1,720,961 research outputs found
Optimization of a Multi-Layered Heater for an Electro-Thermal Ice Protection System for a Composite Wing
No full textIn this work, a multi-layered heater of an electro-thermal ice protection system (IPS) is optimized to minimize the electric energy consumption in de-icing mode. The design parameters are the thickness of the layers. The temperature inside the composite material layer is constraint to a maximum value to avoid material degradation. The temperature distribution inside the heater and the magnitude of ice accretion are evaluated by means of a representative and validated numerical model. Then, the optimization is performed using a derivative-free approach, that is the genetic algorithm, thanks to its suitability of dealing with complex problems and non-linear objective functions. An optimization of the heater layout has been performed and the results show that the electric energy can be reduced by accurately allocating the thickness of each layer. Eventually, the optimized heater is tested with a reference test case considering a NACA0012 with IPS operating in de-icing mode. Results have shown that a reduction in the mean and maximum ice thickness formed on the surface can be obtained by properly allocating the thickness of the different layers of the heater
Automatic roughness characterization of simulated ice shapes
Full text linkDuring in-flight ice accretion, roughness plays an important role since it heavily in-fluences the convective heat transfer and skin friction coefficients. This paper aims to assess the ability of existing ice accretion simulation tools to compute the growing ice's roughness. To this purpose, a technique based on Self Organizing Maps is applied to numerical simulations of in-flight ice accretion to characterize the roughness. The numerical ice predictions are performed using a standard approach comprising RANS computations, Lagrangian particle tracking, the solution of the unsteady Stefan prob-lem, and a morphogenetic model. Numerical simulations are performed on selected benchmark cases from the 1st AIAA Ice Prediction Workshop. Validation of roughness computation is performed on synthetic test cases, while ice roughness is compared directly to that extracted from ice scans. The results of simulated ice shapes compare reasonably well with experimental data. Computations can replicate the trend of the experimental mean ice shape and roughness distribution for both rime and glaze cases
Novel Framework for the Robust Optimization of the Heat Flux Distribution for an Electro-Thermal Ice Protection System and Airfoil Performance Analysis
No full textNumerical Simulations of a Horizontal Axis Wind Turbine in Icing Conditions with and Without Electro-Thermal Ice Protection System
No full textIn this work, a preliminary design of an Electro-Thermal Ice Protection System (IPS) is performed on the NREL 5 MW reference wind turbine. A 3-hour rime icing event is simulated numerically with and without the IPS. The IPS is designed considering a uniform heat flux in the stream-wise and span-wise directions. Two protected regions are considered in the span-wise direction, covering the outer half and the outer third of the blade, respectively. Moreover, different power consumptions are compared, keeping the blade clean or leading to run-back ice formations. The aerodynamic coefficients of each blade section are computed to compare the effect of the different ice shapes at various angles of attack with the reference solution, i.e., the clean blade. The resulting power curves are compared with the clean blade to quantify power and energy losses. Results show that run-back ice can cause worse performance with respect to the ice accretion occurring without IPS. During ice accretion, the energy loss resulting from this simplified IPS design is higher than the one caused by the ice accretion without IPS. However, if the time frame following ice accretion is considered, considerably higher energy savings are obtained when at least the outer third of the blade is kept clean
Investigation of the Influence of Aero-Thermal Non-equilibrium Conditions of an SLD Cloud on Airfoil Icing
No full textOptimization of a Nacelle Electro-Thermal Ice Protection System for Icing Wind Tunnel Testing
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A Comprehensive Numerical Model for Numerical Simulation of Ice Accretion and Electro-Thermal Ice Protection System in Anti-icing and De-icing Mode, with an Ice Shedding Analysis
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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