Variable camber blade with wide-range self-adaptability

Abstract

The invention discloses a variable camber blade with wide-range self-adaptability. The variable camber blade comprises a front blade, a rear blade, a front blade jet device, a rear blade jet device and a rear blade rotating axis. The rear blade can rotate around the rotating axis by a set angle so as to adjust the overall bending degree of the blade. The front blade jet device and the rear blade jet device are respectively arranged near the front edges of the front blade and the rear blade; the jet energy of the front blade jet device and the jet energy of the rear blade jet device both come from the pressure difference between the blade pressure face and the suction face. The jet device can be in a slotted form or a fluid oscillator form, and the position and the jet angle of the jet device are preferably selected; on the premise of ensuring that the structure of the variable camber blade is simple, the variable camber blade can maintain low flow loss in a wide working range through coupling the jet intensity of the front blade jet device and the rear blade jet device with the pressure difference of the positions where the front blade jet device and the rear blade jet device are located and the working state of the blade.

Description

Technical Field

[0001] The invention relates to a variable-camber blade with wide-range adaptability, belonging to the technical field of compressors. Background Art

[0002] The development trend of advanced aircraft engines demands ever-higher thrust-to-weight ratios, higher efficiency, and higher reliability. However, the core component, the high-load multi-stage axial-flow compressor, experiences significant variations in rotor angle of attack under off-design conditions (particularly at low and medium speeds), which can easily induce compressor surge and severely restrict the engine's stable operating margin. To ensure adequate surge margin at low and medium speeds, modern high-load compressors commonly utilize multiple rows of variable stator vanes (VSV). By adjusting the stator vane mounting angle, the rotor inflow angle of attack is altered, thereby adjusting stage matching and load distribution and suppressing surge. For example, advanced civil engine compressors such as the LEAP-X and GE9X utilize five and six rows of variable stator vanes, respectively.

[0003] Existing adjustable stator blades are mainly divided into two types: constant camber and variable camber. Constant camber blades adjust the outlet airflow angle by changing the installation angle through overall rotation. This adjustment method inevitably destroys the original aerodynamic design of the blade while changing the angle of attack, resulting in increased flow losses on the blade surface, especially at larger adjustment angles, where performance decreases significantly. Variable camber blades usually adopt a segmented structure (such as front and rear blades) and leave gaps at the joints. The front section is fixed, and the rear section can be rotated around a specific axis to a set angle to change the overall camber of the blade. In theory, it can better maintain the aerodynamic characteristics of the blade while adjusting the airflow angle.

[0004] However, existing variable camber blade designs still face significant adaptability challenges under a wide range of operating conditions. When faced with a large incoming flow angle (for example, corresponding to medium and low compressor speed conditions), flow separation is very likely to occur on the suction surface of the front blade; when the rear blade is rotated at a larger angle, the suction surface of the rear blade is also faced with a higher risk of flow separation. These flow separation phenomena will not only directly lead to additional aerodynamic losses and reduce the overall efficiency of the compressor, but more importantly, they will seriously weaken the stable operating margin of the compressor and increase the risk of surge. Therefore, how to effectively suppress the flow separation of variable camber blades (especially in the key areas of the front and rear blades) within a wide range of operating conditions (covering different incoming flow angles and rear blade rotation angles) and improve their aerodynamic performance and stability is a key problem that urgently needs to be overcome in this technical field. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a variable-camber blade with wide-range adaptability, so that the variable-camber blade can maintain high aerodynamic performance under different incoming flow angles and rear blade rotation angles, thereby improving the aerodynamic efficiency and stability margin of the engine.

