Abstract This paper presents results of investigations focused on a pressure wave exchanger demonstrator, constructed at the Aerodynamics Division at Warsaw University of Technology. Main flow features of the device were analyzed and experimental data was collected in order to perform validation of CFD calculations. Three different turbulence models (Standard-k-ω, SST-k-ω and SST-SAS) were used in simulations and tested in unsteady conditions. Data in form of: velocity field, shape and position of the contact surface between the driving and the driven medium served to perform comparison between PIV measurements and numerical calculations, which revealed that the best correlation between experiments and numerical data was obtained with SST-SAS turbulence model.