A flexible thin film self-supply flow control device based on a Tesla valve

Abstract

The application discloses a flexible film self-supply flow control device based on Tesla valve and belongs to the field of aircraft design and wind turbine. First, a metal-film mixed skin structure is designed in the application, and a gas cavity body connected with a film skin is arranged below the film skin. Further, a Tesla valve is arranged in front of and behind the gas cavity body. The inlet of the front Tesla valve is communicated with the front opening of the gas cavity body, and the outlet is communicated with the air blowing port on the metal skin of the wing leading edge, so that the gas flows from the cavity to the airfoil in the Tesla valve. The inlet of the rear Tesla valve is communicated with the air suction port on the metal skin of the wing trailing edge, and the outlet is communicated with the rear opening of the gas cavity body, so that the gas flows from the airfoil to the cavity in the rear Tesla valve. Finally, under the action of dynamic stall pulsating aerodynamic load, the film skin generates flow-induced vibration and provides energy for air blowing and suction, and the flow-induced vibration and air blowing and suction are coordinated to generate disturbance to the dynamic stall flow field, so that the purpose of dynamic stall control is achieved.

Description

Technical Field

[0001] This invention belongs to the fields of aircraft design and wind turbines, and relates to a flow control device, specifically a flexible thin-film self-supply flow control device for addressing the dynamic stall problem of airfoils. Background Technology

[0002] Dynamic stall refers to the flow separation around an airfoil / rotor / wind turbine blade undergoing unsteady motions such as periodic oscillations or critical maneuvers, resulting in dynamic hysteresis. This phenomenon is very common in post-stall maneuvers of fighter jets, rotor rotation of helicopters, and deflection of wind turbine blades. Once dynamic stall occurs, it causes a sudden increase in drag, severe fluctuations in the aerodynamic center position, and abrupt changes in aerodynamic torque, and can even induce highly destructive aeroelastic instability phenomena such as stall flutter, seriously affecting the high-speed cruise capability of helicopters, the power generation capability of wind turbines, and the flight safety of fixed-wing aircraft. Therefore, applying flow control to the airfoil to mitigate dynamic stall, reduce aerodynamic load fluctuations, and improve aeroelastic stability is particularly important.

[0003] Common dynamic stall flow control methods include blow-in control, plasma control, and flexible membrane skin control. Blow-in and plasma control are both active flow control methods, which increase the momentum of the fluid within the boundary layer to mitigate dynamic stall. However, blow-in requires high-pressure gas storage devices or pumps, and plasma control requires high-voltage AC power. These auxiliary devices are heavy, significantly increasing the weight of the wing structure and reducing wing performance. Flexible membrane skin control is a passive flow control method. It replaces a portion of the airfoil's skin with a highly flexible membrane, utilizing the interaction between the membrane's elastic deformation and the flow field to control the flow. Studies have found that flexible membrane skin control is effective in static stall conditions, but its effectiveness is limited in dynamic stall situations with high angles of attack and large separation. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a flexible diaphragm self-supply flow control device based on a Tesla valve, which utilizes a flexible diaphragm vibration and blow-suction coordinated control strategy to achieve dynamic stall control of self-supply.

[0005] This invention relates to a flexible thin-film self-supply flow control device based on a Tesla valve, which designs a skin-framed wing, an air chamber with a thin-film skin, and a Tesla valve connecting the two.

[0006] The skin-framed wing is a single-spar wing, with metal skin installed between adjacent wing ribs; air chambers are also installed between adjacent wing ribs, each air chamber consisting of an air chamber body and a thin film skin; wherein, the air chamber body is fixed to the wing spars, and its top circumferential direction is fixedly connected to the metal skin, and the inner cavity of the air chamber body is connected to an opening on the metal skin; furthermore, a thin film skin is laid to seal the opening.

[0007] The Tesla valve includes a leading-edge Tesla valve and a trailing-edge Tesla valve; wherein the leading-edge Tesla valve is arranged between the air chamber and the leading edge of the wing, the inlet of the leading-edge Tesla valve is connected to the front part of the air chamber, and the outlet is connected to the air outlet opened on the leading edge of the wing, so that gas flows from the chamber to the wing surface in the leading-edge Tesla valve; the outlet of the trailing-edge Tesla valve is connected to the rear part of the air chamber, and the inlet is connected to the air inlet opened on the trailing edge of the wing, so that gas flows from the wing surface to the chamber in the trailing-edge Tesla valve.