[0006] To achieve the above object, the present invention is implemented by adopting the following technical solutions: The present invention provides a variable camber blade with wide-range adaptability, comprising: a front blade, a rear blade, a front blade ejector, a rear blade ejector, and a rear blade rotation axis; the rear blade can rotate around the rear blade rotation axis to a set angle θ , to change the overall curvature of the blade; the front blade ejector is arranged near the leading edge of the front blade, and the rear blade ejector is arranged near the leading edge of the rear blade; the jet energy of the front blade ejector and the rear blade ejector are both derived from the pressure difference between the pressure surface and the suction surface of the blade, which is a passive flow control and does not require the introduction of an external air source; the jet intensity of the front blade ejector and the rear blade ejector is coupled with the pressure difference at their position and the working state of the blade, so that the variable curvature blade maintains a low flow loss within a wide working range.

[0007] Furthermore, the blade flow angle α The working range is 0~ α max ,in α max is the design maximum value, and 0°< α max ≤50°; rear blade rotation angle θ The working range is 0~ θ max ,in θ max is the design maximum value, and 0°< θ max ≤50°.

[0008] Furthermore, the blades have four typical working modes: a. When the blade incoming flow angle α ≈0° and the rear blade angle θ When ≈0°, the front blade ejector and the rear blade ejector basically do not produce jet; b. When the blade incoming flow angle α ≈0° and rear blade angle θ When the angle is >0°, the ejector of the front blade basically does not produce any jet, while the ejector of the rear blade produces a jet; c. When the blade incoming flow angle α >0° and rear blade angle θWhen ≈0°, both the front blade ejector and the rear blade ejector produce jets; d. When the blade flow angle α >0° and rear blade angle θ When the angle is >0°, both the front blade ejector and the rear blade ejector generate jets.

[0009] Furthermore, the jet intensity generated by the front blade ejector varies with the blade incoming flow angle within the working range. α The jet intensity generated by the rear blade ejector increases with the increase of α + θ Increase and grow.

[0010] Furthermore, the front blade ejector and the rear blade ejector are in the form of a slotted form for generating a steady jet or a fluid oscillator form for generating an unsteady jet; The slit form includes a jet slit; The fluid oscillator comprises an air inlet, a mixing cavity, a feedback loop and a jet port; the air inlet, the mixing cavity and the jet port are connected in sequence, and the feedback loop is respectively connected to the input end and the output end of the mixing cavity.

[0011] Furthermore, when α max <30°, the front blade ejector is preferably in the form of a slot; when α max When the angle is ≥30°, the front blade ejector is preferably in the form of a fluid oscillator; when( α max + θ max )<30°, the rear blade ejector is preferably in the form of a slot; when ( α max + θ max )≥30°, the rear blade ejector is preferably in the form of a fluid oscillator.

[0012] Furthermore, the front blade ejector inlet is located at the front blade chord coordinate x in1 =0.01 c 1~0.4 c 1. The outlet is located at the chord coordinate of the front blade x out1 =0.01 c 1~0.4 c 1, and | x out1 - x in1 |<0.2c1, where c 1 is the chord length of the front blade; The rear blade ejector inlet is located at the rear blade chord coordinate x in2 =0.01 c 2~0.4 c 2. The outlet is located at the chord coordinate of the rear blade x out2 =0.01 c 2~0.4 c 2, and | x out2 - x in2 |<0.2 c 2, among which c 2 is the chord length of the rear blade.

[0013] Furthermore, the angles between the outlet jet directions of the front blade ejector and the outlet jet directions of the rear blade ejector and the tangent directions of the corresponding blade surfaces at the outlet positions are respectively β 1 and β 2, among which β 1=5°~45°, β 2=5°~45°.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention integrates passive ejectors at the leading edges of the front and rear blades of variable camber blades, achieving adaptive improvement in aerodynamic performance over a wide range of operating conditions. Its core benefits are: a. High efficiency in the design state: When the blades are at the design angle of attack and the rear blade rotation angle is zero, the pressure difference between the ejector inlet and outlet approaches zero, and the jet basically does not work or the intensity is extremely weak, effectively avoiding the additional flow loss introduced by the jet and ensuring high efficiency operation at the design point.

