OPTICAL-PROPERTIES OF A PLANAR TURBULENT JET

A planar heated air jet was constructed. Its flow properties were char acterized and shown to be both reproducible and in good agreement with the results of turbulence theory. The optical properties of the jet w ere studied with the help of a 632.8-nm He-Ne laser beam. The random p hase modulations imposed on the wave front of the beam traversing the jet were measured by interferometric means, and their spectra and vari ance were determined. The one-dimensional phase fluctuation spectrum o beyed a -8/3 power law as predicted by theory, whereas the phase varia nce (phi 2) depended on the jet temperature and was studied for values to as high as 0.4 (rad)(2).