Modification of Horizontal Wind Turbine Blade: A Finite Element Analysis

Turbines are efficient power generators. Because wind energy is a clean fuel source, it is widely utilized in some regions. One of the major factors affecting wind turbine performance is the angle of attack of the blade. The aerodynamics and efficiency can be improved by improvising the lift-to-drag ratio CL/CD to get the best design for wind turbine blades. There are many factors affecting the efficiency of horizontal wind turbine blades such as the angle of attack of the blade. Therefore, this study investigated the effect of the angle of attack on coefficients and forces, particularly on a blade with NACA 4412 airfoil in a horizontal axis wind turbine. The length, thickness, and chord length of the blade were 3m, 0.36m, and 0.12 m respectively. Computational Fluid Dynamics was used to develop to obtain lift and drag coefficients in a horizontal wind turbine blade.  In addition, the correlation between different angles of attack, lift, and drag forces were studied and validated. The results demonstrated that the lift and drag coefficients increase as the angle of attack increases. Furthermore, the optimal angle of attack for this study was 0° because it has the highest lift-to-drag ratio, resulting in the greatest efficiency. The results demonstrated that it is possible to have a different lift and drag coefficient for the same angles of attack at a similar airfoil

Porous high-entropy alloys as efficient electrocatalysts for water-splitting reactions

Porous high-entropy alloys (HEAs) have emerged as promising electrocatalysts for water-splitting reactions, owing to their rich dissimilar active sites, elemental diversity, and multiple functionalities. The rational design of HEAs for water-splitting attracted great interest in improving their current performance, so it is essential to provide timely updates on this field. This review emphasizes the preparation methods of porous HEAs and the effect of their salient features like high configurational entropy, cocktail effect, lattice distortion, and sluggish diffusion on oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). This mini-review also provides some insights into the current limitations and future perspectives to direct research on the development of ideal HEAs for OER and HER

Mesures simultanées non-intrusive de vitesse et température par méthode optique dans une géométrie complexe : Application au collecteur chaud du réacteur refroidi au sodium ASTRID

Thermal hydraulic problems of the upper plenum of ASTRID cannot be studied from the feedback of the reactors and the numerical simulations since the codes do not make it possible to model these problems with a sufficient confidence. To validate the numerical approaches and the design of ASTRID, needs have been identified for experimental models. The representative MICAS model of the upper plenum has been designed for this purpose. To validate the numeric codes, the velocity and temperature fields are mustbe measured. While PIV technique is frequently used at the LTHC, the LASER Induced Fluorescence (LIF) method required development and implementation. The principle of LIF is based on the spontaneous emission of photons by the molecules of a tracer, as a result of the absorption of laser radiation. LIF calibration experiments with a dye were performed to study their fluorescence response. The LIF with two dyes is very interesting too. PIV and LIF with two dyes are applied on a new experimental installation (complex geometry with two jets) conceived during this thesis in order to allow a representative of the model MICAS.Des problématiques thermo-hydrauliques du plénum supérieur d'ASTRID ne peuvent être étudiés à partir du retour d’expérience des réacteurs et des simulations numériques puisque les codes de calcul ne permettent pas de modéliser ces problèmes avec une confiance suffisante. Pour valider les approches numériques et la conception d'ASTRID, il a été identifié des besoins en maquettes expérimentales. La maquette MICAS représentative du plenum supérieur a été conçue à cette fin. Pour valider les codes numériques, les champs de vitesse et de température sont très importants. Si la mesure de champ de vitesse par PIV est fréquemment utilisée au LTHC, la méthode LASER Induced Fluorescence (LIF) a nécessité de développement et mise en œuvre. La fluorescence induite par laser consiste en l'émission spontanée de photons par les molécules d'un traceur, à la suite de l'absorption d'un rayonnement laser. Des expériences d'étalonnage de LIF à un colorant ont été réalisées pour étudier leur réponse en fluorescence. La LIF à deux colorants est très intéressante aussi. PIV et LIF à deux colorants sont appliquées sur une nouvelle installation expérimentale (géométrie complexe à deux jets) conçue pendant cette thèse afin de permettre une représentative de la maquette MICAS

