The effect of blade aerodynamic modelling on the prediction of the blade airloads and the acoustic signature of the HART II rotor

Mary E. Kelly, R.E. Brown

Research output: Contribution to conferencePaper

7 Citations (Scopus)

Abstract

As a rotorcraft descends or manoeuvres, the interactions which occur between the rotor blades and vortical structures within the rotor wake produce highly impulsive loads on the blades and with these a highly intrusive external noise. Brown's Vorticity Transport Model has been used to investigate the influence of the fidelity of the local blade aerodynamic model on the quality of the prediction of the high-frequency airloads associated with blade-vortex interactions and thus on the accuracy with which the acoustic signature of the aircraft can be predicted. The Vorticity Transport Model can resolve very accurately the structure of the wake, and allows significant flexibility in the way that the blade loading can be represented. The predictions of two models for the local blade aerodynamics are compared for all three of the HART II flight cases. The first model is a simple lifting-line model and the second is a somewhat more sophisticated lifting-chord model based on unsteady thin aerofoil theory. A marked improvement in accuracy of the predicted high-frequency airloads and acoustic signature of the HART II rotor is obtained when the lifting-chord model for the blade aerodynamics is used instead of the lifting-line type approach. Errors in the amplitude and phase of the loading peaks are reduced and the quality of the prediction is affected to a lesser extent by the computational resolution of the wake. Predictions of the acoustic signature of the rotor are similarly affected, with the lifting-chord model at the highest resolution producing the best representation of the distribution of sound pressure on the ground plane below the rotor.
LanguageEnglish
Publication statusPublished - 22 Sep 2009
Event35th European Rotorcraft Forum - Hamburg, Gemany
Duration: 22 Sep 200925 Sep 2009

Conference

Conference35th European Rotorcraft Forum
CityHamburg, Gemany
Period22/09/0925/09/09

Fingerprint

Blade
Aerodynamics
Rotor
Acoustics
Signature
Rotors
Prediction
Modeling
Wake
Chord or secant line
Vorticity
Model
Turbomachine blades
Line
Interaction
Fidelity
Airfoils
Aircraft
Vortex
Resolve

Keywords

  • hart II rotor
  • vorticity transport model
  • high-frequency airloads
  • blade-vortex interactions
  • lifting-chord model
  • acoustic signature

Cite this

Kelly, M. E., & Brown, R. E. (2009). The effect of blade aerodynamic modelling on the prediction of the blade airloads and the acoustic signature of the HART II rotor. Paper presented at 35th European Rotorcraft Forum, Hamburg, Gemany, .
Kelly, Mary E. ; Brown, R.E. / The effect of blade aerodynamic modelling on the prediction of the blade airloads and the acoustic signature of the HART II rotor. Paper presented at 35th European Rotorcraft Forum, Hamburg, Gemany, .
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abstract = "As a rotorcraft descends or manoeuvres, the interactions which occur between the rotor blades and vortical structures within the rotor wake produce highly impulsive loads on the blades and with these a highly intrusive external noise. Brown's Vorticity Transport Model has been used to investigate the influence of the fidelity of the local blade aerodynamic model on the quality of the prediction of the high-frequency airloads associated with blade-vortex interactions and thus on the accuracy with which the acoustic signature of the aircraft can be predicted. The Vorticity Transport Model can resolve very accurately the structure of the wake, and allows significant flexibility in the way that the blade loading can be represented. The predictions of two models for the local blade aerodynamics are compared for all three of the HART II flight cases. The first model is a simple lifting-line model and the second is a somewhat more sophisticated lifting-chord model based on unsteady thin aerofoil theory. A marked improvement in accuracy of the predicted high-frequency airloads and acoustic signature of the HART II rotor is obtained when the lifting-chord model for the blade aerodynamics is used instead of the lifting-line type approach. Errors in the amplitude and phase of the loading peaks are reduced and the quality of the prediction is affected to a lesser extent by the computational resolution of the wake. Predictions of the acoustic signature of the rotor are similarly affected, with the lifting-chord model at the highest resolution producing the best representation of the distribution of sound pressure on the ground plane below the rotor.",
keywords = "hart II rotor, vorticity transport model, high-frequency airloads, blade-vortex interactions, lifting-chord model, acoustic signature",
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Kelly, ME & Brown, RE 2009, 'The effect of blade aerodynamic modelling on the prediction of the blade airloads and the acoustic signature of the HART II rotor' Paper presented at 35th European Rotorcraft Forum, Hamburg, Gemany, 22/09/09 - 25/09/09, .

