Experiment and simulation of the recirculation flow in a CVD reactor for monolithic materials

The length of the recirculation zone (reattachment length) of a central jet flowing into an enlarged chamber is studied both experimentally and theoretically. Unlike conventional studies of flow over a backward-facing step or abrupt circular channel expansion flows, the expansion ratio in this study is much greater than 2. This is the condition observed in the CVD reactor for producing bulk monolithic materials. A correlation equation is found to predict the length of the recirculation zone when the expansion ratio is greater than 2. This correlation equation has been confirmed by the present experimental data with an expansion ratio of 15.3 and agrees with the existing data for an expansion ratio of 2.6.