Time resolved concentration measurements were carried out to study scalar quantity diffusion phenomena of coaxial jet in linear velocity gradient of coflowing air. The axisymmetric velocity gradients could be obtained by varying the length of honeycomb cell along with radial direction. The concentration has been measured using Rayleigh scattering technique. From the result of concentration measurement for various velocity gradients, it is found that concentration spreading angle of positive velocity gradient is larger than those of other velocity gradients i.e., negative and zero velocity gradient.
