bluuebunny/crossref_metadata_2025_split huggingface dataset:
Marine Transport of Liquefied Natural Gas
Authors: Clark L. J. 
Published: October 2007

In the past, it has been a matter of concern to many people that natural gas which is available and sometimes flared to waste in desert places of the earth could not be conserved and economically transported as fuel to needy industrial countries. To make such an operation possible, it is necessary to refrigerate the gas, which consists mainly of methane, to a temperature of — 260°F, under which condition it condenses to a liquid and shrinks to one-six-hundredth of its volume as a free gas. In this form and as a boiling liquid, it can be transported in insulated tanks built into ships specially designed for the purpose. Auto-refrigeration maintains the cargo at its boiling point and heat leakage through the insulation causes a small proportion of the cargo to boil off as gas. Such gas can either be re-liquefied by installing a refrigeration plant on board or be used as fuel in the ship's propulsion machinery. The lecture describes the research and development work which led up to the full-scale trials in 1959 for the transportation of liquefied natural gas by sea in the Methane Pioneer. This is followed by a resume of the design requirements, building techniques and subsequent operating experience of the first two commercial ships which entered service in 1964 for the regular carriage of liquefied natural gas from Arzew in Algeria to Canvey Island in the Thames. The design and engineering problems arising in these developments were unusual and varied, and they necessitated close co-ordination in the fields of cryogenics, metallurgy, chemical engineering and naval architecture. Not only were there problems associated with the physical properties of materials and insulants at low temperatures and the large contraction movements and strains induced by temperature change but there were problems of handling a boiling liquid continually releasing gas which, if trapped, could build up dangerous pressures. All these problems had to be faced on the large scale and assessed against the potential hazard of fire and explosion; in addition, they had to be superimposed on the somewhat unpredictable behaviour of a ship at sea whose design criteria were influenced more by experience and empiricism than by basic science. The unusual and unprecedented nature of the project involving safety of life at sea, and affecting other users of rivers, ports and harbours, meant that from the outset there had to be close liaison and co-operation with Government Departments, Ministries, harbour and river authorities, regulatory bodies and local authorities. The successful conclusion of the project confirms the effectiveness of this co-operation and it affirms how the imagination, perseverance and technical skill of a team of engineers can be harnessed in endeavour and achievement.
Special Steels for High Temperature Service
Authors: Kirkby H. W. 
Published: October 2007

In this lecture the author reports on the progress made in the development and application of creep-resisting steels over the last 20 years, with particular reference to research carried out at The Brown-Firth Research Laboratories. The properties of the more established steels are reviewed, along with those of a number of newer steels introduced during this period. These include the 12 per cent chromium variants specially ‘tailor-made’ for aircraft gas turbine discs, two improved austenitic steels and two non-stainless types: a 6 per cent chromium complex steel, and a 2 per cent chromium molybdenum vanadium aluminium nitriding type. Cast austenitic pipe steels are also discussed. The author describes work being carried out with the object of improving the proof strength of austenitic steels, e.g. warm working and alloying with nitrogen. Some information is also presented in respect of the creep ductility properties of a number of the steels mentioned in the paper, with special reference to weld heat effects.
Pressure Vessels of High Proof Strength Warm Worked Stainless Steel
Authors: Kemper M. J. , Morley J. I. , McWilliam J. A. , Slater D. 
Published: October 2007

In order to establish the necessary data to enable high proof strength austenitic stainless steels to be used for the fabrication of pressure vessels, plates were produced with an increased proof stress obtained by the warm working method. The laboratory investigation then showed that it was practicable to raise the proof strength of this material to twice the normal value for fully softened plate with an improvement in the ultimate tensile strength. Following this, two similar experimental vessels were manufactured in normal and high proof strength 18% Cr-8% Ni-Ti stabilized steel and these were subjected to hydraulic pressure testing. The vessel tests showed how stainless steel vessels behave under static pressure application at room temperature, and the behaviour of the high proof strength vessel indicated that it would be quite safe at nearly double the design pressure for the fully softened vessel. The strain hardening of stainless steel, fabricating techniques and weld quality have also been investigated and these are reported upon in the paper. Proposals for design stress criteria and stress values are made in relation to an examination of existing pressure vessel codes and the experimental data.
The Use of Steam Ejectors for the Vacuum Degassing of Steel
Authors: Knight J. 
Published: October 2007

