Assessment of Effects of Pipe Surface Roughness and Pipe Elbows on the Accuracy of Meter Factors Using the Ultrasonic Pulse Doppler Method

The velocity profile of the flow in a pipe and its influence on the profile factor used with conventional flow meters were investigated with ultrasonic pulse Doppler measurements. From the measured velocity profiles, the influences of surface roughness and Reynolds number were characterized qualitatively and quantitatively. As pipe surface roughness changes during plant operation, the velocity profile changes, producing a change in the profile factor. Variation in the Reynolds number also influences the change in the profile factor. Experiments were conducted at high temperature and pressure to evaluate the ultrasonic pulse Doppler method for measuring the flow of nuclear plant cooling water. Helium gas bubbles provided sufficiently persistent ultrasonic reflectors when injected into high-pressure water, permitting the velocity profile of the flow to be obtained under high-temperature and high-pressure conditions using this method.