary layer while suppressing lateral secondary flow, and ensure the conservation of flow area is one of the key issues to be solved. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing sidewall blade fusion design technology, such as the inability to improve the lateral secondary flow problem, the omission of styling space, and low design efficiency. It creatively proposes a blade endwall fusion design method with circumferentially monotonic endwalls, which can ensure that the flow area remains unchanged and has the characteristic of circumferentially monotonic endwalls.

[0009] The method of the present invention first determines the blade fusion shape based on the maximum fusion thickness, position, and leading and trailing edge fusion scale. Then, it determines the monotonic slope angle and position of the endwall based on the lateral secondary flow characteristics. Finally, based on the constraint that the channel area remains unchanged at each axial position, it determines the endwall and blade geometry, thereby achieving a blade endwall fusion design with circumferential monotonicity.

[0010] Beneficial effects

[0011] The method of the present invention has the following advantages compared with the prior art:

[0012] 1. The method of the present invention enhances the ability to control the dihedral angle distribution of the corner region formed by the endwall and the blade, and can simultaneously control the fusion shape of the suction surface and the leading and trailing edges. The root blade element cross section and the endwall are both included in the aerodynamic design space, which is a function that the sidewall blade fusion method does not have.

[0013] 2. The method of the present invention ensures that the channel area of ​​each axial section remains unchanged, avoiding the changes in mass flow rate and operating conditions that may be caused by changes in the metal blockage area, making it more valuable for engineering applications.

[0014] 3. The endwall design of the method of the present invention adopts a circumferential monotonic curve structure, which can ensure good adaptability to working conditions while controlling the transverse secondary flow. Attached Figure Description

[0015] Figure 1 shows the prototype cascade geometry in an embodiment of the method of the present invention;

[0016] Figure 2 is a schematic diagram of the leading edge blade / endwall fusion geometry in an embodiment of the method of the present invention;

[0017] Figure 3 is a schematic diagram of the suction surface blade / endwall fusion geometry in an embodiment of the method of the present invention;

[0018] Figure 4 is a geometric schematic diagram of the monotonic end wall portion in an embodiment of the present invention;

[0019] Figure 5 is a geometric diagram of the axial cross-section in an embodiment of the method of the present invention;

[0020] Figure 6 is a Bezier control curve of the blade / endwall fusion portion in an embodiment of the method of the present invention;

[0021] Figure 7 is the Bezier control curve of the circumferentially monotonic endwall portion in an embodiment of the present invention;

[0022] Figure 8 is a geometrical schematic diagram of the final design result in the embodiment of the method of the present invention. Detailed Implementation

[0023] The method of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] A blade endwall fusion design method with a monotonous endwall circumference includes the following steps:

[0025] Step 1: Input data preparation and checking.

[0026] The required input data includes the blade and endwall geometric coordinates, blade pitch t, ​​and leading edge metal angle β. 1k and trailing edge metallic angle β 2k Leading edge fusion scale W LE and trailing edge fusion scale W TE Maximum fusion thickness Ws and axial position Wsx of suction surface, maximum fusion thickness Wp and axial position Wpx of pressure surface, fusion tilt angle θ, monotonic end wall slope angle β, and maximum slope angle position b. tx And the blade Bezier curve control parameters a1, b1, c1, d1, and the endwall Bezier curve control parameters a2, b2, c2, d2.

[0027] The values ​​of parameters a1, b1, c1, d1, a2, b2, c2, and d2 range from 0 to 1.

[0028] The input data that needs to be checked includes ensuring that the blade channel geometry is periodic and that the geometry of the prototype blade end area is refined (to ensure a smooth blade endwall fusion shape).

[0029] Step 2: Determine the fusion shape of the leading and trailing edges.

[0030] Specifically, it can be based on the leading edge metal angle β 1k The fusion scale direction is determined, and the maximum fusion scale is W. LE The tail rim fusion design adopts β 2k and W TE It is confirmed that the control length of the Bezier curve is determined by a1.

[0031] Step 3: Calculate the geometric coordinates of the maximum fusion position of the suction surface.

[0032] Specifically, the fusion shape of the suction surface blade section is determined based on the maximum fusion thickness Ws, axial position Wsx, and fusion tilt angle θ of the suction surface.

