bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glands for the Entry of Electrical Cables into Pressure Vessels Containing or Surrounded by Conducting Liquids
Authors: Grunwald H. H. 
Published: October 2007

It is often required to house electrical apparatus in pressure vessels capable of withstanding considerable pressure, either external or internal, and to make connection with such apparatus. For this purpose, electrical cables containing one or more insulated conductors must be passed through the walls of the vessel. This paper deals with glands forming the entry of such cables into the vessel. It states the fundamental requirements of cable entry glands and gives a summary of the principles of construction employed. Experimental work is described which led to the development of two designs of gland. The first of these was developed specifically for the entry of submarine telecommunication cables into submerged repeaters containing electronic amplifying equipment, in particular the submerged repeaters used on the British section of the first transatlantic telephone cable system. Both manufacture and testing of these glands are reviewed. The second design dealt with is a simplification of the first, based on the experience gained. Some special operating conditions encountered are mentioned and the means of meeting the resulting additional requirements are discussed.
The Design and Construction of the Compressor for the 8 ft by 8 ft High-Speed Wind Tunnel at R.A.E. Bedford
Authors: Cheshire L. J. , Evans J. Y. G. , Goodsell W. A. , Wolff P. H. W. 
Published: October 2007

The paper, which is in two parts, deals with the steps taken to meet the specified performance and conditions of operation of the compressor for the 8 ft x 8 ft high-speed wind tunnel at Royal Aircraft Establishment (R.A.E.) Bedford. The essential requirements were that the compressor should deliver a quantity differing not greatly from 50 000 ft3/s over a range of pressure ratio 1.15 to 2.50, an important proviso being that special steps must be taken to achieve high efficiencies in the lower range of pressure ratios. Part I deals with the reasoning which led to the adoption of the final design solutions, and the supporting experimental work including the manufacture and testing of a 1/7 scale aerodynamic model necessary to establish the performance characteristics of the compressor before deciding the final blade settings. It was decided to build a ten-stage compressor to run at 750 rev/min having a first-stage blade tip diameter of 17 ft with a blade 2 ft 6 in. long. In order to meet the requirement of good efficiency over the whole working range, the compressor was divided into two parts so that under low pressure ratio conditions only the first four stages are in the circuit, the change from 10 stage to 4 stage operation and vice versa taking place in under twenty minutes. Part II describes the mechanical features and manufacturing processes following from the design decisions given in Part I.
The Mechanical Design of an Experimental Plant-Type Gas Turbine
Authors: Whitehead L. T. 
Published: October 2007

Problems of thermal expansion and insulation encountered in the structural design of steam turbines are accentuated in gas turbines owing to their generally higher operating temperature. This paper describes the construction of a four-stage 8000-b.h.p. gas turbine designed and manufactured at the National Gas Turbine Establishment, and embodying several features offering a solution of these problems. A tubular rotor reinforced by radial discs is required if material is to be used with economy and, in addition, the rotor must be maintained at a temperature which allows full use of the material properties. Heat should be confined as closely as possible to the gas flow annulus to obtain the maximum output of work from the blading and to avoid undesirable thermal stress in the rotor. The insulation of the bearings and the provision of some flexibility between these and the shaft to meet the possibility of damage from excessive heat soakage in an emergency is also important. The methods used to attain the above objectives include rotor discs connected by threaded side-rims of large diameter and cooled by an axial flow of air under the blade roots. Flexible sleeves are fitted between the shaft journals and the roller-type bearings, to inhibit heat flow and to accommodate differential radial expansion. The stator casings are treated as gas-carrying ducts, relieved of mounting constraints and bearing alignment duty by being freely mounted on radially disposed pegs and keys giving freedom for thermal expansion in all directions. Preliminary experiments and rig tests on the bearing mounting sleeves, and on surface treatment to prevent seizure of the screw-thread connections between the rotor discs are described. More than usual attention is given in the design to methods of facilitating inspection and maintenance, and provision is made for replacing individual rotor blades and bearings without separating rotor and stator.
Behaviour of Thick-Walled Steel Cylinders Subjected to Internal Pressure
Authors: Crossland B. , Bones J. A. 
Published: October 2007

