Design method of large-turning-angle variable-camber guide vane

Abstract

The invention relates to the technical field of aero-engines, in particular to a design method of a large-turning-angle variable-camber guide vane. The design method comprises the following steps that S1, design indexes are determined, and the total chord length and the maximum thickness of the guide vane height are determined according to the design indexes; s2, uniformly dividing the guide vane into a plurality of elements from the vane root to the vane tip, and projecting the elements into a two-dimensional plane; s3, determining a bending angle of a back blade mean camber line; s4, determining the posterior leaf consistency and the slotting position of each primitive; s5, calculating the slit exit width of each element in the first corner state; s6, determining the shrinkage ratio of the slit in the first corner state; s7, determining the rear leaf profile of each primitive; s8, determining a slit; s9, a third corner lower slit is determined; s10, determining the rotation center position of the rear leaf of each primitive; and S11, inversely transforming the primitives designed in the two-dimensional plane back to the primitives uniformly divided from the blade root to the blade tip, and carrying out radial stacking. The variable camber guide vane can enlarge the available rotating angle range of the variable camber guide vane.

Description

Technical Field

[0001] The present disclosure relates to the technical field of aero-engines, and in particular to a design method for a large-angle variable-camber guide vane. Background Art

[0002] In the field of aircraft engine design, aircraft compressors need to ensure a certain efficiency and margin, requiring the compressor rotor blades to operate within the available angle of attack range. When the intake conditions change, the engine speed changes, etc., the rotor blade angle of attack may exceed the available angle of attack range, resulting in reduced compressor efficiency or even engine surge. To address this problem, adjustable guide vanes are often used in engine design. By adjusting the installation angle of the adjustable guide vanes, the absolute inlet airflow angle and angle of attack of the moving blades are changed, so that the rotor blades operate within the available angle of attack range, ensuring the efficiency and margin of the compressor.

[0003] The available adjustment range is an important technical indicator of adjustable guide vanes. The larger the available adjustment range, the more conducive it is to ensuring the margin and efficient working range of the compressor, and the higher the degree of freedom in engine design. In addition, in variable cycle engines, the compressor needs to work stably within a wider range. As an adjustment technology, the available adjustment range of adjustable guide vanes is crucial to the engine working range.

[0004] Variable camber guide vanes have a wider available adjustment range than integral adjustable guide vanes. Variable camber guide vanes are guide vanes in aircraft engines that can change their own camber. They are generally divided into two main parts: front vanes and rear vanes. The rear vanes can rotate around the rotating shaft 6 to achieve a change in camber. In the low-pressure compressor and high-pressure compressor of an aircraft engine, the main functions of variable camber guide vanes are: preventing compressor surge, expanding the stable working boundary of the compressor, and adjusting the working state of the compressor.

[0005] The design of variable curvature guide vanes has a high degree of freedom and there are many design parameters. The current design method mainly focuses on modifying the design of an adjustable guide vane, or improving the design by locally optimizing the local geometric shape of the variable curvature guide vane. There is a lack of a complete design process that includes the overall design of the blade, resulting in a long design cycle and limited design effect.

[0006] The main problem with existing variable-camber guide vanes is that the available adjustment range is insufficient, there is a lack of design criteria to refer to during design, and there is no design method that can effectively increase the available adjustment range.

[0007] As the rear blade angle increases from the minimum loss angle, the airflow deflection angle increases, and the total pressure loss coefficient of the variable camber guide vane increases. In particular, when the rear blade angle reaches a certain value, the rear blade suction surface undergoes open separation, and the loss increases significantly. The available adjustment range of the variable camber guide vane two-dimensional blade profile with a circular rear blade leading edge and a circular front blade trailing edge under 0.3 Mach flow is approximately below 25 degrees of the outlet airflow angle.

[0008] The design parameters such as the slot opening form, slot width, and rear blade leading edge shape of the slot between the front and rear blades will change the state of the slot jet, thereby affecting the total pressure loss coefficient and the available adjustment range of the variable curvature guide vane. However, the current variable curvature guide vane does not optimize the slot and the rear blade shape, and the existing variable curvature guide vane design method does not solve the problem of how to design the front blade trailing edge profile, the rear blade leading edge profile, and the rear blade shape at the slot to increase the available adjustment range of the variable curvature guide vane. Summary of the invention

[0009] The present disclosure is proposed in view of the above problems. The present disclosure provides a design method for a variable camber guide vane with a large turning angle.

