EFFLUX FROM A COMPOSITE FLOW NETWORK HAVING FLIP-FLOP FLOW IN PARALLEL WITH SLIT FLOWS

摘要

An experimental study is performed on a composite flow network consisting of a diamond-shaped cylinder bundle sandwiched between two slit flows. Air serves as the working fluid. An YAG laser is used as a light source for illumination. A P1V measurement technique is employed to visualize flow phenomena which are recorded by means of a CCD camera. The cylinder bundle is made of transparent acrylic material and two sets of slit flows of different size are fabricated. For comparison, a traditional flow channel of rectangular cross section and a composite flow network with a diamond-shaped cylinder bundle in parallel with a slit flow on one side are tested. Both velocity vector and vorticity distributions in the efflux region are obtained to determine the flow patterns. It is disclosed that the flip-flop flow generated inside the cylinder bundle assists the slit flows to stretch through suppressing the diffusing phenomenon of the efflux jet stream. The mechanisms for the stable efflux stretching are determined. The study can have an important application to the development of stable fluid films such as air curtains for environmental purification and protection.