A slotted blade with variable attack angle jet automatic start-stop

Abstract

The application discloses a slotted blade with variable attack angle jet flow automatic start-stop, which comprises a compressor blade, a bleed air port, a jet flow port, a jet flow slit, a movable valve, an anti-rotation elastic element, an elastic element groove, a stop step and a hinge; wherein the bleed air port is located on the blade basin side of the compressor blade, the jet flow port is located on the blade back side of the compressor blade, the jet flow slit is connected and penetrates the bleed air port and the jet flow port, the elastic element groove is arranged on the left side of the jet flow slit, the movable valve is installed in the elastic element groove through the anti-rotation elastic element and the hinge, and the stop step is arranged on the right side wall surface of the jet flow slit. According to the application, the jet flow can be automatically started and stopped according to different attack angles without introducing external air source or power supply, so that the external flow separation can be well inhibited under the large attack angle working condition, and the internal flow loss can be maintained to be low when there is no separation under the low attack angle.

Description

Technical Field

[0001] This invention relates to a slotted blade for automatic start-stop of variable angle-of-attack jets, belonging to the field of compressor technology. Background Technology

[0002] In various axial compressors used in applications such as aero gas turbine engines, achieving higher pressure ratios in single-stage compressors has long been a development trend in the compressor field. Historically, increasing the stage pressure ratio of a compressor has primarily been achieved through aerodynamic optimization, such as increasing blade rim velocity and airfoil design. However, the improvement of blade rim velocity is limited by material strength limits, and aerodynamic optimization of airfoil design offers limited performance enhancements at current design levels. When attempting to significantly increase the load on a single-stage compressor beyond current levels, flow separation on the blade back side can occur, causing a sharp drop in compressor pressure ratio and efficiency, and even compressor stall. Therefore, various flow control technologies that can suppress or even eliminate flow separation have received considerable attention from researchers both domestically and internationally.

[0003] Based on existing work in the field of unsteady flow control both domestically and internationally, the relevant technologies can be mainly divided into two categories: (1) Passive flow control technologies, such as slotted blades, tandem blades, stirrups, eddy current generators, etc. (2) Active flow control technologies, such as adsorption compressors, synthetic jets, acoustic excitation, plasma excitation, traveling wave wall control, etc.

[0004] To meet the needs of future compressor blade designs at higher loads, these technologies have significant shortcomings in practical engineering applications. Passive flow control technology is characterized by not requiring external energy input and boasts advantages such as simple structure, ease of implementation, and long lifespan. However, its main drawback is that flow control parameters cannot be adjusted according to changes in operating conditions. For example, although slotted blades typically have lower flow losses than seamless blades under flow separation conditions, in the absence of flow separation, the additional frictional losses within the slots result in greater flow losses for slotted blades compared to seamless blades. Similarly, while mixed-flow typically has lower flow losses than non-mixed-flow under laminar upstream conditions, mixed-flow typically experiences greater flow losses when the flow transitions from laminar to turbulent. Active flow control technology requires external energy input. Its advantage is that flow control parameters can be adjusted according to operating conditions, but it is typically structurally complex, requires an external air or power source, and necessitates numerous auxiliary devices, making its implementation difficult in practical engineering applications. For example, acoustic excitation devices often require the installation of loudspeakers inside the blades, as well as the introduction of additional power and circuit systems that occupy a significant amount of space and weight. Therefore, it is imperative to seek a new technology that combines the strong engineering applicability of passive flow control technology with the strong adaptability to various operating conditions of active flow control technology. Summary of the Invention

[0005] The purpose of this invention is to achieve high aerodynamic efficiency of compressor blades under multiple operating conditions. Specifically, a slotted blade with automatic start-stop of variable angle-of-attack jet is proposed. Without the need for an external air or power source, it can automatically start and stop the jet according to different angles of attack. This not only effectively suppresses external flow separation under high angle-of-attack conditions, but also maintains low internal flow losses when there is no separation at low angles of attack.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0007] This invention provides a slotted blade for automatic start-stop of a variable angle-of-attack jet, comprising: a compressor blade, an air intake, a jet inlet, a jet slot, a rotatable valve, an anti-rotation elastic element, an elastic element groove, a stop step, and a hinge; wherein, the air intake is located on the blade head side of the compressor blade, the jet inlet is located on the blade back side of the compressor blade, the jet slot connects and penetrates the air intake and the jet inlet, the elastic element groove is located on the left side of the jet slot, and the movable valve is mounted on the elastic element via the anti-rotation elastic element and the hinge. Inside the component slot, a stop step is provided on the right wall of the jet slot. When the compressor blade is at a small angle of attack, the pressure difference on both sides of the rotatable valve is low, and the rotatable valve is in a closed state against the stop step under the pre-tightening force of the anti-rotation elastic element. When the compressor blade is at a large angle of attack, the pressure difference on both sides of the rotatable valve is high, and the rotatable valve rotates counterclockwise and is in an open state. The jet outlet generates a jet under the pressure difference between the blade basin and the blade back, which suppresses the flow separation on the blade back surface under the large angle of attack.

