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Friday, July 31, 2020 | History

3 edition of Helicopter tail rotor blade-vortex interaction noise found in the catalog.

Helicopter tail rotor blade-vortex interaction noise

Helicopter tail rotor blade-vortex interaction noise

final technical report

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  • 3 Currently reading

Published by National Aeronautics and Space Administration in [Washington, DC .
Written in English

    Subjects:
  • Noise control.,
  • Acoustical engineering.

  • Edition Notes

    StatementAlbert R. George and S.-T. Chou.
    SeriesNASA contractor report -- NASA CR-183178.
    ContributionsChou, Shau-Tak., United States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL15278639M

      The whup whup noise you hear of a rotor blade are actually mini-sonic booms. Just as the crack of a whip is a sonic boom on a small scale. It is the air gliding over the airfoil and coming back together at the tips that make that noise. The noi. INFLUENCE OF A HELICOPTER TAIL ROTOR SHROUD ON THE INTERACTION NOISE DUE TO THE MAIN ROTOR VORTICES M. Weisgerber, G. Neuwerth Institut fur¨ Luft- und Raumfahrt der RWTH-Aachen Aachen, Germany Abstract In this paper the topic of Blade-Vortex-Interaction (BVI) of the main rotor blade tip vor-tices with the helicopter tail rotor will be.

    A wind tunnel study was performed to investigate the noise characteristics and directivity pattern of a 40 percent scaled helicopter rotor system (BO main/tail rotor model). The major objectives of the study were to establish the importance of the tail rotor with respect to the overall noise radiation and to determine the noise reduction potential of aerodynamically improved blade design. And helicopters can be more or less quiet in certain flight conditions, such as during an approach. This is due to blade vortex interaction (BVI), a type of loading noise. Each main rotor blade also produces a strong tip vortex whose trajectory travels downstream from the rotor .

    Boxwell DA, Schmitz FH, Splettstoesser WR, and Schultz KJ, “ Helicopter Model Rotor-Blade Vortex Interaction Impulsive Noise: Scalability and Parametric Variations,” Journal of the American Helicopter Society, Vol. 32, (1), , pp. 3– doi: /JAHS [Google Scholar]. Schmitz, F.H., â Rotor Noise,â book chapter title from Aeroacoustics of Flight Vehicles: Theory & Practice, re-published by the Acoustical Society of America, Schmitz, F.H., â Reduction of Blade-Vortex Interaction (BVI) Noise Through X-Force Control,â Journal of the American Helicopter Society, Vol. 43, No. 1, Jan.


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Helicopter tail rotor blade-vortex interaction noise Download PDF EPUB FB2

A blade vortex interaction (BVI) is an unsteady phenomenon of three-dimensional nature, which occurs when a rotor blade passes within a close proximity of the shed tip vortices from a previous blade. The aerodynamic interactions represent an important topic of investigation in rotorcraft research field due to the adverse influence produced on rotor noise, particularly in low speed.

This noise mechanism depends strongly on the helicopter flight conditions and the relative location and phasing of the main and tail rotors.

fluctuations of significant magnitude can be generated by tail rotors due to a series of interactions with main rotor tip vortices. Helicopter noise reduction is a topic of research into designing helicopters which can be operated more quietly, reducing the public-relations problems with night-flying or expanding an airport.

In addition, it is useful for military applications in which stealth is required: long-range propagation of helicopter noise can alert an enemy to an incoming helicopter in time to re-orient defenses. The primary source of the impulsive noise from the tail rotor was identified as the interaction of the tail rotor blades with the tail rotor wake.

Indeed, in combined operation, it was almost impossible to discern main rotor tip vortex interactions on the tail rotor because of these ‘self’ by:   Helicopter noise reduction is a topic of research into designing helicopters which can be operated more quietly.

The major source of the noise come from the rotor blade vortex interaction. By attaching spoiler in the helicopter main rotor blades and tail rotors reduce the noise Author: M. Islam, M. Rabbi, M. Uddin. BVI (blade vortex interaction) phenomena cause unsteady loading and noise in the helicopter rotor.

It is difficult to accurately predict BVI aerodynamics and noise, because rotor wake and tip-vortices are numerically dissipated. An illustration of an open book. Books. An illustration of two cells of a film strip. Video. An illustration of an audio speaker. Audio. An illustration of a " floppy disk.

