Visualization of tip vortex flow in an open axial fan by EFD (original) (raw)

The behavior of tip vortex in an axial fan without casing wall (called open axial fan) was discussed and analyzed. The velocity measurement was performed by using two-compon ents Laser Doppler Velocimetry (LDV) system. The detailed velocity and vorticity distribution inside blade passage and downstream of rotor were obtained. Thus the structure of tip vortex and its behavior were graphically visualized by experimental fluid dynamics (EFD). The tip vortex flow trace was indicated with the calculation of vorticity. As a result, it was found that tip vortex was generated at blade tip region near leading edge and it extended to downstream of blade exit with its core tending inward to hub direction. In addition, leading edge vortex was also found at the forepart of the experimental open fan.