A deformable fan for an aviation turbofan engine and an optimization method thereof

Abstract

The present invention discloses a deformable fan for an aviation turbofan engine and an optimization method, belonging to the field of aviation engines. The present invention includes blades, a hub, and a casing. The blades, hub, and casing are all composed of a laminated structure composed of carbon fiber and piezoelectric material. The piezoelectric material is driven by electrodes to drive the entire laminated structure to produce the required micro-deformation of the blades, hub, and casing. By optimizing the layout of the piezoelectric material, high-precision micro-deformation of the deformable fan at three levels: local, array, and overall is achieved. The fast response and large-scale deformation of the three-stage variable-camber blades achieve a wider adjustment capability for the bend angle, inlet angle of attack, and outlet airflow angle. By combining the advantages of large deformation of the variable-camber blade driven by a mechanical structure and high deformation precision of the blade driven by intelligent piezoelectric material, precise control of vortices and shock waves in the blade channel is achieved, flow separation is weakened, and the efficiency and stability of the deformable fan for an aviation turbofan engine are improved under a wide inflow Mach number and a wide reduced speed.

Description

Technical Field

[0001] The present invention belongs to the technical field of aero-engines, and in particular relates to a high-precision, fast-response controllable deformable fan and an optimization method thereof. Background Art

[0002] Future advanced aircraft engine fans must achieve both high aerodynamic performance and wide operating margins across a wide speed range, large airspace, and reduced speed range. Existing technologies typically employ adjustable stator and guide vane technology, where the blades rotate about their axes to adjust the outlet airflow angle, thereby satisfying the inlet airflow direction requirements of the trailing blades and widening the stable operating margin. However, when the stator and guide vane mounting angles are adjusted widely, the angle of attack increases, leading to significant total pressure losses within the stator and guide vanes themselves and disrupting the uniformity and stability of the inlet airflow. Furthermore, variable-camber blades, a special case of adjustable blades, can effectively widen the adjustable blade's outlet airflow angle adjustment range, significantly reducing their own losses and offering the advantage of a large single-actuation deformation. However, they also suffer from two drawbacks: a) gaps between the fixed and rotating portions of variable-camber blades induce significant losses at large rear blade rotation angles; and b) the rear blade's rotation makes it difficult to ensure a continuous and smooth suction and pressure surface, leading to premature flow separation and reduced aerodynamic performance. Summary of the Invention

[0003] In order to solve the shortcomings of the existing mechanical variable-camber blades, the main purpose of the present invention is to provide a deformable fan and optimization method for an aviation turbofan engine, wherein the blades, hub and casing are all composed of a laminated structure composed of carbon fiber and piezoelectric material, and the piezoelectric material is driven by the electrode to drive the entire laminated structure to produce the required micro-deformation of the blades, hub and casing. Through the layout optimization of the piezoelectric material, high-precision micro-deformation of the deformable fan at three levels: local, array and overall can be achieved; through the fast response and large-scale deformation of the three-stage variable-camber blades, a wider adjustment capability of the bending angle, inlet angle of attack and outlet airflow angle can be achieved; in addition, by integrating the advantages of large deformation of variable-camber blades driven by mechanical structure and high deformation accuracy of blades driven by intelligent piezoelectric materials, precise control of blade channel vortices and shock waves can be achieved, flow separation can be further weakened, and the efficiency and stability of the deformable fan for aviation turbofan engines can be improved under a wide inflow Mach number and a wide reduced speed.

[0004] In order to achieve the first objective disclosed in the present invention, the technical solutions adopted are as follows:

