Study and development of a strategy of performance analyses of helicopter engine breathers
Abstract
Air operators try to reduce ever more operation and maintenance costs of helicopters as well as to limit their environmental impact. Consequently, engine manufacturers such as Safran Helicopter Engines must constantly improve the performance level of the engines they develop. To achieve such an improvement, oil and kerosene consumption must be reduced. Oil consumption is mostly due the formation of an oil mist inside bearing chambers. As the air is continuously scavenged, it carries along oil droplets out of the engines. In order to limit the oil wastes, a separator is used which recovers oil drops carried by the flowing air that is vented out. In order to predict with a better level of accuracy the oil consumption and the pressure losses induced by the separator, the present thesis develops a strategy to analyse the two-phase flow within the separator. This strategy relies in the first place on Euler-Lagrange numerical simulation of the oil mist which allow on the one hand to compute the turbulent air flow and the pressure drop induced by the separator and on the other hand to better understand the separation mechanisms and to predict the oil consumption for various operating conditions. Besides, thanks to the funding of the E-Break European project, a test bench has been designed in the framework of this PhD and set up at the Université Libre de Bruxelles. Cross comparisons between measurements and simulations allow to validate the numerical methodology. However, even though pressure drops are correctly predicted by the simulation, improvements are still needed, regarding both the measurement accuracy and the two-phase numerical modeling, in order to provide a satisfactory prediction of the oil consumption.