CN108216617B - Method for suppressing helicopter propeller-vortex interference noise - Google Patents
Method for suppressing helicopter propeller-vortex interference noise Download PDFInfo
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- CN108216617B CN108216617B CN201711481419.3A CN201711481419A CN108216617B CN 108216617 B CN108216617 B CN 108216617B CN 201711481419 A CN201711481419 A CN 201711481419A CN 108216617 B CN108216617 B CN 108216617B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C27/00—Rotorcraft; Rotors peculiar thereto
- B64C27/32—Rotors
- B64C27/46—Blades
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C27/00—Rotorcraft; Rotors peculiar thereto
- B64C27/32—Rotors
- B64C27/46—Blades
- B64C27/467—Aerodynamic features
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Abstract
A method for suppressing helicopter rotor-vortex interference noise relates to a helicopter rotor blade. At least 1 synthetic jet generator is arranged at a proper position of the propeller tip distance from the end face, the synthetic jet generator is powered by a power supply, synthetic jet flow which is backward and downward relative to the advancing direction of the rotor blade is generated on the lower surface of the propeller tip to weaken the vortex strength of the propeller tip and change the falling direction of the synthetic jet flow, and mutual interference between the vortex of the propeller tip and the follow-up propeller blade is avoided, so that the effect of inhibiting the interference noise of the propeller-vortex is achieved. The structural parameters of the synthetic jet generator can be optimized according to specific actual requirements, and the jet intensity can be changed by adjusting the loading electrical parameters of the synthetic jet generator, so that active, flexible and intelligent control is performed on the paddle-vortex interference; the rotor blade tip has the advantages of simple structure, low manufacturing cost, convenience in maintenance, no change of the aerodynamic shape of the original rotor blade tip and the like.
Description
Technical Field
The invention relates to a helicopter rotor blade, in particular to a method for inhibiting helicopter blade-vortex interference noise by utilizing a synthetic jet technology.
Background
The helicopter has the unique performances of vertical take-off and landing, hovering, low-altitude low-speed flight and the like, and is increasingly applied to the fields of national defense and civil use. However, the helicopter has the defect of excessive noise, so that the stealth of the helicopter is reduced in military, the track is easily exposed prematurely, and the battlefield defense and the survival capability of the helicopter are greatly influenced; in the civil aspect, the excessive noise not only affects the riding comfort of passengers, but also causes serious noise pollution, and does not meet the requirement of environmental protection.
Helicopter noise is mainly derived from aerodynamic noise of the rotor, which is generated by unsteady movements and flows caused by the interaction of the blades rotating at high speed with the air. Research has shown that the paddle-vortex interference phenomenon is one of the major factors in generating aerodynamic noise. The paddle-vortex interference phenomenon is a physical interference phenomenon peculiar to a helicopter formed by the meeting of a rotating blade and a vortex line of each blade tip. The vortex line is formed by the tip vortex breaking away from the tip. Therefore, in order to suppress the blade-vortex interference noise of a helicopter rotor, it is necessary to weaken the strength of the blade tip vortex and change its shedding direction so that the vortex line is away from other subsequent blades.
Chinese patent publication No. CN106741922 discloses a rotor noise suppression method, which is based on the principle that an air flow at the front edge of a rotor is guided to the end face of a blade tip by means of forming a hole at the front edge of the blade tip, so that the air flow is emitted perpendicularly to the end face of the blade tip, and the strength of a blade tip vortex is weakened, thereby achieving the effect of reducing the blade-vortex interference noise. The method changes the airflow flow of the blade tip, increases the flow loss, reduces the efficiency of the blade tip, and can not intelligently adjust the bleed air according to the flight state.
In addition, there are other methods for suppressing the disturbance noise of the rotor blade-vortex of a helicopter, such as adding a sweep angle, a dihedral angle and a trailing edge flap to the rotor tip, which have their limitations.
Disclosure of Invention
The invention aims to provide a method for suppressing the interference noise of the rotor blade-vortex of the helicopter by utilizing the synthetic jet technology, aiming at the defects existing in the prior art for suppressing the interference noise of the rotor blade-vortex of the helicopter.