[0033] The radial coordinate Y1 at the location of maximum fusion of the suction surface is represented as:

[0034] Y1=H+Ws-tanβ(0.5t-Ws·tanθ) (1)

[0035] Where H is the radial coordinate at the maximum slope angle, β is the input maximum slope angle parameter, and t represents the blade pitch.

[0036] Step 4: Calculate the geometric coordinates at the maximum fusion position of the pressure surface.

[0037] Specifically, the fusion shape of the blade portion of the pressure surface is determined based on the maximum fusion thickness Wp, the axial position Wpx, and the fusion tilt angle θ.

[0038] Similarly, the radial coordinate Y4 at the maximum fusion position of the pressure surface is represented as follows:

[0039] Y4=H+Wp+tanβ(0.5t-Wp·tanθ) (2)

[0040] Where H is the radial coordinate at the maximum slope angle, β is the input maximum slope angle parameter, and t represents the blade pitch.

[0041] Step 5: Construction of the axial geometric section of the monotonic end wall.

[0042] To construct a monotonic endwall profile, for planar blades, the endwall profile is a straight line with the maximum slope angle from the pressure surface blade fusion section to the suction surface blade fusion section, and the radial position monotonically decreases from the pressure surface to the suction surface. For rotating blades, the endwall radius monotonically decreases from the pressure surface to the suction surface.

[0043] Step 6: Calculate the radial position coordinates of the end wall.

[0044] To ensure the metal area remains constant, given the constraint that the geometric area of ​​each axial cross-section channel is consistent with the prototype, at each axial position, compared to the prototype, the increase in metal area of ​​the fusion portion of the suction and pressure surfaces of the blades, plus the metal area of ​​the monotonic endwall compression, adds up to 0. The expression is as follows:

[0045]

[0046] Substituting the combined geometric coordinates Y1 of the suction surface blade in step 3 and Y4 of the pressure surface blade in step 4, the radial position coordinate H at the maximum slope angle is obtained as follows:

[0047] H = -0.5[(Ws) 2 +Wp 2 ) / tanθ+tanβ(Ws 2 -Wp 2 )] / t (4)

[0048] After obtaining the radial coordinates of the maximum slope angle, substitute them into steps 3 and 4 to obtain the geometric coordinates of the maximum fusion position of the suction surface and the pressure surface.

[0049] Thus, the relative positional relationship between the blade fusion section and the monotonic endwall geometry was determined.

[0050] Step 7: Blade and endwall profile construction.

[0051] Once the axial section of the blade passage is determined, the circumferential profiles of the blade and endwall are controlled using two Bezier curves. For the blade portion, the first Bezier curve starts at the leading edge with a rocker arm length of a1 and ends at the point of maximum suction convergence with a rocker arm length of b1. The second Bezier curve starts at the point of maximum convergence with a rocker arm length of c1 and ends at the trailing edge with a rocker arm length of d1.

[0052] For a circumferentially monotonic end wall, at the position of maximum slope angle b tx To define the boundaries, two Bezier curves are used for control. The joystick length is a2 at the leading edge of the first curve and b2 at the maximum slope angle. The joystick length is c2 at the maximum slope angle of the second curve and d2 at the trailing edge.

[0053] Finally, the leading and trailing edge blade shapes are smoothly connected to the suction and pressure surfaces, thus completing the blade / endwall fusion shape with a monotonous circumference.

[0054] Furthermore, this method may also include step 8: verification of the continuity and geometric smoothness of the design results. After completing the blade / endwall fusion design with monotonic endwall circumference, check the continuity and periodicity of its shape geometry. If there are any abnormalities in the results, carefully check whether the design parameters are within a reasonable range. Under the premise of safe use, both continuity and periodicity should meet the requirements of engineering applications.

[0055] Example

[0056] This embodiment describes a specific implementation of a blade / endwall fusion design method with circumferentially monotonic endwalls as described in this invention.

