Eulerian simulation of the fluid dynamics of helicopter brownout

Catriona Phillips, R.E. Brown

Research output: Contribution to conferencePaper

45 Citations (Scopus)

Abstract

A computational model is presented that can be used to simulate the development of the dust cloud that can be entrained into the air when a helicopter is operated close to the ground in desert or dusty conditions. The physics of this problem, and the associated pathological condition known as 'brownout' where the pilot loses situational awareness as a result of his vision being occluded by dust suspended in the flow around the helicopter, is acknowledged to be very complex. The approach advocated here involves an approximation to the full dynamics of the coupled particulate-air system. Away from the ground, the model assumes that the suspended particles remain in near equilibrium under the action of aerodynamic forces. Close to the ground, this model is replaced by an algebraic sublayer model for the saltation and entrainment process. The origin of the model in the statistical mechanics of a distribution of particles governed by aerodynamic forces allows the validity of the method to be evaluated in context by comparing the physical properties of the suspended particulates to the local properties of the flow field surrounding the helicopter. The model applies in the Eulerian frame of reference of most conventional Computational Fluid Dynamics codes and has been coupled with Brown's Vorticity Transport Model. Verification of the predictions of the coupled model against experimental data for particulate entrainment and transport in the flow around a model rotor are encouraging. An application of the coupled model to analyzing the differences in the geometry and extent of the dust clouds that are produced by single main rotor and tandem-rotor configurations as they decelerate to land has shown that the location of the ground vortex and the size of any regions of recirculatory flow, should they exist, play a primary role in governing the extent of the dust cloud that is created by the helicopter.

Conference

Conference64th American Helicopter Society Annual Forum
CityMontréal, Canada
Period28/04/081/05/08

Fingerprint

Helicopter
Fluid Dynamics
Fluid dynamics
Helicopters
Rotor
Simulation
Entrainment
Dust
Coupled Model
Aerodynamics
Rotors
Model
Decelerate
Situational Awareness
Local Properties
Computational Fluid Dynamics
Physical property
Statistical Mechanics
Vorticity
Computational Model

Keywords

  • helicopter brownout
  • computational fluid dynamics
  • vorticity transport model
  • particulate entrainment

Cite this

Phillips, C., & Brown, R. E. (2008). Eulerian simulation of the fluid dynamics of helicopter brownout. Paper presented at 64th American Helicopter Society Annual Forum, Montréal, Canada, .
Phillips, Catriona ; Brown, R.E. / Eulerian simulation of the fluid dynamics of helicopter brownout. Paper presented at 64th American Helicopter Society Annual Forum, Montréal, Canada, .
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title = "Eulerian simulation of the fluid dynamics of helicopter brownout",
abstract = "A computational model is presented that can be used to simulate the development of the dust cloud that can be entrained into the air when a helicopter is operated close to the ground in desert or dusty conditions. The physics of this problem, and the associated pathological condition known as 'brownout' where the pilot loses situational awareness as a result of his vision being occluded by dust suspended in the flow around the helicopter, is acknowledged to be very complex. The approach advocated here involves an approximation to the full dynamics of the coupled particulate-air system. Away from the ground, the model assumes that the suspended particles remain in near equilibrium under the action of aerodynamic forces. Close to the ground, this model is replaced by an algebraic sublayer model for the saltation and entrainment process. The origin of the model in the statistical mechanics of a distribution of particles governed by aerodynamic forces allows the validity of the method to be evaluated in context by comparing the physical properties of the suspended particulates to the local properties of the flow field surrounding the helicopter. The model applies in the Eulerian frame of reference of most conventional Computational Fluid Dynamics codes and has been coupled with Brown's Vorticity Transport Model. Verification of the predictions of the coupled model against experimental data for particulate entrainment and transport in the flow around a model rotor are encouraging. An application of the coupled model to analyzing the differences in the geometry and extent of the dust clouds that are produced by single main rotor and tandem-rotor configurations as they decelerate to land has shown that the location of the ground vortex and the size of any regions of recirculatory flow, should they exist, play a primary role in governing the extent of the dust cloud that is created by the helicopter.",
keywords = "helicopter brownout, computational fluid dynamics, vorticity transport model, particulate entrainment",
author = "Catriona Phillips and R.E. Brown",
note = "Also published in: Journal of Aircraft (2009), 46 (4), pp1416-1429. This is a variant record V of 27438; 64th American Helicopter Society Annual Forum ; Conference date: 28-04-2008 Through 01-05-2008",
year = "2008",
month = "5",
day = "28",
language = "English",

}

Phillips, C & Brown, RE 2008, 'Eulerian simulation of the fluid dynamics of helicopter brownout' Paper presented at 64th American Helicopter Society Annual Forum, Montréal, Canada, 28/04/08 - 1/05/08, .

