Further measurements in the initial region of an annular jet

Abstract

This paper describes further the results of spectral and correlation measurements relevant to coherent structures in the initial region of a basic annular jet associated with the jet vortices and the wake induced vortices. Evidence has been found that for the wake induced vortices the first mode constituent (m = 1) is more dominant in the region where their pressure intensity is high. Further downstream the first mode constituent becomes only slightly higher than that of the axisymmetric (m = 0) mode. For the jet vortices during their generation and formation near the nozzle exit the first mode constituent is slightly more dominant than the axisymmetric constituent. Further downstream the axisymmetric constituent becomes more dominant. Nevertheless, fairly similar modal and basic characteristics of these two types of vortices are found. © 1984.