Steam ejectors have now become the established pumping system for degassing molten steel because of their high gas handling capacities at low pressures. The stream and ladle degassing processes are described including plant required in addition to the ejectors. Theoretical consideration is given to the operation of a steam ejector, and the design requirements for a complete multi-stage plant to operate at less than 1 torr are discussed. Finally the economies and benefits derived from the processes are outlined and future trends indicated.
Performance Loss of Modern Steam-Turbine Plant Due to Surface Roughness
Authors: Forster V. T. 
Published: October 2007

The serious consequences of blade-path deterioration that may result from boiler carry-over has led to active research into the performance aspects by the Air Flow Laboratory of the English Electric Company at Rugby. This paper reviews some of this work and illustrates the conclusions. Data are required to determine nozzle and blade efficiencies with various types of surface finish, from polished specimens which can be regarded as hydraulically smooth, to the type of deposit build-up and/or surface pitting which can be experienced after periods of operation at site. There is a great variety and randomness embraced by the term ‘surface roughness’. In a practical machine the difficulty is not only to obtain an accurate record of the roughened surface, but to assess its effect on the frictional loss. However, very many data have been obtained on the resistance to flow in pipes and along flat plates with varying degress of sand-grain roughness, and the simple theoretical treatment for turbine nozzles and blades explained in the paper makes use of these data. In this way, it has been possible to derive curves showing efficiency correction factors for both Reynolds number and roughness. The enormous variation in Reynolds number through a modern steam turbine makes this a highly important factor. Experimental work using cascades of typical turbine profiles has also been carried out in the laboratory to try to substantiate the theoretical analysis, various grades of emery paper being used as a yardstick. A fair measure of agreement was obtained, and other workers' results are also available for comparison. The cascade tests of efficiency were also extended to reveal the particular areas on the nozzle convex and concave faces which were more susceptible to performance loss owing to localized roughening. Finally both a 200-MW and a 500-MW steam turbine have been worked through to arrive at the worsening in heat rate that might be expected for specific sand-grain roughness values applied to all nozzle and blade surfaces. This sort of information assists the turbine manufacturer in deciding the extent of refinement necessary in his manufacturing processes to obtain satisfactory finishes. On the other hand, these ex-works finishes may well deteriorate after only short periods of site running according to evidence from many sources. Evidently increasing collaboration on these matters between manufacturers, the electricity boards, and station operators is necessary.
Hydrodynamic Factors Affecting the Design of Valve Plates and Thrust Bearings
Authors: McKeown J. , Milner D. A. , Shute N. A. , Turnbull D. E. 
Published: October 2007

The limitations of analyses of the characteristics of viscous flow systems based on the assumption of constant fluid viscosity have been recognized for a considerable period of time and attempts to overcome them have previously been made by suggesting the use of a ‘mean effective’ value of viscosity. It has become increasingly obvious, however, that the large changes which often occur in the value of the viscosity of most hydraulic fluids suitable for use in fluid power and lubricating systems can no longer be disregarded and a more exact study of the results of the effects produced by variations of both pressure and temperature on the viscosity of such fluids is desirable. The present work contains such an analysis, and consideration is given to a system wherein combined Couette and Poiseuille flows occur. Predictions are made of the effects produced under certain operating conditions by the variation of the viscosity of the fluid with both the instantaneous values of the fluid pressure and the fluid temperature. Methods of applying these results to studies of the operation of valve plates for axial piston pumps and motors, radial face or mechanical seals and hydrostatic thrust bearing design are indicated. Approximate methods of allowing for the effects of heat losses by conduction through the rigid boundaries of the film are suggested and some results of a computer study of these conditions are described.
First Paper: Human Response to Intense Low-Frequency Noise and Vibration
Authors: Guignard J. C. 
Published: October 2007

The frequency-dependent effects of mechanical vibration on human comfort and working efficiency are now clearly recognized, as are the effects of airborne noise on hearing. But vibration and intense noise at very low frequencies can also provoke disturbing non-auditory symptoms which are as yet ill understood. Moreover, the establishment of frequency-and time-dependence of these effects calls for further research. The author reviews current problems in this field and mentions the work of the International Organization for Standardization aimed at defining limits of acceptable human exposure to vibration and intense noise.
Vibratory Feeding
Authors: Redford A. H. , Boothroyd G. 
Published: October 2007

