Optimization of a columnar vortex generator installed over an aircraft carrier ski-jump ramp

Aircraft performances over aircraft carriers are essential in modern navies. Take-off operation is critical due to the short runway available. The ski-jump ramp is a useful system that allows to operate under safe conditions. However, the sharp edge at the end of the runway provokes a region with recirculation bubble and low velocity producing strong flow disturbances. Hence, the aircraft performances are affected and the pilot’s workload is augmented. Previous researches showed that columnar vortex generator reduces the recirculation bubble generated over the end of flight deck. This article presents an in-depth experimental study performed by wind tunnel testing in order to determine the relation between the columnar vortex generator size and the recirculation bubble reduction. Particle image velocimetry is used to investigate the flow field velocity and flow structure around the ski-jump ramp as a non-intrusive experimental technique. Encouraging results were found for the biggest columnar vortex generator studied.

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Three-dimensional characterization of passive flow control devices over an aircraft carrier ski-jump ramp

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410017716195 ◽

2017 ◽

Vol 232 (15) ◽

pp. 2737-2744

Author(s):

R Bardera ◽

A Rodríguez-Sevillano ◽

M León-Calero ◽

J Nova-Trigueros

Keyword(s):

Flow Control ◽

Three Dimensional ◽

Vortex Generator ◽

Geometrical Parameters ◽

Aircraft Carrier ◽

Recirculation Bubble ◽

Passive Flow Control ◽

Passive Flow ◽

Flow Control Devices ◽

Flow Disturbances

The aircraft carrier is a key element in modern navies. On-board operations at sea take place under very severe conditions, which affect the aerodynamic flow on the flight deck. The ski-jump ramp is a curved runway that enables the aircraft to take-off using shorter runway distance. However, this geometry generates strong flow disturbances, mainly characterized by a recirculation bubble at the forward end of the ramp. This phenomenon reduces the aircraft performances and increases the pilot’s workload due to the unsteady forces which appear on the control surfaces. Passive flow control appears as a solution to this problem. Wind tunnel experimental research was developed in this study to mitigate the adverse aerodynamic effects of the ski-jump ramp presence. Different devices were tested using particle image velocimetry. Geometrical parameters of the devices were varied to study the effectiveness and select the best solution. Interesting results were found for the columnar vortex generator configurations. The optimum configuration could be applied shortly to the full-scale problem to reduce the adverse aerodynamic effects during take-off maneuvers.

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Columnar vortex generator for flow control over a ski-jump ramp

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-05-2017-0181 ◽

2018 ◽

Vol 28 (5) ◽

pp. 1156-1168 ◽

Cited By ~ 1

Author(s):

Rafael Bardera ◽

Marina León-Calero ◽

Joaquín de Nova-Trigueros

Keyword(s):

Flow Field ◽

Flow Control ◽

Vortex Generator ◽

Geometrical Parameters ◽

Recirculation Bubble ◽

Content Type ◽

Flow Configuration ◽

Columnar Vortex ◽

Flow Control Devices ◽

Control Devices

Purpose Aircraft carriers are essential for modern naval operations. Takeoff maneuver is critical because of the short runway distance. The ski-jump ramp is a system which increases the angle of attack of the aircraft, so an extra lift is obtained. Regarding the flow configuration over the ski-jump ramp at ahead wind conditions, the complex aerodynamic environment generated by the ramp configuration influences aircraft operations. This flow field is mainly characterized by a low velocity recirculation bubble that reduces aircraft performances. The purpose of this paper is to find a solution to reduce these adverse effects, by means of flow control devices, which opens a wide field of research. Design/methodology/approach This paper presents wind tunnel tests performed to study the flow configuration in the vicinity of the ski-jump ramp and the flow control devices effects. A 1:100 scaled ship model was built to develop experimental tests by using flow control devices fabricated by means of additive manufacturing. Particle image velocimetry technique was used to measure the velocity flow field and the turbulence intensity maps. Findings Interesting results were obtained when the angle between the intersection of the ski-jump ramp and the columnar vortex generator (CVG) is modified. The results showed a high reduction of the recirculation bubble generated over the flight deck. Originality/value CVG has presented encouraging results as a passive flow control device. A study of the variation of CVG geometrical parameters has been developed.