In this paper the literature on the strength of thick-walled cylinders subjected to internal pressure is reviewed and equations are given which enable the initial yield pressure, collapse pressure, and ultimate pressure to be calculated from shear stress-strain data. Pressure tests on thick-walled cylinders made from 0.15 per cent carbon steel, 0.3 per cent carbon steel, and Vibrac steel are described, the maximum pressure reached being 42 ton/in2. For 0.15 per cent carbon steel results of tests on cylinders with a ratio of outer to bore diameter of up to 8.05 are given. Numerous tensile and torsion tests have been carried out on these steels and these are fully reported. For the 0.3 per cent carbon steel which was tested first no measurements were made of initial yield and collapse pressures. The results for the 0.15 per cent carbon steel, however, show good agreement with the calculated values if allowance is made for the influence of shear stress gradient when computing the initial yield pressure. With Vibrac steel the experimental results lie between the two curves computed from the extreme shear stress-strain curves. The experimental pressure-expansion curves at large strains and the ultimate pressures for the three materials all agree very well with the computed values. Values of the ultimate pressures have also been calculated from several empirical equations but they all give considerable errors, though up to a diameter ratio of 4 the mean diameter formula is satisfactory.
The Plastic Flow and Fracture of a ‘Brittle’ Material (Grey Cast Iron) with Particular Reference to the Effect of Fluid Pressure
Authors: Crossland B. , Dearden W. H. 
Published: October 2007

This paper describes tests carried out on a ‘brittle’ material in the form of grey cast iron to investigate the criterion of plastic flow and ultimate failure, and in particular torsion tests carried out with superimposed fluid pressures of up to 35 ton/in2. It is suggested that the results show that the mode of failure is dependent on the volumetric stress acting. For volumetric compressive stresses greater than approximately zero, failure occurs at a critical value of the shear stress, a value which is some function of the volumetric stress. At small or negative values of the volumetric compressive stress failure occurs at a critical value of the maximum tensile stress, a value which may be slightly dependent on the volumetric stress. The shear stress-strain curve is apparently also related to the volumetric stress, and the shear stress-strain curve deduced from a compression test on the shear-stress hypothesis coincides with that found from a torsion test carried out under a pressure approximately equal to the volumetric stress in the compression test. In torsion the strain to failure is raised by pressure; the rate of change of strain with pressure being considerably increased when the fluid pressure is sufficient to suppress completely any tensile component of stress. The strain to failure in compression is greater than in the comparable torsion tests, but this may be explained by the weakening effect of the fluid or the rubber protective film when they are forced into incipient cracks.
Three-Dimensional Flow in Axial Pumps and Fans
Authors: Mikhail S. 
Published: October 2007

This paper describes a research† carried out in the Hydraulics Laboratory of the City and Guilds College, Imperial College, London. Three-dimensional flow in non-free-vortex axial pumps and fans was studied. A rigorous solution of the linearized partial differential equation that describes the flow in non-free-vortex machines was developed. The solution determines the stream surfaces of the mean flow for the case of a thin rotor disc. Two series of machines were tested and the results were used to check the validity of the theoretical analysis. The practical aspects of the possibility of using non-free-vortex flows in the design of axial machines were also studied.
Strength at Elevated Temperatures of Aluminium and Certain Aluminium Alloys
Authors: Inglis N. P. , Larke Eustace C. 
Published: October 2007

The materials examined were a 99.5 per cent aluminium, the 2 1/4 per cent magnesium alloy to B.S. 1476: 1955 NE4, the 3 1/2 per cent magnesium alloy to B.S. 1476: 1955 NE5, a 1 1/4 per cent manganese alloy and the magnesium-silicide alloy to B.S. 1476: 1955 HE30, all being in the form of extruded rod. Excepting for the HE30 alloy, which was fully heat-treated, all tests were carried out with the material in the as-extruded condition. Short-time data covers a temperature range of 20°-250°C, the stress-rupture curves, which mostly extend up to 10 000 h, relating to temperatures of 100°, 150°, 200°, and 250°C. Creep tests, a number of which were taken into the tertiary stage, have been carried out at 200° and 300°C for the 1 1/4 per cent manganese alloy and temperatures employed for the HE30 alloy were 100°, 150°, and 200°C. Stress-rupture tests still in progress and creep data for the remaining three materials will be reported in an addendum. Stress-temperature curves are plotted which enable a direct comparison to be made of the effect of temperature on rupture strength for specified amounts of time. The paper concludes with a fairly detailed report of the effect of time, stress, and temperature on the microstructure and discusses the types of fracture encountered.
Mechanical Marshalling of Railway Wagons in Works Sidings
Authors: Grossmith G. W. 
Published: October 2007

