#### DMCA

## Influence of Transient Flight Maneuvers on Rotor Wake Dynamics And Noise (2004)

### Citations

1563 | An introduction to fluid dynamics - Batchelor - 1967 |

182 | Helicopter Theory, - Johnson - 1980 |

150 | Vortex Methods: Theory and Practice. - Cottet, Koumoutsakos - 2000 |

20 |
Stability, consistency and convergence of time marching free-vortex rotor wake algorithms
- Bhagwat, Leishman
- 2001
(Show Context)
Citation Context ...s the foregoing equation can be written as the partial differential equation ∂r(ψ,ζ) ∂ψ + ∂r(ψ,ζ) ∂ζ 1 = V(r(ψ,ζ)) (3) Ω In discretized form, equation 3 can be written as ∂r ∂r + =-=∂ψ ∂ζ ≈ Dψ + Dζ = ∑V (4) where-=- Dψ is the spatial finite-difference operator and D ζ is the temporal operator, using discretizations Δψ and Δζ, respectively. All of the present calculations were done using a discretization of... |

18 | The lift distribution of swept back wings - Weissinger - 1947 |

11 |
Free-Vortex Filament Methods for the Analysis of Helicopter Rotor
- Leishman, Bhagwat, et al.
- 2002
(Show Context)
Citation Context ...sient maneuver flight conditions. This code is an implementation of Farassat’s retarded-time formulation 1A of the Ffowcs Williams-Hawkings (FW22, 23 H) equation: p ′ (x,t) = p ′ T (x,t) + p′ =-=L (x,t) (5) where the thickness noi-=-se contribution p ′ T is defined as 4πp ′ T (x,t) = Z + f =0 Z f =0 � � ρ0( ˙Un +U˙n) r(1 − Mr) 2 � ρ0Un(r ˙Mr + c(Mr − M2 � )) r 2 (1 − Mr) 3 dS ret dS ret (6)sand the loading... |

8 |
Effect of a rapid blade-pitch increase on the thrust and induced-velocity response of a full-scale helicopter rotor. 3044. National Advisory Committee for Aeronautics
- Carpenter, Fridovich
- 1953
(Show Context)
Citation Context ...noise contribution p ′ L is defined as 4πp ′ Z � 1 ˙Lr L (x,t) = c r(1 − Mr) f =0 2 � dS ret Z � Lr − LM + r2 (1 − Mr) 2 � + 1 Z c f =0 � Lr f =0 � r ˙Mr + c(Mr − M2 ) ���=-=� r 2 (1 − Mr) 3 dS ret ret dS (7) T-=-he FW–H quadrupole term, which is necessary for the prediction of high-speed impulsive noise, has been neglected. In Eq. 6, maneuver influences the thickness noise through the normal component of th... |

8 | A New Model for Rotor Dynamics During Pitch and Roll of a Hovering Helicopter - Rosen, Isser - 1995 |

8 | Aerodynamic Analysis of a Helicopter in Steady Maneuvering Flight Using a Free-Vortex Rotor Wake Model,’’ - Bagai, Leishman, et al. - 1999 |

7 |
Maneuvering Rotorcraft Noise Prediction: A New Code for a New Problem
- Brentner
- 2002
(Show Context)
Citation Context ...s described in threedimensional, incompressible, viscous flow by the Navier-Stokes equations. These can be expressed in a velocity-vorticity (V,ω) formulation as dω dt = −(V · ∇)ω + (ω · ∇=-=)V + νΔ · ω (1)-=- In free-vortex filament methods, the vortex elements are assumed to be singular filaments of constant circulation. In this case, the governing equation for the wake becomes the simpler advection (con... |

7 | Subsonic Unsteady Aerodynamics Caused by Gusts Using the Indicial Method - Leishman - 1996 |

6 | Aeroacoustics of 2-D and 3-D Blade Vortex Interaction Using the - Leishman - 1996 |

5 |
Near Real-Time Simulation of Rotorcraft Acoustics and Flight Dynamics.” American Helicopter Society 59th Annual Forum
- Brentner
- 2003
(Show Context)
Citation Context ...ments are assumed to be singular filaments of constant circulation. In this case, the governing equation for the wake becomes the simpler advection (convection) equation dr dt = V(r,t), r(t = 0) = r0 =-=(2)-=- where r is the position vector of a point on the vortex filament, r0 is the initial position vector, and V is the local velocity field at that point. Because the position vector r is a function of bo... |

4 | The Vortex Ring State as a Spatially and Temporally Developing Wake - Leishman, Bhagwat, et al. - 2002 |

3 | Effectiveness of Current Dynamic Inflow Models in Hover and Forward Flight - Gaonkar, Peters - 1986 |

3 | The Effect of Wake Distortion - Barocela, Peters, et al. - 1997 |

3 | The Role of Filament Stretching in the Free-Vortex Modeling of Rotor Wakes - Ananthan - 2002 |

2 | Apparent Mass Effects on a StiffHinged Rotor Model after Rapid Cyclic and/or Collective Inputs - A FlowVisualization Study,” 27th European Rotorcraft Forum - Jessurun, Pavel, et al. - 2001 |

2 | Modeling the Induced Velocity of a Maneuvering Helicopter,” American Helicopter Society 52 nd Annual National Forum - Keller, Curtiss - 1996 |

1 |
Predictions of Transient Wake Aerodynamics in Response to TimeDependent Pilot Control Inputs
- Ananthan, Leishman
- 2003
(Show Context)
Citation Context ...t) + p′ L (x,t) (5) where the thickness noise contribution p ′ T is defined as 4πp ′ T (x,t) = Z + f =0 Z f =0 � � ρ0( ˙Un +U˙n) r(1 − Mr) 2 � ρ0Un(r ˙Mr + c(Mr − M2 � )) r 2 (=-=1 − Mr) 3 dS ret dS ret (6)sand the loading noise contributi-=-on p ′ L is defined as 4πp ′ Z � 1 ˙Lr L (x,t) = c r(1 − Mr) f =0 2 � dS ret Z � Lr − LM + r2 (1 − Mr) 2 � + 1 Z c f =0 � Lr f =0 � r ˙Mr + c(Mr − M2 ) �� r 2 (1 − Mr)... |