City Research Online

Abstract

Column separation on both the upstream and downstream sides of a valve in an aviation kerosene pipeline was the subject of an investigation involving the method of characteristics to solve the partial differential equations governing pressure transient propagation. Particular attention was given to obtaining accurate velocity results at the instant the predicted pressure at a section reached vapour pressure. A test rig utilizing L.56 aluminium alloy fuel piping and other aircraft standard components and pumping Aviation Kerosene Specification 2494, was employed to investigate the phenomenon and test the computing procedures. For separation upstream of a valve following closure, a comparison of the computed and observed results indicated an accuracy within 3% for the first peak following valve closure and 5% for the cavity duration. Computed results within 10% of the observed were obtained for the later peaks following cavity collapse.Observation and filming of the sequence of events downstream of the valve during and following closure indicated that the air released during initial separation remained out of solution. The effect of this air was significant but could be included, in terms of its partial pressure, in the cavity boundary equations. The predicted cavity collapse pressures were consistently above those observed. Predicted values of maximum and minimum pressures, and their event times, following valve closure were, at worst, within 10% of the observed results. Analysis of the released gas indicated that it had normal air composition. Measurement of column velocity from the films and the use of a hot film probe and anemometer supported the assumptions made with reference to column motion. The hot film probe results demonstrated that this flow measurement technique was practical in this application.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TJ Mechanical engineering and machinery
Departments:	School of Science & Technology > Engineering

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