Laser Planogram Measurements of Turbulent Mixing Statistics in the Near Wake of a Supersonic Cone

摘要

The laser planogram technique is a new method for the study of turbulent mixing. It utilizes a pulsed laser and a particulate tracer to determine the spatial mixing field of tagged and untagged fluids. The laser planogram technique is described along with design considerations. As an example of its implementation, laser planogram measurements were obtained and analyzed to provide turbulent mixing statistics in the wake of a cone at a Mach number of 2.5, and a Reynolds number of 3,000,000. The mean radial concentration profile of tagged material is shown to be a Gaussian in agreement with theory. A (k exp -5/3) spectral dependence on wave number is observed which is characteristic of high turbulent Reynolds number flows. Experimental limitations prevent the resolution of the turbulent scale lengths in the present experiment although the integral scale should be easily resolved with increased data length. (Author)