Towards the impact of flow bi-stability on the launch and recovery of helicopters on ships

Herry, Benjamin; Vorst, J. van der

doi:10.2514/6.2011-7043

Cited by 7 publications

(4 citation statements)

References 8 publications

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“…However, at the position far away from the guardrail height and close to the bridge deck, such as 0.226 m and 4.226 m, the data still maintain good symmetry. Some studies have reported the phenomenon of asymmetric flow in symmetric geometry (Herry, 2010; Prevezer et al, 2002; Syms, 2008). They found the unsteady asymmetric results of symmetric flow in CFD simulation and in wind-tunnel measurement.…”

Section: Numerical Simulation Resultsmentioning

confidence: 99%

Research on wind barrier of canyon bridge-tunnel junction based on wind characteristics

Wang

Chen

2020

Advances in Structural Engineering

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Due to the acceleration effect of the wind by the special geographical location of the canyon bridge-tunnel junction, the traffic safety and stability of this section are difficult to be guaranteed, resulting in frequent traffic accidents. In order to ensure the safety and comfort of vehicles driving on this section, the numerical simulation method based on CFD is adopted to establish the numerical model of the canyon bridge-tunnel junction. The acceleration of the incoming wind speed in the bridge-tunnel junction with a guardrail that is 0.8 m high is analyzed from different canyon spacings, wind directions and heights from the bridge deck. Based on the characteristics of wind field above the bridge deck, two kinds of gradient wind barriers—trapezoidal and stepped—are proposed, and their wind reduction effects and turbulence intensity changes are analyzed. Then the aerodynamic performances of running vehicle are compared. The results show that the stepped wind barrier with 50% porosity and rectangular section railings has the best wind reduction effects, and can noticeably improve the comfort of driving. The aerodynamic coefficients of vehicle are lower with stepped wind barrier.

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Section: Numerical Simulation Resultsmentioning

confidence: 99%

Research on wind barrier of canyon bridge-tunnel junction based on wind characteristics

Wang

Chen

2020

Advances in Structural Engineering

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“…Simple frigate shape (SFS) is a simplified geometry common to the main of frigates usually studied in a first step in both experimental aerodynamics [ 7 , 8 ] and computational simulations [ 9 , 10 ]. This geometry has the most relevant aspects in an aerodynamic sense, as superstructure, bridge, hangar, and flight deck.…”

Section: Simple Frigate Shape Modelmentioning

confidence: 99%

“…A typical case of study in experimental aerodynamics [ 7 , 8 ] and computational simulations [ 9 , 10 ] is the simple frigate shape (SFS). This case is a representative case of study of the flow on the ship flight deck, since it has a simplified geometry common to the main of frigates containing the most relevant aspects in an aerodynamic sense, as superstructure, bridge, hangar, and flight deck.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Flow on a Simple Frigate Shape (SFS)

Mora

2014

The Scientific World Journal

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Helicopters operations on board ships require special procedures introducing additional limitations known as ship helicopter operational limitations (SHOLs) which are a priority for all navies. This paper presents the main results obtained from the experimental investigation of a simple frigate shape (SFS) which is a typical case of study in experimental and computational aerodynamics. The results obtained in this investigation are used to make an assessment of the flow predicted by the SFS geometry in comparison with experimental data obtained testing a ship model (reduced scale) in the wind tunnel and on board (full scale) measurements performed on a real frigate type ship geometry.

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“…The ship airwake environment poses a significant risk to flight operations with helicopters due to the generally unsteady nature of the airwake and the significant variations of downwash and upwash experienced by the helicopter due to vortices and dead-air regions behind the vessel's superstructure 1,2,5,6,9,10,13 . Characterization of the ship airwake environment for safer aircraft launch and recovery is therefore a vivid area in international research, as are the operational and simulation aspects of helicopters flying in the airwakes of ships.…”

Section: Introductionmentioning

confidence: 99%

Computational ship airwake determination to support helicopter-ship dynamic interface assessment

Muijden

Boelens

Vorst

et al. 2013

21st AIAA Computational Fluid Dynamics Conference

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A highly important aspect of safe sea-based helicopter operation is the establishment of ship-helicopter operational limits for current and future helicopter/ship combinations. The capabilities of Computational Fluid Dynamics for the determination of ship airwakes have been investigated, aiming at complementing existing experimental data acquisition techniques consisting of wind tunnel and on-board full-scale measurements. In this paper, computed airwakes based on the Reynolds-averaged Navier-Stokes (RANS) equations as well as on a hybrid RANS-Large Eddy Simulation (LES) approach are compared with experimental data. The resulting airwakes have been converted for usage in a helicopter flight simulator to enable additional feed-back on the reality level of the computational approaches from experienced pilots. It is shown that, from a practical point of view, a useful first impression of the average flow characteristics in the ship airwake can be obtained from steady RANS flow modeling, although the more computationally intensive hybrid RANS-LES approach has an inherently better potential for capturing all of the physical content of the fluctuating flow fields. Nomenclature C v = ratio of local velocity to free-stream velocity, defined as (u 2 + v 2 + w 2 ) 0.5 h = characteristic mesh cell size k = turbulent kinetic energy L = reference length of the ship t = physical time t * = non-dimensional time, in CTS units u = velocity component in x-direction, scaled with U U = reference velocity of the free-stream flow v = velocity component in y-direction, scaled with U w = velocity component in z-direction, scaled with U x, y, z = orthogonal Cartesian coordinate directions β = sideslip angle of reference flow vector β local = local sideslip angle Δt = time step Δt * = non-dimensional time step = vertical deviation of local flow vector from the horizontal plane χ = horizontal deviation of local flow vector from the oncoming flow direction, β local -β ω = specific turbulent dissipation rate CFD = Computational Fluid Dynamics CFL = Courant-Friedrichs-Lewy number, stability criterion for numerical integration CTS = Convective Time Scale, defined as L/U, average time required for a fluid particle to pass the ship

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Towards the impact of flow bi-stability on the launch and recovery of helicopters on ships

Cited by 7 publications

References 8 publications

Research on wind barrier of canyon bridge-tunnel junction based on wind characteristics

Research on wind barrier of canyon bridge-tunnel junction based on wind characteristics

Experimental Investigation of the Flow on a Simple Frigate Shape (SFS)

Computational ship airwake determination to support helicopter-ship dynamic interface assessment

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