Rotor and noise reduction method based on the silent flying principle of owl

Abstract

The invention discloses a rotor and a noise reduction method based on the silent owl flight principle, which relates to the technical field of aircraft, and comprises a blade, wherein the tail of the blade is rotatably mounted with a plurality of trailing edge winglets, and the plurality of trailing edge winglets are arranged in sequence along the length direction of the blade, and the rotating shaft of the trailing edge winglet is parallel to the length direction of the blade, and a rotating mechanism is provided between each trailing edge winglet and the blade, and each rotating mechanism is electrically connected to a controller, and the controller is used to control the action of the rotating mechanism and enable the rotating mechanism to drive the trailing edge winglet to rotate. The rotor and the noise reduction method based on the silent owl flight principle can reduce the sound pressure level of the aerodynamic noise of the helicopter rotor and improve the acoustic stealth characteristics of the helicopter.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft, and in particular to a rotor and a noise reduction method based on the silent flying principle of an owl. Background Art

[0002] Helicopters have advantages that fixed-wing aircraft cannot match, such as vertical take-off and landing and hovering in the air. However, due to the characteristics of large vibration and noise, their use is restricted in many cases. Improving the acoustic stealth performance of military helicopters can greatly improve the survivability of military helicopters; in the civilian sector, helicopters are prohibited from flying over some areas due to the loudness and long propagation direction of helicopter aerodynamic noise. Whether for military or civilian use, the requirements for low noise radiation in modern helicopter design are becoming increasingly urgent, and the International Civil Aviation Organization's requirements for helicopter noise levels are also becoming increasingly stringent. The noise level of helicopters has almost become as important a design indicator as performance, safety, and reliability. Summary of the invention

[0003] The purpose of the present invention is to provide a rotor and noise reduction method based on the owl flight silent principle to solve the problems existing in the above-mentioned prior art, which can reduce the sound pressure level of the aerodynamic noise of the helicopter rotor and improve the acoustic stealth characteristics of the helicopter.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a rotor based on the silent flight principle of an owl, comprising a blade, a plurality of trailing edge winglets are rotatably mounted at the tail of the blade, and the plurality of trailing edge winglets are arranged in sequence along the length direction of the blade, a rotating shaft of the trailing edge winglet is parallel to the length direction of the blade, a rotating mechanism is provided between each of the trailing edge winglets and the blade, and each of the rotating mechanisms is electrically connected to a controller, and the controller is used to control the action of the rotating mechanism and enable the rotating mechanism to drive the trailing edge winglet to rotate.

[0006] Preferably, there is one rotating mechanism corresponding to each of the two sides of the trailing edge winglet in the length direction, and the rotating mechanism is mounted on the blade.

[0007] Preferably, the rotating mechanism includes a gear, two diamond-shaped amplifiers, two pull rods and two racks, one of the diamond-shaped amplifiers is correspondingly connected to one end of the pull rod, the other end of the pull rod is connected to one end of the rack, the other end of the rack extends toward the direction close to the trailing edge winglet, the moving direction of the pull rod is perpendicular to the length direction of the blade, the gear is installed at the root of the trailing edge winglet, the outer periphery of the gear is respectively meshed with the two racks, the two racks are parallel and oppositely arranged, the diamond-shaped amplifier can drive the pull rod to move toward the direction close to the gear, and move the rack away from the diamond-shaped amplifier to drive the gear to rotate, and the gear can drive the trailing edge winglet to rotate.

[0008] Preferably, the diamond amplifier includes a plurality of piezoelectric stacks and two telescopic plates, each of the piezoelectric stacks is installed between the two telescopic plates, and the pull rod is connected to a side of one of the telescopic plates away from the piezoelectric stack. When voltage is applied to the piezoelectric stack, it can extend and drive the telescopic plates and the pull rod to move.

[0009] Preferably, there are nine trailing edge winglets, and the deflection angle range of each trailing edge winglet is -10° to +10°.

[0010] The present invention also provides a noise reduction method based on the silent flying principle of an owl, using the rotor based on the silent flying principle of an owl described in any one of the above technical solutions, comprising the following steps:

[0011] S1: Select an observation point as the calculation point and solve the force L required to cancel the noise in the plane to zero r ;

[0012] S2: L calculated in S1 r The value is transmitted to the controller, and the controller controls the movement of each of the rotating mechanisms, and the rotating mechanisms control the deflection angle of the trailing edge winglet compared to the blade, so that the trailing edge winglet generates a drag less than twice L r value to achieve noise reduction.

