Literatura científica selecionada sobre o tema "Piezoelectric deicing system"

Deicing using piezoelectric actuators is considered as a potential solution to the development of low-energy ice protection systems for rotorcraft. This type of system activates resonant frequencies of a structure using piezoelectric actuators to generate sufficient stress to break the bond between the ice and the substrate. First, a numerical method was validated to assist the design of such systems. Numerical simulations were performed for the case of a flat plate and validated experimentally. The model was then used to study important design parameters such as actuator positioning and activation strategies, and it was concluded that positioning actuators at antinode locations, and activating them in phase with those antinodes to obtain maximum displacements for a given vibration mode. The findings were then used to apply piezoelectric deicing to structures more representative of a helicopter rotor blade. The method was implemented on a thinned Bell 206 main rotor blade and a Bell 206 tail rotor blade. Deicing performance was demonstrated in an icing wind tunnel. Power input to the actuators was below 19 kW/m2 (12 W/inch2) for all structures.

The peak current and vibration peak acceleration are two important parameters in the electroimpulse deicing system. Available data on two parameters are sparse. An experimental setup to measure the peak current and vibration peak acceleration in the electroimpulse deicing system is presented. The measurement is performed in the icing wind tunnel. Rogowski coil’s principle on pulsed current measurement is applied in the electroimpulse deicing discharge current circuit. It is found that calculated results agree with the measured trend. A piezoelectric vibration acceleration sensor is adopted to measure the vibration peak acceleration. Test results show that when the peak current varies linearly, the vibration peak acceleration increases with the increase of discharge voltages and its variation is approximately linear. The experimental results in the electroimpulse deicing system demonstrate that the proposed measuring method is accurate and reliable.

Abstract Piezoelectric actuators are widely used in several applications and are becoming increasingly attractive in aircraft and industrial 
contexts, mainly when efficiency and economical energy conversion are required. One of these applications is the Avionic 
Piezoelectric Deicing System. Piezoelectric actuators are considered as a potential solution for developing a low-energy ice 
protection system for aircraft. This type of system applies vibration to the structure by activating its own resonant frequencies 
to generate sufficient stress to break the ice and cause it to delaminate from the substrate. The deicing mechanism depends 
strongly on the chosen excitation mode, whether it's flexural (bending) mode, extension (stretching) mode, or a combination in 
between, hence affecting the efficiency and effectiveness of the deicing process.
However, it is essential to note that designing the power supply of the deicing system presents a major challenge, since 
piezoelectric actuators exhibit a distinct capacitive behavior in almost all frequencies, and eventually for deicing applications 
requiring high operational frequency.
In this contribution, a proof of concept of a deicing system utilizing lightweight piezoelectric actuators with minimal power
requirement is proposed. Deicing was demonstrated with a power input density of 0.074 W/cm² and a surface ratio of 0.07 
piezoelectric actuator per cm². First, a numerical method for positioning piezoelectric actuators and choosing the proper 
resonance mode was validated to assist in the system’s design. Then, the numerical method was used to implement piezoelectric
deicing on a more representative structure of an aircraft wing or nacelle. Finally, a converter topology adapted for deicing 
application was proposed.

