A pressurized porous surface near the leading edge of a rotorcraft blade, is designed to be used as an active control device which alleviates the aerodynamics of blade vortex interactions (BVI) and thus the impulsive BVI noise levels and signature. The pressurized porous surface can be actuated on an azimuth-dependent deployment schedule or actuated continuously. The pressurized porous surface is supplied with either positively pressurized air, negatively pressurized air, or a combination of both, when actuated. The pressurized porous surface targets the local blade aerodynamics, rather than the vortex strength or blade/vortex separation distance. This targeting can be achieved through use of negatively pressurized air (suction) blowing in a direction normal to the blade surface to reduce the rotor blade's effective thickness resulting in a smaller leading edge radius as perceived by the vortex wake, and positively pressurized air (blowing) to increase the effective thickness resulting in an increase in the leading edge radius of the blade.

Active blowing system for rotorcraft vortex interaction noise reduction

An active control device for use on an aerodynamic structure is provided. The aerodynamic structure includes an outer aerodynamic skin and an interior volume, wherein the outer aerodynamic skin surrounds the interior volume. The active control device includes at least one aperture disposed on the outer aerodynamic skin and a diaphragm disposed in the interior volume of the aerodynamic structure. The at least one aperture connects the outer aerodynamic skin to the interior volume, and the diaphragm in the interior volume is movable between a first position and a second position. Movement of the diaphragm from the first position to the second position pushes air through the at least one aperture and out of the interior volume. Movement of the diaphragm from the second position to the first position draws air through the at least one aperture and into the interior volume. The diaphragm may be circular, or may be oval-shaped.

Oscillating air jets on aerodynamic surfaces

An airfoil camber control apparatus utilizes a cable of shape memory alloy affixed at its ends to a front interior portion of the airfoil. A tensioning system is connected to a rear interior portion of the airfoil and to the cable. When electrical current is applied to the cable to heat it, it returns to its remembered, shorter length, thereby applying tension to the tensioning system to alter the position of the rear portion of the airfoil relative to the front portion.

Variable camber control of airfoil

An adaptive sheet structure with distributed strain actuators is controlled by a dynamic compensator that implements multiple input, multiple output control laws derived by model-based, eg, Linear Quadratic Gaussian (LQG) control methodologies An adaptive lifting surface is controlled for maneuver enhancement, flutter and vibration suppression and gust and load alleviation with piezoceramic elements located within, or enclosed by sheets of composite material at a particular height above the structure's neutral axis Sensors detect the amplitudes of lower order structural modes, and distributed actuators drive or damp these and other modes The controller is constructed from an experimental and theoretical model using conventional control software, with a number of event recognition patterns and control algorithms programmed for regulating the surface to avoid instabilities The number of control states of the compensator is then reduced by removing states having negligible effects on the plant, and a smaller set of control laws are optimized and then adjusted based on analytical models bench and wind-tunnel testing

Multivariable adaptive surface control

The present invention provides a system and method for actively manipulating and controlling aerodynamic or hydrodynamic flow field vortices within a fluid flow over a surface using micro-jet arrays. The system and method for actively manipulating and controlling the inception point, size and trajectory of flow field vortices within the fluid flow places micro-jet arrays on surfaces bounding the fluid flow. These micro-jet arrays are then actively manipulated to control the flow behavior of the ducted fluid flow, influence the inception point and trajectory of flow field vortices within the fluid flow, and reduce flow separation within the primary fluid flow.

System and method to control flowfield vortices with micro-jet arrays

To reduce buffeting caused by separation on the wings of an aircraft, a parameter representing the buffeting in amplitude, frequency and phase is measured. The measuring signal is subjected to filtering intended to establish the characteristics of at least one mode of vibration of the wings and, by actuating a control surface according to a non-stationary law, in a localized region the wings, of alternate stresses are generated whose amplitude and phase are automatically determined to dampen one or several modes of vibration of the wings.

Active method and installation for the reduction of buffeting of the wings of an aircraft

Pour reduire le tremblement provoque par les decollements sur une voilure (11a, 11b) d'aeronef, on mesure un parametre representatif du tremblement en amplitude, frequence et phase, on soumet le signal de mesure a un filtrage destine a mettre en evidence les caracteristiques d'au moins un mode de vibration de la voilure, et on fait appraitre, en actionnant une gouverne (10) suivant une loi instationnaire, dans une region localisee de la voilure, des sollicitations alternees dont l'amplitude et la phase sont automatiquement determinees pour amortir un ou plusieurs modes de vibration de la voiture. To reduce buffeting caused by the detachment of a wing (11a, 11b) of an aircraft, measuring a parameter representative of the dither amplitude, frequency and phase, the measuring signal is subjected to a filtering intended to highlight the features at least one vibration mode of the wing, and is made appraitre by actuating a control surface (10) in a non stationary law, in a localized region of the wing or alternating stresses whose amplitude and phase are determined automatically to absorb one or more car vibration modes.

Process and device using active surfaces to reduce the shaking of an airplane wing

Pour reduire le tremblement provoque par les decollements sur une voilure (11a, 11b) d'aeronef, on mesure un parametre representatif du tremblement en amplitude, frequence et phase, on soumet le signal de mesure a un filtrage destine a mettre en evidence les caracteristiques d'au moins un mode de vibration de la voilure, et on fait appraitre, en actionnant une gouverne (10) suivant une loi instationnaire, dans une region localisee de la voilure, des sollicitations alternees dont l'amplitude et la phase sont automatiquement determinees pour amortir un ou plusieurs modes de vibration de la voiture.

Procédé et installation de réduction du tremblement de la voilure d'un aéronef au moyen de gouvernes actives

The analysis of the effect of perturbations, due to the wind in particular, on the precision of sounding-rocket trajectories shows the advantage of employing attitude control during the first seconds of flight. This concept is applied in the BER stage, which is controlled during the 20 sec of its burning by four cluster-mounted, low-thrust rockets. The total dispersion of the rockets using the BER as a first stage is less than 1°. The controlling system uses signals from gyroscopic sensors; the controlling law, adapted to the characteristics of the sounding rocket whose small fins facilitate the adaptation, is optimized statistically. The operational conditions of BER depend mainly upon the external loads, the margins with respect to the internal saturation in vibratory regime, and the structural coupling. The precision of the flights carried out to date, particularly those with the TITUS rockets observing the sun eclipse of November 1966, as well as the performance characteristics of the rockets equipped with BER, show the advantage of this solution, which is now at the production level.

Jacques Bouttes

Papers

Active method and installation for the reduction of buffeting of the wings of an aircraft

Process and device using active surfaces to reduce the shaking of an airplane wing

Procédé et installation de réduction du tremblement de la voilure d'un aéronef au moyen de gouvernes actives

Controlled booster stage ''BER'' for sounding rockets.

Grey Theory and AHP Applied in Performance Evaluation of Tactical Communication Network Information System