The purpose of this project was to develop a fundamental physical understanding of backdraft phenomena. The research was divided into three phases: exploratory simulations, gravity current modeling, and quantitative backdraft experiments. The primary goal of the first phase was to safely simulate a backdraft in the laboratory. A half-residential-scale compartment was built to conduct exploratory experiments. In the second phase, the gravity current speed and the extent of its mixed region was investigated in a series of scaled salt water experiments. In the final phase, 28 backdraft experiments were conducted in a 1.2m by 1.2m by 2.4m compartment. Histories recorded included: fuel flow rates, upper layer temperatures, lower layer temperatures, opening velocities, compartment pressures, upper layer species concentrations for O2, CO2, CO, and HC. Results