SCALAR DISSIPATION MEASUREMENTS IN THE DEVELOPING REGION OF A JET

Instantaneous planar images of CH//4 mass fraction in the developing region of an isothermal jet were used to calculate instantaneous, mean, root mean square (rms), probability density functions (PDFs), and correlations of scalar dissipation and a scalar. The mass fraction images were derived from CH//4 concentrations obtained by simultaneously recording Raman-scattered light with two cameras oriented perpendicular to a thin sheet of laser light pass through the axis of the jet. The results were used to evaluate modeling assumptions. The radial and axial dissipation components were found to be strongly nonisotropic in the mixing layer at x/d less than equivalent to 13, but isotropic further downstream. At all locations along the centerline the dissipation was isotropic. The scalar and dissipation were found to be highly correlated in the mixing layer but uncorrelated on the jet axis.