Jet emerging from an annular nozzle and impinging onto cylindrical cavity: effect of jet velocity on flow structure and heat transfer rates

摘要

In laser gas assisting processes, nozzles are used to accelerate the impinging gas and attain a proper flow structure to improve the quality of the end product. In this study, the jet emerging from an annular nozzle and impinging onto a cylindrical cavity is considered. The effects of jet velocity at nozzle exit onto the flow structure in the region of the cavity and heat transfer rates from the cavity surface are examined. To resemble the laser-produced cavity, the cavity wall temperature is kept elevated (almost the melting temperature of the substrate material). Reynolds stress turbulence model is exploited to account for the turbulence. In the simulations, four jet velocities, two outer angles of the annular nozzle, and two depths of the cylindrical cavity are employed while air is used for the working fluid. It is found that jet velocity has a significant effect on the heat transfer rates and skin friction, which is more pronounced with increasing cavity depths.