| 摘要 |
<p>A method and a device are used to hydrodynamically generate acoustic pulses in a liquid volume, particularly to generate acoustic pulses in the sea for submarine geophysical measurements. A pipe (1) open at one end surrounds a liquid column with limited length and arriving in the liquid volume on the open end side (2) of the pipe. An axial pressure is suddenly applied to the liquid column extremity opposite to the open extremity (2) of the pipe by accelerating the liquid column in the direction opposite to the open extremity (2) of the pipe, and by suddenly braking it at the extremity of the liquid column opposite to the open extremity (2) of the pipe, either by means of a piston (5) accelerated at the same time as the liquid column and which is stopped by a stop (6), or by means of an auxiliary mass which has been previously accelerated in the direction of the open end of the pipe and which abruptly impacts the extremity of the liquid column opposite to the open end (2) of the pipe. Due to the sudden acceleration of the liquid column at said first extremity, an acoustic pressure pulse is generated and propagated in the liquid column towards the open end (2) of the pipe from which, on the one hand, it radiates as an acoustic pulse in the liquid volume and, on the other hand, it is reflected in the liquid column as a rarefaction wave. The rarefaction wave generates a cavitation which dampens the undesirable resounds in the pipe (1).</p> |