The methods employed for the movement of railway wagons in works sidings have changed very little in 50 years, probably because appliances lending themselves to mechanization were not available. Locomotives, capstans, and winches are unsuitable for combination under centralized or automatic control, owing to their need for men on the locomotives and also on the sidings to handle towing ropes and to work the wagon brakes. Free-running gradients have, owing to the greatly varying running characteristics of wagons, been too uncertain to give sufficiently consistent results. In recent years a number of new appliances for the remote propulsion, braking, and general control of wagon movements have been developed, suitable for employment separately or in combination according to the needs of the problem. The new devices may be broadly classified as mules, track brakes, arresters, traversers, and remotely controlled locomotives. The development of these devices has made possible, and in fact has brought about, new techniques and simpler systems of sidings layout, with economy in cost and great economy in space occupied. In this paper, these recent developments are first described separately, and examples are then given showing how they can be, and have been, applied in combination under centralized control. Wagon marshalling as dealt with by this paper means the remote control or automatic control of a succession of wagon movements in works sidings without the need for application of the wagon brakes at any stage. The main railway marshalling yards are excluded from this review as the problems are, in their case, different.
Experiments on Two-Stroke Engine Exhaust Ports under Steady and Unsteady Flow Conditions
Authors: Benson R. S. 
Published: October 2007

A theoretical and experimental study of the discharge from an engine cylinder to atmosphere was made. The objective of the work was to establish suitable data for the design of exhaust ports. Two theoretical methods were used, in the first method the discharge was analysed by the method of characteristics and it was shown that the discharge was by wave action. The second method neglected the particle velocity in the cylinder. Comparison of the latter method with the solution by characteristics showed good agreement over the main part of the discharge and it was possible by that method to develop a simple design formula for the estimation of the port area. The experimental investigation was carried out on a special machine which simulated in all respects the exhaust-port arrangement of a two-stroke cycle engine. The machine was designed to investigate the effect of port configuration, port timing, cylinder length, engine speed, release pressure, and temperature. By suitably arranging the variables in non- dimensional groups a wide range of engines could be simulated. The flow characteristics of the exhaust ports were examined under both steady and unsteady flow conditions. The following conclusions were drawn: (1) the coefficient of discharge for the exhaust ports increased with cylinder pressure and decreased with increased port area, (2) the coefficient of discharge was lower under dynamic conditions than under steady flow conditions, (3) the dynamic coefficient of discharge decreased with reduction in cylinder length at release, (4) the effect of early port opening was to reduce the blowdown time, (5) the effect of piston movement during discharge was to reduce the effective port area required.
Sealing Characteristics of Stuffing-Box Seals for Rotating Shafts
Authors: Denny D. F. , Turnbull D. E. 
Published: October 2007

There are two distinct modes of operation of a stuffing-box seal. One mode occurs when the axial pressures produced in the packing by tightening the gland-bush are greater than the sealed fluid pressure and the other when they are less. Under the former conditions the fluid pressure distribution is an exponential function of the packed length and the frictional torque increases rapidly with this quantity. With high fluid pressures, however, the relation between fluid pressure and packed length is no longer exponential and most of the fluid pressure drop occurs over the last 10 per cent of the packed length. In addition very little increase in frictional torque occurs when the packed length is increased. Theoretical expressions have been derived for pressure distribution and friction torque and good agreement has been obtained between these and experimental results.
Flash Evaporators for the Distillation of Sea-Water
Authors: Frankel A. 
Published: October 2007

The thermodynamic principles on which the flash evaporator operates are described and some of the reasons for the recent emergence of this type of distillation plant are explained. It is shown that the performance of a flash evaporator is much less dependent on the number of stages used than is the case for a submerged coil unit. The thermodynamic losses involved in using a finite number of stages, and the effects of other losses which are unavoidable in practice, are described and assessed. The actual designs of evaporator vessels are described showing means of avoiding interstage piping or ducting despite the use of a large number of stages. Reference is made to two large-size test rigs built to confirm the basic ideas underlying the development. One was devoted to the exploration of deposition problems and the measurement of heat-transfer data, while the other test rig was used to develop various methods of separating moisture from the vapour produced in the evaporator, and to investigate the flashing-off process. Some of the test results achieved on the rigs are described.
Operation of Rolling-Element Bearings in a Protective Atmosphere
Authors: Cattaneo A. G. , Coit R. A. , Sorem S. S. 
Published: October 2007

To operate at high temperatures, up to 1100°F, bearings must be protected against two sources of early failure: formation of red rust by oxygen attack on the surfaces in either rolling or sliding contact, and rapid wear by local seizure (scuffing) of the cage surfaces in sliding contact with other elements. The first function can be filled for all-ferrous bearings by an atmosphere consisting of a mixture of air and an organic vapour which acts as a reducing agent at elevated temperatures. The performance of the second function requires constituents or additives that form anti-scuffing films. An olefine oxide polymer was found to be a satisfactory reducing agent over the whole temperature range. Conventional extreme pressure (e.p.) additives are effective in preventing scuffing up to about 900°F. Above 900°F the polymer forms an organic film which itself gives some protection against scuffing. Size 206 tool steel bearings have been operated for 100 hours at 1000°F, 10 000 rev/min under considerable radial and axial load; and for 22 hours at 1100° F. With the bearings available thus far, maximum loads are dictated by softening of the metals above 900°F. These high temperatures create special problems in the design of the test equipment with respect to fits, warping and dimensional changes. The rig and procedures used in this work are described.
An Investigation of the Plug Drawing Process
Authors: Blazynski T. Z. , Cole I. M. 
Published: October 2007

