Measurement of Transiently Changing Flow Rates in Oil Hydraulic Column Separation

Abstract

Column separation and subsequent rejoining in an oil hydraulic line usually result in tensile waves and consequent ruptures in an oil column. In order to investigate these phenomena in more detail, it is essential to precisely measure transient flow rates in column separation and rejoining. The aim of the present work is to attain this objective : a method based on the theoretical relation of the flow rate change in a pipe with a kinetically induced pressure difference between the two separate sections. Instead of a conventional differential pressure transducer, two individual pressure gauges are used to measure pressures at the two sections and find the difference between them by subtraction. Theoretically predicted stepwise decreases of the flow rate until the column rejoining have been accurately measured, showing the effectiveness of the method. It is also pointed out that the successive calculus proposed by Zhao et al., which is expected to substantially economize the procedure to obtain flow rates from differential pressure data, may give unrealistic results.