Álvaro Aguinaga

Implicit large eddy simulation of unsteady cloud cavitation around a plane-convex hydrofoil

The present paper focuses on the erosive cavitation behavior around a plane convex hydrofoil. The Zwart-Gerber-Belamri cavitation model is implemented in a library form to be used with the OpenFOAM. The implicit large eddy simulation (ILES) is app-lied to analyze the three dimensional unsteady cavitating flow around a plane convex hydrofoil. The numerical results in the cases under the hydrodynamic-conditions, which were experimentally tested at the high speed cavitation tunnel of the École Polytechnique Fédérale de Lausanne (EPFL), clearly show the sheet cavitation development, the shedding and the collapse of vapor clouds. It is noted that the cavitation evolutions including the maximum vapor length, the detachment and the oscillation frequency, are captured fairly well. Furthermore, the pressure pulses due to the cavitation development as well as the complex vortex structures are reasonably well predicted. Consequently, it may be concluded that the present numerical method can be used to investigate the unsteady cavitation around hydrofoils with a satisfactory accuracy.

Numerical investigation of unsteady cavitation around a NACA 66 hydrofoil using OpenFOAM

The prediction and control of cavitation damage in pumps, propellers, hydro turbines and fluid machinery in general is necessary during the design stage. The present paper deals with a numerical investigation of unsteady cloud cavitation around a NACA 66 hydrofoil. The current study is focused on understanding the dynamic pressures generated during the cavity collapses as a fundamental characteristic in cavitation erosion. A 2D and 3D unsteady flow simulation has been carried out using OpenFOAM. Then, Paraview and Python programming language have been used to characterize dynamic pressure field. Adapted Large Eddy Simulation (LES) and Zwart cavitation model have been implemented to improve the analysis of cloud motion and to visualize the bubble expansions. Additional results also confirm the correlation between cavity formation and generated pressures.

Experimental study of liquid-solid two phase flow over a step using PIV

The present investigation focuses on the water-sand flow through a rectangular tunnel with a step using the Particle Image Velocimetry (PIV). Two cameras with appropriate optical filters have been used to capture each phase image separately. The optical filters were selected according to the optical properties of the sand and fluorescent tracers. Through data processing the experimental flow field such as the velocity profiles of sand and water had been obtained. In order to compare with the experiment, the steady state two phase flow fields were simulated using RANS method with k-ω SST turbulence model. It is noted that the numerical results matches the experimental results fairly good. Furthermore, the flow rates obtained from experimental and numerical velocity profiles also have a good match with the measurement by flow meter. The flow analysis shows that the water velocity variation induced by the presence of the step in the water-sand flow is equivalent to those cases with low sand concentration. However, the sand velocity in downstream region is 5% greater than the water velocity when the cross section is reduced in 25%.

Micro-grid platform based on NODE.JS architecture, implemented in electrical network instrumentation

In this document, I propose a theory about the impact of systems based on microgrids in non-industrialized countries that have the goal to improve energy exploitation through alternatives methods of a clean and renewable energy generation and the creation of the app to manage the behavior of the micro-grids based on the NodeJS, Django and IOJS technologies. The micro-grids allow the optimal way to manage energy flow by electric injection directly in electric network small urbans cells in a low cost and available way. In difference from conventional systems, micro-grids can communicate between them to carry energy to places that have higher demand in accurate moments. This system does not require energy storage, so, costs are lower than conventional systems like fuel cells, solar panels or else; even though micro-grids are independent systems, they are not isolated. The impact that this analysis will generate, is the improvement of the electrical network without having greater control than an intelligent network (SMART-GRID); this leads to move to a 20% increase in energy use in a specified network; that suggest there are others sources of energy generation; but for todays needs, we need to standardize methods and remain in place to support all future technologies and the best option are the Smart Grids and Micro-Grids.