Velocity measurement in high temperature liquid metals using calibration results from the annular channel

Abstract

In this paper, a calibration procedure using the annular channel unit for measuring velocity in high temperature liquid metals is presented. In this calibration procedure, the sphere probe is held stationary in a metal bath, which is moving past the sphere with known velocity. The melting time of a sphere in liquid aluminum was determined by using a load cell to detect precisely the immersion of the sphere into the metal bath, and by utilizing a thermocouple strategically located to determine the melting time of the sphere. It was shown that aluminum spheres with 3.5 cm diameter exhibit better sensitivity in measuring liquid aluminum velocity than spheres of 3.0 and 2.5 cm diameters. The relationship between aluminum velocity and sphere melting time appears to be linear for the range of velocities 0–40 cm/s. Above this range the linear relationship ceased to exist. The comparisons between the results of the annular channel unit calibration procedure, and the results obtained from the calibration procedure in which the sphere was rotating and the aluminum bath remained stationary, revealed that a small deviation of the order of 10% exists under natural convection conditions (i.e. external velocity zero). This deviation becomes even smaller at higher velocities.