[0015] b. Off-design Adaptability: When the blades encounter off-design operating conditions, such as high incoming flow angles or large trailing blade rotation angles, flow separation can occur on the suction surfaces of the leading and trailing blades. In these situations, a significant pressure gradient automatically develops between the ejector inlet and outlet, stimulating the generation of a steady or unsteady jet. This jet effectively suppresses flow separation on the suction surface, significantly improving the blade's aerodynamic performance and stability under these complex operating conditions.

[0016] c. Comprehensive Technical Advantages: This solution has a relatively simple structure, requiring no external active control. It is adaptable to a wide range of operating conditions. The jet generation and intensity are automatically triggered and adjusted by operating conditions, demonstrating strong adaptability. It is easy to implement and has excellent practical value. Ultimately, it achieves a comprehensive improvement in the aerodynamic efficiency of variable-camber blades across the entire operating range. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1It is a schematic diagram of a variable-camber blade with wide-range adaptability (incoming flow with zero angle of attack, rear blades rotated to a set angle, front blades slotted, and rear blades equipped with a fluid oscillator).

[0018] Figure 2 It is a schematic diagram of a blade with wide-range adaptability and variable camber (the incoming flow has zero angle of attack, the rear blade has no rotation angle, and both the front and rear blades are slotted).

[0019] Figure 3 It is a schematic diagram of a variable-camber blade with wide-range adaptability (positive attack angle of incoming flow, no rotation angle of the rear blade, fluid oscillator installed on the front blade, and slotted rear blade).

[0020] Figure 4 It is a schematic diagram of a variable-camber blade with wide-range adaptability (working conditions of positive attack angle of incoming flow, rotation of rear blade to set angle, and fluid oscillators installed on both front and rear blades).

[0021] Figure 5 This is a partial enlarged view of the blade using a slotted ejector.

[0022] Figure 6 This is a partial enlarged view of the blade using a fluid oscillator ejector.

[0023] Figure 7 It is a schematic diagram of the main geometric parameters of a blade with wide-range adaptive variable camber.

[0024] In the figure: 1, front blade; 2, rear blade; 3, front blade ejector; 4, rear blade ejector; 5, rear blade rotation axis; 6, ejection slot; 7, air inlet; 8, mixing chamber; 9, feedback loop; 10, ejection port; α , incoming flow angle of attack; θ , rear blade rotation angle; c 1. Chord length of the front blade; c 2. Chord length of the rear blade; x in1 , chordwise coordinate of the front blade ejector inlet; x in2 , chordwise coordinate of the inlet of the rear blade ejector; x out1 , chordwise coordinate of the front blade ejector outlet; x out2 , chordwise coordinate of the outlet of the rear blade ejector; β 1. The angle between the jet direction at the front blade ejector outlet and the tangent direction of the blade surface; β 2. The angle between the jet direction at the outlet of the rear blade ejector and the tangent direction of the blade surface. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0027] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0028] Example 1, as Figure 1 As shown, this embodiment introduces a variable camber blade with wide-range adaptability, which includes: a front blade 1, a rear blade 2, a front blade ejector 3, a rear blade ejector 4, and a rear blade rotation axis 5. The rear blade 2 can rotate around the rear blade rotation axis 5 to a set angle. θ , to change the overall curvature of the blade; the front blade ejector 3 is arranged near the leading edge of the front blade 1, and the rear blade ejector 4 is arranged near the leading edge of the rear blade 2; the jet energy of the front blade ejector 3 and the rear blade ejector 4 is derived from the pressure difference between the pressure surface and the suction surface of the blade, which is a passive flow control and does not require the introduction of an external air source; the jet intensity of the front blade ejector 3 and the rear blade ejector 4 is coupled with the pressure difference at their position and the working state of the blade, so that the variable curvature blade maintains a low flow loss within a wide working range.

[0029] like Figure 3 As shown, the blade flow angle α The working range is 0~α max ,in α max is the design maximum value, and 0°< α max ≤50°. Figure 1 As shown, the rear blade 2 rotates at an angle of θ The working range is 0~ θ max ,in θ max is the design maximum value, and 0°< θ max ≤50°.