[0008] Furthermore, the anti-rotation elastic element is made of an elastic material, including but not limited to metal and rubber, and is used to provide a clockwise counter-torque M to the rotatable valve that is positively correlated with the rotation angle θ. When θ is zero, the anti-rotation elastic element has a preload torque M0. The configuration of the anti-rotation elastic element includes, but is not limited to, a hexahedron or a spring shape.

[0009] Furthermore, there is a gap b between the rotatable valve and the right side wall of the jet slit, where b is 1 to 20% of the air inlet width w.

[0010] Furthermore, the height h of the stop step is 1 to 25% of the width w of the air inlet and h > b.

[0011] Furthermore, if the compressor blades just separate, the pressure difference across the rotating elastic element is ΔP1; at the maximum operating angle of attack of the compressor blades, the pressure difference across the rotating elastic element is ΔP2, and the maximum rotation angle is θm. Then, the preload torque M0 of the anti-rotation elastic element is 0.5(wb). 2 L△P1, where L is the spanwise length of the anti-rotation elastic element.

[0012] Furthermore, the rotational stiffness of the anti-rotation elastic element is k = 0.5 (wb). 2 L(△P2-△P1) / θm.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0014] This invention provides a slotted blade for automatic start-stop of a variable angle-of-attack jet. Relying solely on its own structure, it can automatically start and stop the jet under different angle-of-attack conditions, thereby adaptively suppressing external flow separation and reducing internal flow losses. It does not require an external air or power source or external auxiliary devices, thus possessing advantages such as structural simplicity, strong adaptability, and high engineering practicality. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a slotted blade with automatic start-stop for a variable angle-of-attack jet under high angle-of-attack conditions.

[0016] Figure 2 This is a schematic diagram of a slotted blade with automatic start-stop function for a variable angle-of-attack jet under low angle-of-attack conditions.

[0017] Figure 3 A magnified view of the rotatable valve in the open state (under high angle of attack conditions);

[0018] Figure 4 A magnified view of the rotatable valve in the closed state (under small angle of attack conditions).

[0019] In the diagram: 1. Compressor blade; 2. Air intake port; 3. Jet port; 4. Jet slot; 5. Rotatable valve; 6. Anti-rotation elastic element; 7. Elastic element groove; 8. Stop step; 9. Hinge. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] Example 1

[0024] This embodiment describes a slitted blade with automatic start / stop for variable angle-of-attack jets, comprising: a compressor blade 1, an air intake 2, a jet inlet 3, a jet slit 4, a rotatable valve 5, an anti-rotation elastic element 6, an elastic element groove 7, a stop step 8, and a hinge 9. The air intake 2 is located on the blade head side, the jet inlet 3 is located on the blade back side, the jet slit 4 connects and penetrates the air intake 2 and the jet inlet 3, the elastic element groove 7 is located on the left side of the jet slit 4, the movable valve 5 is mounted in the elastic element groove 7 via the anti-rotation elastic element 6 and the hinge 9, and a stop step 8 is provided on the right wall of the jet slit 4. Figure 2 As shown, when the incoming flow velocity of compressor blade 1 is at a small angle of attack α, the pressure difference across the rotatable valve 5 is low, causing the rotatable valve 5 to be in a closed state against the stop step 8 under the preload torque of the anti-rotation elastic element 6 (see...). Figure 4 This reduces the flow friction loss within the jet slot 4; for example... Figure 1 As shown, when the incoming flow velocity of compressor blade 1 is at a large angle of attack α, the pressure difference across the rotatable valve 5 is high. This pressure difference causes the rotatable valve 5 to overcome the elastic torque of the anti-rotation elastic element 6 and rotate counterclockwise, thus putting the rotatable valve 5 in the open state (see...). Figure 3 At this time, the jet outlet 3 generates a jet under the pressure difference between the blade basin and the blade back, which can suppress the flow separation 11 on the blade back surface under high angle of attack conditions, thereby improving the compressor performance.

[0025] The anti-rotation elastic element 6 is made of an elastic material, including but not limited to metals and rubber, and is used to provide the rotatable valve 5 with a clockwise counter-torque M that is positively correlated with the rotation angle θ, and when θ is zero (e.g. Figure 4 As shown, the anti-rotation elastic element 6 has a preload torque M0. The configuration of the anti-rotation elastic element 6 can be, but is not limited to, a hexahedron or a spring shape.

[0026] There is a gap b between the rotatable valve 5 and the right side wall of the jet slit 4. The value of b should be 1% to 20% of the width w of the air inlet 2 (e.g., ...). Figure 3 (As shown). The value of this gap should ensure that, under all operating conditions, the rotatable valve 5 does not come into contact with or rub against the wall of the jet slit 4 during rotation, so as to ensure the service life of the component.

[0027] The height h of the stop step 8 should be 1 to 25% of the width w of the air inlet 2, and h > b (e.g., Figure 3 (As shown). Since the stop step 8 will generate a certain flow loss when the rotatable valve 5 is open, its height h should be as small as possible while still satisfying the requirements of stopping and sealing the rotatable valve 5.

