Effect of coating material on heat transfer and skin friction due to impinging jet onto a laser producedhole

Jet impingement onto a two-layer structured hole in relation to laser drilling is investigated. The hole consists of a coating layer and a base material. The variations in the Nusselt number and the skin friction are predicted for various coating materials. The Reynolds stress turbulent model is incorporated to account for the turbulence effect of the jet flow and nitrogen is used as the working fluid. The study is extended to include two jet velocities emanating from the conical nozzle. It is found that coating material has significant effect on the Nusselt number variation along the hole wall. In addition, the skin friction varies considerably along the coating thickness in thehole.

► Coating material has significant effect on flow field in the hole.
► Coating material of high melting temperature enhances Nusselt number and skin friction.
► Nusselt number demonstrates different behaviors for coating and base material.