A PHENOMENOLOGICAL MODEL FOR PREDICTING THE THERMAL LOADING TO A CYLINDRICAL VESSEL IMPACTED BY HIGH-PRESSURE NATURAL-GAS JET FIRES

An integral model of jet fires, originally developed for free fires, h as been extended to predict the internal flame structure of jet fires normally impacting cylindrical obstacles, and to predict the radiative and convective loading on the impacted obstacle, based on that flame structure. Predictions of mean temperatures, gaseous species and soot concentrations, provided by the integral model, are used in an adaptat ion of the discrete transfer method and a single grey-plus-clear gas r adiation model to determine radiative fluxes. An independent assessmen t of the performance of the model in determining radiative heat transf er is presented for both laboratory and field scale fires. Convective loading to the impacted obstacle is determined via a Nusselt number/Re ynolds number correlation, where local mean velocities, temperatures a nd thermodynamic properties of the flow are derived from the integral model. The performance of the complete model for predicting total flux es to impacted obstacles has been assessed by comparing model predicti ons with data obtained from field scale experiments. In situations whe re the simplifying assumptions of the integral model for flame structu re can be applied, predictions of the model are shown to be in good ag reement with the available data.