[0057] The application scenario of this embodiment is a planar blade cascade with an inlet Mach number of 0.7, a chord length of 70 mm, and a span of 100 mm. According to the implementation steps of this invention, a blade / endwall fusion design with circumferentially monotonic endwalls is performed on the planar blade cascade in its initial state as shown in Figure 1. The specific implementation steps are as follows:

[0058] First, the input data is read in, including the geometric coordinates of the blade and endwall, as shown in Figure 1. The blade pitch t = 35 mm; the leading edge metal angle β... 1k =50.38°, trailing edge metallic angle β 2k =33.32°, leading edge fusion scale W LE =3mm, trailing edge fusion dimension W TE=2mm, maximum fusion thickness of suction surface Ws = 3mm; axial position Wsx = 21%, a dimensionless quantity of axial chord length; maximum fusion thickness of pressure surface Wp = 2mm; axial position Wpx = 18%, a dimensionless quantity of axial chord length; fusion tilt angle θ = 45°; monotonic end wall slope angle β = 7°; maximum slope angle position b tx =63%, which is the dimensionless quantity of axial chord length; the blade Bezier curve control parameters are a1=0.3, b1=0.3, c1=0.5, d1=0.5; and the endwall Bezier curve control parameters are a2=0.4, b2=0.5, c2=0.6, d2=0.3.

[0059] By checking the endwall coordinates, we ensure that the channel geometry meets the periodicity requirement; by checking the spanwise section coordinates and quantity of the blades, we ensure that the end zone geometry is effectively densified.

[0060] The fusion shape of the leading and trailing edges is determined based on the shaping method shown in Figure 2, and the fusion size is determined by W. LE and W TE Control, direction by β 1k and β 2k It is confirmed that the control length of the Bezier curve is determined by a1.

[0061] Based on the modeling method shown in Figure 3, the geometric coordinates Y1 at the maximum fusion position of the suction surface are determined, and the geometric coordinates Y2 at the maximum fusion position of the pressure surface are calculated using the same method.

[0062] For this planar blade cascade, the monotonic endwall axial geometry is shown in Figure 4. The endwall monotonically descends from the pressure surface to the suction surface, controlled by a straight line with a slope of β.

[0063] The radial position coordinate H of the endwall can be calculated based on the geometric relationship in Figure 5. That is, based on the constraint that the increased metal area of ​​the blade fusion part is equal to the metal area of ​​the monotonic endwall pressing down, H can be calculated by substituting the corresponding input parameters. Then, by substituting the expressions for Y1 and Y4, the axial cross-sectional geometric relationship of the blade fusion shape with monotonic endwall circumference can be obtained.

[0064] The blade profile is controlled by the Bezier curve shown in Figure 6. The blade tip profile curve can be obtained based on the maximum fusion position Wsx and the blade Bezier curve control parameters a1, b1, c1, d1.

[0065] The circumferentially monotonous endwall profile is controlled by the Bezier curve shown in Figure 7, based on the position of the maximum slope angle b. tx Determine the boundary between the two Bezier curves, and determine the Bezier curve lever length based on the input parameters a2, b2, c2, and d2.

[0066] The final blade / endwall fusion design with a monotonous circumferential endwall is shown in Figure 8. The blade and endwall shapes are geometrically continuous and smooth, meeting the design requirements.