[0005] The present invention discloses a deformable fan for an aviation turbofan engine, comprising blades, a hub, and a casing. The blades, hub, and casing are all composed of a laminated structure composed of carbon fiber and piezoelectric material. In the laminated structure, carbon fiber wraps the piezoelectric material and the driving electrode. The piezoelectric material driven by the electrode drives the entire laminated structure to produce the required micro-deformation of the blades, hub, and casing. By optimizing the layout of the piezoelectric material, high-precision micro-deformation of the deformable fan at three levels: local, array, and overall is achieved. The micro-deformation of the blades cannot meet the requirements of variable cycle engines or turboramjet combination engines for efficient and stable operation in a wide speed range and large airspace. A three-stage variable camber blade configuration driven by a mechanical structure is adopted. The three-stage variable camber configuration is based on a multi-hinge connection mechanical structure driven by a motor, which drives the front blade and tail blade to rotate around the axis, achieving fast response and large-scale deformation of the three-stage blade configuration of the front blade, middle blade, and tail blade, thereby achieving a wider adjustment capability of the bending angle, inlet angle of attack, and outlet airflow angle. On the basis of fast response and large-scale deformation, in order to further solve the problems of the three-stage variable camber blade, The configuration has the problem of discontinuous smoothness of the blade surface when rotating. Since the laminated structure of the blade adopts intelligent piezoelectric fiber composite materials, the high-precision micro-deformation of the three-stage variable-curvature blade configuration is achieved by changing the voltage applied to the driving electrode. That is, the three-stage variable-curvature blade configuration combines the advantages of large deformation of variable-curvature blades driven by mechanical structure and high deformation accuracy of blades driven by intelligent piezoelectric materials, thereby achieving precise control of blade channel vortices and shock waves, further weakening flow separation, and improving the efficiency and stability of the deformable fan used in aviation turbofan engines under a wide inflow Mach number and a wide reduced speed.

[0006] The blades are divided into rotor blades and stator blades.

[0007] The present invention discloses a method for operating a deformable fan for an aviation turbofan engine as follows:

[0008] At low reduced speeds or low-speed cruising, the variable-camber blades are driven by a motor to rotate about their axes, increasing the installation angles of the variable-camber rotor leading blades, rotor tail blades, and variable-camber stator leading and tail blades, thereby reducing the rotor and stator blade inlet angle of attack. Furthermore, to meet the fan pressure ratio adjustment requirements, the amount of work performed is increased by reducing the counterclockwise rotation angle β of the rotor tail blades, improving the overall pressure ratio, while increasing the clockwise rotation angle γ of the stator leading blades and reducing the clockwise rotation angle δ of the stator tail blades. Furthermore, to meet the fan pressure ratio adjustment requirements, the amount of work performed is increased by increasing the counterclockwise rotation angle β of the rotor tail blades, reducing the overall pressure ratio, while reducing the clockwise rotation angle γ of the stator leading blades and increasing the clockwise rotation angle δ of the stator tail blades. Furthermore, the static pressure ratio is reduced by increasing the counterclockwise rotation angle β of the rotor tail blades and reducing the overall pressure ratio, while reducing the clockwise rotation angle γ of the stator leading blades and increasing the clockwise rotation angle δ of the stator tail blades. On the other hand, by adjusting the voltage to control the carbon fiber / piezoelectric material laminate structure on the blade surface to produce the required deformation, the overall curvature, thickness, height and chord length of the blade are adjusted to ensure a smooth transition between the front blade, tail blade and middle blade, and to reduce the gap in the seam and weaken the leakage loss; at the same time, the shape of the hub and casing is controlled by voltage changes to increase the flow area, reduce the blade tip clearance, and improve the engine thrust under low-speed cruising.

[0009] At high reduced speeds or high-speed cruising, the variable-camber blades are driven by motors to rotate about their axes, reducing the installation angles of the variable-camber rotor leading blades, tail blades, and the variable-camber stator leading blades and tail blades, thereby reducing the rotor and stator blade inlet angle of attack. Furthermore, to meet the fan pressure ratio adjustment requirements, increasing the clockwise rotation angle β of the rotor tail blades increases the amount of work done and improves the overall pressure ratio, while simultaneously reducing the counterclockwise rotation angle γ of the stator leading blades and increasing the counterclockwise rotation angle δ of the stator tail blades. Reducing the clockwise rotation angle β of the rotor tail blades reduces the amount of work done and reduces the overall pressure ratio, while simultaneously increasing the counterclockwise rotation angle γ of the stator leading blades and reducing the counterclockwise rotation angle δ of the stator tail blades reduces the static pressure ratio. On the other hand, by adjusting the voltage, the carbon fiber / piezoelectric material laminate structure on the blade surface produces the required deformation, thereby adjusting the overall curvature, thickness, height and chord length of the blade, ensuring a smooth transition between the front / tail blade and the middle blade, and reducing the seam gap to weaken the leakage loss; at the same time, by adjusting the shape of the hub and casing through voltage changes, adjusting the flow area and reducing the blade tip clearance, the thrust of the engine under high-speed cruising is adjusted.