The effect of blade aerodynamic modelling on the prediction of the blade airloads and the acoustic signature of the HART II rotor. / Kelly, Mary E.; Brown, R.E.

2009. Paper presented at 35th European Rotorcraft Forum, Hamburg, Gemany, .

Research output: Contribution to conferencePaper

TY - CONF

T1 - The effect of blade aerodynamic modelling on the prediction of the blade airloads and the acoustic signature of the HART II rotor

AU - Kelly, Mary E.

AU - Brown, R.E.

PY - 2009/9/22

Y1 - 2009/9/22

N2 - As a rotorcraft descends or manoeuvres, the interactions which occur between the rotor blades and vortical structures within the rotor wake produce highly impulsive loads on the blades and with these a highly intrusive external noise. Brown's Vorticity Transport Model has been used to investigate the influence of the fidelity of the local blade aerodynamic model on the quality of the prediction of the high-frequency airloads associated with blade-vortex interactions and thus on the accuracy with which the acoustic signature of the aircraft can be predicted. The Vorticity Transport Model can resolve very accurately the structure of the wake, and allows significant flexibility in the way that the blade loading can be represented. The predictions of two models for the local blade aerodynamics are compared for all three of the HART II flight cases. The first model is a simple lifting-line model and the second is a somewhat more sophisticated lifting-chord model based on unsteady thin aerofoil theory. A marked improvement in accuracy of the predicted high-frequency airloads and acoustic signature of the HART II rotor is obtained when the lifting-chord model for the blade aerodynamics is used instead of the lifting-line type approach. Errors in the amplitude and phase of the loading peaks are reduced and the quality of the prediction is affected to a lesser extent by the computational resolution of the wake. Predictions of the acoustic signature of the rotor are similarly affected, with the lifting-chord model at the highest resolution producing the best representation of the distribution of sound pressure on the ground plane below the rotor.

AB - As a rotorcraft descends or manoeuvres, the interactions which occur between the rotor blades and vortical structures within the rotor wake produce highly impulsive loads on the blades and with these a highly intrusive external noise. Brown's Vorticity Transport Model has been used to investigate the influence of the fidelity of the local blade aerodynamic model on the quality of the prediction of the high-frequency airloads associated with blade-vortex interactions and thus on the accuracy with which the acoustic signature of the aircraft can be predicted. The Vorticity Transport Model can resolve very accurately the structure of the wake, and allows significant flexibility in the way that the blade loading can be represented. The predictions of two models for the local blade aerodynamics are compared for all three of the HART II flight cases. The first model is a simple lifting-line model and the second is a somewhat more sophisticated lifting-chord model based on unsteady thin aerofoil theory. A marked improvement in accuracy of the predicted high-frequency airloads and acoustic signature of the HART II rotor is obtained when the lifting-chord model for the blade aerodynamics is used instead of the lifting-line type approach. Errors in the amplitude and phase of the loading peaks are reduced and the quality of the prediction is affected to a lesser extent by the computational resolution of the wake. Predictions of the acoustic signature of the rotor are similarly affected, with the lifting-chord model at the highest resolution producing the best representation of the distribution of sound pressure on the ground plane below the rotor.

KW - hart II rotor

KW - vorticity transport model

KW - high-frequency airloads

KW - blade-vortex interactions

KW - lifting-chord model

KW - acoustic signature

M3 - Paper

ER -

Kelly ME, Brown RE. The effect of blade aerodynamic modelling on the prediction of the blade airloads and the acoustic signature of the HART II rotor. 2009. Paper presented at 35th European Rotorcraft Forum, Hamburg, Gemany, .