Velocity near-field of variable density turbulent jets

Abstract An experimental investigation of the near-field region of variable density turbulent jets is presented. The velocity measurements are performed using a two-component laser Doppler anemometer in an axisymmetric jet of helium, air or CO2 exhausting into a low-speed air coflow. Pseudo-similarity considerations, using the initial density ratio, give a good 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 is more rapid than that of a heavier gas with either the same exit momentum flux or at the same Reynolds number.