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Blunt trailing edge airfoil modification methods have shown that a compromise between aerodynamic performance and structural benefits can be achieved. Two modification methods are studied: the cutting off method and the added thickness method. Two-dimensional simulations were obtained in Ansys CFX® for a typical Reynolds number of 3.2 million. A Taguchi Method experiment is conducted for the study of the four-digit NACA airfoil family with the proposed modification methods. A detailed study for the NACA 4421 modified with several trailing edge thickness values was completed. The results obtained show that the increase in the maximum lift coefficient, the delayed stall and the drag coefficient increase are common to all modification methods studied, whereas it is proven that for the cutting off method the lift coefficient curve displacement to higher angles of attack is caused by the loss of camber. Finally, it was proved that the added thickness method produces larger maximum lift coefficients and larger critical angles of attack than the cutting off method. [ABSTRACT FROM AUTHOR]

This paper is a computational study of the behaviour of aerodynamic characteristics of NACA (National Advisory Committee for Aeronautics, today known as NASA) profiles with tailored trailing edges. 39 different profiles 4-digit NACA family were studied during the research. A computational research was made, using simple theoretical models to explain and to understand the results. The results describe the changes in lift and drag characteristics and changes in stall angle of attack. [ABSTRACT FROM AUTHOR]

El presente artículo pretende ilustrar sobre las actuales ventajas del uso del dirigible en actividades militares, con especial énfasis en la vigilancia, para su uso potencial en Colombia. Esta alternativa de aeronave debe ser tenida en cuenta para una toma de decisiones acertada en la actual situación de conflicto que vive el país. [ABSTRACT FROM AUTHOR]

The present article, briefly, describes the theoretical design procedure of Wells turbines, typically utilized in Pneumatic Wave Energy Conversion Systems (PWECS). The principle behind the PWECS consists of extracting the pneumatic energy caused by an oscillating water column by the entrance of water waves in enclosed spaces. The paper establishes the design and experimental testing of a small permanent magnet generator suited for the wells turbine under development. The adequate matching between the Wells turbine and the generator has been conceived as a portable 50w d.c. electricity generation device; to be used, either, to powering telecommunications systems in military operations or to power navigation aids in rivers or at sea [ABSTRACT FROM AUTHOR]