[0010] According to one aspect of the present disclosure, a design method for a large-angle variable-camber guide vane is provided, comprising the following steps:

[0011] S1, determine the design index, and determine the total chord length and maximum thickness of the guide vane height according to the design index;

[0012] S2, divide the guide vane from the root to the tip into multiple primitives evenly and project them into a two-dimensional plane;

[0013] S3, determine the bending angle of the arc line in the posterior lobe of each primitive;

[0014] S4, determine the back leaf consistency of each primitive, and determine the slit position according to the back leaf consistency; the criterion of the back leaf consistency is:

[0015] σ≥2sin(β out ) / q;

[0016] Among them, σ is the posterior leaf consistency, β out is the design outlet geometry angle of the blade height at the first turning angle, and q is a constant coefficient;

[0017] S5, calculating the exit width of each primitive narrow gap under the first corner state;

[0018] S6, determining the contraction ratio of the slit in the first rotation angle state;

[0019] S7, generating the leaf shape of each primitive;

[0020] S8, determine the slit;

[0021] S9, determining the lower slit of the third corner;

[0022] S10, determining the rotation center position of the posterior lobe of each primitive;

[0023] S11, transform the primitives designed in the two-dimensional plane back to primitives evenly divided from the blade root to the blade tip, and perform radial stacking.

[0024] According to the design method of a large turning angle variable camber guide vane according to one aspect of the present disclosure, in step S3, the curvature angle of the camber line in the rear blade is determined by the following formula:

[0025] θ=0.5*(β min +β max )-s*(β max -β min );

[0026] Where θ is the posterior leaflet bending angle, β min is the minimum exit geometry angle corresponding to the blade height design requirement, β max is the maximum exit geometry angle required for the blade height position design, and s is a constant coefficient.

[0027] According to the design method of a large turning angle variable camber guide vane according to one aspect of the present disclosure, in step S5, the outlet width of each elementary slit in the first turning angle state is calculated by the following formula:

[0028]

[0029] Among them, W out is the slit outlet width that should be selected for this blade height, TH is the maximum thickness of the blade at this blade height determined according to the design indicators, ρ is the density of the incoming flow in the first turning angle state, U is the air flow velocity in the mainstream area in the first turning angle state, ν is the air viscosity, and Re is a constant coefficient.

[0030] According to the design method of large turning angle variable camber guide vanes described in one aspect of the present disclosure, in step S6, the method for determining the contraction ratio of the slit in the first turning angle state is to control the ratio of the slit outlet velocity to the mainstream velocity between 1.0 and 1.1, and select the contraction ratio according to the incoming flow Mach number, Reynolds number, and the first turning angle.

[0031] According to the design method of large turning angle variable camber guide vane described in one aspect of the present disclosure, in step S7, determining the blade profile of each primitive rear blade includes:

[0032] The curvature distribution form of the rear blade suction surface 7 is strong front loading, and the peak curvature position is located at the slit outlet. The primitive blade shape of each rear blade with different blade heights is generated through parametric modeling. The selection criterion of the peak curvature is that the angle between the jet airflow at the slit outlet and the horizontal direction is less than 15 degrees.

[0033] According to the design method of large turning angle variable curvature guide vane described in one aspect of the present disclosure, in step S8, the method for determining the slit is as follows: the slit inlet width and the slit outlet width at the first turning angle of the primitive are used to calculate the position of the slit inlet point and the slit outlet point on the front blade trailing edge profile line, and an arc horizontal to the slit outlet is used to connect the slit inlet and outlet points on the front blade trailing edge to form the rear half of the front wall profile line of the slit, and a smooth curve is used to connect the slit inlet and the front blade pressure surface to form the front half of the slit.

[0034] According to the design method of the large turning angle variable camber guide vane described in one aspect of the present disclosure, the calculation formula of the radius of the arc is:

[0035]

[0036] Where R is the radius of the arc, T ∥ It is the horizontal distance between the highest point and the most forward point at the first corner of the leading edge of the rear leaf, and it is the vertical distance between the highest point and the most forward point at the first corner of the leading edge of the rear leaf.

[0037] According to the design method of a variable-camber guide vane with a large turning angle described in one aspect of the present disclosure, step S9 includes determining whether there is a commonly used third turning angle in addition to the maximum turning angle and the minimum turning angle;

[0038] If there is a third turning angle, according to step S4 and step S5, the slit inlet width and the slit outlet width at the common turning angle are calculated.

[0039] According to a design method for a large turning angle variable camber guide vane according to one aspect of the present disclosure, step S10 includes:

[0040] The position satisfying the slit inlet width and the slit outlet width in the first rotation angle state and the third rotation angle state is taken as the rotation center position of the rear leaf.

[0041] The design method of a large turning angle variable camber guide vane according to one aspect of the present disclosure also includes:

[0042] S12, evaluating whether there is open separation at the first corner, if so, adjusting the rear leaf consistency and slit geometry parameters according to the evaluation result, and repeating steps S1 to S11 until there is no open separation at the first corner.