[0030] The variable camber blade with wide-range adaptability has four typical working modes: like Figure 2 As shown, when the blade incoming flow angle α ≈0° and the rear blade angle θ When ≈0° (i.e., under design conditions), the inlet and outlet pressure differences of the front blade ejector 3 and the rear blade ejector 4 are close, and basically no jet is generated, thereby reducing the flow loss inside the ejector under design conditions.

[0031] like Figure 1 As shown, when the blade incoming flow angle α ≈0° and rear blade angle θ When the angle is >0° (large blade curvature state), the pressure difference between the inlet and outlet of the front blade ejector 3 is close, and basically no jet is generated; the rear blade ejector 4 has a significant inlet and outlet pressure difference, thereby generating a jet, which can suppress the flow separation on the suction surface of the rear blade.

[0032] like Figure 3 As shown, when the blade incoming flow angle α >0° and rear blade angle θ When ≈0° (large blade angle of attack), both the front blade ejector 3 and the rear blade ejector 4 have significant inlet and outlet pressure differences, thereby generating jets to suppress flow separation at the suction surface of the front or rear blade.

[0033] like Figure 4 As shown, when the blade incoming flow angle α >0° and rear blade angle θ When the angle of attack is greater than 0° (the blade has a large camber state), both the front blade ejector 3 and the rear blade ejector 4 have a significant inlet and outlet pressure difference, thereby generating a jet to suppress the flow separation at the suction surface of the front and rear blades.

[0034] like Figures 1 to 4 As shown, the pressure difference between the inlet and outlet of the front blade ejector 3 changes with the blade flow angle within the working range. αThe jet intensity also increases with the blade flow angle. α Similarly, the jet intensity generated by the rear blade ejector 4 increases with the increase of α + θ Increase and grow.

[0035] The front blade ejector 3 and the rear blade ejector 4 are in the form of a slot for generating a steady jet or a fluid oscillator for generating an unsteady jet.

[0036] like Figure 5 As shown, the slit form includes a jet slit 6; like Figure 6 As shown, the fluid oscillator comprises an air inlet 7, a mixing chamber 8, a feedback loop 9 and a jet port 10. The air inlet 7, the mixing chamber 8 and the jet port 10 are connected in sequence, and the feedback loop 9 is connected to the input end and the output end of the mixing chamber 8 respectively.

[0037] like Figure 1 Or 2, when α max <30°, the front blade ejector 3 is preferably in the form of a slot; Figure 3 Or as shown in 4, when α max When the angle is ≥30°, the front blade ejector 3 is preferably in the form of a fluid oscillator.

[0038] like Figure 2 Or as shown in 3, when ( α max + θ max )<30°, the rear blade ejector 4 is preferably in the form of a slot; Figure 1 Or as shown in 4, when ( α max + θ max )≥30°, the rear blade ejector 4 is preferably in the form of a fluid oscillator.

[0039] like Figure 7 As shown, the inlet of the front blade ejector 3 is located at the chord coordinate of the front blade 1 x in1 =0.01 c 1~0.4 c 1. The outlet is located at the chord coordinate of the front blade 1 x out1 =0.01 c 1~0.4 c 1, and | x out1 - x in1 |<0.2c1, wherec 1 is the chord length of the front blade 1. The inlet of the rear blade ejector 4 is located at the chord coordinate of the rear blade 2 x in2 =0.01 c 2~0.4 c 2. The outlet is located at the chord coordinate of the rear blade 2 x out2 =0.01 c 2~0.4 c 2, and | x out2 - x in2 |<0.2 c 2, among which c 2 is the chord length of the rear blade 2.

[0040] like Figure 7 As shown, the angles between the outlet jet directions of the front blade ejector 3 and the rear blade ejector 4 and the tangent direction of the corresponding blade surface at the outlet position are respectively β 1 and β 2, among which β 1=5°~45°, β 2=5°~45°.

