Browsing by Author "Larifi, Mohamed Amine"
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- Forces and drag coefficients for cylinders in a wind tunnelPublication . Larifi, Mohamed Amine; Rosa, Sérgio; Ferchichi, YassineThe use of experimental resources to obtain forces and drag coefficients is increasingly applied mainly for simulating complex problems in a real way, ensuring reliable, fast and practical results, a field of interest in modern industry, especially in the automotive and aerospace industries. who want to develop projects for machines, equipment and means of transport, increasingly aerodynamic. In this context, drag forces express the total resistance of a body being traversed by a fluid in the direction of a flow. Therefore, this study proposed the simulation in a subsonic wind tunnel of the external flow in smooth cylinders, and then in rough ones, by inserting sandpaper on their surfaces. These bodies, although simple, have complex flow patterns and a high level of applicability as they are useful in real application situations, such as flow in submerged pipes and the pillars of a bridge that, in external flow, suffer the forces of drag. Thus, this work presents results of several measurements of drag on smooth cylinders, and for five different surface roughness listed as a function of their respective relative roughness. The results for cylinders without roughness are validated by comparing tables and curves of experimental drag coefficients in the literature, here taken as expected values from theoretical ones. The cylinders with roughness, on the other hand, were only presented in a qualitative comparison in relation to the values of the same model without roughness because, despite the effort to maintain stability during the reading of drag forces, the measurement system (with a resolution of 0.01 N) was greatly influenced by the presence of vibrations at high speeds causing some limitations. However, the experimental practice in the laboratory allowed to verify what was expected through the theoretical foundation of the external flows of cylinders as a function of the flow regime (Reynolds number) and the approximate behavior of the drag coefficient curves for different roughness.