Highly localized pressure perturbations induced by laser absorptive heating in the shear layer of a gas jet

A technique for creating a localized pressure perturbation by laser heating the absorbing gas inside the flow field is described. The effect of the laser-induced pressure pulse is to trigger the development of turbulent structures, which then evolve in time. With such external perturbation, the nozzle gas concentration is measured simultaneously at 10,000 points within a plane intersecting the flow by using two-dimensional imaging of the Lorentz-Mie scattered light from aerosols seeded in the flow. The instantaneous and time-averaged spatial distributions of the perturbed flow field are presented, as is the rms fluctuation of the concentration.