The effect of rotor design on the fluid dynamics of helicopter brownout

Catriona Phillips, Hyo Wan Kim, R.E. Brown

Research output: Contribution to conferencePaper

6 Citations (Scopus)

Abstract

Helicopters operating close to the ground in dusty environments tend to generate large clouds of dust in the surrounding air. These clouds can obscure the pilot's view of the ground and lead to a dangerous condition known as brownout. Given the intimate relationship between the induced flow feld around the rotor and the process through which the particulate matter becomes airborne and is subsequently transported, it has been speculated that the design of its rotor may influence the shape and size of the dust clouds that are produced by any particular type of helicopter. This paper presents a study of the influence of two key geometric properties of the rotor on the development of these dust clouds. A particle transport model is coupled to Brown's Vorticity Transport Model to represent the dynamics of the particulate-air system surrounding a generic helicopter rotor under various flight conditions. The number of blades on the rotor is altered, whilst keeping the solidity constant, thus altering the distribution of vorticity that is released onto the ground. In addition, the twist of the blades is varied in order to investigate the effect of the resultant changes in the distribution of induced downwash on the evolution of the dust cloud. The study suggests that, in general, the larger the number of blades, and the higher the blade twist, the less dense the dust clouds that are produced under brownout conditions. It appears thus that the characteristics of the dust clouds are indeed sensitive to the geometry of the rotor and hence that careful aerodynamic design may allow the severity of brownout to be ameliorated.
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

Helicopter
Fluid Dynamics
Fluid dynamics
Helicopters
Rotor
Dust
Rotors
Blade
Vorticity
Twist
Helicopter rotors
Aerodynamic Design
Particulate Matter
Particle Transport
Air
Particles (particulate matter)
Turbomachine blades
Design
Aerodynamics
Tend

Keywords

  • helicopter brownout
  • particle transport model
  • vorticity transport model
  • rotor geometry
  • rotor aerodynamics

Cite this

Phillips, C., Kim, H. W., & Brown, R. E. (2009). The effect of rotor design on the fluid dynamics of helicopter brownout. Paper presented at 35th European Rotorcraft Forum, Hamburg, Gemany, .
Phillips, Catriona ; Kim, Hyo Wan ; Brown, R.E. / The effect of rotor design on the fluid dynamics of helicopter brownout. Paper presented at 35th European Rotorcraft Forum, Hamburg, Gemany, .
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Phillips, C, Kim, HW & Brown, RE 2009, 'The effect of rotor design on the fluid dynamics of helicopter brownout' Paper presented at 35th European Rotorcraft Forum, Hamburg, Gemany, 22/09/09 - 25/09/09, .

The effect of rotor design on the fluid dynamics of helicopter brownout. / Phillips, Catriona; Kim, Hyo Wan; Brown, R.E.

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

Research output: Contribution to conferencePaper

TY - CONF

T1 - The effect of rotor design on the fluid dynamics of helicopter brownout

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AU - Kim, Hyo Wan

AU - Brown, R.E.

PY - 2009/9/22

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N2 - Helicopters operating close to the ground in dusty environments tend to generate large clouds of dust in the surrounding air. These clouds can obscure the pilot's view of the ground and lead to a dangerous condition known as brownout. Given the intimate relationship between the induced flow feld around the rotor and the process through which the particulate matter becomes airborne and is subsequently transported, it has been speculated that the design of its rotor may influence the shape and size of the dust clouds that are produced by any particular type of helicopter. This paper presents a study of the influence of two key geometric properties of the rotor on the development of these dust clouds. A particle transport model is coupled to Brown's Vorticity Transport Model to represent the dynamics of the particulate-air system surrounding a generic helicopter rotor under various flight conditions. The number of blades on the rotor is altered, whilst keeping the solidity constant, thus altering the distribution of vorticity that is released onto the ground. In addition, the twist of the blades is varied in order to investigate the effect of the resultant changes in the distribution of induced downwash on the evolution of the dust cloud. The study suggests that, in general, the larger the number of blades, and the higher the blade twist, the less dense the dust clouds that are produced under brownout conditions. It appears thus that the characteristics of the dust clouds are indeed sensitive to the geometry of the rotor and hence that careful aerodynamic design may allow the severity of brownout to be ameliorated.

AB - Helicopters operating close to the ground in dusty environments tend to generate large clouds of dust in the surrounding air. These clouds can obscure the pilot's view of the ground and lead to a dangerous condition known as brownout. Given the intimate relationship between the induced flow feld around the rotor and the process through which the particulate matter becomes airborne and is subsequently transported, it has been speculated that the design of its rotor may influence the shape and size of the dust clouds that are produced by any particular type of helicopter. This paper presents a study of the influence of two key geometric properties of the rotor on the development of these dust clouds. A particle transport model is coupled to Brown's Vorticity Transport Model to represent the dynamics of the particulate-air system surrounding a generic helicopter rotor under various flight conditions. The number of blades on the rotor is altered, whilst keeping the solidity constant, thus altering the distribution of vorticity that is released onto the ground. In addition, the twist of the blades is varied in order to investigate the effect of the resultant changes in the distribution of induced downwash on the evolution of the dust cloud. The study suggests that, in general, the larger the number of blades, and the higher the blade twist, the less dense the dust clouds that are produced under brownout conditions. It appears thus that the characteristics of the dust clouds are indeed sensitive to the geometry of the rotor and hence that careful aerodynamic design may allow the severity of brownout to be ameliorated.

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KW - vorticity transport model

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Phillips C, Kim HW, Brown RE. The effect of rotor design on the fluid dynamics of helicopter brownout. 2009. Paper presented at 35th European Rotorcraft Forum, Hamburg, Gemany, .