An experimental study was carried out to investigate flow structures in the duct of a rotary energy recovery device (RERD). In order to visualize the flow field, a new type structure of the RERD was proposed in this experiment, which had a fixed duct and two rotating ports. A two-dimensional particle image velocimetry (PIV) measurement was performed to visualize the flow structure in the duct of the RERD. The turbulent flow structure in the duct was analyzed. The instantaneous vorticity contours and associated vectors showed the generation of vorticities in the duct. Moreover, the formation of the small-scale-vortex would significantly increase the flow instability and the fluid mixing rate. These results may be beneficial to researchers in better understanding the flow dynamic in the duct of a RERD and optimize the operating conditions and structural parameters of it.
