Experimental and theoretical studies of turbine meters in two-phase flows.

Antony. Mark, Philip (1992) Experimental and theoretical studies of turbine meters in two-phase flows. PhD thesis, University of Liverpool.

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Abstract

This thesis presents the findings from a three year research project into the performance of turbine meters in two-phase flows. The aim was to determine the geometrical changes needed to be made to the rotor design to allow it to register total volumetric flow when subjected to two-phase flows. A single-phase model is presented based on airfoil theory and including retarding torque terms, velocity profile and blade interference effects. Differences of less than 1% between experimental and theoretical results, over the operating range of the meter are shown. The performance of a range of meters in various two-phase flows is discussed. With the exception of the 40 degree rotor in water/air the results may be summarized as follows. At low flow rates, of between 5 and 20 to 30l/s, the meters tend to underestimate total volumetric flow by up to -10% at void fractions of 25%. The greater the void fraction the greater the underestimation. At high liquid flow rates, above 30 to 40l/s, the meters overestimate total volumetric flow rate by as much as 8% at a 25% void fraction. A reasoned arguement is presented to explain the performanceof the meters in two-phase flow. This is based on phase distribution effects, influenced by the varying flow patterns, which alters the magnitude of the driving torque developed radially along each blade. Using this explanation the single-phase model is developed to encompass two-phase flow. Agreement between experimental and theoretical results is good, particularly in that the sense of the meter error is correctly predicted by the model. Quantatively, errors of less than 2% are achieved. From this model, it was apparent that simple geometrica1 changes to the rotors' design were unlikely to bring about the changes in performance needed to meet the original aim of the project. It must therefore be accepted that, in its existing form and using established pulse total ising techniques, the turbine meter is not suitable for use as a two-phase flow measurement device. The author has discovered a relationship between fluctuations in rotor angular velocity and flow void fraction. It is shown that after suitable processing a single characteristic may be used to describe the meters' response to all void fractions up to 25%, the limit of the test facilities. After calibration of the meter, at a single void fraction, it can be used to indicate both void fraction and flow rate directly. Even at this early stage of development, errors of less than 10% are being achieved in indicated void fraction. This technique is covered by a patent, the rights to which are held by the DTI as the funding body.

Item Type:	Thesis (PhD)
Depositing User:	Symplectic Admin
Date Deposited:	20 Oct 2023 19:44
Last Modified:	20 Oct 2023 19:54
DOI:	10.17638/03175646
Copyright Statement:	Copyright © and Moral Rights for this thesis and any accompanying data (where applicable) are retained by the author and/or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge.
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3175646