[0010] The present invention also discloses a method for optimizing a deformable fan for an aviation turbofan engine, which is used to optimize the deformable fan for the aviation turbofan engine. The method for optimizing a deformable fan for an aviation turbofan engine comprises the following steps:

[0011] a) Determine the engine inflow velocity based on the aircraft's cruising speed. When the inflow velocity or reduced speed is lower than the design value, the leading and trailing blades of the variable-camber stator blades rotate about their axes toward an increased installation angle. When the inflow velocity or reduced speed is higher than the design value, the leading and trailing blades of the variable-camber stator blades rotate about their axes toward a decreased installation angle. Determine the relative velocity direction of the inlet air based on the axial inflow velocity and reduced speed, combined with the velocity triangle. The rotation angle of the leading rotor blades is then determined based on the angle-of-attack loss characteristics. The rotation angle of the trailing rotor blades is also determined based on the overall compression ratio requirements. The rotation angle of the leading stator blades is determined based on the angle-of-attack loss characteristics and the absolute airflow angle at the rotor outlet. The rotation angle of the trailing stator blades is then determined based on the static pressure ratio and outlet airflow direction requirements.

[0012] b) Based on the mechanical characteristics and piezoelectric-driven deformation characteristics of the carbon fiber / piezoelectric material laminate structure, the deformation characteristics of the typical cross-sectional blade profile and blade height of the three-dimensional blade under aerodynamic and centrifugal forces are obtained, and the coupled deformation characteristics of the carbon fiber / piezoelectric material laminate structure under the action of a certain superposition voltage and position layout are obtained.

[0013] c) Based on the three-section variable-camber blade obtained in step b) using a carbon fiber / piezoelectric material laminate structure, and combining the force-deformation characteristics under the two operating conditions described in step a), the deformation characteristics of the blade shape and the gap between the leading and trailing blades and the middle blades under the coupled effects of aerodynamic forces, centrifugal forces, and piezoelectric drive are determined. Furthermore, the aerodynamic loss and pressure ratio characteristics of the deformable fan are obtained using numerical simulation tools. The simulation results are compared with the optimization targets. If the performance does not meet the requirements, the rotation angle of the leading and trailing blades of the stator blades in step a) and the layout of the piezoelectric materials in step b) are adjusted. This process is repeated until the aerodynamic performance meets the required indicators, thereby achieving the optimization of the deformable fan for the aviation turbofan engine.

[0014] By optimizing the layout of piezoelectric materials, high-precision micro-deformation of the deformable fan at the local, array, and overall levels can be achieved. The implementation method is as follows:

[0015] Step 1: By wrapping the piezoelectric material on the blade surface as a whole, the blade thickness, blade curvature, blade angle, blade body curvature, blade height, and blade chord length are adjusted as a whole, thereby achieving an overall adjustment with a relatively large adjustment amount and a wide coverage range.

[0016] Step 2: By placing piezoelectric material in a local area of ​​the blade channel, the blade / channel dihedral angle, local blade curvature, the gap between the leading and trailing blades and the middle blade, or the blade tip gap are controlled to achieve precise adjustment of the adjustment area and a small coverage area. The local area of ​​the blade channel includes the casing, end wall, or suction angle area.

[0017] Step ③: By arranging the piezoelectric material array in the blade channel, the advantages of precise adjustment area and large coverage range are achieved.

[0018] On the basis of achieving the adjustments in steps ①②③ above, by integrating the advantages of large deformation of variable-camber blades driven by mechanical structures and high deformation precision of blades driven by intelligent piezoelectric materials, precise control of vortices and shock waves in the blade channel can be achieved, further weakening flow separation, and improving the efficiency and stability of the deformable fan used in aviation turbofan engines under a wide inflow Mach number and a wide reduced speed.

[0019] Beneficial effects:

[0020] 1. This invention discloses a deformable fan for an aviation turbofan engine and its optimization method. This method combines mechanically structured three-stage variable-camber blades with intelligent piezoelectric fiber deformable blades, leveraging the advantages of both. Large blade deformations are achieved using the mechanically structured variable-camber blades, while small, precise deformations are achieved using the intelligent piezoelectric fiber material. Furthermore, by attaching the intelligent piezoelectric material to the blade surface or directly using a carbon fiber / piezoelectric laminate, the problem of surface discontinuity and smoothness that occurs with traditional mechanical variable-camber blades during rotation is avoided.