[0008] Therefore, when the dynamic stall flow field generates pulsating aerodynamic loads above the membrane skin, the membrane skin undergoes dynamic elastic deformation under the action of the pulsating aerodynamic loads, which in turn disturbs the dynamic stall flow field and changes the dynamic stall aerodynamic characteristics of the wing. At the same time, it acts on the air inside the air cavity, converting the vibration energy of the membrane skin into the kinetic energy of the air inside the air cavity. When the membrane skin bends upward, gas enters the air cavity from the trailing edge air intake through the trailing edge Tesla valve. When the membrane skin bends downward, gas inside the air cavity is blown out from the leading edge air outlet through the leading edge Tesla valve, thus simultaneously achieving air intake and air intake control, achieving the effect of coordinated flow control of membrane skin vibration and air intake and air intake.

[0009] The advantages of this invention are:

[0010] 1. The present invention is a flexible thin film self-supply flow control device based on a Tesla valve. Based on a metal-thin film hybrid skin structure, the thin film skin generates flow-induced vibration under the action of dynamic stall pulsating aerodynamic load. The flow-induced vibration, in turn, disturbs the dynamic stall flow field, thereby achieving the purpose of dynamic stall control.

[0011] 2. This invention relates to a flexible diaphragm self-supplying flow control device based on a Tesla valve. The flexible diaphragm skin, cavity, and Tesla valve form a blow-in / suck-out device, converting the flow-induced vibration energy of the flexible diaphragm skin into the energy required for blow-in / suck-out. This diaphragm vibration energy is used to increase the airflow velocity at the blow-in / suck-out inlet, eliminating the need for bulky auxiliary devices and avoiding significant added mass to the wing. It offers advantages such as ease of engineering application, simple structure, and long service life. Furthermore, the coordinated flow control of blow-in / suck-out and the flexible diaphragm skin can provide better dynamic stall control.

[0012] 3. The present invention is a flexible film self-supply flow control device based on a Tesla valve. By utilizing the unidirectional flow characteristics of the Tesla valve, only air intake occurs near the trailing edge and only air blowing occurs near the leading edge. This enables controllable blowing / intake at specific chordal positions of the wing and can further improve the dynamic stall flow control effect. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the flexible thin-film self-supply flow control device based on a Tesla valve according to the present invention.

[0014] Figure 2 This is a schematic diagram of the gas chamber structure in the flexible thin-film self-supply flow control device based on the Tesla valve of the present invention.

[0015] Figure 3 This is a schematic diagram showing the installation position of the Tesla valve in the flexible thin-film self-supplying flow control device based on the Tesla valve of the present invention.

[0016] Figure 4 This is a schematic diagram of the control principle of the flexible thin film self-supply flow control device based on the Tesla valve of the present invention.

[0017] In the picture:

[0018] 1-Wing rib; 2-Spar; 3-Metal skin; 4-Membranous skin; 5-Air cavity;

[0019] 6-Air inlet 7-Air outlet 8-Tesla valve. Detailed Implementation

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] This invention relates to a flexible thin-film self-supplying flow control device based on a Tesla valve, comprising three parts: a skin-framed wing, an air chamber 5 with a thin-film skin 4, and a Tesla valve 8 that controls the unidirectional flow of air. Figure 1 As shown.

[0022] The skin-framed wing is a single-spar wing, comprising wing ribs 1, wing spars 2, and metal skin 3.

[0023] The wing spars 2 are arranged along the span of the wing, and wing ribs 1 are fitted onto them at equal intervals. The wing spars 2 and wing ribs 1 are connected by corner plates to form the wing skeleton structure. Metal skins 3 are provided between adjacent wing ribs 1. The metal skins 3 are arranged along the outer edge of the wing ribs 1, and their outer surface is flush with the circumferential wall of the wing ribs 1. The two sides of the metal skins 3 are fixed to the opposite sides of the two adjacent wing ribs by riveting, forming a single-spar wing structure.