[0043] As will be described in detail below, according to the design method of the variable curvature guide vane with large turning angle according to the embodiment of the present disclosure, the blade root to the blade tip is evenly divided into multiple primitives, and projected onto a two-dimensional plane, and a calculation formula for the rear blade consistency is proposed, and then the slit outlet width, the contraction ratio of the slit in the first turning angle state, the blade shape of each primitive rear blade, the trailing edge of the front blade, the slit under the third turning angle, and the rotation center position of each primitive rear blade are determined in sequence, and then the primitive designed in the two-dimensional plane is inversely transformed back to the primitive evenly divided from the blade root to the blade tip, and radial stacking is performed. In some implementations, the two-dimensional plane is perpendicular to the radial direction. The present disclosure can finely control the flow field in key areas such as the slit inside the variable curvature guide vane and the slit outlet, and radial stacking is performed considering the slit geometry of different blade heights and different turning angles, so as to achieve the beneficial effect of suppressing the open separation of the airflow at multiple different turning angles, especially large turning angles, controlling its loss, and improving the available turning angle range of the variable curvature guide vane.

[0044] It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the technology as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and other purposes, features and advantages of the present disclosure will become more apparent by describing the embodiments of the present disclosure in more detail in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0046] Figure 1 is a front view of the variable guide vane proposed in the present disclosure;

[0047] Figure 2 is a top view of the variable guide vane proposed in the present disclosure at a certain turning angle;

[0048] Figure 3 is a top view of the variable guide vane proposed in the present disclosure at another turning angle;

[0049] Figure 4 is a flowchart of the steps of the design method proposed in the present disclosure;

[0050] Figure 5 It is the overall modeling parameter diagram of the variable camber guide vane proposed in the present disclosure;

[0051] Figure 6 is the two-dimensional projection diagram of the slit at the i-th blade height position of the variable curvature guide vane;

[0052] Figure 7 is a characteristic diagram of outlet airflow angle and total pressure loss in preferred embodiment 1 of the present disclosure;

[0053] Figure 8 is a comparison diagram of the Mach number cloud diagram of the blade mid-section when the rotation angle is 30° between the preferred embodiment 1 and the circular variable camber guide vane;

[0054] Fig. 9 : is a comparison diagram of the total pressure loss coefficient distribution of the section at 25% of the chord length behind the trailing edge of the preferred embodiment 2 and the circular variable camber guide vane when the turning angle is 30°;

[0055] Fig.10 is a local geometrical schematic diagram of a 50% blade height slit of a preferred embodiment 2 of the present disclosure;

[0056] Fig.11 is the spanwise distribution diagram of the total pressure loss of the preferred example 2 and the circular gap variable camber guide vane at a rotation angle of 40°;

[0057] Fig.12a It is the total pressure loss cloud diagram of the gap streamline and the position of 50% chord length from the trailing edge of the circular gap variable curvature guide vane at a 40° turning angle;

[0058] Figure 12b It is a cloud diagram of the total pressure loss at the gap streamline and 50% chord length from the trailing edge of the variable camber guide vane at a 40° turning angle in the preferred embodiment 2 of the present disclosure;

[0059] Fig.13 This is the blade profile of the preferred example 3 proposed in the present disclosure at a rotation angle of 0°;

[0060] Fig.14 This is the blade profile of the preferred example 3 proposed in the present disclosure at a rotation angle of 47°;

[0061] Fig.15 It is the total pressure loss characteristic of the preferred example 3 and the circular gap variable camber guide vane;

[0062] Fig.16 This is the Mach number cloud diagram of the preferred example 3 under the extreme working condition of the rear blade rotation angle of 57°.

[0063] Description of reference numerals:

[0064] 1-front blade, 2-rear blade, 3-slit, 4-slit outlet, 5-slit inlet, 6-rotating axis, 7-rear blade suction surface, 8-front blade trailing edge, 9-rear blade leading edge, 10, rear blade median arc line. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solution and advantages of the present disclosure more obvious, the exemplary embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments of the present disclosure, and it should be understood that the present disclosure is not limited to the exemplary embodiments described here.

[0066] In order to solve the problems raised in the background technology, the present disclosure proposes a design method for a large turning angle variable curvature guide vane, please refer to Figures 1 to 3 The variable curvature guide vane in the present invention includes two components, namely, a front blade 1 and a rear blade 2, wherein the front blade 1 is fixed, and the rear blade 2 can rotate around the rotating shaft 6, and a slit 3 is formed between the front blade 1 and the rear blade 2. The geometric shapes of the front blade 1 and the rear blade 2 are determined by several modeling parameters of parametric modeling. The modeling parameters are selected according to the design criteria, and a suitable radial stacking method is selected to achieve the control of the geometric shape of the slit at different blade heights and different rotation angles, so as to improve the flow structure and achieve the beneficial effects of low loss and wide adjustment range. The key modeling parameters include the chord length of the rear blade 2 of several blade height primitives from 0% to 100% blade height position, the width of the slit outlet 4, the width of the slit inlet 5, the curvature distribution form of the rear blade suction surface 7, and the peak curvature of the rear blade suction surface.

[0067] Please refer to Figures 1 to 6 , the method proposed in the present disclosure comprises the following steps,

[0068] S1, determine the design indicators, and determine the total chord length and maximum thickness of the guide vane height according to the design indicators; in the specific implementation, specify the parameters directly related to the design indicators. The design indicators include the maximum adjustment angle of the blade as a whole, the total chord length and maximum thickness of each blade height, and the geometric angle distribution of the rear blade outlet required from 0% to 100% blade height position in the first turning angle state. According to the design indicators, specify the total chord length and maximum thickness of each blade height of the variable curvature guide vane.

