Ultrasound flow measurement apparatus and method for determining the flow rate

An ultrasound flow measurement apparatus for determining a flow rate of a fluid flowing in a line having a line wall, the ultrasound flow measurement apparatus having:

• at least one measurement path at which a first ultrasonic transducer and a second ultrasonic transducer are arranged substantially on opposite sides of a diameter of the line, opposite one another with the flowing fluid between them, and
• an evaluation unit that is configured to calculate the flow rate from a time of flight difference of ultrasonic pulses along said at least one measurement path in a first direction with the flow and a second direction against the flow,
• wherein the first ultrasonic transducer and the second ultrasonic transducer are positioned such that a specific part pulse is isolated in time in a received signal of a respective receiving ultrasonic transducer, with the specific part pulse corresponding to one of a direct sound, a reflected sound, an axially broken fluid sound, and an azimuthally broken fluid sound,
• and wherein the first ultrasonic transducer and the second ultrasonic transducer are arranged on opposite sides along a secant line extending across a path within confines of the line wall at a secant angle of at least 17° and at most 43′, with the secant angle being an angle measured in a cross-section of the line of said at least one measurement path projected onto the cross-section with respect to a diameter of the line extending through the first ultrasonic transducer and thereby providing the isolation in time of the specific part pulse so as to isolate the specific part pulse as a part pulse of interest in the received signal.