[0024] Inside the single-spar wing with the aforementioned structure, an air chamber 5 is installed between each of two adjacent wing ribs 1. The air chamber 5 is a rectangular box structure, with a thin film skin 4 sealing its top surface. Simultaneously, a rectangular opening is formed on the upper surface of the metal skin 3 between adjacent wing ribs 1. The rectangular opening is the same size as the thin film skin 4, allowing the thin film skin 4 to contact the outside environment through the rectangular opening. The structure and specific installation method of the air chamber 5 are as follows:

[0025] like Figure 2 As shown, the inner cavity shape of the air chamber 5 is the same as that of the rectangular opening on the metal skin 3, but its size is slightly smaller than that of the rectangular opening on the metal skin 3. Two hollow bosses 501 connected to the inner cavity of the air chamber 5 are designed on the bottom surface of the air chamber 5 for connecting the Tesla valve 8.

[0026] The air chamber 5 is connected to a portion of the wing spars 2 between the two protrusions 501 on its bottom surface through the recess 502 formed between the two protrusions 501 on its bottom surface. The air chamber 5 is fixed after the bottom surface of the recess 502 is completely attached to the top surface of the wing spars 2.

[0027] Furthermore, the outer edges of the four circumferential sides of the top of the air cavity 5 are fixedly connected to the rectangular opening on the metal skin 3; this achieves the connection and fixation between the air cavity 5 and the wing. The four circumferential sides of the thin film skin 4 are fixed to the inner edges of the four circumferential sides of the top of the air cavity 5 by adhesive, so that the thin film skin 4 is embedded in the rectangular opening. At the same time, the thickness of the thin film skin 4 is the same as the thickness of the metal skin 3, and its shape and size are the same as the rectangular opening on the metal skin 3, so that the circumferential side of the thin film skin 4 is connected to the four circumferential sides of the rectangular opening.

[0028] Inside the aforementioned single-spar wing equipped with air chamber 5, five Tesla valve mounting positions are evenly distributed along the wing span between adjacent wing ribs 1. At each Tesla valve mounting position, two Tesla valves 8 are installed along the chord direction. Based on the chordal arrangement of the two Tesla valves 8, they are classified as leading-edge Tesla valves and trailing-edge Tesla valves, as follows: Figure 3 As shown, at the installation positions of the five Tesla valves, the inlet of the leading-edge Tesla valve is connected to an equal-sized outlet on the front sidewall of the front protrusion 501 of the air chamber 5, and is sealed circumferentially; the outlet of the leading-edge Tesla valve 8 is connected to an equal-sized blowing port 6 on the metal skin 3 located at the leading edge of the wing, and is sealed circumferentially; thus, the gas flows from the chamber to the wing surface within the leading-edge Tesla valve in a forward flow. The inlet of the trailing-edge Tesla valve is connected to an intake port 7 on the metal skin 3 located at the trailing edge of the wing, and is sealed circumferentially; the outlet of the trailing-edge Tesla valve 8 is connected to an intake port on the rear sidewall of the rear protrusion 501 of the air chamber 5, and is sealed circumferentially; thus, the gas flows from the wing surface to the chamber within the trailing-edge Tesla valve.

[0029] The number of Tesla valve mounting positions can be designed according to the span of the wing between adjacent wing ribs 1. Since the Tesla valve 8 installed at each Tesla valve mounting position will affect the airflow within the range, it is optimal to make the range of airflow affected by all Tesla valves 8 cover the entire wing.

[0030] like Figure 4 As shown, when the incoming flow velocity is Under the influence of the flow field, the wing undergoes rigid pitch oscillations around its axis of rotation, resulting in dynamic stall. By installing a self-supplying flow control device with the aforementioned structure on the wing, when the dynamic stall flow field generates pulsating aerodynamic loads above the thin film skin 4 (between chordal positions x1 and x2), the thin film skin 4 undergoes dynamic elastic deformation under the action of these pulsating aerodynamic loads. This deformation, in turn, disturbs the dynamic stall flow field, thereby altering the dynamic stall aerodynamic characteristics of the wing. Simultaneously, the air acting within the air chamber 5 converts the vibrational energy of the thin film skin 4 into the kinetic energy of the air within the air chamber 5. When the thin film skin 4 bends upward, gas enters the air chamber 5 from the trailing edge intake port 7 via the trailing edge Tesla valve. When the thin film skin 4 bends downward, gas within the air chamber 5 is blown out from the leading edge exhaust port 6 via the leading edge Tesla valve, thus simultaneously achieving air intake and exhaust control. This achieves the effect of coordinated flow control of the vibration of the thin film skin 4 and air intake and exhaust.

