Patent ID: 8694270

Claim:
A multiphase flowmeter for determining at least one characteristic of a first phase flowing in a pipe, wherein at least a second phase is also present in the pipe, the multiphase flowmeter comprising: a first transducer configured to emit a first pulse signal into the first phase at a first incident angle with respect to a straight line that is perpendicular to an interior pipe wall, the first pulse signal being in an ultrasonic range, wherein: the first transducer is configured to be coupled to an exterior pipe wall; and the absolute value of the first incident angle in the first phase is configured to be at least 10 degrees and at most 80 degrees; and the first pulse signal and a first return echo signal produced by the first pulse signal and received by the first transducer are used to determine a first time-of-flight; a second transducer configured to emit a second pulse signal into the first phase at a second incident angle with respect to the straight line that is perpendicular to the interior pipe wall, the second pulse signal being in the ultrasonic range, wherein: the second transducer is configured to be coupled to the exterior pipe wall; and the absolute value of the second incident angle in the first phase is configured to be less than 10 degrees, whereby the absolute value of the second incident angle is configured to have a substantially normal incidence; the second pulse signal and a second return echo signal produced by the second pulse signal and received by the second transducer are used to determine a second time-of-flight; and a processor configured to process a speed of sound in the first phase from the first and the second time-of-flight and to process the at least one characteristic of the first phase using the processed speed of sound.