EVALUATION OF THE CUMULATIVE FORMATION OF HIGH-SPEED LIQUID JETS

1 .　INTRODUCTIONHigh speedliquidjetsareoftenseeninrainerosionsimulationofaircraftandmissiles ,JilbertandField1] and jetcuttingofmaterials ,Kob ayashi2 ] .Inthegenerationofjets ,itistechnicallyinterestingtoknowhowtooperatetheexperimen talfacilityattheoptimumconditiontoobtainthejetvelocitymostefficiently .ThisisdescribedbyShiandTakayama3] ,ShiandItoh4 ] ,ShiandIt oh5] .Intheearlieststudyofa pulsedhigh speedliquidjet ,BowdenandBrunton6 ] puttheliquidinanozzleandthenusedaslugimpact…

EVALUATION OF THE CUMULATIVE FORMATION OF HIGH-SPEED LIQUID JETS

This paper describes the generation of pulsed, high-speed liquid jets using the cumulation method. This work mainly includes (1) the design of the nozzle assembly, (2) the measurement of the jet velocity and (3) flow visualization of the injection sequences. The cumulation method can be briefly described as the liquid being accelerated first by the impact of a moving projectile and then further after it enters a converging section. The experimental results show that the cumulation method is useful in obtaining a liquid jet with high velocity. The flow visulization shows the roles of the Rayleigh-Taylor and Kelvin-Helmholtz instabilities in the breakup of the liquid depend on the jet diameter and the downstream distance. When the liquid jet front is far downstream from the nozzle exit, the jet is decelerated by air drag. Meanwhile, large coherent vortex structures are formed surrounding the jet. The liquid will break up totally by the action of these vortices. Experimental results showing the effect of the liquid volume on the jet velocity are also included in this paper. Finally, a method for measuring the jet velocity by cutting two carbon rods is examined.