[0031] In summary, the flexible thin-film self-supply flow control device based on a Tesla valve designed in this invention not only has a control effect on "film flow-induced vibration," but also on "blowing / suction control." The effect of blow-suction control is not primarily to induce skin flow-induced vibration, but rather to directly blow / suction air into the flow field to improve flow separation. Through the "synergistic effect" of these two control methods, a control effect greater than the sum of its parts is achieved.

Claims

1. A flexible diaphragm self-supply flow control device based on a Tesla valve, characterized in that: The design includes a skinned skeleton wing, air chambers with thin-film skin, and a Tesla valve connecting the two. The skin-framed wing is a single-spar wing, with metal skin installed between adjacent wing ribs; at the same time, air chambers are installed between adjacent wing ribs, and the top surface of the air chambers is covered with a thin film skin for sealing. The aforementioned air chamber is fixed to the wing spars, and its top circumferential direction is fixed to the metal skin, with the thin film skin on the top surface of the air chamber located in the opening on the metal skin; The Tesla valve includes a leading-edge Tesla valve and a trailing-edge Tesla valve; The leading-edge Tesla valve is located between the air chamber and the leading edge of the wing. The inlet of the leading-edge Tesla valve is connected to the front of the air chamber, and the outlet is connected to the air outlet opened on the leading edge of the wing, so that the gas flows from the air chamber to the wing surface in the leading-edge Tesla valve. The outlet of the trailing-edge Tesla valve is connected to the rear of the air chamber, and the inlet is connected to the air inlet opened on the trailing edge of the wing, so that the gas flows from the wing surface to the air chamber in the trailing-edge Tesla valve. When the dynamic stall flow field generates pulsating aerodynamic loads above the membrane skin, the membrane skin undergoes dynamic elastic deformation under the action of the pulsating aerodynamic loads, which in turn disturbs the dynamic stall flow field and changes the dynamic stall aerodynamic characteristics of the wing; at the same time, it acts on the air in the air cavity, converting the vibration energy of the membrane skin into the kinetic energy of the air in the air cavity. When the membrane skin bends upward, gas enters the air chamber from the trailing edge air intake through the trailing edge Tesla valve; when the membrane skin bends downward, the gas in the air chamber is blown out from the leading edge air outlet through the leading edge Tesla valve, thus simultaneously achieving air intake and air intake control, and achieving the effect of coordinated flow control of membrane skin vibration and air intake and air intake.

2. The flexible thin-film self-supply flow control device based on a Tesla valve as described in claim 1, characterized in that: The air chamber is a rectangular box structure with two hollow bosses on the bottom surface that communicate with the interior of the air chamber. The front boss has an opening that communicates with the inlet of the front edge Tesla valve, and the rear boss has an opening that communicates with the outlet of the rear edge Tesla valve.

3. The flexible thin-film self-supply flow control device based on a Tesla valve as described in claim 2, characterized in that: The air chamber is fixed to the wing spars by inserting and fitting between the recessed part between the two protrusions on the bottom surface.

4. The flexible diaphragm self-supply flow control device based on a Tesla valve as described in claim 1, characterized in that: The inner cavity of the air chamber has the same shape as the opening on the metal skin, but its size is smaller than the opening size; the outer edge of the top of the air chamber is fixedly connected to the opening on the metal skin in the circumferential direction; the inner edge of the top of the air chamber is fixedly connected to the thin film skin in the circumferential direction.

5. The flexible thin-film self-supply flow control device based on a Tesla valve as described in claim 1, characterized in that: Between adjacent wing ribs, the leading-edge Tesla valves and trailing-edge Tesla valves are arranged at equal intervals along the wing span, and the influence of all Tesla valves along the wing span on the airflow must cover the entire wing.

Images