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A Preliminary Investigation of the Behavior of Condensable Jets Discharged Into Water

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Preliminary observations on the behavior of submerged steam nozzles discharging into stationary and moving water are described, and photographs are presented to show the changes in appearance of the steam jet from variations in chamber pressure andor water velocity. Plots were made of measured static pressure distributions along the longitudinal axis of both a converging nozzle and one of the de Laval type. No operating difficulties were noted for either type nozzle with supersonic exit velocities. The design of a steam nozzle did not appear to be altered by demands of underwater operation, excepting that heat transfer from a nozzle exposed to rapidly flowing cold water might cause appreciable reduction in performance. The findings indicate that a propulsion system designed to use a condensable propellant is as practicable as one using a noncondensing gas. No difficulties in design or operation which can be attributed to the condensability of the exhaust were encountered from considerations of silence and smoothness of operation, the condensing jet was superior. A missile running in an air-supported cavity was studied to determine the effect of the discharge of a condensable jet propulsion unit upon the over-all size and shape on the cavity sheath surrounding the missile. A comparison was made with former experiments in which the propulsion unit used a noncondensing gas for the propellant. The effect of a supersonic jet of steam on the size and shape of an axially symmetric, air-supported cavity was identical with that of a similar jet of noncondensable gas. In both cases the jet sweeps away the air within the cavity and reduces its length by virtue of the increased cavitation number.

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  • Fluid Mechanics

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