3-D Turbulent density field diagnostics by tomographic Moiré technique

Abstract

 A novel whole-field optical method for mapping three-dimensional intensity of a turbulent density field is described. The method is based on the measurement of the local contrast degradation of Moiré fringes due to turbulence. For mapping the three-dimensional turbulence the tomographic technique was applied. The method was demonstrated by measuring the structure function constant of a hot, turbulent density jet. The results clearly show the high turbulent regions in the mixing shear layer at the jet edges and in the jet center, which corresponds to the wake behind the heating element of the jet generator. The optical setup is simple and can be automated. The method fits the tomographic technique and a high number of data values can be obtained from one record.