Recursive least squares calibration and tomographic imaging with an ultrasonic transducer array

Abstract

Travel time measurements from an acoustic array interrogating a fluid within the cross-section of a pipe include systematic errors: from mispositioning of array elements, group delays from the transceiver circuits at each element, and acoustic propagation effects between transmitter/receiver pairs. An enhanced calibration model is described which includes the influence of these error sources, and a recursive least squares solution is applied to find calibration travel-time corrections that minimize systematic errors. This enhanced calibration model is applied in-situ to an acoustic transducer array, resulting in increased accuracy and precision of acoustic travel-time measurements. Tomographic images of fluid velocities are derived from these travel-time measurements. The fluid velocities are mapped to known velocities of individual fluid phases, resulting in tomographic images of multiphase flows.Travel time measurements from an acoustic array interrogating a fluid within the cross-section of a pipe include systematic errors: from mispositioning of array elements, group delays from the transceiver circuits at each element, and acoustic propagation effects between transmitter/receiver pairs. An enhanced calibration model is described which includes the influence of these error sources, and a recursive least squares solution is applied to find calibration travel-time corrections that minimize systematic errors. This enhanced calibration model is applied in-situ to an acoustic transducer array, resulting in increased accuracy and precision of acoustic travel-time measurements. Tomographic images of fluid velocities are derived from these travel-time measurements. The fluid velocities are mapped to known velocities of individual fluid phases, resulting in tomographic images of multiphase flows.