Swirler flow field characteristics in a sudden expansion combustor geometry using PIV

The present study investigates the flow field characteristics of a swirler in a sudden expansion model combustion chamber of square geometry, using particle image velocimetry (PIV). Detailed mean and RMS velocities, vorticity, Reynolds shear stress, turbulent intensity, pseudo turbulent kinetic energy were obtained at various cross sections downstream of the swirler and in plane along the inlet flow direction. A central toroidal recirculation zone (CTRZ) and corner recirculation zone (CRZ) was observed and characterized. Another instability due to swirl effect called as precessing vortex core (PVC) has been observed at far downstream of the swirler, in plane located at Z/D =2.5 (D, diameter of the swirler). The turbulent intensity, TI (RMS velocity magnitude/mean velocity magnitude) is observed to be as high as 20 in several cross sectional planes indicating high levels of turbulence generated due to the swirling effect which promote rapid mixing.