VELOCITY NEAR-FIELD OF VARIABLE-DENSITY TURBULENT JETS

An experimental investigation of the near-held region of variable dens ity turbulent jets is presented. The velocity measurements are perform ed using a two-component laser Doppler anemometer in an axisymmetric j et of helium, air or CO2 exhausting into a low-speed air coflow. Pseud o-similarity considerations, using the initial density ratio, give a g ood collapse of the mean axial velocity evolutions for gases with very different densities. The comparison of the statistical moments up to the fourth-order confirm that the development of a lower density gas i s more rapid than that of a heavier gas with either the same exit mome ntum flux or at the same Reynolds number. Copyright (C) 1996 Elsevier Science Ltd.