Study on Flow Characteristics of Five Rectangular Jets Arrayed in a Line

The effect of nozzle orientation on the flow characteristics of five rectangular jets with an aspect ratio of 2 was experimentally investigated using an X-type hot-wire probe. Four kinds of nozzle orientations were tested, i.e., five nozzles oriented along the major plane (Ma-Ma-Ma-) and the minor plane (Mi-Mi-Mi-), and five nozzles oriented with the alternate planes of major and minor plane (Ma-Mi-Ma- and Mi-Ma-Mi-). The Reynolds number based on the nozzle outlet mean velocity and the equivalent diameter de was Re = 1.5 × 104. The length of the potential core of the rectangular jets is xc ≈ 3de in all nozzle orientations. In the upstream of the combined point (CP), for Ma-Ma-Ma-, Mi-Mi-Mi-, and Ma-Mi-Ma-, the nozzle orientation has no influence on the flow characteristics of five rectangular jets along the jet centerline. However, for Mi-Ma-Mi-, the "Side jet 1" adjacent to the middle jet is elongated due to the axis-switching phenomenon. Thus, the combined point (CP) moves downstream. In the downstream of the CP, the increment rate of the half-velocity width of the whole merged five rectangular jets decreases less than that of the single rectangular jet and triple rectangular jets due to the axis-switching phenomenon of these merged jets.