[0069] S2, divide the guide vane from the blade root to the blade tip evenly into multiple primitives, and project them into a two-dimensional plane; according to the meridian line of the engine hub and the casing, divide the variable camber guide vane from the blade root to the blade tip evenly into n primitives, and project each primitive into a two-dimensional plane, so as to perform subsequent design for each primitive. In specific implementation, the two-dimensional plane is a two-dimensional plane perpendicular to the radial direction of the blade.

[0070] S3, determine the bending angle of the rear blade middle arc line 10; according to the outlet airflow angle range required by the design requirements, the rear blade bending angle is selected by compromise. In this step, the bending angle of the rear blade middle arc line 10 is determined by the following formula:

[0071] θ=0.5*(β min +β max )-s*(β max -β min );

[0072] Where θ is the posterior leaflet bending angle, β min is the minimum exit geometry angle corresponding to the blade height design requirement, β maxis the maximum exit geometry angle required by the blade height position design, and s is a constant coefficient. The distribution form of the rear blade bending angle designed by this formula is consistent with the exit geometry angle distribution form of the design index. The value range of parameter s is 0.15~0.25.

[0073] S4, determine the back leaf consistency and the opening position of each primitive; the criterion of the back leaf consistency is:

[0074] σ≥2sin(β out ) / q;

[0075] Among them, σ is the posterior leaf consistency, β out is the design outlet geometry angle of the blade height at the first turning angle, q is a constant coefficient; the value range of parameter q is between 0.8 and 1.3. According to this formula, the rear blade density is determined, and then the rear blade chord length of each blade height is obtained, and then the relative position of the slit between the front blade and the rear blade is obtained, and the maximum thickness of the variable camber guide vane as a whole is set to this position.

[0076] S5, calculating the outlet width of each primitive slit in the first rotation angle state; in this step, the outlet width of each primitive slit in the first rotation angle state is calculated by the following formula:

[0077]

[0078] Among them, W out is the slit outlet width that should be selected for this blade height, TH is the maximum thickness of the blade at this blade height determined according to the design index, ρ is the density of the incoming flow at the first turning angle, U is the air velocity in the mainstream area at the first turning angle, ν is the air viscosity, and Re is a constant coefficient. The value of parameter Re is greater than 125.

[0079] S6, determine the contraction ratio of the slit in the first turning angle state; the method for determining the contraction ratio of the slit in the first turning angle state is to control the ratio of the slit outlet velocity to the mainstream velocity between 1.0 and 1.1, and select the contraction ratio according to the incoming flow Mach number, Reynolds number, and the first turning angle. For design scenarios where the initial value of the contraction ratio is given before evaluating the outlet velocity or a shorter design cycle is required, the recommended range of the slit contraction ratio is between 0.4 and 0.6. According to the contraction ratio, the slit inlet width W is calculated. in .

[0080] S7, determine the blade shape of each primitive rear blade; the curvature distribution form of the rear blade suction surface 7 is strong front loading, and the peak curvature position is located at the slit outlet 4, and the primitive blade shape of each blade height rear blade is generated through parameterized modeling, and the selection criterion of the peak curvature is that the angle between the jet airflow at the slit outlet 4 and the horizontal direction is less than 15 degrees. This ensures that the slit outlet 4 has a strong Coanda effect locally, the airflow can flow along the wall, and the rear blade suction surface 7 is not easy to separate.

[0081] S8, determine the slit; in this step, one of the keys to determine the slit is to first determine the trailing edge of the front blade, wherein the method for determining the trailing edge of the front blade is to use the slit inlet width and the slit outlet width at the first corner of the primitive, calculate the position of the slit inlet point and the position of the slit outlet point on the front blade trailing edge 8 profile line, use an arc horizontal to the slit outlet 4 to connect the slit inlet and outlet points on the front blade trailing edge 8 to form the rear half of the front wall profile line of the slit, use a smooth curve to connect the slit inlet 5 and the front blade pressure surface to form the front half of the slit.

[0082] The calculation formula of the radius of the arc is:

[0083]

[0084] Where R is the radius of the arc, T ∥ It is the horizontal distance between the highest point and the most forward point under the first corner at the leading edge of the rear leaf 9, and it is the vertical distance between the highest point and the most forward point under the first corner at the leading edge of the rear leaf 9.

[0085] S9, determine the slit at the third turning angle; in this step, determine whether there is a common turning angle in addition to the maximum turning angle and the minimum turning angle; if there is a third turning angle, calculate the slit inlet width and the slit outlet width at the common turning angle according to steps S4 and S5.

