Étude expérimentale et numérique d'écoulements supersoniques en éjecteur avec et sans condensation
First of all, the objective of the thesis is to improve the comprehension of incondensable compressible flows in ejectors for all states of flow susceptible to appear. For that reason, in the first part of the thesis, the physics of compressible flows was studied with emphasis on implementation of numerical methods, more specifically on turbulence models used. Standard k -[varepsilon] turbulence model was selected because it simulates adequately flow phenomena present in dry air powered ejectors. This is a sine qua non condition for the application of a model on to more complex flows such as flow with condensation. A thorough parametric study of ejectors operation gave prominence to particular operation regimes. This is one of this work's originalities since only little of those phenomena have been studied to this day. Furthermore, this first part allows a better anticipation of ejectors regimes and, therefore, facilitates their design. The second part of this thesis takes into account phenomenology of condensation/evaporation by adding it to the incondensable flow models while using the results of the parametric study. An experimental study based on visualisations of an ejector condensation zone is used for comparison. The complete study was realized with the Computational Fluid Dynamics (CFD) software FLUENT in which a 2D axisymetric model of condensation in high speed flow was implemented. Mass condensation fields in ejectors obtained by simulation are compared to experimental laser tomography measurements. It was emphasized that these measurements were in agreement with the numerical results. Again, this is one of this thesis' originalities since no study has been realised on the visualisation and comparison of condensation fields in ejectors.
- Génie – Thèses