Flow characteristics of a three-dimensional wall jet strongly confined by a vertical baffle

To examine the flow characteristics of a three-dimensional wall jet strongly confined by a vertical baffle, flow field measurements were performed on the horizontal and vertical planes crossing the nozzle center using a two-dimensional particle image velocimetry system. The experiment considered four Reynolds numbers: 5084, 8179, 11 052, and 13 926, with a fixed nozzle-to-baffle spacing of 2 d (where d is the nozzle diameter). The results show that the upward and corner wall jets are formed after the three-dimensional wall jet impinges on the vertical baffle. Due to the influence of the recirculation structure on the upward wall jet, it decays more rapidly in the maximum velocity than the corner wall jet. At the same Reynolds number, the jet spreading rates of both jets are comparable. Self-similarity is observed in the normalized time-averaged velocity and Reynolds stress profiles using their half-widths and local maxima values, and their scaling laws are obtained. Two-point spatial correlation and proper orthogonal decomposition analyses reveal that the turbulent structures in the corner wall jet possess lower energy and smaller scales compared to those in the upward wall jet. This study is the first to reveal detailed flow characteristics of the three-dimensional wall jet extremely constrained by a vertical baffle. The findings offer valuable insights for informing the design of engineering structures with complex flow configurations.