[0086] Specifically, if the engine design requires that the variable camber guide vane has a third rotation angle Δθ2 in addition to the first rotation angle position and the second rotation angle position, then its slit geometry must also meet the design criteria. According to steps S4 and S5, the slit inlet width and outlet width of each blade height element under Δθ2 are calculated.

[0087] If the variable camber guide vane has only two common working modes, the first angle and the second angle, then Δθ2 is selected to be equal to the minimum design angle, that is, Δθ2 = β min , specify the slit outlet width to be 0 at this time to ensure that there is no geometric interference between the front and rear leaves within the full rotation angle range from opening to closing of the rear leaf.

[0088] S10, determining the rotation center position of each primitive rear leaf; taking the position satisfying the slit inlet width and the slit outlet width in the first rotation angle state and the third rotation angle state as the rotation center position of the rear leaf.

[0089] S11, reverse transform the primitives designed in the two-dimensional plane back to primitives evenly divided from the root to the tip of the blade, and perform radial stacking. First, determine the two virtual rear blade positions according to the optimal slit geometry of each blade height element at two rotation angles, then use the fixed points of the two virtual rear blade positions as the rotation axis 6 position, and finally translate each blade height primitive so that the rotation axis 6 positions of different blade heights are on a straight line. Translate the slit profile and rear blade of each blade height primitive as a whole in the blade height plane, align the rotation center position of the rear blade of each blade height, reverse transform the blade height primitive designed in the two-dimensional plane back to n primitives evenly divided from the root to the tip of the blade, and perform radial stacking. Check whether each part of the blade meets the processing technology requirements, and the design is completed.

[0090] In the specific implementation, step S12 is also included, and step S12 is to evaluate whether there is open separation at the first corner. If so, the rear leaf consistency and slit geometry parameters are adjusted according to the evaluation result, and steps S1 to S11 are repeated until there is no open separation at the first corner.

[0091] The following is a further explanation with reference to specific examples.

[0092] In preferred embodiment 1, the design method of the present invention is used to design a variable camber guide vane with a usable range of 0 to 30 degrees in an aircraft engine. In this example, in a real engine flow path, the design index provides that the total chord length of the blade root is 64 mm, the total chord length of the blade tip is 88 mm, and the maximum thickness design index is: the maximum thickness of the blade root is 4.4 mm, and the blade tip is 6.1 mm.

[0093] According to the meridian lines of the hub and casing of the engine at the variable curvature guide vane, the engine flow path is divided into 12 primitives, and each primitive is projected onto a two-dimensional plane.

[0094] According to the consistency selection criterion σ≥2sin(β out ) / q; q≈1.0 is taken to limit the selection of the rear leaf density of each leaf height. Taking the leaf root, leaf middle and leaf tip as examples, the rear leaf density is selected as: 1.48, 1.25, 1.13 respectively, and the density of other leaf heights is selected as shown in Table 1. The opening position of the slit is determined according to the density.

[0095] Table 1: The consistency and bending angle of the rear leaf of the preferred embodiment 1

[0096]

[0097] In the design index of the preferred embodiment 1, the available range of the average outlet airflow angle is required to be 0° to 30°. Taking the blade root, blade middle and blade height as examples, the spanwise distribution requirement is that the outlet airflow angles of the three sections of the blade root, blade middle and blade height are -8.8°, -1.9° and 4.2° respectively when the rear blade turns at 0°. Since the maximum available outlet airflow angle is less than 30°, it is relatively easy to achieve. Therefore, according to the rear blade bending angle criterion θ= The rear blade bending angle of each blade height is directly specified as the minimum outlet airflow angle. The rear blade bending angle of each blade height section is selected as shown in Table 1.

[0098] At the first turning angle of 30°, according to the slit outlet width design criteria The slit outlet width was selected to be 0.55 mm.

[0099] The slit contraction ratio of each blade height is selected so that the ratio of the slit exit velocity to the mainstream velocity is u jet / Contraction ratio of u≈1.

[0100] The rear blade selects a blade type with a strong front loading and a peak curvature at the slit outlet. The peak curvature satisfies the angle α between the jet airflow at the slit outlet and the horizontal direction. jeet <15°.

[0101] According to the slit outlet width and contraction ratio, the positions of the slit inlet and outlet points on the front blade trailing edge profile are calculated, and the slit inlet and outlet points on the front blade trailing edge are connected using a horizontal arc at the outlet to form the front wall profile of the slit, which together with a part of the leading edge of the rear blade constitutes the slit.

[0102] Choose Δθ2=β min That is, at the second rotation angle, the width of the slit outlet of each leaf height section is specified to be 0.2 mm, and the geometry is checked to ensure that there is no geometric interference between the front and rear leaves within the full rotation angle range from opening to closing of the rear leaf.

[0103] The fixed point between the first rotation angle rear lobe geometry of each lobe height primitive and the virtual rear lobe geometry under the rotation angle Δθ2 is calculated as the rotation center position of the rear lobe at this lobe height.