The method comprises the following specific steps:
at least 1 synthetic jet generator is arranged at a proper position of the propeller tip distance from the end face, the synthetic jet generator is powered by a power supply, synthetic jet flow which is backward and downward relative to the advancing direction of the rotor blade is generated on the lower surface of the propeller tip to weaken the vortex strength of the propeller tip and change the falling direction of the synthetic jet flow, and mutual interference between the vortex of the propeller tip and the follow-up propeller blade is avoided, so that the effect of inhibiting the interference noise of the propeller-vortex is achieved.
The suitable position can be 5-60 mm.
The synthetic jet generator is provided with an inner cavity and a jet outlet with the caliber of 0.5-3 mm, and the jet outlet is located on the lower surface of the blade tip and is flush with the lower surface. The synthetic jet generator can cause the pressure of the gas in the cavity to increase suddenly in a physical mode by loading an electric signal, and the high-pressure gas is sprayed out from the jet outlet to form high-speed jet; and then the cavity is in a negative pressure state, outside air is sucked in, jet flow in the next period is formed again, and continuous periodic jet flow is used for inhibiting paddle-vortex interference. The physical mode can adopt discharge heating, piezoelectric action or mechanical work and the like.
The synthetic jet flow generator is provided with a closed cavity and a small hole communicated with the outside, and can generate high-speed jet flow which is jetted outwards through loading electric signals.
The synthetic jet generator can be combined with a sensor, a computer and a program control power supply, jet intensity is changed by adjusting loading electrical parameters according to the flight state of the helicopter, jet is accurately adjusted, effective suppression is carried out on paddle-vortex interference noise under different flight states, and intelligent control is achieved. The electrical parameters include output voltage, output frequency or duty cycle of the power supply, etc.
The synthetic jet generator is mounted at the tip of the rotor and is designed to generate a jet that is emitted in a rearward and downward direction relative to the direction of forward travel of the rotor blade. The backward component of the jet flow accelerates the gas flow near the lower surface of the blade tip, so that the pressure of the lower surface is reduced, the vortex strength of the blade tip is weakened, and the interference noise of the blade-vortex is weakened; the downward component of the jet flow causes the tip vortex line to deflect downwards, and the falling direction of the tip vortex is changed to avoid contact with the subsequent blade, so that the generation of the interference noise of the helicopter rotor blade-vortex is prevented.
Compared with other existing helicopter rotor blade-vortex interference noise suppression methods, the method has the following outstanding technical effects:
1) the structural parameters of the synthetic jet generator can be optimized according to specific actual requirements, and the jet intensity can be changed by adjusting the loading electrical parameters (such as the output voltage of a power supply, or the output frequency, the duty ratio and the like) of the synthetic jet generator, so that active, flexible and intelligent control can be performed on the paddle-vortex interference; the rotor blade tip has the advantages of simple structure, low manufacturing cost, convenience in maintenance, no change of the aerodynamic shape of the original rotor blade tip and the like.
2) The synthetic jet is of various types, such as spark discharge plasma synthetic jet, piezoelectric synthetic jet, mechanical synthetic jet, etc., the forming principle of the jet is basically the same, and although the working principle of the generator is different, the generator can be used in the invention.
Drawings
Fig. 1 is a schematic diagram of tip vortex generation.
FIG. 2 is a schematic diagram illustrating the principle of the method for suppressing the disturbance noise of the blade-vortex according to the present invention.
FIG. 3 is a view of a synthetic jet along direction A.
Detailed Description
The embodiment of the invention comprises the following specific steps:
at least 1 synthetic jet generator is arranged at a proper position of the propeller tip distance from the end face, the synthetic jet generator is powered by a power supply, synthetic jet flow which is backward and downward relative to the advancing direction of the rotor blade is generated on the lower surface of the propeller tip to weaken the vortex strength of the propeller tip and change the falling direction of the synthetic jet flow, and mutual interference between the vortex of the propeller tip and the follow-up propeller blade is avoided, so that the effect of inhibiting the interference noise of the propeller-vortex is achieved.
The suitable position is 5-60 mm.
The synthetic jet generator is provided with an inner cavity and a jet outlet with the caliber of 0.5-3 mm, and the jet outlet is located on the lower surface of the blade tip and is flush with the lower surface. The synthetic jet generator can cause the pressure of the gas in the cavity to increase suddenly in a physical mode by loading an electric signal, and the high-pressure gas is sprayed out from the jet outlet to form high-speed jet; and then the cavity is in a negative pressure state, outside air is sucked in, jet flow in the next period is formed again, and continuous periodic jet flow is used for inhibiting paddle-vortex interference. The physical mode can adopt discharge heating, piezoelectric action or mechanical work and the like.
