A new ultrasonic measuring tube principle is presented which is usable for a wide range of tube diameters. The measuring device consists of a square tube in which two transducers and two special reflectors me mounted. In addition to these special reflectors, three wall reflections are used to form a helical sound path which integrates the flow independently from the fluid flow profile. The fluid velocity is derived from the difference in travel time between up and down stream travelling wave packets. In order to gain a measurement accuracy (linearity) of /spl plusmn/1% in a velocity range of 1:100, aspects of body sound, reflectional and zero flow effects must be taken into account. The progress gained by the new measuring principle is discussed on the basis of simulation and experimental investigations. Results are presented for different temperatures and over a wide range of flow velocities. The potential applications comprise flow measurement of liquids in the industry as well as heat metering in hot water supply.
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