[0028] The preload torque M0 and rotational stiffness k of the anti-rotation elastic element 6 are given by the design. If the compressor blade 1 just separates, the pressure difference across the rotating elastic element 6 is ΔP1; at the maximum operating angle of attack of the compressor blade 1, the pressure difference across the rotating elastic element 6 is ΔP2, and the maximum rotation angle is θm (e.g., ...). Figure 3 (As shown). Therefore, M0 = 0.5(wb). 2 L△P1, k=0.5(wb) 2 L(△P2-△P1) / θm, where L is the spanwise length of the anti-rotation elastic element 6 (e.g., Figure 3 (As shown).

[0029] Example:

[0030] like Figure 1 As shown, for a typical low-speed compressor stator blade with high diffusion, the chord length is 60mm and the maximum thickness is 6mm. The bleed inlet and jet inlet are designed at approximately 60% of the chord length from the leading edge. When the inlet Mach number Ma≈0.1 and the angle of attack α≈5°, the compressor blades are just about to separate, at which point the static pressure difference coefficient ΔCp≈0.3 at the bleed inlet and jet inlet. At the maximum operating angle of attack with separation (Ma≈0.1, α≈15°), the static pressure difference coefficient ΔCp≈0.8. Selecting a bleed inlet width w=2.1mm, an anti-rotation elastic element spanwise length L=10mm, and a maximum rotation angle θm=40° for the rotary valve, we can estimate that for α≈5°, the pressure difference across the rotary valve ΔP≈208Pa; for α≈15°, the pressure difference across the rotary valve ΔP≈260Pa. Therefore, the preload torque M0≈4.2×10⁻⁶ Pa can be calculated. -5 N·m, rotational elastic coefficient k≈9.9×10 N·m, anti-rotational elastic element -5 N·m / rad. When the rotatable valve is at its maximum rotation angle θm, the jet velocity generated at the jet outlet is approximately 30 m / s. Furthermore, the gap b between the rotatable valve and the right wall of the jet slit can be selected as 0.1 mm, and the height h of the stop step can be selected as 0.4 mm.

[0031] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A slotted blade for automatic start-stop of a variable angle-of-attack jet, characterized in that, include: The compressor blade (1), air intake (2), jet inlet (3), jet slit (4), rotatable valve (5), anti-rotation elastic element (6), elastic element groove (7), stop step (8), and hinge (9) are provided. The air intake (2) is located on the blade head side of the compressor blade (1), the jet inlet (3) is located on the blade back side of the compressor blade (1), the jet slit (4) connects and penetrates the air intake (2) and the jet inlet (3), the elastic element groove (7) is located on the left side of the jet slit (4), and the rotatable valve (5) is mounted on the spring via the anti-rotation elastic element (6) and the hinge (9). Inside the element slot (7), a stop step (8) is provided on the right wall of the jet slot (4). When the compressor blade (1) is in a small angle of attack condition, the pressure difference between the two sides of the rotatable valve (5) is low. Under the pre-tightening force of the anti-rotation elastic element (6), the rotatable valve (5) is in a closed state against the stop step (8). When the compressor blade (1) is in a large angle of attack condition, the pressure difference between the two sides of the rotatable valve (5) is high. The rotatable valve (5) rotates counterclockwise and is in an open state. The jet port (3) generates a jet under the pressure difference between the blade basin and the blade back, which inhibits the flow separation on the blade back surface under the large angle of attack condition.

2. The slotted blade for automatic start-stop of variable angle-of-attack jets according to claim 1, characterized in that, The anti-rotation elastic element (6) is made of an elastic material, which may include metal or rubber, and is used to provide a clockwise counter-torque M to the rotatable valve (5) that is positively correlated with the rotation angle θ. When θ is zero, the anti-rotation elastic element (6) has a preload torque M0. The configuration of the anti-rotation elastic element (6) includes a hexahedron or a spring shape.

3. The slotted blade for automatic start-stop of variable angle-of-attack jet according to claim 2, characterized in that, There is a gap b between the rotatable valve (5) and the right side wall of the jet slit (4), and the value of b is 1 to 20% of the width w of the air inlet (2).

4. The slotted blade for automatic start-stop of variable angle-of-attack jet according to claim 3, characterized in that, The height h of the stop step (8) is 1 to 25% of the width w of the air inlet (2) and h > b.

5. The slotted blade for automatic start-stop of variable angle-of-attack jet according to claim 4, characterized in that, If the compressor blade (1) just separates, the pressure difference on both sides of the anti-rotation elastic element (6) is ΔP1; when the compressor blade (1) is at its maximum working angle of attack, the pressure difference on both sides of the anti-rotation elastic element (6) is ΔP2, and the maximum rotation angle is θm, then the preload torque M0 of the anti-rotation elastic element (6) is 0.5(wb). 2 L△P1, where L is the spanwise length of the anti-rotation elastic element (6).

6. The slotted blade for automatic start-stop of variable angle-of-attack jets according to claim 5, characterized in that, The rotational stiffness of the anti-rotation elastic element (6) is k = 0.5(wb). 2 L(△P2-△P1) / θm.

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