[0013] Preferably, in S1, solve L r The formula is

[0014]

[0015] Where τ is the delay time, c0 is the speed of sound, M r is the Mach number component of the line connecting the sound source and the observation point, M is the Mach number at the sound source, and p' T is the thickness noise sound pressure value corresponding to the observation point, and r is the distance from the sound source to the observation point.

[0016] Compared with the prior art, the present invention has achieved the following technical effects:

[0017] The rotor and noise reduction method based on the owl flight silent principle provided by the present invention has a plurality of trailing edge winglets rotatably mounted on the tail of the blade, and the plurality of trailing edge winglets are arranged in sequence along the length direction of the blade, thereby simulating the sawtooth structure of the owl's wings, so as to realize the rectification of the airflow blowing through the rotor blade by imitating the flight state of the owl, and the rotation axis of the trailing edge winglet is parallel to the length direction of the blade, so that the rotation plane of the trailing edge winglet is perpendicular to the blade, and then by adjusting the angle of the trailing edge winglet compared to the blade, a sound pressure load noise with a direction sign opposite to that of the thickness noise can be generated, thereby reducing the thickness noise in the propeller disc plane. A rotating mechanism is provided between each trailing edge winglet and the blade, and each rotating mechanism is electrically connected to a controller. The controller is used to control the action of the rotating mechanism and enable the rotating mechanism to drive the trailing edge winglet to rotate, thereby realizing active control. The silent flight motion process of the sawtooth structure of owl wings is simulated by the up and down deflection of multiple trailing edge winglets, thereby reducing the sound pressure level of the helicopter rotor aerodynamic noise and improving the helicopter's acoustic stealth performance. At the same time, by adjusting the angle of each trailing edge winglet, the airflow blowing through the rotor blades can be rectified to offset the thickness noise, so that the blades can "cut" the air more quietly without excessively sacrificing lift. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 is a schematic diagram of the rotor based on the owl flight silent principle in the first embodiment in a non-working state;

[0020] Figure 2 is a schematic diagram of the rotor based on the owl flight silent principle in the first embodiment in a working state;

[0021] Figure 3 yes Figure 2 A magnified schematic diagram of point A;

[0022] Figure 4 is a structural schematic diagram of the rotating mechanism in the first embodiment;

[0023] Figure 5 is a schematic diagram of the structure of the diamond amplifier in the first embodiment;

[0024] Figure 6 is a schematic diagram of the installation position of the gear in the first embodiment;

[0025] Figure 7 is a schematic diagram of the position of the far-field observation point in the forward flight / hovering state in the second embodiment;

[0026] Figure 8 is a schematic diagram of the effective noise reduction area in the hovering state in the second embodiment;

[0027] Fig. 9 is a schematic diagram of the effective noise reduction area in the forward flight state in the second embodiment;

[0028] Fig.10 This is a schematic diagram of the noise reduction effect of the observation point 100R in front of the propeller disc in the second embodiment;

[0029] Fig.11 It is a schematic diagram of the helicopter motion state at a certain observation point in the second embodiment;

[0030] Fig.12 It is a regional noise reduction effect diagram under different control laws in Example 2;

[0031] In the figure: 100 - rotor based on the silent flying principle of owl, 1 - blade, 2 - trailing edge winglet, 3 - diamond amplifier, 4 - pull rod, 5 - rack, 6 - gear, 7 - telescopic plate, 8 - piezoelectric stack. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The purpose of the present invention is to provide a rotor and a noise reduction method based on the silent flying principle of an owl, so as to solve the technical problems of high noise and difficulty in noise reduction of existing helicopters.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Embodiment 1

