Stability and contraction of a rectangular liquid metal jet in a vacuum environment

Hydrodynamic similarity criteria and experimental data are reported here fr om experiments underway at UCLA that simulate the slab jets of the HYLIFE-I I inertial fusion reactor. The current experimental setup produces a 2 x 20 mm slab jet, and reaches a maximum Reynolds number 5 x 10(4), correspondin g to a jet velocity of 12 m/s. A high-speed camera is used to obtain and an alyze data. Two major phenomena are observed, the inversion taxis-switching ) of the slab jet owing to surface tension and corner vortices; and surface waves due to turbulent velocity profile relaxation. The main purpose of th is series of experiments is the study of the rapid inversion (almost 50% of the jet over the length of interest) seen in previous experiments. It is s hown here that this was due to secondary flows caused by features of orific e nozzle design. Current experiments show an inversion length considerably in excess of analytic correlations based on 2-D inviscid theory. For parame ters approaching HYLIFE-II jets, inversion length is shown to be more than several hundred non-dimensional lengths. (C) 2000 Elsevier Science B.V. All rights reserved.