Avaliação do desgaste erosivo água-areia e água-ar-areia em tubulações de 4 através de técnicas de CFD e de experimentos laboratoriais

Abstract

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.