Influence of Conical and Annular Nozzle Geometric Configurations on Flow and Heat Transfer Characteristics due to Flow Impingement onto a Flat Plate

Jet impingement onto a flat surface is considered, and the influence of the geometric configurations of conical and annular nozzles on the flow structure, heat transfer rates, and skin friction are examined in relation to laser machining applications. The governing equations of flow are solved numerically using a control-volume approach. Four cone angles of each nozzle are accommodated while keeping the nozzle height and exit area the same in the simulations, in accordance with laser machining applications. Jet emerging from the pipe and impinging onto a flat plate is accommodated to compare the flow and heat transfer characteristics due to the jet emerging from the nozzles. It is found that nozzle cone angles have significant effect on the flow structure in the region close to the flat plate, which in turn modify the heat transfer rates from the plate surface. Moreover, increasing cone angle results in radial acceleration of the flow in both the viscous sublayer and the turbulent boundary layer, which, in turn, enhances the heat transfer rates considerably as compared to a pipe flow situation.