The synthetic jet flow generator is provided with a closed cavity and a small hole communicated with the outside, and can generate high-speed jet flow which is jetted outwards through loading electric signals.
The synthetic jet generator can be combined with a sensor, a computer and a program control power supply, jet intensity is changed by adjusting loading electrical parameters according to the flight state of the helicopter, jet is accurately adjusted, effective suppression is carried out on paddle-vortex interference noise under different flight states, and intelligent control is achieved. The electrical parameters include output voltage, output frequency or duty cycle of the power supply, etc.
The synthetic jet generator is mounted at the tip of the rotor and is designed to generate a jet that is emitted in a rearward and downward direction relative to the direction of forward travel of the rotor blade. The backward component of the jet flow accelerates the gas flow near the lower surface of the blade tip, so that the pressure of the lower surface is reduced, the vortex strength of the blade tip is weakened, and the interference noise of the blade-vortex is weakened; the downward component of the jet flow causes the tip vortex line to deflect downwards, and the falling direction of the tip vortex is changed to avoid contact with the subsequent blade, so that the generation of the interference noise of the helicopter rotor blade-vortex is prevented.
As shown in fig. 1 and 2, when the helicopter is flying forward, the rotor rotates at an angular velocity ω, and an air flow with a velocity V flows through the tip of the advancing blade, creating a pressure difference between the upper and lower surfaces of the tip, the pressure of the upper surface being P1Pressure of lower surface is P2And P is1＜P2Under the action of the pressure gradient, the gas on the lower surface will flip up around the tip to form an upward-rolling tip vortex Г as shown in fig. 1 and 21. Its vortex axis l1May contact subsequent blades and generate a blade-vortex interference noise.
As shown in fig. 3, a synthetic jet generator G is mounted at the tip of the helicopter blade. The generator G is buried in the blade tip, the jet flow outlet of the generator G is flush with the lower surface of the blade tip, and the jet flow direction is backward and downward relative to the advancing direction of the blade.
As shown in FIGS. 1 and 2, the rotating blade will generate a tip vortex Г at the tip1，Г1Will fall off and extend backwards to form vortex line l1Interacting with subsequent blades, generating a blade-vortex interference noise. After the synthetic jet generator is started, a high-speed synthetic jet J is generated at the jet port O on the lower surface of the blade tip, and the direction of the high-speed synthetic jet J is backward and downward relative to the advancing direction of the blade (as shown in figure 3). Backward component J of synthetic jet JrThe flow velocity of gas behind the lower surface of the blade tip can be accelerated, the original flow field is changed, so that the local pressure distribution is changed, the pressure at the position is reduced, the pressure gradient of the upper surface and the lower surface is weakened, the formation of a blade tip vortex is hindered, and the blade-vortex interference noise is weakened. On the other hand, the downward component J of the synthetic jet JdAdding a downward velocity component to the tip flow, promoting Г1Is converted into Г2Changing the falling direction of the tip vortex to form a tip vortex line l1Is deflected downwards to l2To avoid contact with subsequent blades and thereby inhibit the helicopter rotorThe paddle-vortex interferes with noise.
Claims (8)
1. A method for suppressing helicopter propeller-vortex interference noise is characterized by comprising the following specific steps:
at least 1 synthetic jet generator is arranged at a proper position of the tip from the end face, the synthetic jet generator is powered by a power supply, synthetic jet flow which is backward and downward relative to the advancing direction of the rotor blade is generated on the lower surface of the tip to weaken the vortex strength of the tip, the falling direction of the synthetic jet flow is changed, the mutual interference of the vortex of the tip and the follow-up blade is avoided, and the effect of inhibiting the interference noise of the blade-vortex is achieved;
the synthetic jet generator loads an electric signal to enable the pressure of gas in the cavity to be increased suddenly in a physical mode, and high-pressure gas is sprayed out from a jet outlet to form high-speed jet; and then the cavity is in a negative pressure state, outside air is sucked in, jet flow in the next period is formed again, and continuous periodic jet flow is used for inhibiting paddle-vortex interference.