[0021] 2. This invention discloses a deformable fan and optimization method for an aviation turbofan engine. This design utilizes a variable camber structure to rapidly adjust the inlet and outlet airflow angles, thereby reorganizing shock waves and vortex structures and ensuring stable fan operation over a wide range of incoming Mach numbers and speeds. Furthermore, piezoelectric materials drive the carbon fiber / piezoelectric laminate blades to undergo high-precision micro-deformation, locally, in arrays, and overall, to regulate shock waves, vortices, and key separation flow structures, further reducing flow separation and ensuring efficient fan operation.

[0022] 3. The present invention discloses a deformable fan and optimization method for an aviation turbofan engine. According to the cruising speed and reduced speed of the deformable fan for the aviation turbofan engine, the fan is divided into two operating modes: low reduced speed or low-speed cruise, and high reduced speed or high-speed cruise. Under low reduced speed or low-speed cruise, on the one hand, by increasing the installation angle of the variable curvature rotor and stator front blades, the inlet angle of attack is reduced, flow separation is weakened, and aerodynamic losses are reduced; on the other hand, according to the pressure ratio requirements, the fan total pressure ratio and static pressure ratio are adjusted by adjusting the installation angle of the rotor and stator tail blades. In addition, by adjusting the voltage to regulate the carbon fiber / piezoelectric material laminated structure on the blade surface to produce the required deformation, the overall curvature, thickness, height and chord length of the blade are adjusted to ensure a smooth transition between the front blade, tail blade and middle blade, and to reduce the gap between the seams and reduce leakage losses; at the same time, by regulating the shape of the hub and casing through voltage changes, the flow area is increased, the blade tip clearance is reduced, and the engine efficiency under low-speed cruise is improved.

[0023] At high reduced speeds or high-speed cruising, on the one hand, the inlet angle of attack is lowered by reducing the variable-camber rotor-stator front blade installation angle, weakening flow separation and reducing aerodynamic losses. On the other hand, according to the required boost ratio, the fan's total pressure ratio and static pressure ratio are adjusted by adjusting the rotor and stator tail blade installation angles. In addition, by adjusting the voltage to produce the required deformation of the carbon fiber / piezoelectric material laminate structure on the blade surface, the overall blade curvature, thickness, height, and chord length are adjusted to ensure a smooth transition between the front / tail blade and the middle blade, and the gap between the seams is reduced to reduce leakage losses. At the same time, by varying the voltage to control the shape of the hub and casing, the flow area is adjusted, the blade tip clearance is reduced, and the engine efficiency at high-speed cruising is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the meridian structure of a deformable fan for an aviation turbofan engine according to the present invention.

[0025] Figure 2 A schematic diagram of the B2B cross-sectional blade profile of a deformed fan for an aviation turbofan engine according to the present invention.

[0026] Among them: 10-front lobe slit, 5-tail lobe rotation axis, 7-piezoelectric material structure, α-front lobe rotation angle, β-tail lobe rotation angle, b1-front lobe axial chord length, b2-middle lobe axial chord length, b3-tail lobe axial chord length.

[0027] Figure 3 A schematic diagram of the rotation adjustment of the front and rear blades of the B2B section rotor and stator of a deformable fan for an aviation turbofan engine of the present invention in a low reduced speed or low speed cruise mode, wherein Figure 3 (a) is a high-precision, fast-response controllable deformable fan rotor at low reduced speed or low-speed cruising. Figure 3 (b) is a high-precision, fast-response controllable deformable fan stator at low reduced speed or low-speed cruising.

[0028] Figure 4 A schematic diagram of the rotation adjustment of the front and rear blades of the B2B section rotor and stator of a deformable fan for an aviation turbofan engine of the present invention in a high reduced speed or high-speed cruise mode, wherein Figure 4 (a) is a high-precision, fast-response controllable deformable fan rotor at high reduced speed or high-speed cruising. Figure 4 (b) is a high-precision, fast-response controllable deformable fan stator under high reduced speed or high-speed cruising.

[0029] Figure 5 Schematic diagram of the cross section of the hollow fan blade with array distributed piezoelectric driven deformation structure of the present invention.

