EXPERIMENTAL-ANALYSIS OF INTERNAL ENERGY-TRANSPORT IN THE PRESENCE OFCOHERENT MOTION

The paper presents the internal energy budget in the initial region of the slightly heated free round jet in the presence of column-mode coh erent structures. The budget was obtained by the quantitative evaluati on of the shares of particular streams of internal energy transported in the flow-field considered. The input data for calculations have bee n obtained by the hot-wire measurements of three components of instant aneous velocity and instantaneous temperature. All the terms of the in ternal energy budget have been determined experimentally except the pr essure-velocity term which was treated as a closing quantity. The resu lts of the study suggest, that the internal energy of the flow is dete rmined by the mutual balance of convection realized by the mean, oscil latory and random components of motion accompanied by the work of pres sure-velocity correlations. It appears furthermore, that the heat tran sfer in the initial jet area is realized mainly by random fluctuations of proper turbulence motion, generated, however, in substantial part by coherent structures existing in the flow-field considered. (C) 1997 Elsevier Science Ltd.