Measurements of gas velocities and temperatures in a large open pool fire

There is an interest in determining the response and survivability of a variety of items subject to engulfment in a large fire which may occur in a transportation accident. In order to estimate this response, knowledge of the thermal and flow conditions prevailing in these pool fires is required. Few experiments have been performed with large (>3 meter diameter) fires. In particular, velocity measurements in the continuous flame region of low Froude number fires are very scarce. Scaling up the results of small pool fires is problematic due to the large number of relevant dimensionless variables to be matched. A total of -- 48,500 liters of JP-4 fuel was burned in a 9x18 meter pool, producing peak temperatures in excess of 12300C (22500F), over much of the instrumented region of the flame. Temperatures were measured at 28 locations throughout the continuous flame region with 1.587 mm OD Inconel sheathed, ungrounded, type K thermocouples. Four 0.127 mm diameter bare wire thermocouples used to make high frequency response temperature measurements. Velocities were measured at four vertical stations near the centerline of the pool, with glass coated, velocity probes. Heat fluxes were estimated from measurements on and near vertically suspended mild steel plates. As is often the case in fires of this size, the effects of mild ambient winds on the measurements were pronounced. Attempts have been made to mitigate these effects by the application of conditional sampling. Temperatures are compared with measurements made in other large aviation fuel fires. The measured velocities are slightly less than would be predicted from an empirical model that was developed from experimental results for methane diffusion flames that are orders of magnitude smaller