Software. An illustration of two photographs. Full text of "Helicopter tail rotor blade-vortex interaction noise". Helicopter tail rotor blade-vortex interaction noise A study is made of helicopter tail rotor noise, particularly that due to the interactions with main rotor tip vortices.

Summarized here are present analysis, the computer codes, and the results of several test cases. The aim of this program is to reduce the noise generated by so-called blade-vortex interactions (BVI), which occur when a blade impacts a vortex, created at the tip of the blade of any helicopter.

Although their capability is effective in the civil transportation, noise is a major problem. Helicopters produce many kinds of noise, such as blade-vortex interaction (BVI) noise, high-speed impulsive (HSI) noise, engine noise, transmission noise, tail rotor noise, blade-wake interaction (BWI) noise, main-rotor/tail-rotor interaction noise.

Reduction of helicopter blade-vortex interaction noise by active rotor control technology Progress in Aerospace Sciences, Vol. 33, No. Turbulence structure resulting from a perpendicular airfoil-vortex interaction. Of the noise generated by the tail rotor blades, noise arising from blade vortex interaction is significant source of helicopter operating noise.

Blade vortex interaction noise arises primarily from interfering tip vortices interacting with the corresponding trailing tail rotor blades. Helicopter Tail Rotor Orthogonal Blade Vortex Interaction termed a Blade Vortex Interaction (BVI).

Tail rotor BVIs occur for a wide range of Apart from performance, the radiated noise from helicopters, both civil and military, has always been a cause for concern. In. The features on the wrecked tail rotor could also have been for noise reduction purposes. such as Blade Vortex Interaction (BVI) noise and High Speed Impulsive (HSI) noise, become dominant in.

A Wind Tunnel Based Study of Helicopter Tail Rotor Blade Vortex Interaction, (). Acoustic Flight Test Results for the Sikorsky S Quiet Tail Rotor at Reduced Tip Speed. An Analytical Model for Prediction of Main Rotor/Tail Rotor Interaction Noise, AIAA paper A generic single main rotor and tail rotor helicopter has been simulated in high speed forward, and quartering, flight using the Vorticity Transport Model.

Blade Vortex Interaction noise is. A Study on Propeller & Rotor Noise and Reduction of their acoustic intensity. Summary: During the passage of a propeller aircraft or a helicopter, it is a valid question to ask why these types of aircraft emit a noise so powerful and over such a long distance.

from the study of the motor to the interactions between the pure aerodynamic. A Comparative Study of Tail Rotor Noise Mechanisms Journal of the American Helicopter Society, Vol. 31, No.

4 Concepts for reduction of blade-vortex interaction noise. Helicopter Blade-Vortex Interaction Noise with Comparisons to CFD Calculations MEGAN S MCCLUER Ames Research Center Summary A comparison of experimental acoustics data and computational predictions was performed for a helicopter rotor blade interacting with a parallel vortex.

The experi-ment was designed to examine the aerodynamics and. A tail rotor can be recessed into the fairing of the tail (a fenestron) to reduce noise below the helicopter.

This type of rotor has eight to 12 blades, rather than the two to four in a conventional tail rotor, which increases the frequency of the noise and causes it to be reduced by the atmosphere.

The tail rotor can be placed within a shroud. Both of these technologies are able to reduce noise by minimizing the blade-vortex interaction of the main rotor on a helicopter.

Blade-vortex interaction is the source of the pulsating sound most.J. American Helicopter Soc., vol. 27, no. 4, Oct.pp. 11â ) Figure A Physical causes of helicopter blade-vortex interaction noise. (Source: Schmitz, F. H.

and Sim. B., Sketch from HAI briefing, Los Angeles, CA ) Figure A Geometry of the BVI interaction process. Technical Discussion of Helicopter Noise Figure A-6 shows.Blade-vortex interaction Last updated Octo Helicopter blade tip vortex simulation by DLR Tip vortex rollup.

A blade vortex interaction (BVI) is an unsteady phenomenon of three-dimensional nature, which occurs when a rotor blade passes within a close proximity of the shed tip vortices from a previous blade. The aerodynamic interactions represent an important topic of investigation.