| The goal of the research reported here is to develop methods whereby pressure drop, void fraction, and flow pattern for horizontal two-phase flow of gases and non-Newtonian liquids can be predicted simply from knowledge of fluid properties, flow rates, and pipe size. The scope of investigation includes experimental work on two-phase flow patterns of annular, intermittent, and stratified flow, as well as the transitions among these patterns. Experimental tests have been performed using several Newtonian and pseudoplastic liquids to cover a wide range of viscosity and pseudoplasticity. The experimental work has also been complemented by the development of analytical models for each flow pattern, in which predictive equations account quantitatively for the shear-dependent viscosity of the liquid phase.; For pressure drop and holdup, models obtained by modifying existing correlations for Newtonian liquids yield good agreement between theory and experiment for annular flow and for stratified wavy flow. Pseudoplasticity of the liquid, entrainment of liquid droplets in the gas, and aeration of dispersed bubbles in the liquid are predicted to reduce both pressure drop and holdup significantly and experimental results tend to confirm these trends. Pseudoplasticity also affect flow pattern transition. In particular, shear-thinning increases the void fraction of the two-phase mixture and thus causes the transition to annular flow to occur at higher gas velocities than for Newtonian liquids of comparable zero-shear viscosity. This effect can be predicted from a correlation developed in this work.; Another feature of this study is the experimental development of a capacitance sensor for void fraction measurement of two-phase flow in cylindrical channels. Theoretical prediction of the device's behavior is also presented. |
