| 摘要 |
<p>A water gun seismic source for use in underwater environments has a sleeve valve (100) for opening a jet aperture (37, 101) to enable jets of pressurized water to be emitted for the generation of a seismic signal. The water is pressurized by a drive piston (3) which is reciprocated to a cocked position for pressurizing the water for the jets. A compressed air operated cocking mechanism (4, 7, 8, 76 or 110-199 or 200-260) is coupled to the piston for cocking it. The cocking mechanism may utilize a cocking piston (7) slideable on a shaft (7) connected to the drive piston (3) which cocking piston is returned to a position where any load due to such cocking piston is decoupled from the shaft. The sleeve valve (100) may be biased to close the jet aperture ports (101) by compressed air and opened with high timing resolution when the pressurized water held back by the sleeve valve is applied to actuate it (via 40, 41, 50 & 43). Compressed air may be released in the vicinity of the jet aperture ports to be entrained with the jets and assist in forming the vapor cavities which collapse to produce the seismic signal. When compressed air is used to help nucleate the vapor cavities it may also be applied, instead of the pressurized water, to the seat of the sleeve valve to actuate the sleeve valve and open the jet aperture ports.</p> |
