INTERFEROMETRIC MEASUREMENT AND TOMOGRAPHY OF THE DENSITY FIELD OF SUPERSONIC JETS

The density field of cylindrical supersonic jets is investigated by Ma ch-Zehnder interferometry. The optical phase shift is extracted from t he interferograms by digital image processing. Disturbing turbulence e ffects in the free shear layer are eliminated by sequential averaging of the phase shifts of several experimental images. The resulting stea dy state phase shift is used to calculate time-averaged interferograms and to reconstruct the density field by computerized tomography. The obtained results are compared with theoretical predictions and good qu antitative agreement is found.