Analysis of Turbulent Scales in Variable Density Jets Using Laser Anemometry Techniques

This experimental study is concerned with the effect of density variations on the development of a turbulent jet. Our interest concerns the large turbulent scales in order to understand how density variations affect these structures involved in the mixing process. The integral scale evolutions are estimated from laser velocimetry measurements (PIV or LDV). Comparisons between the results obtained in an air jet and a helium jet are given in the development zone (X/D_j < 20), so that the effect of strong density variations (ratio 1 to 7) on these scales is deduced.