2011 Volume 53 Issue 182 Pages 296-306
The dynamics of flow structures in the near field of orifice plane jets with sharp-edged and right-angle exit profiles are studied experimentally. The operating velocities of the jet flow are within U0=5–20 m/s. Test results show that the evolution of the jet flow is significantly influenced by the initial orifice exit profiles. The initial fluctuating velocities of orifice plane jets are higher than the case of contoured nozzle plane jets. The vena contracta effect plays a crucial role in the flow development of the orifice plane jet. The length of potential core, mixing characteristics and turbulence properties are also extensively investigated in this paper. The energy transfer characteristics can be aptly characterized by the evolution of coherent structures. The kinetic energy gained at the immediate orifice exit is contributed to by mean energy advection. The fluctuation kinetic energy implants into the turbulent flow through turbulent energy advection at the vortex merging process because no positive value for turbulent energy production is observed there.