[0036] like Figure 1-Figure 6As shown, the present embodiment provides a rotor 100 based on the owl flight silent principle, including a blade 1, a plurality of trailing edge winglets 2 are rotatably mounted on the tail of the blade 1, and the plurality of trailing edge winglets 2 are sequentially arranged along the length direction of the blade 1, thereby simulating the sawtooth structure of the owl's wing, so as to realize the rectification of the airflow blowing through the rotor blade 1 by imitating the flight state of the owl, the rotation axis of the trailing edge winglet 2 is parallel to the length direction of the blade 1, so that the rotation plane of the trailing edge winglet 2 is perpendicular to the blade 1, and then by adjusting the angle of the trailing edge winglet 2 compared to the blade 1, a sound pressure load noise with a direction sign opposite to that of the thickness noise can be generated, thereby reducing the sound pressure load noise in the disc plane. In order to reduce the thickness noise, a rotating mechanism is provided between each trailing edge winglet 2 and the blade 1, and each rotating mechanism is electrically connected to a controller. The controller is used to control the action of the rotating mechanism and make the rotating mechanism drive the trailing edge winglet 2 to rotate, so as to realize active control. The silent flight motion process of the sawtooth structure of the owl's wings is simulated by the up and down deflection of multiple trailing edge winglets 2, so as to reduce the sound pressure level of the aerodynamic noise of the helicopter rotor and improve the acoustic stealth performance of the helicopter. At the same time, by adjusting the angle of each trailing edge winglet 2, the airflow blowing through the rotor blade 1 can be rectified to offset the thickness noise, so that the blade 1 can "cut" the air more quietly without excessively sacrificing lift.

[0037] Specifically, there is a rotating mechanism corresponding to each side of the trailing edge winglet 2 in the length direction, and the rotating mechanism is installed on the blade 1. By arranging the rotating mechanism on both sides of the trailing edge winglet 2 and avoiding the upper and lower surfaces of the trailing edge winglet 2, it is possible to avoid affecting the resistance adjustment of the trailing edge winglet 2.

[0038] The rotating mechanism includes a gear 6, two diamond-shaped amplifiers 3, two pull rods 4 and two racks 5. One diamond-shaped amplifier 3 is connected to one end of a pull rod 4, and the other end of the pull rod 4 is connected to one end of a rack 5. The other end of the rack 5 extends toward the direction close to the trailing edge winglet 2. The moving direction of the pull rod 4 is perpendicular to the length direction of the blade 1, so as to facilitate the adjustment of the angle of the trailing edge winglet 2 compared to the blade 1 to achieve resistance adjustment. The gear 6 is installed at the root of the trailing edge winglet 2, and the outer periphery of the gear 6 is respectively meshed with the two racks 5. The two racks 5 are parallel and relatively arranged, so that the two racks 5 can be moved separately to achieve The forward and reverse rotation of gear 6 finally realizes the upward and downward deflection of the trailing edge winglet 2. The diamond amplifier 3 can drive the pull rod 4 to move in the direction close to the gear 6, and the pull rod 4 drives the rack 5 to move in the direction away from the diamond amplifier 3. In this process, since the gear 6 is meshed with the rack 5, the gear 6 can be driven to rotate with the movement of the rack 5. The gear 6 is a fixed gear and will not rotate compared to the trailing edge winglet 2. Therefore, the rotation of the gear 6 drives the trailing edge winglet 2 to rotate, and the angle of the trailing edge winglet 2 is adjusted, and finally the resistance is adjusted, imitating the movement process of the silent flight of the owl, and reducing the thickness noise through the principle of sound pressure superposition. At the same time, when the diamond amplifier 3 drives one rack 5 to move, its power is much greater than the resistance brought to the gear 6 by the other rack 5, so the influence of the other rack 5 on the gear 6 can be ignored.

