The detection of tethered and rising bubbles using multiple acoustic techniques

Abstract

There exists a range of acoustic techniques for characterizing bubble populations within liquids. Each technique has limitations, and complete characterization of a population requires the sequential or simultaneous use of several, so that the limitations of each find compensation in the others. Here, nine techniques are deployed using one experimental rig, and compared to determine how accurately and rapidly they can characterize given bubble populations. These are, specifically ͑i͒ two stationary bubbles attached to a wire; and ͑ii͒ injected, rising bubbles.

Quantification of undersea gas leaks from carbon capture and storage facilities, from pipelines and from methane seeps, by their acoustic emissions

“…The question is to what extent that answer is accurate, which cannot be ascertained without independent measurements, and certainly is a question which should be asked whenever the environmental conditions differ significantly from the forward model on which the physics is based (Leighton et al 1998b(Leighton et al , 2002Boyd & Varley 2001;Manasseh et al 2001). While such independent measurements can be conducted to validate the technique (Leighton et al 1996(Leighton et al , 1997, in the field they may not be available, and so tests should be performed to examine whether the estimated bubble spectral generation rate can be discounted. A minimum test (which tests the process, not the model) is to determine whether the measured acoustic spectrum is reconstituted, when the estimated bubble spectral generation rate is inserted into the forward problem.…”

Physical Exchanges at the Air–Sea Interface: UK–SOLAS Field Measurements

“…18) from a train of acoustic pulses (3-197 kHz), transmitted from near the base of the spar and measured by hydrophones at three locations between the transmitter and the surface. The bubble population is inferred from the additional acoustic attenuation as a result of the bubbles between pairs of hydrophones (Leighton et al 2004;Coles and Leighton 2007). The second acoustic system monitors the signal backscattered from the bubble cloud by an upward-looking sonar and therefore giving an estimate of the overall size and shape of the bubble cloud as it is advected past the buoy.…”

“…16). are the most applicable (Leighton 2004; however, they can contain ambiguities that require a cross-check against an independent measurement ( Leighton et al 1996Leighton et al , 1997Vagle and Farmer 1998). The spar buoy was equipped with two acoustic and one optical system for determining the bubble population.…”

Dolphin-Inspired Target Detection for Sonar and Radar

“…Studies also include attempts to mitigate or exploit the detrimental effects of bubbles, for example in the cavitation erosion of turbines and propellers Szantyr, Koronowicz, 2006), ship noise and its environmental impact (Kozaczka, Grelowska, 2004;Parks et al, 2007;Grelowska et al, 2013), and the sonar clutter that oceanic bubbles can produce. With improvements in computing resources, and increases in the power of sonar sources and the bandwidth of receivers (Kozaczka, Grelowska, 1999;Ainslie, 2010), it became clear that the bubbles can readily be driven to produce nonlinear effects (Leighton et al, 1997;2004a;Lauterborn et al, 2008; Baranowska, 2012), although the models used in sonar studies to describe such scattering were predominantly linear and steady state (Clarke, Leighton, 2000; Ainslie, . This paper reviews investigations into whether the inherent nonlinearity in bubble acoustics can improve sonar performance in bubbly water.…”