58653 - Experimental Investigation of the Confinement Effects in Radial-Radial Swirlers 

An experimental study is performed to investigate the effect of confinement ratio on the mean and instantaneous flow field of a counter rotating radial-radial type swirler by using Particle Image Velocimetry (PIV) technique. Confinement ratio is defined as the ratio of the burner cross section area to swirler exit area. The effects of the confinement ratio have been investigated by use of pointwise measurement techniques [ Fu et. al., 2005] and it was shown to have a crucial impact on the swirling flow. In this study, time-resolved two-dimensional two-component (2D2C) and two-dimensional three-component (2D3C, i.e., stereoscopic) PIV measurements are being performed to obtain unsteady planar flow fields. Four different confinement ratios (i.e., 8, 16, 64 and unconfined) are considered at a swirl number (the ratio of the axial flux of the tangential momentum to axial flux of the axial momentum) of 1.2. The PIV data is captured at the mid-plane of the jet and five different cross-stream sections. Both instantaneous and time-averaged flow structures, including the analysis of the first and second order statistical moments (for the available components) under the influence of the confinement will be included in the draft version of the paper. The dominant coherent flow structures will be identified by use of the proper orthogonal decomposition (POD) method.