A study on ceiling jet flow behaviour

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A series of experiments that focused on the flow behavior of ceiling jet, which flows under an unconfined ceiling, were conducted. Based on the experimental results, empirical formula for temperature rise and velocity decreasing, thickness and distribution against radial distance were developed considering the effect of inclination angle.To examine the effect of fire source shape to the ceiling jet flow, the rectangular fire source was employed. By comparing the temperature rise decreasing and temperature distribution with them obtained by a square fire source, typical difference for temperature rise decreasing against radial distance was confirmed. Detailed measurements of the temperature rise and velocity in a horizontal tunnel with a rectangular cross section were conducted to examine the effect of side wall on the ceiling jet. Empirical relationship to estimate the decrease in the ceiling jet temperature rise and velocity along the horizontal axis of the tunnel was developed.