Abstract
This paper describes a study on a drycalibration method for application of an ultrasonic flowmeter to the fields such as nuclear or thermal power plants where high temperature and pressurized fluids are used in coolant or feedwater systems.
For the measurement of the flow quantity using the ultrasonic flowmeter, it is important to obtain a correction coefficient of the rate of line averaged axial velocity to plane averaged axial velocity.
We have developed analytical method to predict the turbulent flow profiles in the cross sections of piping including bends. The method is based on parabolic flow model and k-ε model with wall functions for the near-wall regions.
The axial velocity profiles and the correction coefficients predicted by the analytical method were compared with the experimental results for water and liquid sodium in various L/D conditions.
The both results were shown to be in approximate agreement within about 5% accuracy for the flow profiles and about 2% accuracy for the correction coefficients, though the piping had the 90° bend with a very small redius of curvature. In the case of small L/D conditions, it was also shown that the reverse flow effects could not be disregarded in the predominant direction. However, the accuracy of the dry-calibration by using the analytical method was confirmed to be within about 2% as things were.
