RCAAP Repository

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Deep water oil production imposes several challenges to the oil companies. One of the greatest difficulties is related to the damages that the flexible riser pipes are subjected. These pipes conduct the produced oil to the platform. They are also used to inject water in the well in order to recover its production capacity. Among the damages mentioned, its worth to mention the abrasive wear that takes place at the touchdown point (TDP). In order to reduce this tribological degradation, PU coats have been used at the TDP region. Considering the diversity of PU that can be used in this application, it is highly desired that the PU plaques quality are controlled before its installation. Based on this demand, a portable apparatus was designed and constructed in the Laboratory for Friction and Wear at the Federal University of Uberlândia to simulate the tribological interactions between the riser pipe and the sea bed. So this work aims to produce WC-Co indenter for this test apparatus. To accomplish that, the following steps were proposed: a) equipment preparation for wear tests; b) determination of test parameters (cycle number and load) through a full factorial design; c) geometric and dimensional control of the indenters before and after machining processes; d) realization of wear tests before and after machining the indenters; e) machining of indenters using honing and lapping and f) analysis of the improvements achieved on the wear results. The results obtained allowed the following conclusions: 1) the proposed machining processes and parameters for are appropriate to manufacture the indenter In accordance with their selected dimensional and geometric tolerances. Roughness values of about 2.0 μm has been reduced by at least 60%, while for values lower than 2.0 μm this reduction was at least 33%, and 2) abrasion tests using the new indenters provide more precise and reliable results.

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Currently, for an engineering company remain competitive, is vital to reduce the time spent in execution projects in order to reduce costs (man - hour). In this context, this work aims to contribute with the time reduction in the analysis of non-isothermic three-dimensional flows, applying the AMR technique (Adaptive Mesh Refinement Location Technique) and Immersed Boundary, allowing the use of Cartesian mesh. The mathematical model and numerical solution was implemented in AMR3D code, in development at the Laboratório de Mecânica dos Fluidos ( MFLab ), designed for applications in multiphase flows with nonstatic boundaries. In a more simplified approach, this work deals with single-phase flow with static boundaries. Verification and validation tests for the energy equation are presented through manufactured solutions and flows in driven cavities. According to the results presented in this study, the mathematical and numerical models were satisfactory for the solution of the energy equation for incompressible, non-isothermal flows with constant physical properties, allowing the development of future works considering non-isothermic two-phase flows with non-static boundaries.

The purpose of this work is to evaluate the erosive wear caused by sand impinging particles on a 90° elbow wall, in a four inches pipe. This evaluation was made with computational fluid dynamics (CFD) techniques, experimentation in a laboratory Loop equipment, interferometry and scanning electron microscopy (SEM). Different parameters were tested through computational method (CFD), varying fluids, velocities, flow types (water one-phase and air-water two-phase) and pipe materials (4140 Steel and Aluminum). In the experimental analysis only one condition was set and this condition compared to the same condition computationally simulated. For measuring the erosive wear rate, the experimental analysis of the surface thickness loss (interferometry), was unable to capture a representative wear value, what was confirmed by the computational simulation. The analysis through microscope, showed the acting wear mechanism. With the obtained results, it was possible to see that in low velocities the pipe wall erosive wear is very small, showing also the sand deposition in the bottom of the pipe. It was also possible to see the necessity of an experimental structure for parameters used in the simulation determination, since the erosion models commonly used in CFD uses a lot of experimentally determined data. Another important issue to note was de hardness to obtain pure erosive wear. The coupons also showed corrosive wear, beyond erosive wear, showing a synergy wear effect on the pipe walls. A lot of problematic conditions brought much knowledge about the done analysis, as for example, the work fluid heat and consequently the system heat by the centrifugal pipe action, damaging the experiment autonomy. The sand injection also showed its convergence troubles with the experiment, the same way, the restitution coefficient used in the computational simulation.

This work presents the coupling between two different formulations applied to flow simulation and analysis of wind rotors, integral and differential formulations. First, for the integral formulation is defined a control volume where the variables problem are defined, as well as the necessaries working hypothesis, then a proposed mathematical modeling is defined. Simulations through NACA airfoils, using Computational Dynamic Fluids, are performed in order to evaluate drag and lift coefficients, to be used in the integral formulation. The Navier-Stokes equations are solved in house and the Smagorinsky turbulence model with Van Driest damping function is retained. The computational code is implemented with structured cartesian mesh, where the airfoil is modeled using the Immersed Boundary Methodology. The results of simulation through a NACA0012 airfoil are shown for several attack angles and Re = 10000. Results of energetic efficiency are presented for a horizontal axis wind turbine using the integral formulation, where the coefficients are given by differential formulations.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior