The influence of moving cages on airflow in mine shafts

Wilkie, Alan (1960) The influence of moving cages on airflow in mine shafts. PhD thesis, University of Glasgow.

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The investigation took the form of a programme of tests on a model shaft fitted with buntons, guides and moving cages. The range of Reynold's Numbers available was from 250,000 to 450,000. During the years 1953-56, A. Stevenson studied the factors influencing shaft pressure losses produced by stationary cages, and noted also the effect of streamlined cages in reducing these losses. The present work is an extension of Stevenson's work and includes the effects produced by cages in notion. These effects are compared with those produced by stationary cages and the relative importance of the cage effects and the general shaft resistance is established. The movement of the cages in the model shaft was expected to produce small fluctuations superimposed on air pressures in the range 0 to 14 inches W,G, (0 to 0,5 p.s.i.) which had to be continuously recorded. When the investigations were begun in 1956 no manometer capable of recording such small pressure fluctuations was in commercial production and it was necessary to build one. The thesis contains details of the development of suitable pressure-recording apparatus. The methods available for recording fluctuating fluid pressures are discussed and trials with electric resistance strain gauge transducers and with variable capacitance type transducers are described. These show the latter type to be more suitable and a satisfactory prototype is eventually produced. The factors affecting the response of the apparatus to fluctuating pressures are also considered In the experimental work the tests first cover stationary two-deck and four-deck cages with and without straight-sided fairings supported in two different patterns of guides. Gage resistances are expressed as Pressure Drop Coefficients (P.D.C.) and particular attention is paid to the magnitude and extent of the increase in combined cage P.D.C. when two cages of a winding system are within the zone where their combined resistance varies with the distance between them. The length of this zone is shown to be less than 4 shaft diameters in all cases and the variations in P.D.C, when the cages are within it are shown in detail. The use of fairings is shown to produce some reductions in the cage P.D.C. The work is then extended to note the effects of cages in motion. The tests cover a range of cage speeds and can be divided as follows I- a) Teats on the influence of passing cages on shaft resistance, b) Tests on the influence of passing cages on conditions upstream from the passing place, c) Tests on the influence of passing cages on conditions downstream from the passing place, d) Tests on the influence of a cage passing a point on conditions at that point. The results show that the moving of cages can produce considerable disturbance and often very rapid changes in the airflow conditions in mine shafts. These effects, however, are usually of fairly short duration. The use of fairings is shown to reduce the disturbances and make the changes less rapid but this is usually done at the expense of an increase in the duration of the effects.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: G Hibbard
Keywords: Mining engineering
Date of Award: 1960
Depositing User: Enlighten Team
Unique ID: glathesis:1960-73544
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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