Calculated Turbulent-Flow Meter Factors for Nondiametral Paths Used in Ultrasonic Flowmeters

Abstract

In applying the ultrasonic contrapropagation method to the measurement of flow in highly attenuating fluids, or to fluids in conduits having only limited access, it is sometimes necessary to interrogate along a path other than the conventional tilted diameter or midradius chordal paths. The meter factor K, which relates the path average to the area-averaged flow velocity, is derived from Nikuradse profiles for several new paths. The results enable one to locate transducers so that for the chosen type of path, K will be (a) minimally dependent on Re, and/or (b) approximately equal to unity, or (c) represented by a simple function of Re. For smooth-wall steady flow conditions, the error in the calculated K’s is estimated as ±2 percent ± the effect due to the disturbance of Nikuradse profiles by the transducers.