Conditional sampling of velocity in a turbulent nonpremixed propane jet

Simultaneous axial and radial velocities have been measured throughout a turbulent nonreacting propane jet under high Reynolds number conditions using a two-color laser velocimeter. The objective of the measurements has been to obtain a better understanding of the flow structure and mixing process in turbulent, nonpremixed, variable-density jets. Velocity measurements conditional on fluid originating from the jet and from the coflowing airstream were obtained by alternately seeding only the jet fluid and the coflowing air. In addition to information on mean and fluctuating quantities, conditionally sampled probability density distributions of axial and radial velocity and the joint probability distributions are presented. The results show that differences in the conditional velocity statistics (i.e., means and higher moments) at a location are dependent on the degree of prior mixing. In regions near the centerline where sufficient mixing has occurred, the conditionally sampled statistics agree well whereas, in the mixing region between the central jet and the outer coflowing air, insufficient mixing has occurred and significant differences are observed.