Flame extension length beneath a horizontal eave in fire-induced thermal plume ejected from a compartment

This work focuses on the flame extension length beneath a horizontal eave in fire-induced thermal plume ejected from a compartment window. Series of small scale experiments are conducted in a cubic compartment of 0.4 m with a facade wall and a variable window. A noncombustible board is installed horizontally attached to the facade wall to simulate the eave upon building facade. The window dimensions, the vertical distance of horizontal eave to the window top and the total heat release rate are altered in our experiments. Two CCD cameras are employed to record the ejected flame videos from both front and lateral directions. Results show that the flame extension behavior appears when the horizontal eave level is lower than the corresponding free facade flame tip. The flame extends almost symmetrically, becoming longer for a higher excess heat release rate, but turning shorter when the horizontal eave is moved up. A dimensionless model in relation to the free visible flame height, the excess heat release rate and the vertical height of horizontal eave is well developed based on experimental observations. The findings would provide an important basis in the practically applications of horizontal eaves for better building fire protections.