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Title: Flow in nests of tubes
Author: Wallis, R. Pendennis
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1937
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Experiments were carried out with nests of cylindrical tubes arranged in rectangular and staggered formation. Curves showing the variation of total resistance of a nest with varying velocities were obtained for the flow of air and of water. By the aid of specially designed Pitot tubes the hydraulic loss through a nest was explored and curves were obtained showing the longitudinal and transverse distribution of velocity of the fluid between rows of tubes. The pressure distribution at the surface of several of the tubes was determined and the form drag on tubes of various rows compared. From these curves an estimate of the total form drag was obtained and this is compared with the total hydraulic resistance. In some of the experiments a transparent box with the air flow coloured with smoke was used to study the formation of eddies at the back of the tubes and the general flow pattern of the fluid stream between the tubes. These results were confirmed and studied in greater detail with the aid of an Ahlborn tank using aluminium dust as an indicator. By the latter method the effect of rectangular and staggered arrangements of tubes was studied and the effect of variation of spacing of the tubes explored. An insight into the nature of the eddying motion was derived and in one case the difference of using tubes of elliptical instead of circular cross-section was examined. The theoretical velocity distribution of the fluid as it converged between the first row of tubes was investigated. This was carried out in a shallow electric tray with a uniform drop of E.M.F. from one end to the other. Large discs of paraffin wax were used to represent the tubes and the longitudinal and transverse velocity distributions in the gap were ascertained. The results were correlated with the work of other investigators in the various problems encountered.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available