Numerical study of the turbulent hydraulic flow in Venturi tubes for didactic purposes in Fluid Mechanics
Livia Luchi Rabello1; Walquiria Vieira Dias Gava1; Bruno Furieri1; Enilene Lovatte1
1 Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo (IFES)
doi:10.20906/CPS/CILAMCE2017-0968
Resumo
One of the most used instruments for flow measurement in hydraulic investigation is the Venturi tube, which is based on a very simple technique, reducing the area of passage of the flow, which consequently results in an increase in velocity magnitude and turbulence. Venturi tubes are advantageous because they are self-cleaning and therefore have the characteristic of being used to measure flow rate with large amount of sediment, which is a recurrent condition in environmental flows, thus justifying the relevance of this study to several areas of engineering, specially water resources and sanitation. The work concentrated on investigating the flow inside these structures as part of Fluid Mechanics in undergraduate courses. In this, students are presented, besides the mathematical theory and equation necessary to understand the problems, the influence of discretization, numerical method and turbulence models in final results. The present work has the general objective to evaluate, through computational modeling, Venturi tubes designed with the CFD (Computational Fluid Dynamics) tool using ANSYS Fluent software. In order to identify the greatest number of parameters and variables essential to the understanding of the phenomena involved in the flow in Venturi tubes the following points were addressed in tested cases: (i) variation in the geometry of the pipe strangulation section, (ii) refinement of the mesh (Iii) turbulence modelling and (iv) methods of spatial interpolation. A qualitative analysis of the tool, indicated that it is interesting to facilitate the understanding of the complex equations and theories involved in the prediction of turbulent flows and the use of numerical methods. The main numerical results obtained showed the strong influence of mesh refinement in the central region of the Venturi tube, as well as its correct association with the appropriate turbulence model. The computational tool has proven useful in checking recirculation zones that can become sediment accumulation when applicable.
Palavras-chave: Numerical methods; Venturi tube; Fluid Mechanics; Hydraulics; Turbulent flow