Particle Image Velocimetry (PIV) was used to measure the turbulent flow fields over single and dual rectangular cavities. Four sets of PIV measurements were acquired, corresponding to two Reynolds numbers per each cavity configuration. The cavity depth based Reynolds number was varied between 21,000 and 42,000, while the cavity length-to-depth ratio was fixed at four. Galilean decomposition is used to present instantaneous velocity fields. Turbulent velocity fields are presented using Reynolds decomposition into mean and fluctuating components. Characteristics of the instantaneous and time-averaged velocity fields corresponding to a single cavity configuration are in agreement with the observations from previous studies. All mean flow field results display a large vortical structure spanning the entire length and height of each cavity. In the case of a dual cavity configuration, the free shear layer and trailing edge regions of the second cavity were found to always display higher streamwise and crosswise flow fluctuations in comparison with the first cavity. Furthermore, a wider free shear layer region is observed in the second cavity, in comparison with the first cavity.
PIV measurements of turbulent flows in a 61-pin wire-wrapped hexagonal fuel bundle