[0030] Among them: 1-variable curvature rotor front blade, 2-variable curvature rotor middle blade, 3-variable curvature rotor tail blade, 4-front blade rotation axis, 5-tail blade rotation axis, 6-variable curvature stator, 7-locally distributed carbon fiber / piezoelectric material laminate structure, 8-array distributed carbon fiber / piezoelectric laminate structure, 9-overall distribution carbon fiber / piezoelectric laminate structure, 10-front blade / middle blade gap, 11-variable curvature stator front blade, 12-variable curvature stator tail blade, 13-variable curvature stator tail blade.

[0031] Figure 6 The present invention discloses a flow chart for optimizing a deformable fan with the characteristics of high precision, fast response and large-scale deformation. DETAILED DESCRIPTION

[0032] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below with reference to the accompanying drawings and examples.

[0033] Example 1:

[0034] like Figures 1 to 5 As shown, this embodiment discloses a deformable fan for an aviation turbofan engine, including a variable curvature rotor front blade 1, a variable curvature rotor middle blade 2, a variable curvature rotor tail blade 3, a front blade rotating shaft 4, a tail blade rotating shaft 5, a variable curvature stator 6, a locally distributed carbon fiber / piezoelectric material laminate structure 7, an array-distributed carbon fiber / piezoelectric laminate structure 8, an overall distributed carbon fiber / piezoelectric laminate structure 9, a front blade / middle blade gap 10, a variable curvature stator front blade 11, a variable curvature stator tail blade 13, and a variable curvature stator tail blade 13.

[0035] The rotors and stators of the deformable fan are all three-section variable-camber blades, and the front blades 1 and the tail blades 3 can rotate around the axes 4 and 5 respectively. Figure 1 As shown, it is possible to achieve rapid and large-scale adjustment of the blade inlet geometric angle and curvature, so as to achieve the purpose of reducing the non-design operating angle of attack and adjusting the boost ratio over a wide range. The blade material is a carbon fiber / piezoelectric laminate structure. According to actual needs, it can be arranged as a locally distributed carbon fiber / piezoelectric material laminate structure 7, an array-distributed carbon fiber / piezoelectric material laminate structure 8, or an overall distributed carbon fiber / piezoelectric material laminate structure 9, as shown in FIG. Figure 1 As shown, by adjusting the electrode voltage, the piezoelectric material is driven to produce the required high-precision deformation: on the one hand, it can be used to change the blade thickness and curvature, thereby regulating the blade loss; on the other hand, it can be used to reduce the gap between the adjustable blade rotor and stator blade tips and the gap between the cambered front tail blade 1 and the middle blade 2, as shown in FIG. Figure 2 As shown, leakage losses are reduced.

[0036] This example discloses a method for operating a deformable fan for an aviation turbofan engine:

[0037] like Figure 3As shown, at low reduced speed or low-speed cruising, the variable-camber blades are driven by a motor to rotate about their axes, increasing the installation angles of the variable-camber rotor leading blades 1 and trailing blades 3, and the variable-camber stator leading blades 11 and trailing blades 13, thereby reducing the rotor and stator blade inlet angle of attack. Furthermore, to meet the fan pressure ratio adjustment requirements, the amount of work performed is increased by reducing the counterclockwise rotation angle β of the rotor trailing blade 3, improving the overall pressure ratio. Meanwhile, the static pressure ratio is increased by increasing the clockwise rotation angle γ of the stator leading blade 11 and reducing the clockwise rotation angle δ of the stator trailing blade 13. Meanwhile, the amount of work performed is reduced by increasing the counterclockwise rotation angle β of the rotor trailing blade 3, reducing the overall pressure ratio. Meanwhile, the static pressure ratio is reduced by reducing the clockwise rotation angle γ of the stator leading blade 11 and increasing the clockwise rotation angle δ of the stator trailing blade 13. On the other hand, by adjusting the voltage to control the carbon fiber / piezoelectric material laminate structure on the blade surface to produce the required deformation, the overall curvature, thickness, height and chord length of the blade are adjusted to ensure a smooth transition between the front / tail blade and the middle blade, and the seam gap is reduced to reduce leakage losses; at the same time, the shape of the hub and casing is controlled by voltage changes to increase the flow area and reduce the blade tip clearance, which helps to improve the engine thrust under low-speed cruising.

