Three Component LDA Measurements in Swirling Jets

Previous studies of swirling jets have revealed faster growth rates in the near field in comparison to their non-swirling counterparts. Recently, the growth rates and turbulent properties of the swirling jet in the far field have been shown to relax to those of the non-swirling jet. The current effort seeks to bridge these two regions by performing velocity surveys in the near and far field of a Re=100000 swirling jet using three-component Laser Doppler Anemometry (LDA). Surveys are performed for various levels of swirl number, the ratio of angular momentum flux to linear momentum flux, from 0 to 0.4. Two different exit swirl profiles are studied, and the measurements are carried out in a region from the nozzle exit to 40 diameters downstream. In addition to bridging the near- field and far-field results, the mean data and turbulence statistics provide the means to examine the relaxation of these jets to their far-field form. Further, the separation of the axial and tangential flows and the scaling suggested by Ewing may be evaluated.