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An Extended Flexible Job Shop Scheduling Model for Flight Deck Scheduling with Priority, Parallel Operations, and Sequence Flexibility

Scientific Programming ◽

10.1155/2017/2463252 ◽

2017 ◽

Vol 2017 ◽

pp. 1-15 ◽

Cited By ~ 5

Author(s):

Lianfei Yu ◽

Cheng Zhu ◽

Jianmai Shi ◽

Weiming Zhang

Keyword(s):

Differential Evolution ◽

Job Shop ◽

Job Shop Scheduling ◽

Time Budget ◽

Differential Evolution Algorithm ◽

Mixed Integer ◽

Aircraft Carrier ◽

Evolution Algorithm ◽

Improved Differential Evolution Algorithm ◽

Flight Deck

Efficient scheduling for the supporting operations of aircrafts in flight deck is critical to the aircraft carrier, and even several seconds’ improvement may lead to totally converse outcome of a battle. In the paper, we ameliorate the supporting operations of carrier-based aircrafts and investigate three simultaneous operation relationships during the supporting process, including precedence constraints, parallel operations, and sequence flexibility. Furthermore, multifunctional aircrafts have to take off synergistically and participate in a combat cooperatively. However, their takeoff order must be restrictively prioritized during the scheduling period accorded by certain operational regulations. To efficiently prioritize the takeoff order while minimizing the total time budget on the whole takeoff duration, we propose a novel mixed integer liner programming formulation (MILP) for the flight deck scheduling problem. Motivated by the hardness of MILP, we design an improved differential evolution algorithm combined with typical local search strategies to improve computational efficiency. We numerically compare the performance of our algorithm with the classical genetic algorithm and normal differential evolution algorithm and the results show that our algorithm obtains better scheduling schemes that can meet both the operational relations and the takeoff priority requirements.

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Study of the Effect of a Plug with Torsion Channels on the Mixing Time in a Continuous Casting Ladle Water Model

Metals ◽

10.3390/met11121942 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1942

Author(s):

Gerardo Aguilar ◽

Gildardo Solorio-Diaz ◽

Alicia Aguilar-Corona ◽

José Angel Ramos-Banderas ◽

Constantin A. Hernández ◽

...

Keyword(s):

Continuous Casting ◽

Mixing Time ◽

Tangential Velocity ◽

Water Model ◽

Mixing Times ◽

Low Velocity ◽

Velocity Magnitude ◽

Image Velocimetry ◽

Casting Ladle ◽

Upward Direction

The use of porous plugs in injecting gas through the bottom of a ladle forms vertical plumes in a very similar way to a truncated cone. The gas plume when exiting the plug has a smaller diameter compared to that formed in the upper zone of the ladle because inertial forces predominate over buoyancy forces in this zone. In addition, the magnitude of the plume velocity is concentrated in an upward direction, which increases the likelihood of low velocity zones forming near the bottom of the ladle, especially in lower corners. In this work, a plug with spiral-shaped channels with different torsion angles is proposed, with the objective that the gas, when passing through them, has a tangential velocity gain or that the velocity magnitude is distributed in the three axes and does not just focus on the upward direction, helping to decrease low velocity zones near the bottom of the ladle for better mixing times. For the experimentation, we worked in a continuous casting ladle water model with two configuration injections, which in previous works were reported as the most efficient in mixing the steel in this ladle. The results obtained using the PIV technique (particle image velocimetry) and conductimetry technique indicate that the plugs with the torsion channels at angles of 60° and 120° improve the mixing times for the two injection configurations.

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Flight Deck Design of the Next Generation Aircraft Carrier

Naval Engineers Journal ◽

10.1111/j.1559-3584.2000.tb03305.x ◽

2000 ◽

Vol 112 (3) ◽

pp. 69-75 ◽

Cited By ~ 2

Author(s):

W. Baker ◽

S. D. Brennan ◽

M. Husni

Keyword(s):

Next Generation ◽

Aircraft Carrier ◽

Flight Deck Design ◽

Flight Deck

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Fundamental Studies of Vortices Induced by a Vortex-Generator for Automotive Applications

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.553.211 ◽

2014 ◽

Vol 553 ◽

pp. 211-216

Author(s):

Asiful Islam ◽

Graham Doig

Keyword(s):

Turbulence Models ◽

Vortex Generator ◽

Automotive Applications ◽

Passive Flow Control ◽

Passive Flow ◽

Flow Control Devices ◽

Simple Geometry ◽

Image Velocimetry ◽

Control Devices ◽

Spatial Trajectory

For automotive applications, passive flow control devices can be used to reduce, delay or prevent flow separation. This study explores the nature of vortex generation and behaviour, numerically and experimentally, for a simple geometry at a Reynolds Number (Rex) of 5×105 and 1.945×106. The setup comprised a triangular vane vortex-generator mounted on a shallow ramp referenced from literature. Flow over the isolated ramp was validated with past experimental particle-image-velocimetry (PIV) data, which also highlighted the relative performance of various turbulence models. A parametric study was undertaken with the vane orientation defined by an angle-of-attack (β) and stream-wise location (xedge/xVG). These results revealed relationships between geometric parameters of the vortex generator, as well as the influence of the boundary layer thickness (hVG/δ), on the spatial trajectory of induced vortices.

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