An extension of single phase flow turbulent pipe flow concepts to two-phase flow

Abstract

This thesis describes a series of investigations into the hydraulic and thermal characteristics of various turbulent two-phase pipe flows, arising from one particular way of extending to two-phase flow, concepts previously developed for single phase pipe flow, e.g. mixing length, turbulent core, wall boundary or sub-layer, roughness, Reynolds analogy, etc.

This approach predicted a logarithmic core profile of local volumetric flux as a function of wall distance. Accounting for a range of different possible sub-layer fluid structures, it led to a dimensionless profile, and hence directly to a wall friction factor, in terms of dimensionless parameters chosen according to the type of sub-layer.

A 'friction regime' concept was developed, with regimes classified by sub-layer type and two characteristic integers which serve to determine the profile. The relations developed were based on the analysis of world-wide experimental two-phase flow data, and a number of practically useful new friction factor correlations resulted. For a number of different 'friction regimes', the work was supplemented by additional models and analyses and applied to the prediction of average void fraction, heat transfer coefficient, critical heat flux, pulse propagation velocity and choked flow rate. In many cases, significant agreement was achieved between predictions and published data for which simultaneous measurements of several parameters guaranteed experimental consistency. Open Access - CC BY-NC-ND 3.0