Numerical evaluation of the ground vortex

Sammanfattning: This master thesis covers the realization of a CFD calibration study regarding the numerical simulation of the ground vortex phenomenon. As part of InVIGO project (EU CleanSky2), wind tunnel test campaigns were performed using a nacelle model combined with a movable raised floor. Those tests allowed the gathering of an unprecedented amount of experimental data regarding this phenomenon, via the implementation of pressure measurements and stereo-PIV acquisition. Measured velocity fields were also post-processed to compute vortex characterization indices. In the context of this study, several Python scripts are developed to process this data through the computation of total pressure and velocity maps. A calculation matrix of 28 representative points is chosen among test cases and the corresponding nacelle geometry is prepared to generate a series of high resolution structured mesh (18.22 million cells) using an existing ICEM macro. For every case, corresponding CFD calculations are implemented on elsA using the RANS resolution method associated with the Spalart-Allmaras turbulence model. In parallel, a series of CFD post-processing scripts are developed using Cassiopée modules, in order to extract pressure/velocity maps and compute both distortion and convergence indices. Also, a Safran AE in-house script dedicated to vortex characterization is not only implemented to compute vortex indices, but also upgraded with an additional vortex profile extraction functionality. The cross-analysis of numerical and experimental data thus collected is performed, allowing the assessment of the great calculation representativeness regarding the overall inlet flow topology as well as the vortex apparition. The comparison of vortex characterization indices displays common tendencies, however disparities regarding the implemented processing methodologies along with convergence difficulties encountered for some vortex cases highlights the need to put the relevance of those results into perspective.