Quantitative visualization of a submerged pseudoplastic jet using particle image velocimetry

摘要

A preliminary experimental study of a pseudoplastic jet flow is reported in this paper. The velocity field was measured using Particle Image Velocimetry. Unlike a Newtonian jet, the pseudoplastic jet was observed to experience a sudden drop in its velocity at a reproducible position downstream of the nozzle for the range of velocities examined. This position moved downstream with an increase in the nozzle exit velocity. The center-line streamwise velocity decayed as X{sup}-15 to X{sup}-30 withinthe terminating region of the jet for three different nozzle exit velocities of 2.43, 3.17, and 5.42 m/s. This decay is in contrast to X{sup}-1 decay for a turbulent or laminar Newtonian jet. The location of the terminating region did not appear to scalewith Reynolds number, Plasticity number, or Hedstrom number. At Reynolds numbers of 3000 and 6400, the instantaneous streamwise velocity maps indicated that the flow was fairly laminar, with a sinuous instability appearing at the higher Reynolds numbercondition. Close observation of the jet indicated that local turbulence could exist within regions of high shear rate. Further detailed study is required to confirm this observation.