Sensitivity of tail rotor noise to helicopter configuration in forward flight

Timothy M. Fletcher, Karthikeyan Duraisamy, Richard Brown

Research output: Contribution to conferencePaper

3 Citations (Scopus)

Abstract

Understanding the mechanisms that lead to the production of noise by tail rotors across a broad range of flight conditions and helicopter configurations remains an active area of research. Furthermore, designers require numerical models that are able to efficiently and accurately predict the acoustic signature of the helicopter. Predictions made using the Vorticity Transport Model in conjunction with a linear acoustics code, in which the Ffowcs Williams-Hawkings equation is solved for the sound pressure level on a horizontal observer plane beneath a scaled model of the Bo-105 helicopter, have been shown to compare well with measurements made during the HeliNOVI experiments. As the vertical distance between the tail rotor and the main rotor is reduced, the acoustic signature of the tail rotor changes considerably. Both the blade-vortex interactions that occur between the tail rotor blades and their tip vortices, and the interactions between the tail rotor blades and the tip vortices trailed behind the main rotor blades, act as major sources of loading noise. The work presented in the paper suggests strongly, however, that the apparent acoustic advantages of a tail rotor with a particular sense of rotation cannot be considered independently of the vertical location of the tail rotor with respect to the main rotor.

Conference

Conference65th American Helicopter Society Annual Forum
CityTexas, USA
Period27/05/0929/05/09

Fingerprint

Helicopters
Rotors
Acoustics
Turbomachine blades
Vortex flow
Vorticity
Numerical models
Acoustic waves

Keywords

  • tail rotor noise
  • vorticity transport model
  • Ffowcs Williams-Hawkings equation
  • loading noise

Cite this

Fletcher, T. M., Duraisamy, K., & Brown, R. (2009). Sensitivity of tail rotor noise to helicopter configuration in forward flight. Paper presented at 65th American Helicopter Society Annual Forum, Texas, USA, .
Fletcher, Timothy M. ; Duraisamy, Karthikeyan ; Brown, Richard. / Sensitivity of tail rotor noise to helicopter configuration in forward flight. Paper presented at 65th American Helicopter Society Annual Forum, Texas, USA, .
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title = "Sensitivity of tail rotor noise to helicopter configuration in forward flight",
abstract = "Understanding the mechanisms that lead to the production of noise by tail rotors across a broad range of flight conditions and helicopter configurations remains an active area of research. Furthermore, designers require numerical models that are able to efficiently and accurately predict the acoustic signature of the helicopter. Predictions made using the Vorticity Transport Model in conjunction with a linear acoustics code, in which the Ffowcs Williams-Hawkings equation is solved for the sound pressure level on a horizontal observer plane beneath a scaled model of the Bo-105 helicopter, have been shown to compare well with measurements made during the HeliNOVI experiments. As the vertical distance between the tail rotor and the main rotor is reduced, the acoustic signature of the tail rotor changes considerably. Both the blade-vortex interactions that occur between the tail rotor blades and their tip vortices, and the interactions between the tail rotor blades and the tip vortices trailed behind the main rotor blades, act as major sources of loading noise. The work presented in the paper suggests strongly, however, that the apparent acoustic advantages of a tail rotor with a particular sense of rotation cannot be considered independently of the vertical location of the tail rotor with respect to the main rotor.",
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note = "65th American Helicopter Society Annual Forum ; Conference date: 27-05-2009 Through 29-05-2009",

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Fletcher, TM, Duraisamy, K & Brown, R 2009, 'Sensitivity of tail rotor noise to helicopter configuration in forward flight' Paper presented at 65th American Helicopter Society Annual Forum, Texas, USA, 27/05/09 - 29/05/09, .

Sensitivity of tail rotor noise to helicopter configuration in forward flight. / Fletcher, Timothy M.; Duraisamy, Karthikeyan; Brown, Richard.

2009. Paper presented at 65th American Helicopter Society Annual Forum, Texas, USA, .

Research output: Contribution to conferencePaper

TY - CONF

T1 - Sensitivity of tail rotor noise to helicopter configuration in forward flight

AU - Fletcher, Timothy M.

AU - Duraisamy, Karthikeyan

AU - Brown, Richard

PY - 2009/5/27

Y1 - 2009/5/27

N2 - Understanding the mechanisms that lead to the production of noise by tail rotors across a broad range of flight conditions and helicopter configurations remains an active area of research. Furthermore, designers require numerical models that are able to efficiently and accurately predict the acoustic signature of the helicopter. Predictions made using the Vorticity Transport Model in conjunction with a linear acoustics code, in which the Ffowcs Williams-Hawkings equation is solved for the sound pressure level on a horizontal observer plane beneath a scaled model of the Bo-105 helicopter, have been shown to compare well with measurements made during the HeliNOVI experiments. As the vertical distance between the tail rotor and the main rotor is reduced, the acoustic signature of the tail rotor changes considerably. Both the blade-vortex interactions that occur between the tail rotor blades and their tip vortices, and the interactions between the tail rotor blades and the tip vortices trailed behind the main rotor blades, act as major sources of loading noise. The work presented in the paper suggests strongly, however, that the apparent acoustic advantages of a tail rotor with a particular sense of rotation cannot be considered independently of the vertical location of the tail rotor with respect to the main rotor.

AB - Understanding the mechanisms that lead to the production of noise by tail rotors across a broad range of flight conditions and helicopter configurations remains an active area of research. Furthermore, designers require numerical models that are able to efficiently and accurately predict the acoustic signature of the helicopter. Predictions made using the Vorticity Transport Model in conjunction with a linear acoustics code, in which the Ffowcs Williams-Hawkings equation is solved for the sound pressure level on a horizontal observer plane beneath a scaled model of the Bo-105 helicopter, have been shown to compare well with measurements made during the HeliNOVI experiments. As the vertical distance between the tail rotor and the main rotor is reduced, the acoustic signature of the tail rotor changes considerably. Both the blade-vortex interactions that occur between the tail rotor blades and their tip vortices, and the interactions between the tail rotor blades and the tip vortices trailed behind the main rotor blades, act as major sources of loading noise. The work presented in the paper suggests strongly, however, that the apparent acoustic advantages of a tail rotor with a particular sense of rotation cannot be considered independently of the vertical location of the tail rotor with respect to the main rotor.

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KW - vorticity transport model

KW - Ffowcs Williams-Hawkings equation

KW - loading noise

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Fletcher TM, Duraisamy K, Brown R. Sensitivity of tail rotor noise to helicopter configuration in forward flight. 2009. Paper presented at 65th American Helicopter Society Annual Forum, Texas, USA, .