[0039] The diamond amplifier 3 includes a plurality of piezoelectric stacks 8 and two telescopic plates 7. Each piezoelectric stack 8 is installed between the two telescopic plates 7, and the pull rod 4 is connected to one side of the telescopic plates 7 away from the piezoelectric stack 8. When an alternating voltage is applied to the piezoelectric stack 8, the piezoelectric stack 8 will be extended, thereby driving the telescopic plate 7 and the pull rod 4 to produce a small displacement, and then the deflection angle of the trailing edge winglet 2 is adjusted through the meshing of the rack 5 and the gear 6. The two diamond amplifiers 3 on the periphery of the same gear 6 are controlled separately. When the trailing edge winglet 2 needs to deflect downward, it is only necessary to apply voltage to start the upper diamond amplifier 3, thereby causing the trailing edge winglet 2 to rotate downward. When the trailing edge winglet 2 needs to deflect upward, it is similarly necessary to start the lower diamond amplifier 3. In addition, the diamond amplifiers 3 on both sides of the trailing edge winglet 2 are connected in series at the upper side and at the lower side, thereby causing the two upper diamond amplifiers 3 to act at the same time, and the two lower diamond amplifiers 3 to act at the same time, thereby ensuring the stable deflection of the trailing edge winglet 2. At the same time, the magnitude of the applied voltage will affect the distance that the diamond amplifier 3 drives the pull rod 4 to extend, and then the deflection amplitude of the trailing edge winglet 2 can be changed by controlling the magnitude of the alternating voltage. When the voltage is stopped, the diamond amplifier 3 can restore its original shape.

[0040] There are nine trailing edge winglets 2, and the deflection angle range of each trailing edge winglet 2 is -10° to +10°. In the actual production process, technicians in this field can make adaptive changes to the number of trailing edge winglets 2 according to actual needs.

[0041] Embodiment 2

[0042] like Figure 7-Figure 12 As shown, this embodiment provides a noise reduction method based on the owl flying silent principle, using the rotor 100 based on the owl flying silent principle in the first embodiment,

[0043] When the helicopter is in a normal flight state and does not need to perform noise control, each trailing edge winglet 2 is in a folded state, that is, the deflection angle of the trailing edge winglet 2 compared to the blade 1 is 0°, which is basically consistent with the shape of a conventional rotor, and the impact on the aerodynamic performance of the helicopter can be reduced to a minimum;

[0044] When it is necessary to control the in-plane noise of the helicopter (such as a civilian helicopter flying over a residential area or a military helicopter performing a battlefield mission), an alternating voltage is applied to the piezoelectric stack 8, so that the diamond amplifier 3 above or below the gear 6 controls the pull rod 4 to extend, drives the rack 5 to move, and rotates the gear 6 to control the trailing edge winglet 2 to rotate to an appropriate angle to achieve a working state;

[0045] If the trailing edge winglet 2 is in working state, the deflection angle of each trailing edge winglet 2 needs to be controlled. Since the direction of the resistance required to offset needs to be along the line connecting the sound source and the observation point, the generated load noise is consistent with the thickness noise to be offset. Therefore, during the rotation of the trailing edge winglet 2, the deflection angle of each trailing edge winglet 2 needs to be adjusted by controlling the voltage to ensure that the direction of the resistance generated by all trailing edge winglets 2 can be along the line connecting the sound source and the observation point.

[0046] In the specific noise reduction adjustment process, it is necessary to first select an observation point as the calculation point to solve the force Lr required to cancel the noise in the plane to zero. The solution formula is:

[0047]

[0048] Where τ is the delay time, c0 is the speed of sound, Mr is the Mach number component of the line connecting the sound source and the observation point, M is the Mach number at the sound source, and p' T is the thickness noise sound pressure value corresponding to the observation point, r is the distance from the sound source to the observation point, and except for the required Lr, the other values ​​in the formula can be obtained using the CLORNS-sound pressure calculation code in the thickness noise calculation process.

[0049] The controller controls the deflection angle of the trailing edge winglet 2 through the Lr value calculated as above, and changes the voltage of the piezoelectric stack 8 corresponding to each trailing edge winglet 2 to change the deflection angle of the trailing edge winglet 2. The greater the upward deflection of the trailing edge winglet 2 (maximum 10°), the greater the resistance generated. At the same time, the different deflection angles of multiple trailing edge winglets 2 can also be used to generate greater resistance, thereby controlling the size of the resistance generated.

[0050] When the force generated by the deflection of all trailing edge winglets 2 is Lr, the thickness noise at the observation point can be offset to zero. As long as the force generated by the mechanism is controlled to be less than twice Lr, a noise reduction effect can be achieved.

[0051] For a helicopter in a hovering state, the method can reduce the noise of an annular belt surrounding the helicopter at a fixed distance; for a helicopter in a forward flight state, the method can reduce the noise of an area that maintains a certain relative distance from the helicopter.

