Standing-wave thermoacoustic engines and refrigerators utilize gas oscillations and stacks to produce thermoacoustic effects. The flow morphology at the inlets/exits of the stack affects the heat transfer processes and the viscous flow losses in the heat exchangers. In this work, the flow morphology and the size of the disturbance zone are investigated experimentally for different plate-end shapes (rectangular, circular and triangular) at different drive ratios, using Particle Image Velocimetry. The plates are placed inside a resonator filled with air at atmospheric conditions and the oscillations are generated by a loudspeaker operates at the resonance frequency of the system. The size of the disturbance zone is identified as the distance between the furthest axial location the vortex reaches and the location at which it forms. The results reveal that the size of the disturbance zone generally increases with the increase of the drive ratio for all plate-end shapes. At the same drive ratio, the use of circular-end plates reduces the size of disturbance zones with respect to rectangular-end plates. The use of triangular-end plates with 30-degree cone angle causes further reduction in the disturbance zone size. The flow morphology in all cases is presented and analyzed qualitatively. At a drive ratio of 3 %, the disturbance zone extends to a distance of 5.6 mm, 3.3 mm and 1.7 mm for the rectangular, circular and triangular ends, respectively. These values are 14.7 mm, 12 mm and 10.6 mm at a drive ratio of 7 %.
