An optical method for measuring the intensity of fluctuations of the concentration of an inert impurity in supersonic flow

A local optical probe facility and method are described for measuring the intensity of turbulent pulsations of the concentration of a passive additive in a supersonic flow. The source of light is a He-Ne laser emitting at 6328 A, and finely dispersed oil vapors serve as the light scattering additive. Fields of the mean and rms concentration pulsations of the additive in different sections of the wind tunnel corresponding to a different value of turbulent diffusion were measured by this method and also by photographing the wake of the laser beam and subsequent photometric analysis of the negative.