The object of this work has been to obtain agreement between the existing theory of tube drawing with a plug, and experimental results, and thus to be able to predict the behaviour of the metal when conditions of drawing are altered. As the basis of theoretical study Sachs's approximate theory has been chosen, and mild steel containing 012 per cent carbon has been used as the test material. The use of the theory requires the knowledge of the true mean yield stress of the metal undergoing plastic deformation, as well as that of the value of the coefficient of friction. The method of establishing those two quantities is discussed in detail. Drawing stresses are calculated and it is shown that close overall agreement exists between theory and practice and that, therefore, the mathematical formulae can be used with confidence. The components of the total work done in drawing a tube are determined and discussed, and the adverse effect of sink on the magnitude of redundant work is indicated.
Maximum Reduction in Cold Strip Rolling
Authors: Avitzur B. 
Published: October 2007

An analytical equation is derived for the prediction of maximum reductions possible as dependent on the process variables. The results of this equation are presented in graphical form for a wide range of the process variables. A simple experimental procedure is suggested for the determination of the coefficient of friction. The process variables are: The roll radius R0, initial t i and final t f strip thickness, material yield limit σ0 at uniaxial tensile test with yield limit σoi at initial thickness and σo f at final exit thickness, front pull stress σxf and back pull stress σxb, the coefficient of friction μ, and the rolling speed U. The power balance is set for the rolling operation. The powers computed are: (1) the useful power consumed as internal work of deformation of the strip, called sometimes ‘The homogeneous power’; (2) power consumed by the back pull on the strip; (3) power supplied by the front pull on the strip; (4) power consumed by the friction between the rolls and the strip; and (5) power supplied by the rolls. From the equation: sum of the powers = 0, a dependence of the process variables one on each other is established. From this dependence the coefficient of friction can be computed at maximum reduction, and this gives a simple procedure for the experimental determination of the average coefficient of friction. With the coefficient of friction, yield limit, dimensions of the strip and roll and the values of the front and back pull known, from a given graph the maximum reduction possible can then be computed or picked.
Pulsation Damping Systems for Large Reciprocating Compressors and Free-Piston Gas Generators
Authors: Wallace F. J. 
Published: October 2007

The pulsation problems inherent in installations comprising large and relatively slow speed-reciprocating compressors or engines, both on the induction and delivery side, have been recognized for many years. The problem of pulsating flow has recently become particularly acute with the large-scale introduction of free-piston gas generators which, because of their unique mode of operation and the fact that they are usually installed in groups drawing from a common air manifold and delivering to a common exhaust duct, are particularly sensitive to such pulsations and where a rigorous approach to the problem is imperative. The present paper is concerned exclusively with intake systems which usually consist of two distinct elements, namely the individual damping system for each gas generator and a common ducting system for the entire group of gas generators, from which the individual damping systems draw their air supply. The individual damping systems take the form of one or two large smoothing chambers or damping capacities connected by Venturi-shaped ducts to each other (when two chambers are used) and to the common ducting system, the gas generators drawing air from these smoothing chambers through pipes which may be arranged to give some ram effect with resultant improved volumetric efficiency. The object of the individual damping systems is to ensure that the magnitude of the pulsations reaching the common ducting system is sufficiently low to prevent harmful pulsations which could cause damage to air filters, or even to property in the vicinity, particularly if resonances are excited in the common ducting system. A typical intake system for an eight gas generator installation is shown in Fig. 1. The paper is concerned solely with the method of analysis applicable to the individual damping systems, not with the external ducting system. The latter should present no difficulties if the individual systems are properly designed. The method of analysis is based on mechanical vibration theory, the governing equations for the damping systems—conveniently referred to as acoustic systems—being identical with those of better known mechanical systems. The equivalent electrical systems are given in an appendix, with a view to facilitating the analysis of damping systems with the aid of analogue computers. The object of the analysis is first to put the design of such damping systems on a sound theoretical basis and secondly to facilitate the calculation of optimum dimensions, given permissible pressure drop and pulsation amplitude outside the system, as well as the form of the suction pulse of the gas generator. The latter is most conveniently represented as a harmonic series using Fourier analysis. The present paper is based on the author's own experience in this field and, though restricted to purely theoretical considerations to avoid excessive length, the material contained in the paper is confirmed by a substantial body of experimental work.