[0104] The slit front wall profile and rear blade of the 12 blade height primitives are translated as a whole in the blade height plane to align the rotation center of the rear blade of each blade height. In the plane where each primitive is located, the geometry of the front blade except the trailing edge is translated circumferentially so that the thickness of the front blade at the slit outlet is the minimum thickness allowed by the processing technology of 0.1mm. Use a smooth profile to connect the slit inlet and the front blade pressure surface. The blade height primitive designed in the two-dimensional plane is transformed back to 12 primitives evenly divided from the blade root to the blade tip, and the design is completed.

[0105] Figure 7 : is the total pressure loss characteristic diagram of the preferred example 1 and the circular slit variable camber guide vane at different rotation angles. It can be seen that at most rotation angles, especially at large rotation angles, the preferred example 1 has lower losses. If the total pressure loss is 0.06 as the standard, the preferred example 1 expands the maximum outlet airflow angle from 19° to 29°.

[0106] Figure 8It is a cloud diagram of the Mach number of the blade section at a turning angle of 30°. It can be seen that at a turning angle of 30°, large-scale separation occurs on the suction surface of the rear blade of the circular slit variable curvature guide vane, while in the preferred example 1, since the slit jet is controlled, large-scale separation does not occur on the suction surface of the rear blade, and the total pressure loss is low.

[0107] Fig. 9 This is the total pressure loss distribution diagram of the section at 25% of the chord length behind the trailing edge of the trailing blade at a turning angle of 30°. It can be seen that due to the separation flow of the trailing blade of the circular slit variable camber guide vane, its wake is very wide and the total pressure loss in the wake is large. In preferred example 1, since there is no large-scale separation on the suction surface of the trailing blade, the wake is narrow and the loss in the wake is low.

[0108] In preferred embodiment 2, part of the design criteria of the present invention is used to design variable camber guide vanes.

[0109] Table 2 is the design requirements of preferred example 2, including two working conditions. According to the geometric requirements in the design index, the hub and casing profile of preferred example 2 are specified. Seven sections are arranged in the span direction, and each section has a rear blade bending angle of 0° in the blade. The rear blade bending angles of the blade root and blade tip are given according to the pre-rotation in the design requirements, and the bending angles of the remaining sections are calculated by interpolation.

[0110] Table 2 Design requirements for preferred example 2

[0111]

[0112] The initial value is determined by using the slit outlet width and contraction ratio selection criteria of the present invention. At a design turning angle of 40° and at a blade height position of 50%, the slit inlet and outlet widths are adjusted within a certain range. The losses at different inlet and outlet widths are evaluated through CFD calculation to select the optimal inlet and outlet width.

[0113] According to the width of the slit inlet and outlet, under the constraint of the outlet level, the radius The arc is used as the upper half of the front blade trailing edge 8, and the lower half of the front blade trailing edge 8 uses a cubic curve to transition with the pressure surface to construct a trumpet-shaped slot inlet to increase the total pressure at the slot inlet, such as Fig.10 .

[0114] The rear blade shape of each blade height primitive satisfies the suction surface curvature distribution form of strong front loading, and the peak curvature position is located at the slot outlet 4.

[0115] According to the design principle that there is no geometric interference between the front and rear leaves at a 0° rotation angle, the rotation center position of the rear leaves in each leaf height section is selected, the rotation center positions of the rear leaves at each leaf height are aligned, and radial stacking is performed to complete the design.

[0116] Fig.11The total pressure loss of the preferred example 2 and the circular gap variable curvature guide vane at a 40° turning angle is distributed in the span direction. The total pressure loss of the circular gap variable curvature guide vane is greater than 0.2 along the span direction, and the maximum total pressure loss coefficient reaches more than 0.6 at the blade tip. The result of the preferred example 2 is that the total pressure loss coefficient near the mainstream 50% span height drops significantly to less than 0.04. Above 70% of the blade height in the span direction, the total pressure loss coefficient of the preferred example 2 drops by more than 0.3 compared with the circular gap variable curvature guide vane. Below 20% of the blade height in the span direction, the total pressure loss coefficient of the preferred example 2 drops by about 0.1.

[0117] Please refer to Fig.12a and Figure 12b It can be seen that for the circular gap variable camber guide vane, the gap flow streamlines undergo large-scale separation at the full span height of the rear blade suction surface 7, and the streamlines near the blade tip are particularly chaotic, so a high total pressure loss area appears near the blade tip in the total pressure loss cloud diagram at the 50% chord length section of the outlet. For the preferred example 2, the high total pressure loss area in the total pressure loss cloud diagram at the 50% chord length section of the outlet is greatly reduced, and the total pressure loss intensity is also greatly reduced.

[0118] In preferred embodiment 3, two-dimensional blade profile design is performed using part of the design criteria of the present invention.

[0119] The design index of the preferred embodiment 3 is the maximum outlet geometric angle β max =47°, minimum exit geometry angle β min = 0°, according to θ = 0.5*(β min +β max )-s*(β max -β min ) Select the posterior leaf bending angle to be 12°.