[0052] The above method is mainly used to control thickness noise. When controlling other aerodynamic noise:

[0053] It is necessary to observe the motion state of the trailing edge feathers of an owl, fit the state, and obtain the motion formula of multiple trailing edge winglets 2. According to the obtained motion formula, each trailing edge winglet 2 is moved in a manner specified by the formula, that is, by applying an alternating voltage, the diamond amplifier 3 at the upper or lower end is extended, driving the pull rod 4 and the gear 6 to move the trailing edge winglet 2 to rotate an appropriate angle, and finally changing the direction of the airflow blowing through the helicopter blade 1, imitating the flight state of an owl, and rectifying the airflow blowing through the rotor blade 1.

[0054] By using the rotor 100 based on the owl flight silent principle in the first embodiment and the noise reduction method based on the owl flight silent principle in the second embodiment, the rotor aerodynamic noise can be specifically controlled by installing nine trailing edge winglets 2 on the trailing edge of the blade 1. When the helicopter is in a hovering state, the in-plane noise within a certain distance range from the sound source can be controlled to reduce the sound pressure level by more than 3dB and reduce the sound propagation range.

[0055] The noise reduction effect at a single control point is as follows Fig.10 As shown in Figure 2, the noise reduction effect in the propeller disc plane is as follows: Fig.12 shown.

[0056] The present specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A rotor based on the silent flying principle of an owl, characterized by: A propeller comprises a blade, wherein a plurality of trailing edge winglets are rotatably mounted at the tail of the blade, and the plurality of trailing edge winglets are sequentially arranged along the length direction of the blade, and the rotation axis of the trailing edge winglet is parallel to the length direction of the blade, and a rotation mechanism is arranged between each trailing edge winglet and the blade, and each of the rotation mechanisms is electrically connected to a controller, and the controller is used to control the movement of the rotation mechanism and enable the rotation mechanism to drive the trailing edge winglet to rotate; The two sides of the trailing edge winglet in the length direction each correspond to a rotating mechanism, and the rotating mechanism is installed on the blade; The rotating mechanism includes a gear, two diamond-shaped amplifiers, two pull rods and two racks. One of the diamond-shaped amplifiers is connected to one end of the pull rod, and the other end of the pull rod is connected to one end of the rack. The other end of the rack extends toward the direction close to the trailing edge winglet. The moving direction of the pull rod is perpendicular to the length direction of the blade. The gear is installed at the root of the trailing edge winglet. The outer periphery of the gear is respectively meshed with the two racks. The two racks are parallel and oppositely arranged. The diamond-shaped amplifier can drive the pull rod to move toward the direction close to the gear and move the rack away from the diamond-shaped amplifier to drive the gear to rotate. The gear can drive the trailing edge winglet to rotate.

2. The rotor based on the owl flight silent principle according to claim 1 is characterized by: The diamond amplifier includes a plurality of piezoelectric stacks and two telescopic plates, each of the piezoelectric stacks is installed between the two telescopic plates, and the pull rod is connected to a side of one of the telescopic plates away from the piezoelectric stack. When voltage is applied to the piezoelectric stack, it can extend and drive the telescopic plates and the pull rod to move.

3. The rotor based on the owl flying silent principle according to claim 1 is characterized by: There are nine trailing edge winglets, and the deflection angle range of each trailing edge winglet is -10° to +10°.

4. A noise reduction method based on the silent flying principle of an owl, characterized in that: Using the rotor based on the owl flight silent principle described in any one of claims 1 to 3 comprises the following steps: S1: Select an observation point as the calculation point and solve the force L required to cancel the noise in the plane to zero r ; S2: L calculated in S1 r The value is transmitted to the controller, and the controller controls the movement of each of the rotating mechanisms, and the rotating mechanisms control the deflection angle of the trailing edge winglet compared to the blade, so that the trailing edge winglet generates a drag less than twice L r value to achieve noise reduction.

5. The noise reduction method based on the owl flight silent principle according to claim 4 is characterized in that: In S1, solve for L r The formula is Where τ is the delay time, c0 is the speed of sound, M r is the Mach number component of the line connecting the sound source and the observation point, M is the Mach number at the sound source, and p ′ T is the thickness noise sound pressure value corresponding to the observation point, and r is the distance from the sound source to the observation point.

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