Highly resolve large eddy simulations of a transitional air-helium buoyant jet in a two vented enclosure: validation against particle image velocimetry experiments.
Résumé
The article deals with LES simulations of an air-helium buoyant jet in a two vented enclosure
and their validation against particle image velocimetry experiments. The main objective is to test
the ability of LES models to simulate such scenarios. These types of scenarios are of first interest
considering safety studies for new hydrogen systems. Three main challenges are identified. The two
first are the ability of the LES model to account for a rapid laminar-to-turbulence transition, mainly due to the buoyancy accelerations, and the Rayleigh-Taylor instabilities that can develop due to sharp density gradients. The third one is the outlet boundary conditions to be imposed on the
vent surfaces. The influence of the classical pressure boundary condition is studied by comparing
the simulations results when an exterior region is added in the simulations. The comparisons
against particle image velocimetry experiments show that the use of an exterior domain gives more
accurate results than the classical pressure boundary condition. This result and the description of
the phenomena involved are the main outlets of the article.