[0120] At the first turning angle, the criterion for selecting the slit outlet width is, Among them, Re>125; at the minimum design angle β min That is, at the 0° exit geometry angle, the slit exit width is specified to be ≈ 0, ensuring that there is no geometric interference between the front and rear blades within the full rotation angle range. During the rotation from 47° to 0°, the slit exit width is continuously reduced to achieve the effect of gradually blocking the slit at a small rotation angle and reducing the mixing loss of the jet.

[0121] Under the conditions of the first turning angle and the design requirement of the inlet Mach number of 0.3, the CFD calculation evaluation was carried out by changing the slit contraction ratio with 0.5 as the initial value, and changing the ratio of the slit outlet velocity to the mainstream velocity u jet / u is controlled within the range of 1.0 to 1.1 to obtain the optimal contraction ratio of the slit. Then the slit inlet width W is calculated. in .

[0122] According to the width of the slit inlet and outlet, under the constraint of the outlet level, the radius The arc is used as the upper half of the front blade trailing edge 8, and the lower half of the front blade trailing edge 8 uses a cubic curve to transition with the pressure surface, constructing a trumpet-shaped slot inlet to increase the total slot inlet pressure.

[0123] The suction surface of the rear blade adopts a curvature distribution in the form of strong front loading. The maximum curvature point is located at the slot exit, and then the curvature decreases rapidly.

[0124] According to CFD calculation, the preferred embodiment 3 not only has a lower loss at the design rear blade outlet geometric angle of 35°, but also has an available angle range of more than 35°. Fig.13 , Fig.14 .

[0125] Fig.15 This is a comparison chart of the total pressure loss of the preferred example 3 at different turning angles and the circular gap variable curvature guide vane when the Mach number is equal to 0.3. It can be seen that after the circular gap variable curvature guide vane turns at an angle of 25 degrees, the rear blade suction surface 7 appears open separation and the loss increases rapidly; in the entire turning angle range, the total pressure loss coefficient of the preferred example 3 is greatly reduced compared with the circular gap variable curvature guide vane, and the available outlet airflow angle range is expanded from about 28° of the circular gap variable curvature guide vane to about 52°.

[0126] Fig.16 It is a Mach number cloud diagram of the preferred example 3 under the condition of the rear blade extreme rotation angle of 57°. It can be seen that under the extreme condition of the rear blade angle of 57°, the rear blade suction surface 7 of the preferred example 3 does not show open separation phenomenon.

[0127] In the above, the design method of the variable curvature guide vane with a large turning angle according to the embodiment of the present disclosure is described with reference to the accompanying drawings. Through a high-degree-of-freedom blade overall modeling method, geometric parameters such as the rear blade density, slit width, slit contraction ratio and the curvature at 9 points on the leading edge of the rear blade are selected according to design criteria. The flow field in key areas such as the slit inside the variable curvature guide vane and at 4 slit outlets is finely controlled, and the slit geometries of different blade heights and different turning angles are radially stacked, thereby achieving the beneficial effects of suppressing open separation of airflow at multiple different turning angles, especially large turning angles, controlling its losses, and increasing the available turning angle range of the variable curvature guide vane.

[0128] By controlling the outlet width and contraction ratio of the slit, precise control of the jet velocity can be achieved to achieve the optimal jet velocity. The curvature distribution form of the suction surface 7 of the rear blade and the maximum curvature of the leading edge can be controlled through the modeling method, ensuring that the rear blade does not undergo open separation while achieving better wall-attached flow. Therefore, the present application can achieve a wider angle adjustment range than other variable curvature guide vanes and smaller losses within the available angle range.

[0129] The CFD calculation results show that under the condition of an incoming flow of Mach number 0.3, the blade profile designed as a whole using the design principles of this application increases the available outlet airflow angle range of the variable camber guide vane from no more than 27 degrees to no more than 41 degrees. The experimental results show that under the condition of an incoming flow of Mach number 0.1, the blade profile designed as a whole using the design principles of this application increases the available outlet airflow angle range of the variable camber guide vane from no more than 25 degrees to no more than 40 degrees.

[0130] It should be noted that, in some embodiments, the first angle may be a maximum angle, the second angle may be a minimum angle, and the third angle may be other commonly used angles except the maximum angle and the minimum angle.

[0131] The basic principles of the present disclosure are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present disclosure are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, and are not limitations. The above details do not limit the present disclosure to the necessity of adopting the above specific details to be implemented.

[0132] The block diagrams of the devices, apparatuses, equipment, and systems involved in this disclosure are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including," "comprising," "having," and the like are open words, referring to "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or," and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0133] Additionally, as used herein, "or" used in a list of items beginning with "at least one" indicates a separate list, so that, for example, a list of "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not mean that the example described is preferred or better than other examples.

[0134] It should also be noted that in the system and method of the present disclosure, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present disclosure.

