No abstract

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.

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 takeoff 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 takeoff maneuvers.

The article presents a research in the field of morphing wings (adaptive wing geometry) developed over a prototype of micro-unmanned air vehicle based on smart materials technology. This morphing wing will optimize the aircraft performance features. Modifying the curvature of the wing, the micro-unmanned air vehicles will adjust its performance in an optimum mode to cruise flight condition as well as in the phases of takeoff and landing. The installation of mechanical elements for control surfaces in small size aircraft means, on some occasions, an extra complexity. In addition, it takes into account an increase in aircraft weight. In this research, the adaptive wing geometry is based on macro-fiber composites, so that its position on the inner surfaces of the wing allows the appropriate modification of the curvature, adapting them to the flight profile. This research will present the conceptual design of the vehicle, computational calculations, experimental results of the wind tunnel testing, validations using non-intrusive techniques (particle image velocimetry) and a theoretical–experimental analysis of the macro-fiber composite effects over the wing. An Arduino board will perform the control parameters of the macro-fiber composite deformation. With these analytical, computational, and experimental results, the most relevant conclusions are presented.