Heat transfer of impinging axisymmetric jets with a mesh screen in the nozzle : 2nd report, for the case of large mesh size

As in the first report, the effect of a mesh screen on impinging heat transfer has been experimentally studied in relation to the flow characteristics of an axisymmetric jet. The mesh screen was installed in the nozzle, 10mm upstream from its exit. Five types of mesh screen with relatively large mesh size were used. The jet Reynolds number based on the nozzle diameter and the nozzle exit velocity was kept constant at Re=17800. It is shown that the effects of the mesh screen on the flow characteristics of a free jet, and the heat transfer characteristics of an impinging jet, are appreciable. When the diameter of mesh wire is large, the velocity potential core of the jet is shorter than that without the mesh screen, and the local heat transfer coefficients augment in the case of the short nozzle-to-plate distance. This technique of heat transfer augmentation using a mesh screen with large mesh size is a very attractive method for industrial applications because the heat transfer coefficients over extensive impinging regions are increased and made uniform by the installation of the 4 mesh screen.