[0038] Another working method of a controllable deformable fan with high precision, fast response, and large-scale deformation disclosed in this example is:

[0039] like Figure 4 As shown, at high reduced speeds or high-speed cruising, the variable-camber blades are driven by a motor to rotate about their axes, reducing the installation angles of the variable-camber rotor leading blades 1 and trailing blades 3, and the variable-camber stator leading blades 11 and trailing blades 13, thereby reducing the rotor and stator blade inlet angle of attack. Furthermore, to meet the fan pressure ratio adjustment requirements, increasing the clockwise rotation angle β of the rotor trailing blade 3 increases the amount of work performed and improves the overall pressure ratio, while simultaneously reducing the counterclockwise rotation angle γ of the stator leading blade 11 and increasing the counterclockwise rotation angle δ of the stator trailing blade 13 to improve the static pressure ratio. Reducing the clockwise rotation angle β of the rotor trailing blade 3 reduces the amount of work performed and reduces the overall pressure ratio, while simultaneously increasing the counterclockwise rotation angle γ of the stator leading blade 11 and reducing the counterclockwise rotation angle δ of the stator trailing blade 13 to reduce the static pressure ratio. On the other hand, by adjusting the voltage, the carbon fiber / piezoelectric material laminate structure on the blade surface produces the required deformation, thereby adjusting the overall curvature, thickness, height and chord length of the blade, ensuring a smooth transition between the front / tail blade and the middle blade, and reducing the seam gap to weaken the leakage loss; at the same time, by adjusting the shape of the hub and casing through voltage changes, adjusting the flow area and reducing the blade tip clearance, the thrust of the engine under high-speed cruising is adjusted.

[0040] This embodiment also discloses a method for optimizing a deformable fan for an aviation turbofan engine, which is used to optimize the deformable fan for the aviation turbofan engine. Figure 6 As shown, the following steps are included:

[0041] a) Determine the engine inflow velocity based on the aircraft's cruising speed. When the inflow velocity or reduced speed is lower than the design value, the leading blades 1 and 11, and the trailing blades 3 and 13 of the variable-camber stator blades rotate about their axes toward an increased installation angle. When the inflow velocity or reduced speed is higher than the design value, the leading blades 1 and 11, and the trailing blades 3 and 13 of the variable-camber stator blades rotate about their axes toward a decreased installation angle. Determine the relative velocity direction of the inlet air based on the axial inflow velocity and reduced speed, combined with the velocity triangle. The rotation angle of the rotor leading blade 1 is then determined based on the angle-of-attack loss characteristics. The rotation angle of the rotor trailing blade 3 is also determined based on the overall compression ratio requirements. The rotation angle of the leading blade 11 is determined based on the angle-of-attack loss characteristics of the stator blades and the absolute airflow angle at the rotor outlet. The rotation angle of the trailing blade 13 is then determined based on the static pressure ratio and outlet airflow direction requirements.

[0042] b) Based on the mechanical characteristics and piezoelectric-driven deformation characteristics of the carbon fiber / piezoelectric material laminate structure, the deformation characteristics of the typical cross-sectional blade profile and blade height of the three-dimensional blade under aerodynamic and centrifugal forces are obtained, and the coupled deformation characteristics of the carbon fiber / piezoelectric material laminate structure under the action of a certain superposition voltage and position layout are obtained.

[0043] c) Based on step b), a three-section variable-camber blade using a carbon fiber / piezoelectric material laminate structure is obtained. Combined with the force-deformation characteristics under the two operating conditions described in step a), the deformation characteristics of the blade shape, the gaps between the leading rotor blades 1 and 11, the tail blades 3 and 13, and the middle blades 2 and 12 under the coupled effects of aerodynamic forces, centrifugal forces, and piezoelectric drive are obtained. Furthermore, the aerodynamic losses and pressure ratio characteristics of the deformable fan are obtained using numerical simulation tools. The simulation results are compared with the optimization targets. If the performance does not meet the requirements, the rotation angles of the leading rotor blades 1, 3, 11, and 13 in step a) and the layout of the piezoelectric materials 7, 8, and 9 in step b) are adjusted. This process is repeated until the aerodynamic performance meets the required index, thereby achieving the optimization of the deformable fan for the aviation turbofan engine.

