COMPOSITE FLOW NETWORKS FOR STRETCHING/STABILIZING EFFLUX FLUID FILMS

摘要

An experimental study is performed on various types of composite flow networks to determine the optimum one which produces the best - longest and stable - efflux jet stream. The composite flow networks being investigated consist of diamond-shaped cylinder bundles and slit-flow channels being arranged in series, parallel and/or combination with slit-flow channel. The diamond-shaped cylinder bundle is the principal unit in the composite flow network which is characterized by self-excited flip-flop flow oscillation with uniform flow-rate jet streams. Experimental results are obtained for the PIV (particle image velocimetry) images at strategic flow cross sections, the visualized images of efflux jet-stream, streak line patterns and vorticity contour distribution, and the velocity contour distribution. The following conclusions have been derived: (ⅰ) It is possible to produce multi-phase inter-facial phenomena induced by a combination of the intersecting flow (within a diamond-shaped cylinder bundle) as the main stream, the flip-flop flow containing a longitudinal vortex coexisting in parallel with the slit-flows having vortex shearing direction varying with the contacting phase, (ⅱ) By utilizing composite fluids having the flip-flop flows coexisting with the slit flows, the stretching and formation of stable fluid films can be expected. (ⅲ) Applications become feasible in air curtain and various kinds of environmental security devices together with development of their design guidelines.