長方形トリプル噴流の流れ特性に関する研究

～ノズル配向の影響～

抄録

The effect of the nozzle orientation on the flow characteristics of triple rectangular jets with an aspect ratio of 2 was studied experimentally using an X-type hot wire probe. Four nozzle orientations were tested, i.e., triple nozzles oriented along the major plane (Ma-Ma-Ma) and the minor plane (Mi-Mi-Mi), and triple nozzles oriented with the alternate planes of major and minor (Mi-Ma-Mi and Ma-Mi-Ma). Reynolds number based on the nozzle outlet mean velocity and the equivalent diameter was 1.5 × 10⁴. In upstream of the combined point (CP), the nozzle orientation has no influence on the flow characteristics of triple rectangular jets along the jet centerline. However, the velocity and turbulent kinetic energy near the symmetry line of Mi-Mi-Mi increase more than that of other orientations. In downstream of the CP, i.e., x/d_e ≥ 22, the growth of the half-velocity width of triple rectangular jets decreases less than that of the single rectangular jet due to the axis-switching phenomenon. The jets for Ma-Ma-Ma and Ma-Mi-Ma have a large growth of the half-velocity width as compared to the other orientations.