Abstract:

ESDU 95012 provides guidance on obtaining viscometric data necessary for estimating pressure drop in pseudohomogeneous (non-settling) fluids. ESDU 95012 briefly reviews the classification of fluids according to their rheological type, listing classes of fluid likely to exhibit non-Newtonian behaviour. A procedure for assessing the subdivision into settling and non-settling fluids is given. The determination of shear stress versus shear rate (the flow curve) through viscometric measurement is detailed for tube, coaxial cylinder, rotating disc, cone and plate, and parallel plate viscometers. For each type the measurement of shear stresses and shear rates is explained, sources of error are discussed and appropriate correction methods indicated, and advantages and limitations are listed. The method of deciding which type to use in various circumstances is considered and summarised in a table and the equipment to be used is outlined. Flow curve generation and interpretation is discussed.ESDU 04005 illustrates by means of a worked example the precedure for using a tube viscometer to measure viscometric data and the subsequent calculations necessary to correct the data and develop the flow curve. Computer programs for making those full-scale pressure loss estimations from the flow curve are given in ESDU 91025. ESDU 97034 provides an introductory guide to the identification, classification and characterisation of non-Newtonian fluids, including measurement methods.