LOCAL PARAMETERS IN COCURRENT MERCURY-NITROGEN FLOW

Abstract

Two instruments were developed which can be used to study the structure of two-phase flow: first, an electrical probe capable of measuring local values of the gas fraction, bubble frequency, and bubble-size spectra; second, an impact probe that can be used to measure the local liquid velocity. These instruments were used to measure local flow parameters in cocurrent mercury-nitrogen slug flow. These results are presented in tabular and graphical form. In addition, a photographic study was made to determine the shape of the individual slugs. The gas fraction and velocity profiles were analyzed by a modification of the variable-density model to include local slip. Results showed that the distribution of the phases is not important in determining the average phase velocity ratio, and that the average slip is a result of local buoyant forces. The photographic study showed that the structure of mercurynitrogen flow is much differert from air-water flow. The slugs are asymmetric, with the gas rising up one wall and the mercury ilowing down the opposite wall. This is a result of the high-surface energy of the mercury and, consequently, non-wetting of the wall. Because of the dissimilarity of flow structures, the correlations derived for air- water flow are not applicable to mercury-nitrogen flow. (auth)