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

Abstract

A technique to create 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 simultaneouslyat 10(4) points within a plane intersecting the flow by using two-dimensional imaging of the Lorenz-Miescatteredlight 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.