Heat transfer and flow structures in an excited circular impinging jet

Flow structures and heat transfer are investigated experimentally in an excited circular impinging jet with small nozzle-lo-plate spacing (H/D less than or equal to 2). The local heat transfer in the wall-jet region is found to be sensitive to the excitation frequency. Enhancement and reduction of the local heat transfer in the wall-jet region can be attained by forcing the impinging jet near the natural frequency and its subharmonic, respectively. The relationship between the vortical structures and local hear transfer is studied by the means of flow visualization, heat transfer spectra and correlation between velocity and heat transfer. Copyright (C) 1996 Elsevier Science Ltd.