Numerical assessment of confinement effect and flow structure in case of hydrogen release in a two-vented cavity
Résumé
We present numerical results from direct numerical
simulations (DNS) of an air-helium buoyant jet in a two-vented
cavity. Geometrical configuration of the cavity is chosen to
ensure a bi-layer stratification distribution of helium, which is
commonly assumed in relevant industrial models. A series of
computations with different horizontal sizes of cavity is
performed to determine the optimal dimensions, for which the
helium buoyant jet and the top mixture layer are not influenced
by the end walls. Results are analysed in terms of flow structure
and helium concentration distribution, but also of inlet mass flux
of fresh air and of helium outlet flux, as fluxes are kept free
through the vents. Additionally, buoyancy flux in the jet
corresponding to Mortonâs theory (1956) is calculated to deduce
entrainment coefficient and compared with literature.