Patent ID: 8401805

Claim:
An ultrasonic multiphase flowmeter, comprising: a plurality of ultrasonic wave transmitting/receiving means that are disposed on a periphery of a pipe in which a multiphase flow containing a reflector flows, transmit an ultrasonic wave into said multiphase flow and receive at least a reflected wave from said reflector and a reflected wave from an interface in said multiphase flow; flow velocity distribution calculating means that calculates a spatiotemporal flow velocity distribution for a plurality of positions in the direction of transmission of said ultrasonic wave that is substantially continuous in the temporal direction based on data on each reflected wave received by said ultrasonic wave transmitting/receiving means; interface position determining means that has at least any of a difference operation section that performs at least any of a spatial difference operation for a flow velocity distribution at a predetermined time in said spatiotemporal flow velocity distribution and a temporal difference operation for a flow velocity distribution at a predetermined position in said spatiotemporal flow velocity distribution and a binarization operation section that performs a binarization operation to determine whether each flow velocity in said spatiotemporal flow velocity distribution is equal to or lower than a predetermined threshold or not and determines an interface position based on information on the operation; and flow rate calculating means that calculates a flow rate by integrating a part of said spatiotemporal flow velocity distribution up to the interface position determined by said interface position determining means with respect to the cross-sectional area of said pipe.