Fire Safety Science Digital Archive

This paper discusses a new 3-D experimental data that were obtained by a laser-sheet-particle-tracking (LSPT) technique for a spreading flame over n-butanol. The major heat transfer process between the flame's leading edge and the liquid is a highly transient phenomenon involving both liquid and gas phases. These interact with each other through exchanges of momentum, heat, and mass. We improved our original 2-D LSPT and made it applicable to study 3-D measurement. Using this new 3-D LSPT we measured a series of velocity profiles in a pulsating flame spread over n-butanol at different distances above or below the liquid surface and obtained 3-D flow visualization in both liquid and gas phases. The new LSPT confirmed the existence of twin vortex flow on the liquid surface and deep in the liquid a few mm below the surface. These vortices gradually disappear as the laser sheet moves down from the liquid surface. A similar twin-vortex structure in the gas phase was also observed for the first time. These results proved that the convective flow in both liquid and gas phases is 3-D in nature in the three trays we have used.