[0044] By optimizing the layout of piezoelectric materials, high-precision micro-deformation of the deformable fan at the local, array, and overall levels can be achieved. The implementation method is as follows:

[0045] Step 1: By wrapping the piezoelectric material on the blade surface as a whole, the blade thickness, blade curvature, blade angle, blade body curvature, blade height, and blade chord length are adjusted as a whole, thereby achieving an overall adjustment with a relatively large adjustment amount and a wide coverage range.

[0046] Step 2: By placing piezoelectric material in a localized area of ​​the blade passage, the blade / passage dihedral angle, local blade curvature, and the gaps or tip clearances between leading and trailing blades 1, 3, 11, and 13, and between middle blades 2 and 12, precise adjustment of the adjustment area and a small coverage area is achieved. The localized blade passage includes the casing, end wall, or suction angle area.

[0047] Step ③: By arranging the piezoelectric material array in the blade channel, the advantages of precise adjustment area and large coverage range are achieved.

[0048] On the basis of achieving the adjustments in steps ①②③ above, by integrating the advantages of large deformation of variable-camber blades driven by mechanical structures and high deformation precision of blades driven by intelligent piezoelectric materials, precise control of vortices and shock waves in the blade channel can be achieved, further weakening flow separation, and improving the efficiency and stability of the deformable fan used in aviation turbofan engines under a wide inflow Mach number and a wide reduced speed.

[0049] The above specific description further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A deformable fan for an aviation turbofan engine, characterized by: The invention comprises blades, a hub and a casing; the blades, the hub and the casing are all composed of a laminated structure composed of carbon fiber and piezoelectric material; in the laminated structure, the carbon fiber wraps the piezoelectric material and the driving electrode; The electrodes drive the piezoelectric material to drive the entire laminate structure to produce the micro-deformation required for the blades, hub and casing; A three-stage variable-camber blade configuration driven by a mechanical structure is adopted. The three-stage variable-camber blade configuration is based on a multi-hinge connection mechanical structure driven by a motor to drive the front and rear blades to rotate around the axis; The blades are divided into rotor blades and stator blades; By optimizing the layout of piezoelectric materials, high-precision micro-deformation of the deformable fan at the local, array, and overall levels is achieved. The implementation method is as follows: Step 1: By wrapping the piezoelectric material on the surface of the blade as a whole, the blade thickness, blade camber, blade angle, blade body curvature, blade height, and blade chord length are adjusted as a whole, achieving an overall adjustment with a relatively large adjustment amount and a wide coverage range; Step 2: By placing piezoelectric materials in a local area of ​​the blade channel, the blade / channel dihedral angle, the local blade curvature, the gap between the leading and trailing blades and the middle blades, or the blade tip gap are controlled to achieve precise adjustment of the adjustment area and a small coverage area; the local blade channel includes the casing, end wall, or suction surface angle area; Step 3: By arranging the piezoelectric material array in the blade channel, the advantages of precise adjustment area and wide coverage are achieved; On the basis of achieving the adjustments in steps ①②③ above, by integrating the advantages of large deformation of variable-camber blades driven by mechanical structures and high deformation precision of blades driven by intelligent piezoelectric materials, precise control of vortices and shock waves in the blade channel can be achieved, further weakening flow separation, and improving the efficiency and stability of the deformable fan used in aviation turbofan engines under a wide inflow Mach number and a wide reduced speed.

