Experimental Investigation of Liquid Entrainment in Gas in Horizontal Pipes

Abstract

The objective of this project is to investigate experimentally the phenomena of liquid entrainment in gas in horizontal pipes. This report contains the results of an experimental study on wave characterization. Entrainment in annular flow in horizontal pipes has been studied experimentally. It has been found out that wave characteristics and entrainment fraction are strongly interrelated and must be utilized together in any related analysis. Two experimental facilities, 2-inch and 6-inch diameter, have been designed, constructed and utilized for entrainment measurements in stratified and annular horizontal flow. For the 2-inch flow loop, the range of superficial liquids velocities are 0.35 cm/s to 10 cm/s, and from 2 m/s to 80 m/s for the superficial gas velocities. For the 6-inch flow loop, the ranges of the superficial liquid velocities and superficial gas velocities are from 0.35 cm/s to 10 cm/s and from 2 m/s to 20 m/s, respectively. Appropriate instrumentation for entrainment (adjustable liquid film extractor) and liquid film characteristics (conductance probes and multi-channel conductivity meter) measurements have been developed and implemented. The effects of fluid properties on entrainment and wave characteristics have been studied by utilizing air-water-Butanol solution (surface tension effects) and air-water-Glycerin solution (viscosity effects). Simultaneous measurements have been carried out for both wave characteristics and entrainment for a wide range of flow conditions. Closure relationships have been developed based on the data for wave celerity, frequency, amplitude and spacing. The entrainment fraction has been normalized with the maximum entrainment fraction and correlated with the ratio of the superficial gas velocity to the superficial gas velocity at the onset. The wave amplitude (Δhw) normalized by the film thickness (hL) tends to values of Δhw / hL = 0.2 to 0.3 for high gas rates. The wave spacing (Lw) for air-water normalized by the mean film thickness (hL) exhibits a clear linear behavior with gas velocity, almost independent of the liquid velocity.