EXPERIMENTAL STUDY FOR TRANSIENT HEAT TRANSFER FROM A FLAT PLATE UNDER AIR IMPINGEMENT

Abstract

The present work represent an experimental study to verify the transient heat transfer characteristics of a target plate under air impingement from different orifice sizes (D=5, 10, 15 and 20mm), with orifice to plate distance ratio (H/D=2, 4, 6 and 8). Air jet velocities is varied in the range (Uj=18-40m/s) representing (Re=7100-11900). The heat transfer coefficient on the target plate are calculated on the basis of two dimensional infinite case. The local variation of Nusselt number in the transient period is measured. The values are compared to that at the steady state condition. Results show that the Nusselt values are maximum at state of impingement process and decays with time on proceeding of the cooling process and also with space reaching the plate edge.

Keywords

• jet cooling
• heat transfer on a flat plate
• transient impingement