Eulerian simulation of the fluid dynamics of helicopter brownout. / Phillips, Catriona; Brown, R.E.

2008. Paper presented at 64th American Helicopter Society Annual Forum, Montréal, Canada, .

Research output: Contribution to conferencePaper

TY - CONF

T1 - Eulerian simulation of the fluid dynamics of helicopter brownout

AU - Phillips, Catriona

AU - Brown, R.E.

N1 - Also published in: Journal of Aircraft (2009), 46 (4), pp1416-1429. This is a variant record V of 27438

PY - 2008/5/28

Y1 - 2008/5/28

N2 - A computational model is presented that can be used to simulate the development of the dust cloud that can be entrained into the air when a helicopter is operated close to the ground in desert or dusty conditions. The physics of this problem, and the associated pathological condition known as 'brownout' where the pilot loses situational awareness as a result of his vision being occluded by dust suspended in the flow around the helicopter, is acknowledged to be very complex. The approach advocated here involves an approximation to the full dynamics of the coupled particulate-air system. Away from the ground, the model assumes that the suspended particles remain in near equilibrium under the action of aerodynamic forces. Close to the ground, this model is replaced by an algebraic sublayer model for the saltation and entrainment process. The origin of the model in the statistical mechanics of a distribution of particles governed by aerodynamic forces allows the validity of the method to be evaluated in context by comparing the physical properties of the suspended particulates to the local properties of the flow field surrounding the helicopter. The model applies in the Eulerian frame of reference of most conventional Computational Fluid Dynamics codes and has been coupled with Brown's Vorticity Transport Model. Verification of the predictions of the coupled model against experimental data for particulate entrainment and transport in the flow around a model rotor are encouraging. An application of the coupled model to analyzing the differences in the geometry and extent of the dust clouds that are produced by single main rotor and tandem-rotor configurations as they decelerate to land has shown that the location of the ground vortex and the size of any regions of recirculatory flow, should they exist, play a primary role in governing the extent of the dust cloud that is created by the helicopter.

AB - A computational model is presented that can be used to simulate the development of the dust cloud that can be entrained into the air when a helicopter is operated close to the ground in desert or dusty conditions. The physics of this problem, and the associated pathological condition known as 'brownout' where the pilot loses situational awareness as a result of his vision being occluded by dust suspended in the flow around the helicopter, is acknowledged to be very complex. The approach advocated here involves an approximation to the full dynamics of the coupled particulate-air system. Away from the ground, the model assumes that the suspended particles remain in near equilibrium under the action of aerodynamic forces. Close to the ground, this model is replaced by an algebraic sublayer model for the saltation and entrainment process. The origin of the model in the statistical mechanics of a distribution of particles governed by aerodynamic forces allows the validity of the method to be evaluated in context by comparing the physical properties of the suspended particulates to the local properties of the flow field surrounding the helicopter. The model applies in the Eulerian frame of reference of most conventional Computational Fluid Dynamics codes and has been coupled with Brown's Vorticity Transport Model. Verification of the predictions of the coupled model against experimental data for particulate entrainment and transport in the flow around a model rotor are encouraging. An application of the coupled model to analyzing the differences in the geometry and extent of the dust clouds that are produced by single main rotor and tandem-rotor configurations as they decelerate to land has shown that the location of the ground vortex and the size of any regions of recirculatory flow, should they exist, play a primary role in governing the extent of the dust cloud that is created by the helicopter.

KW - helicopter brownout

KW - computational fluid dynamics

KW - vorticity transport model

KW - particulate entrainment

UR - http://strathprints.strath.ac.uk/27438/

M3 - Paper

ER -

Phillips C, Brown RE. Eulerian simulation of the fluid dynamics of helicopter brownout. 2008. Paper presented at 64th American Helicopter Society Annual Forum, Montréal, Canada, .