[0041] The following describes the contents involved in the above embodiment in conjunction with a preferred embodiment.

[0042] like Figure 1 As shown, based on a typical conventional variable camber blade, the chord length of the front blade is c 1=30 mm, rear blade chord length c 2=30 mm, designed maximum incoming flow angle of attack α max =10°, the maximum turning angle of the blade after design θ max =40°, the front blade adopts slotted ejector (such as Figure 5 ), where the chordwise coordinate of the front blade ejector inlet is x in1 =3 mm, chordwise coordinate of the front blade ejector outlet x out1 =6 mm; the rear blade adopts a fluid oscillator ejector (such as Figure 6 ), where the chordwise coordinate of the rear blade ejector inlet is x in2 =3 mm, chordwise coordinate of the rear blade ejector outlet x out2 =6 mm. In the design state ( α =0° and θ=0°), the front and rear blade ejectors basically do not produce jets. In the non-design state ( α >0° and θ >0°), the ejector on the front blade produces a steady jet, and the ejector on the rear blade produces an unsteady jet, which can effectively suppress the flow separation at the suction surfaces of the front and rear blades.

[0043] The working principle of a variable camber blade with wide-range adaptability is as follows: the front blade ejector 3 of the device is set near the leading edge of the front blade 1, and the rear blade ejector 4 is set near the leading edge of the rear blade 2. The jet energy of both is derived from the pressure difference between the pressure surface and the suction surface of the blade. It is a passive flow control and does not require the introduction of an external air source. The rear blade 2 can rotate around its rear blade rotation axis 5 by an angle of θ To change the overall curvature. Within the working range, the pressure difference between the inlet and outlet of the front blade ejector 3 changes with the blade incoming flow angle. α The jet intensity also increases with the blade flow angle. α Similarly, the jet intensity generated by the rear blade ejector 4 increases with α + θ Since the inlet and outlet of ejectors 3 and 4 are close to each other in the chord direction of the blade, under the design working condition, the ejector basically does not produce any jet, thus avoiding additional flow loss. Under the non-design working condition, the flow separation strength of the suction surface of the front blade 1 is related to the incoming flow angle. α Positive correlation, the flow separation strength of the suction surface of the rear blade 2 is α + θ The constant or unsteady jets generated by the front blade ejector 3 and the rear blade ejector 4 can effectively suppress flow separation on the corresponding blade. Therefore, through the jet action of the front blade ejector 3 and the rear blade ejector 4 and the coupling design with flow separation, adaptive flow control of the variable camber blade is achieved, thereby maintaining low operating flow losses over a wide operating range.

[0044] The innovation of the present invention is that it proposes an effective solution to the problem that airflow separation is prone to occur on the suction surfaces of the front blade and the rear blade of a variable-curvature blade at a large angle of attack or large curvature. Specifically, a slot or fluid oscillator structure is provided in the leading edge region of the front blade and the rear blade. By utilizing the characteristic that the pressure difference between the inlet and outlet of the structure increases significantly under large angles of attack or large curvature conditions, a steady or unsteady jet is induced. The jet directly acts on the boundary layer of the suction surface of the front blade or the rear blade, effectively suppressing the occurrence of flow separation. On the one hand, this solution significantly improves the aerodynamic performance of the variable-curvature blade under large angles of attack or large curvature conditions; on the other hand, under the design state (zero angle of attack and zero curvature), due to the small pressure difference between the inlet and outlet, the slot or fluid oscillator structure will not generate significant internal flow, thereby avoiding the additional flow loss caused thereby.

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A variable camber blade with wide-range adaptability, characterized in that: include: A front blade (1), a front blade (1), a rear blade (2), a front blade ejector (3), a rear blade ejector (4), and a rear blade rotation axis (5), wherein the rear blade (2) can rotate around the rear blade rotation axis (5) to a set angle θ , so as to change the overall curvature of the blade; the front blade ejector (3) is arranged at one end of the front blade (1) close to the leading edge, and the rear blade ejector (4) is arranged at one end of the rear blade (2) close to the leading edge; Wherein, the jet energy of the front blade ejector (3) and the rear blade ejector (4) both comes from the pressure difference between the pressure surface and the suction surface of the blade; The jet intensities of the front blade ejector (3) and the rear blade ejector (4) are coupled with the pressure difference at their locations and the working state of the blades.