2. The method for suppressing helicopter blade-vortex interference noise according to claim 1, wherein said suitable location is 5 mm to 60 mm.
3. The method of suppressing helicopter blade-vortex interference noise according to claim 1, wherein said synthetic jet generator has an inner cavity and a jet outlet with a diameter of 0.5-3 mm, said jet outlet being located on and flush with the lower surface of the blade tip.
4. A method of suppressing helicopter rotor-vortex interference noise according to claim 1, wherein said physical means employs electrical discharge heating, piezoelectric action, or mechanical work.
5. The method of suppressing helicopter rotor-vortex interference noise according to claim 1, wherein said synthetic jet generator has a closed chamber and an orifice communicating with the outside, capable of generating a high-velocity jet that is ejected outwardly by applying an electrical signal.
6. The method according to claim 1, wherein the synthetic jet generator combines a sensor, a computer and a programmable power supply, and adjusts the jet by adjusting the loading electrical parameters to change the jet intensity according to the flight state of the helicopter, so as to effectively suppress the interference noise of the propeller and the vortex in different flight states, thereby achieving intelligent control.
7. The method of suppressing helicopter rotor-vortex interference noise according to claim 6, wherein said electrical parameter comprises an output voltage, an output frequency, or a duty cycle of a power source.
8. A method of suppressing a helicopter blade-vortex interference noise according to claim 1 wherein the synthetic jet generator is mounted at the tip of the rotor and is designed to generate a jet that is directed in a rearward and downward direction relative to the direction of forward travel of the rotor blade, the rearward component of the jet accelerating the flow of gas near the lower surface of the tip, causing the pressure at the lower surface to decrease, thereby attenuating the tip vortex intensity and attenuating the blade-vortex interference noise; the downward component of the jet flow causes the tip vortex line to deflect downwards, and the falling direction of the tip vortex is changed to avoid contact with the subsequent blade, so that the generation of the interference noise of the helicopter rotor blade-vortex is prevented.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711481419.3A CN108216617B (en) | 2017-12-29 | 2017-12-29 | Method for suppressing helicopter propeller-vortex interference noise |
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| CN201711481419.3A CN108216617B (en) | 2017-12-29 | 2017-12-29 | Method for suppressing helicopter propeller-vortex interference noise |
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| CN108216617A CN108216617A (en) | 2018-06-29 |
| CN108216617B true CN108216617B (en) | 2020-04-24 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112896503A (en) * | 2021-03-18 | 2021-06-04 | 厦门大学 | Helicopter rotor blade capable of restraining tip vortex of blade |
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| CN110844115B (en) * | 2019-10-18 | 2022-04-12 | 中国直升机设计研究所 | Method for judging effectiveness of data of propeller vortex interference noise and blade flapping load |
| CN111252243B (en) * | 2020-01-21 | 2022-08-05 | 南京航空航天大学 | Helicopter rotor blade down-turning reverse blade tip driving mechanism based on centrifugal mass block |
| CN112487360B (en) * | 2020-11-20 | 2022-12-30 | 中国直升机设计研究所 | Rotor wing propeller vortex interference noise whole-period averaging method based on statistical analysis |
| CN113705116B (en) * | 2021-04-20 | 2023-05-23 | 中国直升机设计研究所 | Helicopter low-noise flight guiding method |
| CN113335509B (en) * | 2021-06-03 | 2022-07-01 | 南京航空航天大学 | Flow control method for helicopter blade |
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| CN114201819B (en) * | 2021-12-06 | 2024-01-12 | 南京航空航天大学 | Helicopter active noise suppression device integrating acoustic array and in-pitch control |
| CN114044135A (en) * | 2021-12-17 | 2022-02-15 | 厦门大学 | Method and device for suppressing high-speed pulse noise of helicopter and helicopter |
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Patent Citations (7)
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| US3936013A (en) * | 1973-12-17 | 1976-02-03 | Shao Wen Yuan | Vortex control |
| US5562414A (en) * | 1994-06-30 | 1996-10-08 | Kawada Industries, Inc. | Noise reduction device for rotorcraft |
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| CN112896503A (en) * | 2021-03-18 | 2021-06-04 | 厦门大学 | Helicopter rotor blade capable of restraining tip vortex of blade |
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