Fire Safety Science Digital Archive

In order to investigate the gravity current speed and the extent of its mixed region in backdraft experiments, a series of scaled salt water experiments were conducted. The scaling parameters are the Froude number, v* = v / ??gh, and the normalized density difference, ? = (p0 – p1)/p1, where 1 indicates initial conditions in the compartment (fresh) and 0 indicates conditions in the ambient (salt). The scaled compartment (0.3m x 0.15m x 0.15m) was fitted with a variety of end openings: fill, slot, door, and window. Video and photo data indicate that the mixing layer which rides on the gravity current in the fill opening case expands to occupy nearly the entire current in the partial opening cases. Results for the scaled current height, h*=h0/h1 and v* respectively are: fill (0.5, 0.44), slot (0.38, 0.32), door (0.33, 0.35), and window (0.29~0.22). These data are independent of ? and are in-good agreement with limit calculations from the literature.