Pulse-jet water propulsor

DETAILED DESCRIPTION As illustrated in FIGS.
2(a and b) and 3, the "boiler" is an integral part of the tube, and the momentum acquired by the water column as it moves toward the boiler is relied upon to hold the interface in the boiler long enough to produce a useful quantity of steam at high pressure.
Stability of the interface between the steam and the water is obtained because, for most of the cycle, the water column is being accelerated toward the boiler.
It is only accelerated away from the boiler when close to it or actually inside it, and this leaves very little time for the then unstable interface to actually disintegrate.
A P-V diagram of the unit's operation is given in FIG.
3.
For most of the cycle, the steam is condensing and the interface is slowing down from its initial rapid explusion from the boiler.
A "condensing section" is formally required, but in many practical cases, contact of the exhaust end of the tube with the ambient fluid is sufficient to provide this heat sink.
Since the fluid interface is in the boiler for only a very short period of time, it is important that sufficient heat for one cycle be "stored" in the boiler wall material, and that this heat be released to the water rapidly.
This implies either a material having high conductivity and high specific heat or a material having high conductivity and substantial weight.
The copending application discloses these basic concepts.
As shown in FIG.
4, this invention utilizes a high speed pulse jet having an inlet valve and an internal piston cycle.
Initially charged with water downwards motion of the piston results in a pressure build-up which closes the intake valve and expels a propulsive jet to the exhaust.
When the pressure above the piston has fallen to a sufficiently low value, the downward movement is terminated and the piston starts to rise, allowing a fresh charge of water to enter the intake valve.
The piston is driven by pressure changes above it, in the same sense as any conventional engine, and these pressure changes may be induced in any of a variety of conventional ways using internal combustion (Diesel, Ott cycles), vapor (Rankine cycle) or gas pressure change (Stirling, Ericsson or Roesel cycles)