On the near-field flow structure and mode behaviors for the right-angle and sharp-edged orifice plane jet

The study of flow structures in a sharp-edged and right-angle orifice plane jet was investigated experimentally by means of hot-wire technique and smoke flow visualization. The results indicate that the vena contracta effect depends upon the Reynolds number as well as the geometric configuration of the orifice exit. The vena contracta effect in the sharp-edged orifice plane jet is much significant and to suppress the development of coherent structures. In addition, the sharp-edged orifice plane jet is considered more complexity since two competing initial instability frequencies were found at Re = 10,300 or above. Meanwhile, two types of instability modes exist in the orifice plane jet, i.e. varicose and sinuous mode. These instability modes were observed to depend upon the Reynolds number and geometric configuration of orifice exit as well.