2. The variable camber blade with wide-range adaptability according to claim 1, characterized in that: The incoming flow angle of the front blade (1) α The working range is 0~ α max ,in α max is the design maximum value, and 0°< α max ≤50°.

3. The variable camber blade with wide-range adaptability according to claim 2, characterized in that: The rotation angle of the rear blade (2) θ The working range is 0~ θ max ,in θ max is the design maximum value, and 0°< θ max ≤50°.

4. The variable camber blade with wide-range adaptability according to claim 3, characterized in that: The blades have four working modes: When the blade flow angle α ≈0° and the rear blade angle θ When ≈0°, the front blade ejector (3) and the rear blade ejector (4) do not generate jets; When the blade flow angle α ≈0° and rear blade angle θ When the angle is >0°, the front blade ejector (3) does not generate a jet, and the rear blade ejector (4) generates a jet; When the blade flow angle α >0° and rear blade angle θ At ≈0°, both the front blade ejector (3) and the rear blade ejector (4) generate jets; When the blade flow angle α >0° and rear blade angle θ When the angle is >0°, both the front blade ejector (3) and the rear blade ejector (4) generate jets.

5. The variable camber blade with wide-range adaptability according to claim 3, characterized in that: The jet intensity generated by the front blade ejector (3) varies with the blade incoming flow angle within the working range. α The jet intensity generated by the rear blade ejector (4) increases with the working range. α + θ Increase and grow.

6. The variable camber blade with wide-range adaptability according to claim 1, characterized in that: The front blade ejector (3) and the rear blade ejector (4) are in the form of a slotted ejector for generating a steady jet or a fluid oscillator for generating an unsteady jet, wherein: The slit form includes a jet slit (6); The fluid oscillator comprises an air inlet (7), a mixing chamber (8), a feedback loop (9) and a jet port (10), wherein the air inlet (7), the mixing chamber (8) and the jet port (10) are connected in sequence, and the feedback loop (9) is respectively connected to the input end and the output end of the mixing chamber (8).

7. The variable camber blade with wide-range adaptability according to claim 6, characterized in that: when α max <30°, the front blade ejector (3) is in the form of a slot; when α max When the angle is ≥30°, the front blade ejector (3) is in the form of a fluid oscillator; when( α max + θ max )<30°, the rear blade ejector (4) is in the form of a slot; when ( α max + θ max )≥30°, the rear blade ejector (4) is in the form of a fluid oscillator.

8. The variable camber blade with wide-range adaptability according to claim 7, characterized in that: The inlet of the front blade ejector (3) is located at the chord coordinate of the front blade (1) x in1 =0.01 c 1~0.4 c 1. The outlet is located at the chord coordinate of the front blade (1) x out1 =0.01 c 1~0.4 c 1, and | x out1 - x in1 |<0.2c1, where c 1 is the chord length of the front blade (1).

9. The variable camber blade with wide-range adaptability according to claim 8, characterized in that: The inlet of the rear blade ejector (4) is located at the chord coordinate of the rear blade (2) x in2 =0.01 c 2~0.4 c 2. The outlet is located at the chord coordinate of the rear blade (2) x out2 =0.01 c 2~0.4 c 2, and | x out2 - x in2 |<0.2 c 2, among which c 2 is the chord length of the rear blade (2).

10. The variable camber blade with wide-range adaptability according to claim 9, characterized in that: The angles between the outlet jet directions of the front blade ejector (3) and the outlet jet directions of the rear blade ejector (4) and the tangent directions of the corresponding blade surfaces at the outlet positions are respectively β 1 and β 2, among which β 1=5°~45°, β 2=5°~45°.

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