[0067] The above description is merely an illustrative embodiment of the present invention, and the present invention should not be limited to the content disclosed in this embodiment and the accompanying drawings. Any equivalent or modified versions made without departing from the spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. A blade endwall fusion design method with a circumferentially monotonous endwall, characterized in that, First, the blade fusion shape is determined based on the maximum fusion thickness, location, and leading-to-tail edge fusion scale. Then, the endwall monotonic slope angle and location are determined based on the transverse secondary flow characteristics. Finally, the endwall and blade geometry are determined based on the constraint that the channel area remains constant at each axial position. Step 1: Input data preparation and checking; The input data to be prepared includes the blade and endwall geometric coordinates, blade pitch t, ​​and leading-edge metal angle β. 1k and trailing edge metallic angle β 2k Leading edge fusion scale W LE and trailing edge fusion scale W TE Maximum fusion thickness Ws and axial position Wsx of suction surface, maximum fusion thickness Wp and axial position Wpx of pressure surface, fusion tilt angle θ, monotonic end wall slope angle β, and maximum slope angle position b. tx And the blade Bezier curve control parameters a1, b1, c1, d1, and endwall Bezier curve control parameters a2, b2, c2, d2; the values ​​of parameters a1, b1, c1, d1, a2, b2, c2, d2 range from 0 to 1; among them, the input data that needs to be checked includes the blade channel geometry needing to satisfy periodicity and the prototype blade end region geometry being refined; Step 2: Determine the leading edge and trailing edge fusion shape; based on the leading edge metal angle β 1k The fusion scale direction is determined, and the maximum fusion scale is W. LE The tail rim fusion design adopts β 2k and W TE Step 3: Calculate the geometric coordinates at the maximum fusion position of the suction surface; determine the fusion shape of the suction surface blade part according to the maximum fusion thickness Ws, axial position Wsx and fusion tilt angle θ; where, the radial coordinate Y1 at the maximum fusion position of the suction surface is expressed as: Y1=H+Ws-tanβ(0.5t-Ws·tanθ) (1) where, H is the radial coordinate at the maximum slope angle, β is the input maximum slope angle parameter, and t represents the blade pitch; Step 4: Calculate the geometric coordinates at the maximum fusion position of the pressure surface; determine the fusion shape of the pressure surface blade part according to the maximum fusion thickness Wp, axial position Wpx and fusion tilt angle θ; where, similar to the suction surface, the radial coordinate Y4 at the maximum fusion position of the pressure surface is expressed as: Y4=H+Wp+tanβ(0.5t-Wp·tanθ) (2) Where H is the radial coordinate at the maximum slope angle, β is the input maximum slope angle parameter, and t represents the blade pitch; Step 5: Monotonic endwall axial geometry section construction; For planar blades, from the pressure surface blade fusion section to the suction surface blade fusion section, the endwall profile is a straight line with the maximum slope angle as the slope, and the radial position monotonically decreases from the pressure surface to the suction surface; For rotating blades, the endwall radius monotonically decreases from the pressure surface to the suction surface; Step 6: Endwall radial position coordinate calculation; Given the constraint that the geometric area of ​​each axial section channel is consistent with the prototype, at each axial position, compared with the prototype, the increase in metal area of ​​the suction surface and pressure surface blade fusion section plus the metal area of ​​the monotonic endwall pressure is 0, and the expression is: Substituting the combined geometric coordinates Y1 of the suction surface blade in step 3 and Y4 of the pressure surface blade in step 4, the radial position coordinate H at the maximum slope angle is obtained as: H = -0.5[(Ws 2 +Wp 2 ) / tanθ+tanβ(Ws 2 -Wp 2 (4) After obtaining the radial coordinates of the maximum slope angle position, substitute them into steps 3 and 4 to obtain the geometric coordinates of the maximum fusion position of the suction surface and the pressure surface; Step 7: Blade and endwall profile construction; After determining the axial section of the blade channel, the circumferential profiles of the blade and endwall are controlled by two Bezier curves respectively; Among them, for the blade part, the starting point of the first Bezier curve is the leading edge, and the rocker arm length is a1; the ending point is the maximum fusion position of the suction surface, and the rocker arm length is b1; the starting point of the second Bezier curve is the maximum fusion position, and the rocker arm length is c1; the ending point is the trailing edge, and the rocker arm length is d1; for the circumferentially monotonic endwall, the maximum slope angle position b tx To define the boundaries, two Bezier curves are used for control. The rocker arm length is a2 at the leading edge of the first curve and b2 at the maximum slope angle. The rocker arm length is c2 at the maximum slope angle of the second curve and d2 at the trailing edge. Finally, the blade shape of the leading and trailing edges is smoothly connected to the suction and pressure surfaces. This completes the blade / endwall fusion shape with a monotonous circumferential endwall.

2. The blade endwall fusion design method with monotonous circumferential endwall as described in claim 1, characterized in that, Step 8: Continuity and geometric smoothness verification of design results; After completing the blade / endwall fusion design with monotonous endwall circumference, check the continuity and periodicity of its shape geometry. If there are any abnormalities in the results, carefully check whether the design parameters are within a reasonable range. Under the premise of proper use, both continuity and periodicity should meet the engineering application requirements. The blade / endwall shape geometry should be continuous and smooth, meeting the design requirements.

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