Les contraintes environnementales, ainsi que leur impact sur l'opinion publique, ont conduit les équipementiers aéronautiques à accélérer la transition énergétique en aéronautique à travers l'avion plus électrique (More Electric Aircraft - MEA). Nous assistons donc à une augmentation progressive de la place de l'énergie électrique dans les applications embarquées. Ceci se traduit par une tendance à remplacer les systèmes non propulsifs (hydrauliques et pneumatiques) par des chaînes de conversion électromécanique. Ces sous-systèmes sont en effet souvent plus performants, dynamiques et précis avec des délais de maintenance plus courts que leurs équivalents hydrauliques. Le système de dégivrage est un candidat de choix pour cette transition.L'accumulation de glace sur les aéronefs a été reconnue comme risque majeur dans le domaine de l'aéronautique dès le début du XX^e siècle. Les solutions actuellement utilisées en vol, telles que le flux d'air chaud, les boudins pneumatiques, les systèmes électrothermiques, le fluide chimique ou les systèmes électromécaniques impulsifs/expulsifs, offrent une protection plus ou moins efficace, mais présentent des inconvénients tels qu'une consommation d'énergie significative, un encombrant ou une applicabilité limitée à certains types d'aéronefs. De plus, dans le cadre des avions plus électriques, les systèmes dépendants des moteurs thermiques sont susceptibles de devenir obsolètes, ouvrant ainsi la voie à de nouveaux systèmes électriques.Le système électromécanique piézoélectrique de protection contre le givre s'est récemment révélé pertinent en termes de consommation d'énergie et de masse embarquée, et fait l'objet de cette thèse. Celle-ci se concentre sur la conception d'un système de dégivrage piézoélectrique résonnant, ainsi que sur son alimentation associée. Ce système repose sur l'utilisation des actionneurs piézoélectriques pour exciter la structure à dégivrer à une fréquence donnée. Lorsque cette fréquence correspond aux fréquences naturelles de la structure, l'amplitude des vibrations augmente, générant des niveaux élevés de contraintes et de déformations, dépassant éventuellement les résistances critiques de la glace (traction/compression, adhésion ou les deux).L'objectif de cette thèse est donc de développer d'un premier temps un prototype capable de démontrer une protection efficace et rapide contre le givre avec une consommation d'énergie minimale. Pour ce faire, une méthodologie de positionnement et de pilotage des actionneurs est proposée, utilisant une analyse analytique et modale par éléments finis pour identifier les modes de résonance les plus contributifs au dégivrage. Une validation expérimentale en plusieurs étapes afin d'arriver à un prototype de dégivrage opérationnel est assurée.Dans un second temps, l'accent est mis sur le développement d'une alimentation de puissance adaptée aux actionneurs piézoélectriques dans le cadre du dégivrage piézoélectrique. Compte tenu de la dépendance du comportement électrique des actionneurs à la charge mécanique et à la température, certains aspects doivent être pris en compte lors de la conception de l'alimentation électrique. Une recherche exhaustive dans la littérature est entreprise pour identifier les topologies appropriées pour piloter des charges piézoélectriques, conduisant à la proposition de la topologie ARCPI-LLCC. Cette dernière offre des avantages significatifs en termes de performances globales du système, notamment en termes de compensation de l'énergie réactive et de réduction du taux de distorsion harmonique.Enfin, l'ARCPI-LLCC est utilisée pour piloter le prototype de dégivrage conçu selon la méthodologie proposée. Les résultats obtenus démontrent un dégivrage opérationnel avec un rendement optimisé, validant ainsi l'efficacité de la technologie de dégivrage piézoélectrique dans le contexte de l'électrification des avions
Environmental constraints and their impact on public opinion have led the aircraft industry to accelerate the energy transition in aeronautics toward a "More Electric Aircraft" (MEA). Therefore, we are witnessing a gradual increase in the role of electrical energy in onboard applications. This electrification trend aims to replace all non-propulsive systems (hydraulic and pneumatic) with electromechanical alternatives in order to optimize aircraft performance, decrease operating and maintenance costs, increase dispatch reliability, and reduce gas emissions. Among the systems affected by this transition is the deicing system. The deicing system is a prime candidate for this transition.Ice accumulation on aircraft has been recognized as a major risk in aviation since the early 20th century. Currently employed in-flight solutions, such as hot air flow, pneumatic boots, electrothermal systems, chemical fluid, or impulsive/expulsive electromechanical systems, offer varying degrees of effectiveness but come with drawbacks such as significant energy consumption, bulkiness, or limited applicability to certain aircraft types. Furthermore, within the context of more electric aircraft, systems dependent on thermal engines are most likely to become obsolete, paving the way for new electrical systems.The electromechanical piezoelectric ice protection system has recently proven to be relevant in terms of energy consumption and integration and is the focus of this thesis. It concentrates on the design of a resonant piezoelectric deicing system and its associated power supply. This system relies on the use of piezoelectric actuators to excite the structure to be deiced at a given frequency. When this frequency matches the natural frequencies of the structure, the magnitude of vibration increases, generating high levels of stress and deformation, eventually exceeding the critical strengths of the ice (traction/compression, adhesion, or both).The objective of this thesis is to develop, initially, a prototype capable of demonstrating efficient and rapid ice protection with minimal energy consumption. To achieve this, a methodology for positioning and controlling the actuators is proposed, utilizing analytical and modal finite element analysis to identify the most contributing resonance modes to deicing. Experimental validation through several stages is ensured to obtain an operational deicing prototype.Subsequently, emphasis is placed on the development of a power supply tailored to piezoelectric actuators for deicing purposes. Given the dependence of the electrical behavior of actuators on mechanical load and temperature, certain aspects must be considered when designing the electrical power supply. An exhaustive literature search is conducted to identify suitable topologies for driving piezoelectric loads, leading to the proposal of the ARCPI-LLCC topology. The latter offers significant advantages in terms of overall system performance, particularly in reactive energy compensation and harmonic distortion reduction.Finally, the ARCPI-LLCC is employed to drive the deicing prototype designed according to the proposed methodology. The results demonstrate operational deicing with optimized efficiency, thus validating the effectiveness of piezoelectric deicing technology in the context of aircraft electrification

<div class="section abstract"><div class="htmlview paragraph">This paper proposes an extension to curved surfaces of a design method of piezoelectric ice protection systems established for planar surfaces. The method is based on a finite element analysis which enables the fast computation of the resonant modes of interest to de-ice surfaces as leading edges. The performance of the modes of interest is assessed according to their deicing capacity estimated from the electro-mechanical coupling between the electric charge of the piezoelectric actuators and the strain energy in the structure. The method is illustrated on a NACA 0024 airfoil. Several experimental tests are conducted in an icing wind tunnel to verify the numerical predictions of the ice shedding and the operation of the system.</div></div>