Simultaneous Temperature and Velocity measurements by LIF and PIV in a complex geometry

International audienceAdvanced Sodium Technological Reactor for Industrial Demonstration ASTRID is a project of construction of a 4th generation reactor cooled by sodium. There are thermal-hydraulic issues of upper plenum of ASTRID which can’t be studied from past reactors feedback and numerical simulations since the calculation codes do not allow to model these problems with sufficient confidence .Thus in order to validate thenumerical approaches and systems concept of ASTRID, it is important to measure temperature and velocity simultaneously using optical measurement techniques. For these reasons, a prototype is developed to study the thermal hydraulic behavior of ASTRID. Sodium experiments are very complicated to perform since sodium is opaque and reacts violently with water. Thus it is more practical to perform measurements on a water model since both have similar physical properties concerning viscosity and density. From what preceded, the MICAS mockup was designed . It is a water model of the ASTRID, made up of PMMA foroptical measurements since laser methods will be implemented to measure both temperature and velocity. The challenge in implementing non-intrusive optical techniques to simultaneously measure temperature and velocity on the MICAS mock up resides in designing the experiments so that they are carried out under ambient optical conditions with accuracy and precision attained as much as possible during the execution. Laser Induced Fluorescence LIF and Particle Image Velocimetry PIV are used to measure temperature and velocity respectively. In the LIF technique, a dye absorbs a portion of the excitation energy and spon-taneously reemits a portion of the absorbed energy as fluorescence. Calibration experiments using onecolor LIF were carried out to choose the right dyes. The fluorescence response of three dyes: FL27, RhWTand Rh6G was studied as function of three parameters: dye concentration, laser power and temperature variation from 20°C till 60°C. After that, two color LIF technique will be carried out using two dyes, one temperature dependent and the other insensitive using a pulsed 532 nm Nd:YAG laser .The temperature isdetermined from the ratio of the signal of two dyes, which have highly different temperature sensitivities. When pulsed lasers are used for the excitation of the fluorescence, their irradiance usually exceeds thesaturation intensity of common fluorescent dyes. Therefore, the fluorescence signal loses its linear depen-dence on the laser irradiance. Studies have shown that this loss of linearity is not necessarily an importan tsource of error for the ratio metric methods. Experiments are followed by coupling between PIV and LIF ona simple aquarium and then on the complex geometry MICAS. The same optical approach will be appliedon another experiment which is in progress of preparation. It is a representative prototype and a dimen-sional analysis of the thermal hydraulics of the core in the MICAS mock up. The mixture of the two jets of different temperatures must be studied. The first jet is being hot and the second cold. The prototype aimsto study the interaction between two jets at different temperature

Numerical and experimental investigation to design a novel morphing airfoil for performance optimization

Optimizing flying objects' wing performance has attracted a significant attention in the last few decades. In this article, some of the main mechanisms for changing the geometry of the wing were investigated and a new mechanism is proposed to improve the aerodynamic performance of the airplane wing. The designs have been simulated and analyzed from both aerodynamic and control points of view. In aerodynamic simulations using CFD methods, two airfoils of NACA series 6 with specifications 65-212 and 65-2012 were modeled. The results indicated that both airfoils used have a better performance compared to others in a certain range of the angle of attack. Subsequently, a new mechanism is proposed to change the wing geometry to optimize its structure. In the proposed mechanism, the structures of airfoils and wings consist of two fixed and moving parts, which can change their geometry with the help of a control circuit. The fixed part has a grooved track, and as the moving part moves in the direction of the grooves, the curvature of the upper and lower parts of the wing changes. The design control circuit includes an angle sensor, a micro controller, and a servomotor. The CFD results are entered into the micro controller as code. At any moment, the micro controller receives the angle data from the angle sensor and by comparing them with the CFD data, and issuing a command to the servomotor, it situates the wing curvature in the optimal state at all times. The built mechanism was tested at an attack angle of 0° and 25°. The results showed that the different parts of the mechanism work with very high precision and put the geometric shape of the wing in an optimal state in a completely intelligent way. It should be noted that the average error in test for t/c and Xt/c was 15.3% and 9%, respectively