THEORETICAL AND EXPERIMENTAL-STUDY OF THE FALLING CYLINDER VISCOMETER

The falling cylinder viscometer (FCV) has been investigated both theor etically and experimentally. Although the use of this instrument goes back to the early work of Bridgeman because of its suitability for hig h pressure measurements, a fundamental study of the flow field around the cylinder has not yet been reported. The study presented here allow s the prediction of end effects without resorting to empirical correct ions or instrument calibration. The investigation was carried out over a wide range of cylinder diameters and lengths and an operating param eter, the Geometry Number, has been defined which characterizes the FC V and is solely determined by the dimensionless cylinder diameter and length. A correlation equation from which the Geometry Number can be c alculated is presented which can be used to design viscometers for par ticular applications. The agreement between the analytical and experim ental results of the Geometry Number, the measured viscosity of standa rd fluids and the repeatability and accuracy are all within one percen t. Both the theoretical analysis and experimental data indicate that f alling cylinder viscometers based on the correlated equation can be ac curate and absolute viscometers.