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This paper deals with the actuation system design of a full-scale morphing aileron for regional aircraft. The aileron is allowed to smoothly change its geometrical configuration and perform the in-flight transition from a baseline shape to a set of optimal morphed ones pre-defined on the basis of aerodynamic requirements. The design of such innovative aileron is aimed not only at substituting the conventional aileron installed on a real aircraft but also to provide additional functionality. The aileron is free to rotate around its main hinge axis and it is also allowed to smoothly modify camber with two independent actuation systems. In such manner it can be used also during cruise with a symmetric deflection between the two half wings in order to reduce drag in off design condition. To accomplish variable aileron shape, a rigid-body mechanism was designed. The proposed aileron architecture is characterised by segmented adaptive ribs rigidly linked each other with spanwise reinforcements such as spars and stringers in a multi-box arrangement. Each rib is split into two movable plates connected by means of rotational hinges in a finger-like mechanism. The mechanism is driven by a load-bearing actuator by means of a kinematic chain opportunely tied based on the structural requirements in terms of shape to be matched and load to be withstood. The proposed device is an innovative arrangement of the quick-return mechanism composed of a beam leverage, commercial linear guides and a crank. The actuator shaft is directly inserted in the crank, which transmits the rotation to the linear guide that slide along a rail moving upward or downward the beam thus resulting in a camber variation. The entire aileron is moved by three leverages internally contained and distributed along the first two bays while the most external ribs are considered passive and their movement slaved. Two actuation layouts are analytically and numerically studied, the analytical theory is presented and validated by means of a multi-body simulation. Moreover, a linear static analysis was carried out under the hypothesis of glued contact between linear guides components simulating a jamming condition. This assumption has been formulated because it represents the most severe condition that envelop all the operative loads to which the actuation system is subjected. The analyses conducted are preliminarily aimed to verify that no failure occur under the imposed loads. In this first design loop, the vertical static force acting on the linear carriage exceeded allowable value and then a new configuration with double-sided linear guides was then investigated.
Particle transport, acceleration and energization are phenomena of major importance for both space and laboratory plasmas. Despite years of study, an accurate theoretical description of these effects is still lacking. Validating models with self-consistent, kinetic simulations represents today a new challenge for the description of weakly collisional, turbulent plasmas. We perform simulations of steady state turbulence in the 2.5-dimensional approximation (three-dimensional fields that depend only on two-dimensional spatial directions). The chosen plasma parameters allow to span different systems, going from the solar corona to the solar wind, from the Earth’s magnetosheath to confinement devices. To describe the ion diffusion we adapted the nonlinear guiding centre (NLGC) theory to the two-dimensional case. Finally, we investigated the local influence of coherent structures on particle energization and acceleration: current sheets play an important role if the ions’ Larmor radii are of the order of the current sheet’s size. This resonance-like process leads to the violation of the magnetic moment conservation, eventually enhancing the velocity-space diffusion.
A new wing-tip concept with morphing upper surface and interchangeable conventional and morphing ailerons was designed, manufactured, bench and wind-tunnel tested. The development of this wing-tip model was performed in the frame of an international CRIAQ project, and the purpose was to demonstrate the wing upper surface and aileron morphing capabilities in improving the wing-tip aerodynamic performances. During numerical optimisation with ‘in-house’ genetic algorithm software, and during wind-tunnel experimental tests, it was demonstrated that the air-flow laminarity over the wing skin was promoted, and the laminar flow was extended with up to 9% of the chord. Drag coefficient reduction of up to 9% was obtained when the morphing aileron was introduced.
The development of adaptive morphing wings has been individuated as one of the crucial topics in the greening of the next generation air transport. Research programs are currently running worldwide to exploit the potentiality of morphing concepts in the optimisation of aircraft efficiency and in the consequent reduction of fuel burn. Among these, SARISTU represents the largest European funded research project which ambitiously addresses the challenges posed by the physical integration of smart concepts in real aircraft structures; for the first time ever, SARISTU will experimentally demonstrate the structural feasibility of individual morphing concepts concerning the leading edge, the trailing edge and the winglet on a full-size outer wing belonging to a CS-25 category aircraft. In such framework, the authors intensively worked on the definition of aeroelastically stable configurations for a morphing wing trailing edge driven by conventional electromechanical actuators. Trade off aeroelastic analyses were performed in compliance with CS-25 airworthiness requirements (paragraph 25.629, parts (a) and (b)-(1)) in order to define safety ranges for trailing-edge inertial and stiffness distributions as well as for its control harmonics. Rational approaches were implemented in order to simulate the effects induced by variations of trailing-edge actuators’ stiffness on the aeroelastic behaviour of the wing also in correspondence of different dynamic properties of the trailing-edge component.
Reliable aeroelastic models and advanced computational strategies were properly implemented to enable fast flutter analyses covering several configuration cases in terms of structural system parameters. Already available finite elements models were processed in MSC-NASTRAN® environment to evaluate stiffness and inertial distributions suitable for the stick-equivalent idealisation of the reference structure. A parametric stick-equivalent model of the reference structure was then generated in SANDY3.0, an in-house developed code, that was used for the definition of the coupled aero-structural model as well as for the solution of aeroelastic stability equations by means of theoretical modes association in frequency domain.
Obtained results were finally arranged in stability carpet plots efficiently conceived to provide guidelines for the preliminary design of the morphing trailing-edge structure and therein embedded actuators.