LOCAL CHARACTERISTICS OF IMPINGEMENT HEAT-TRANSFER WITH OBLIQUE ROUNDFREE-SURFACE JETS OF LARGE PRANDTL NUMBER LIQUID

An experimental study was performed to investigate the local convectiv e heat transfer from a vertical heated surface to an obliquely impingi ng circular free-surface jet of transformer oil. The effect of jet inc lination was examined in the range of Reynolds number between 235 and 1745 with jet angle from 90 to 45 deg. Maximum heat transfer coefficie nt was found to decrease with the increasing of jet inclination, while its location shifted to the upstream side. Correlations were develope d to predict the variations of the magnitude and the location of the p eak heat transfer. Profiles of local Nusselt number were measured both in x and y-axes. The profiles along s axis displayed an increasing as ymmetry with increasing jet inclination. An empirical correlation was presented for predicting the y-axis profiles. With y-axis profiles, a symmetry appeared inside the stagnation zone, but a gravity-induced as ymmetry was observed outside that zone. (C) 1997 Elsevier Science Ltd. All rights reserved.