[0135] Various changes, substitutions, and modifications of the techniques described herein may be made without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims of the present disclosure is not limited to the specific aspects of the processes, machines, manufactures, compositions of events, means, methods, and actions described above. Currently existing or later to be developed processes, machines, manufactures, compositions of events, means, methods, or actions that perform substantially the same functions or achieve substantially the same results as the corresponding aspects described herein may be utilized. Thus, the appended claims include such processes, machines, manufactures, compositions of events, means, methods, or actions within their scope.

[0136] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0137] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A design method for a large turning angle variable camber guide vane, characterized in that: The following steps are included: S1, determine the design index, and determine the total chord length and maximum thickness of the guide vane height according to the design index; S2, divide the guide vane from the root to the tip into multiple primitives evenly and project them into a two-dimensional plane; S3, determine the bending angle of the arc line in the posterior lobe of each primitive; S4, determine the back leaf consistency of each primitive, and determine the slit position according to the back leaf consistency; the criterion of the back leaf consistency is: σ≥2sin(β out ) / q Among them, σ is the posterior leaf consistency, β out is the design outlet geometry angle of the blade height at the first turning angle, and q is a constant coefficient; S5, calculating the exit width of each primitive narrow gap under the first corner state; S6, determining the contraction ratio of the slit in the first rotation angle state; S7, generating the leaf shape of each primitive; S8, determine the slit; S9, determining the lower slit of the third corner; S10, determining the rotation center position of the posterior lobe of each primitive; S11, transform the primitives designed in the two-dimensional plane back to primitives evenly divided from the blade root to the blade tip, and perform radial stacking.

2. The design method of the large turning angle variable camber guide vane according to claim 1, characterized in that: In step S3, the bending angle of the arc line in the rear leaf is determined by the following formula: θ=0.5*(β min +b max )-s*(β max -b min ); Where θ is the posterior leaflet bending angle, β min is the minimum exit geometry angle corresponding to the blade height design requirement, β max is the maximum exit geometry angle required for the blade height position design, and s is a constant coefficient.

3. The design method of the large turning angle variable camber guide vane according to claim 1, characterized in that: In step S5, the outlet width of each elementary slit in the first rotation angle state is calculated by the following formula: Among them, W out is the slit outlet width that should be selected for this blade height, TH is the maximum thickness of the blade at this blade height determined according to the design indicators, ρ is the density of the incoming flow in the first turning angle state, U is the air flow velocity in the mainstream area in the first turning angle state, ν is the air viscosity, and Re is a constant coefficient.

4. The design method of the large turning angle variable camber guide vane according to claim 1, characterized in that: In step S6, the method for determining the contraction ratio of the slit in the first turning angle state is to control the ratio of the slit outlet velocity to the mainstream velocity between 1.0 and 1.1, and select the contraction ratio according to the incoming flow Mach number, Reynolds number, and the first turning angle.

5. The design method of the large turning angle variable camber guide vane according to claim 1, characterized in that: In step S7, the leaf type of each primitive is determined to include: The curvature distribution form of the rear blade suction surface 7 is strong front loading, and the peak curvature position is located at the slit outlet. The primitive blade shape of each rear blade with different blade heights is generated through parametric modeling. The selection criterion of the peak curvature is that the angle between the jet airflow at the slit outlet and the horizontal direction is less than 15 degrees.

6. The design method of the large turning angle variable camber guide vane according to claim 3, characterized in that: In step S8, the method for determining the slit is to use the slit inlet width and the slit outlet width at the first corner of the primitive, calculate the position of the slit inlet point and the slit outlet point on the front blade trailing edge profile line, use an arc horizontal to the slit outlet to connect the slit inlet and outlet points on the front blade trailing edge to form the rear half of the front wall profile line of the slit, and use a smooth curve to connect the slit inlet and the front blade pressure surface to form the front half of the slit.

7. The design method of the large turning angle variable camber guide vane according to claim 6, characterized in that: The calculation formula for the radius of the arc is, Where R is the radius of the arc, T ∥ It is the horizontal distance between the highest point and the most forward point at the first corner of the leading edge of the rear leaf, and it is the vertical distance between the highest point and the most forward point at the first corner of the leading edge of the rear leaf.

8. The design method of large turning angle variable camber guide vane according to claim 6, characterized in that: Step S9 includes determining whether there is a commonly used third turning angle in addition to the maximum turning angle and the minimum turning angle; If there is a third turning angle, according to step S4 and step S5, the slit inlet width and the slit outlet width at the common turning angle are calculated.

9. The design method of the large turning angle variable camber guide vane according to claim 8, characterized in that: Step S10 includes, The position satisfying the slit inlet width and the slit outlet width in the first rotation angle state and the third rotation angle state is taken as the rotation center position of the rear leaf.

10. The design method of a large turning angle variable camber guide vane according to any one of claims 1 to 9, characterized in that: Also includes, S12, evaluating whether there is open separation at the first corner, if so, adjusting the rear leaf consistency and slit geometry parameters according to the evaluation result, and repeating steps S1 to S11 until there is no open separation at the first corner.

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