2. The deformable fan for an aviation turbofan engine according to claim 1, characterized in that: At low reduced speed or low-speed cruising, the variable-curvature blades are driven by an electric motor to rotate around the axis, thereby increasing the installation angles of the variable-curvature rotor front blades, rotor tail blades, and variable-curvature stator front blades and stator tail blades, respectively, thereby reducing the rotor and stator blade inlet angle of attack; further, in response to the fan pressure ratio adjustment requirements, the amount of work is increased by reducing the counterclockwise rotation angle β of the rotor tail blades, and the total pressure ratio is improved. At the same time, the static pressure ratio is improved by increasing the clockwise rotation angle γ of the stator front blades and reducing the clockwise rotation angle δ of the stator tail blades; the amount of work is reduced by increasing the counterclockwise rotation angle β of the rotor tail blades. , reduce the total boost ratio and at the same time reduce the static pressure ratio by reducing the clockwise rotation angle γ of the front stator blade and increasing the clockwise rotation angle δ of the tail stator blade; on the other hand, by adjusting the voltage to regulate the carbon fiber / piezoelectric material laminate structure on the blade surface to produce the required deformation, thereby adjusting the overall curvature, thickness, height and chord length of the blade to ensure a smooth transition between the front blade, tail blade and middle blade, and reducing the gap in the seam to reduce leakage loss; at the same time, by regulating the shape of the hub and casing through voltage changes, the flow area is increased, the blade tip clearance is reduced, and the engine thrust under low-speed cruising is improved; At high reduced speed or high-speed cruising, the variable-curvature blades are driven by an electric motor to rotate around the axis, and the installation angles of the variable-curvature rotor front blade, tail blade and variable-curvature stator front blade and tail blade are reduced respectively, thereby reducing the rotor and stator blade inlet angle of attack; further, in response to the fan pressure ratio adjustment demand, the amount of work is increased and the total pressure ratio is improved by increasing the clockwise rotation angle β of the rotor tail blade, while the static pressure ratio is improved by reducing the counterclockwise rotation angle γ of the stator front blade and increasing the counterclockwise rotation angle δ of the stator tail blade; the amount of work is reduced and the total pressure ratio is reduced by reducing the clockwise rotation angle β of the rotor tail blade The static pressure ratio is reduced by increasing the counterclockwise rotation angle γ of the front stator blade and reducing the counterclockwise rotation angle δ of the tail stator blade. On the other hand, the voltage is adjusted to regulate the carbon fiber / piezoelectric material laminate structure on the blade surface to produce the required deformation, thereby adjusting the overall curvature, thickness, height and chord length of the blade to ensure a smooth transition between the front / tail blade and the middle blade, and reducing the seam gap to reduce leakage loss. At the same time, the hub and casing shape are regulated by voltage changes, the flow area is adjusted, and the blade tip clearance is reduced, thereby adjusting the thrust of the engine at high-speed cruising.

3. A method for optimizing a deformable fan for an aviation turbofan engine, for optimizing the deformable fan for an aviation turbofan engine according to claim 1, characterized in that: The following steps are included: The engine inflow velocity is determined according to the cruising speed of the aircraft. When the inflow velocity or the reduced speed is lower than the design value, the front and tail blades of the variable-curvature stator blades rotate around the axis in the direction of increasing the installation angle; when the inflow velocity or the reduced speed is higher than the design value, the front and tail blades of the variable-curvature stator blades rotate around the axis in the direction of decreasing the installation angle; according to the axial inflow velocity and the reduced speed, the relative speed direction of the intake air is determined in combination with the speed triangle, and the rotation angle of the rotor front blade is determined in combination with the angle of attack loss characteristics, and the rotation angle of the rotor tail blade is determined in combination with the total compression ratio requirement; the rotation angle of the stator front blade is determined according to the angle of attack loss characteristics of the stator blade and the absolute airflow angle of the rotor outlet, and the rotation angle of the stator tail blade is determined according to the static pressure ratio and the outlet airflow direction requirements; b) Based on the mechanical characteristics and piezoelectric-driven deformation characteristics of the carbon fiber / piezoelectric material laminate structure, the deformation characteristics of the typical cross-sectional profile and blade height of the three-dimensional blade under aerodynamic and centrifugal forces are obtained, and the coupled deformation characteristics of the carbon fiber / piezoelectric material laminate structure under the action of a certain superposition voltage and position layout are obtained; c) Based on the three-section variable-camber blade using a carbon fiber / piezoelectric material laminate structure obtained in step b), combined with the stress-deformation characteristics under the two working conditions in step a), the deformation characteristics of the blade shape and the gap between the leading and trailing blades / middle blades under the coupling of aerodynamic force, centrifugal force and piezoelectric drive are obtained, and the aerodynamic loss and pressure ratio characteristics of the deformable fan are obtained through numerical simulation tools; the simulation results are compared with the optimization target. If the performance does not meet the requirements, the rotation angle of the leading and trailing blades of the stator blades in step a) and the layout of the piezoelectric materials in step b) are adjusted, and the process is repeated until the aerodynamic performance meets the index requirements, thereby achieving the optimization of the deformable fan for the aviation turbofan engine.

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