Calculations of Flow Characteristics for Two-phase Flow in Annular Converging-diverging Nozzles


Book Description

An analytical method is presented for determining the flow characteristics of a two-phase flow of liquid drops in a gas stream as the mixture expands through an annular converging-diverging nozzle. The subject analysis can be utilized to predict the liquid velocity, gas velocity, static pressure, and droplet diameter as a function of AXIAL DISTANCE ALONG THE NOZZLE FOR A TWO-PHASE FLOW THAT CONTAINS APPROXIMATELY 10 TIMES AS MUCH LIQUID AS GAS BY WEIGHT. Two nozzle configurations were investigated. Both had the same converging angle of 20 degrees, throat radius of 1 in., inlet area of 3.287 sq. in., throat area of 0.267 sq. in. and exit area of 2.450 sq. in. One nozzle had a total diverging angle of 7 degrees and the other had a total diverging angle of 21 degrees. Flow rates of between 8 and 11 lb/sec of water and between 1.0 and 1.3 lb/sec of air were utilized. The liquid and gas were expanded from a low velocity and a pressure of 500 psig to ambient pressure. The theoretical and experimental pressure profiles matched closely for both nozzles investigated. The thrust was predicted to an accuracy of approximately 3% for the short nozzle, but to an accuracy of only approximately 20% for the long nozzle.













Numerical Simulation of Two-phase Flow with Front-capturing


Book Description

Because of the complexity of two-phase flow phenomena, two-phase flow codes rely heavily on empirical correlations. This approach has a number of serious shortcomings. Advances in parallel computing and continuing improvements in computer speed and memory have stimulated the development of numerical simulation tools that rely less on empirical correlations and more on fundamental physics. The objective of this work is to take advantage of developments in massively parallel computing, single-phase computational fluid dynamics of complex systems, and numerical methods for front capturing in two-phase flows to develop a computer code for direct numerical simulation of two-phase flow. This includes bubble/droplet transport, interface deformation and topology change, bubble/droplet interactions, interface mass, momentum and energy transfer.







Two-Phase Gas-Liquid Flow in Pipes with Different Orientations


Book Description

This book provides design engineers using gas-liquid two-phase flow in different industrial applications the necessary fundamental understanding of the two-phase flow variables. Two-phase flow literature reports a plethora of correlations for determination of flow patterns, void fraction, two- phase pressure drop and non-boiling heat transfer correlations. However, the validity of a majority of these correlations is restricted over a narrow range of two -phase flow conditions. Consequently, it is quite a challenging task for the end user to select an appropriate correlation/model for the type of two-phase flow under consideration. Selection of a correct correlation also requires some fundamental understanding of the two-phase flow physics and the underlying principles/assumptions/limitations associated with these correlations. Thus, it is of significant interest for a design engineer to have knowledge of the flow patterns and their transitions and their influence on two-phase flow variables. To address some of these issues and facilitate selection of appropriate two-phase flow models, this volume presents a succinct review of the flow patterns, void fraction, pressure drop and non-boiling heat transfer phenomenon and recommend some of the well scrutinized modeling techniques.