Production of free surface water jets using focused underwater shock waves
Date
2014-04-29
Authors
Karnovsky, Hilton
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Abstract
It is possible to produce concentrated free surface water jets by rapidly accelerating a
geometrically shaped curved deflector plate below the free water surface. This
principle has been established using a self focusing electromagnetic acoustic source
(FEMAS) and this report verifies it using a shock tube based mechanical analogue of
that system. The shape, form and speed o f the water jets produced vary between the
two systems. Discrete pressure measurements using a needle hydrophone positioned
at different points below the free water surface are presented. The variation in
pressure amplitudes recorded highlight the scatter and uncertainty inherent in a
complex coupled system, while the form o f the pressure trace is dependant on the
mechanical design o f the system in use and the position o f the needle hydrophone in
the pressure field. To better understand the experimental system, a computer
simulation using commercially availa ble non-linear dynamic analysis software has
been developed. This shows that the water surface jets result from the overall
hydrodynamic, flow initiated by rapid movement o f the deflector plate below the water
surface.