Analysis of a compliantly suspended acoustic velocity sensor

Abstract

The dynamics of a compliantly suspended acoustic velocity sensor having a spherical geometry are analyzed using theory and experiment. The analysis starts with a review of the motion associated with an unconstrained solid sphere when subjected to an acoustic plane wave in an unbounded inviscid fluid medium. The theory is then modified to account for the inclusion of an inertial sensor and an external suspension system. Accordingly, the open-circuit receiving response of a geophone-based and accelerometer-based device is derived. Density variations associated with the sphere and the surrounding fluid medium are assessed along with the effects fluid viscosity. Wave effects in the sphere and the suspension system are also analyzed.

Eddy-current non-inertial displacement sensing for underwater infrasound measurements

“…1(a). 7 Here m S is the mass of the buoyant body, m 0 is the mass of the displaced fluid, m a is the added mass of fluid, M t is the transducer proof (inertial) mass, and C t and R t are the a) Author to whom correspondence should be addressed.…”

“…[4][5][6][7] The body oscillates due to incident acoustic wave with velocity V 0 , which is equal to the fluid particle velocity of the incident wave; the body is often modeled as a neutrally buoyant sphere. 6,9 The essential part of the imbedded transducer is a proof mass.…”

“…Existing, or prototyped, underwater acoustic vector sensors (AVS) [4][5][6][7] are often designed as neutrally buoyant rigid bodies having built-in inertia-type sensing elements, such as accelerometers or moving coil geophones. These sensors operate from tens, or hundreds, of Hertz to approximately 10,000 Hz; they lose considerable sensitivity at ULF, primarily due to the fundamentals of inertial sensing.…”

Design and implementation of a shielded underwater vector sensor for laboratory environments

“…[1][2][3][4][5] There are two main components to a p-a underwater vector sensor: a pressure sensor and a particle velocity sensor. A p-a probe with high acceleration sensitivity should be nearly neutrally buoyant in water.…”

Azimuth-elevation direction finding using a microphone and three orthogonal velocity sensors as a non-collocated subarray

“…Mathematically, for an acoustic vector-sensor located at the Cartesian coordinates' origin, it would have the 4 Â 1 array-manifold [5][6][7][8] aðh; /Þ …”