Measuring Flow Using Spectrally Resolved Rayleigh Scattering

An experimental study has been conducted to demonstrate the feasibility of using spectrally resolved Rayleigh scattering to nonintrusively measure the instantaneous properties of the flow in a small supersonic wind tunnel. Unlike conventional probe flow measurements, Rayleigh scattering of a laser beam does not perturb the flow. Because the Rayleigh scattering uses the actual gas molecules that make up the flow under study, it is not necessary to seed the flow. Another important advantage of this technique is that properties of the flow can be determined simultaneously at multiple locations along the laser beam; moreover, if the laser beam is pulsed, then these flow properties can be obtained at multiple locations with a single laser pulse.