Plate-type reactor fuel is getting increasing attentions as it features excellent heat transfer ability and compact structure. Turbulence mixing accompanied with momentum and mass exchange is typical phenomena in the converging region downstream of parallel plane fuels. To deepen understanding turbulence mixing characteristics and obtain more benchmark data for CFD, an experimental study was conducted by 2D particle image velocimetry (2D-PIV). Ensemble average profile of velocity, vorticity, turbulence intensity, as well as Reynolds stress are analyzed, respectively.
Results reveal that two kinds of merging points (mp) were found, i.e., flows from two side jets merge at y/d = 3 (mp1), and flows from middle three jets merge at y/d = 7.6(mp2). The decay of vertical velocity decreases fast primarily until y/d = 6, then slightly increases until y/d = 8.8, and finally decreases gradually. Decay of velocity magnitude of present study decreases sharply until y/d = 6.4, then decreases gradually. This tendency of five-parallel jets is similar to the result of two-parallel jets. From flow visualization, the vortex scale decreases once the vortex formed. The vorticity reaches its maximum at about y/d = 1.3 and then decreases gradually. Consistently with the indicated of velocity distribution, the vorticity distribution tends to mild with the flow developing downstream. However, the location of vortex center is affected by spanwise momentum exchange. Vortices started moving closer around the mp2 indicating a strong combination of activities. Spanwise turbulence intensity shows strong fluctuations existed around mp1 implying that the main momentum transfer happened in the merging region.