A brief review of previous work on the mechanics of vibratory conveying is presented followed by a new theoretical analysis of vibratory feeding on a track which vibrates with simple harmonic motion and where a phase difference may exist between the parallel and normal components of the track motion. For a wide range of practical conditions, the theoretical predictions are found to agree closely with the results of experimental tests. These show that certain fundamental limitations exist in the performance of conventional feeder drives where the two components of track motion are in-phase. From further theoretical and experimental work, it is shown that under conditions where the appropriate phase difference exists between the two components of track motion, many practical advantages over conventional vibratory feeding are obtained. With a new design of vibratory bowl feeder drive based on the results of the work, significantly higher conveying velocities may be obtained under stable feeding conditions and, further, these high conveying velocities are virtually independent of the coefficient of friction between the component and the track. The results of the present work apply equally to the design of spiral elevators and in-line vibratory feeders.
Some Cavitation Effects in Spool Valve Orifices
Authors: McCloy D. , Beck A. 
Published: October 2007

The existence of cavitation in hydraulic equipment leads to inefficient operation, mechanical damage, and vibration. The performance of valves in fluid power control systems is affected by cavitation. The spool valve finds numerous applications in this field and it is essential that these effects be thoroughly understood. In this paper a study is made of the occurrence of cavitation and its effect on the discharge characteristics of spool valves. It is shown that over a range of flow conditions cavitation has a profound effect on the flow coefficient.
Second Paper: Extrusion of Steel and Titanium
Authors: Austin E. R. , Davies R. , Bakhtar F. 
Published: October 2007

This paper describes the results of forward and backward extrusion tests on steel and titanium specimens at very high impact speeds, using reductions in area of 44 to 86 per cent. The specimens were in all cases of 1-in diameter, 1.5 in long. For the cold forward extrusion of steel, impact speeds over the range 68-310 ft/s were used. Comparison of mean extrusion and work of deformation at these high speeds was made with the values arising at very low speed. Extrusion pressures were minimal in the impact velocity range 40-80 ft/s. Tests using steel billets preheated to temperatures between 300 and 600°C showed no great advantage in preheating above 400°C. This degree of preheating showed considerable advantages over the cold process, in that extrusion pressures were much reduced, product quality was improved, and higher extrusion ratios could be obtained. Limited backward extrusion tests at 66 ft/s proved the feasibility of the process. Gold forward extrusion of titanium at 65 and 167 ft/s was successful only at the relatively low reductions in area of 44 and 61 per cent. At higher degrees of deformation, the extruded product broke into small pieces.
Influence of Coupled Asymmetric Bearings on the Motion of a Massive Flexible Rotor
Authors: Morton P. G. 
Published: October 2007

The rotors of a majority of rotating machines are supported upon bearings whose flexibility has a significant effect on the dynamics of the system. Supports incorporating hydrodynamically maintained oil films in particular, in addition to possessing different stiffness and damping in mutually perpendicular planes, exhibit non-reciprocal coupling between motions in these planes. The author develops the equations of motion for a rotor-bearing system of this type, and describes how both the response to an out-of-balance forcing and the unstable behaviour of such a system may be predicted by evaluating separately the dynamical characteristics of the rotor and the bearings. The method is applicable to systems in which the rotor is axisymmetric and has an arbitrary mass and stiffness distribution symmetrically disposed about its centre of span. Some new aspects of the resonant and unstable behaviour of rotating shafts are brought out due to the nature of the method of solution. Theoretical predictions are compared and agree very well with the results of tests on a 1380 lb model rotor supported on two 4 in diameter cylindrical journal bearings.
Third Paper: Traction in Elastohydrodynamic Contacts
Authors: Plint M. A. 
Published: October 2007

Measurements of frictional traction in a circular elastohydrodynamic contact have been made over a comprehensive range of conditions. The results suggest the existence of a limiting shear strength in the fluid film and this is shown to be a function of temperature and contact size. Existing theories of fluid behaviour under extreme conditions of stress are considered and some modifications are suggested. The contribution of asperity contact to surface traction is examined.
Fourth Paper: Shear Behaviour of Elastohydrodynamic Oil Films at High Rolling Contact Pressures
Authors: Johnson K. L. , Cameron R. 
Published: October 2007

The variation with sliding speed of the traction transmitted by E.H.L. oil films has been measured in a rolling contact disc machine, at contact pressures up to 260,000 lbf/in2 and at various rolling speeds and disc temperatures. From the traction measurements at very low sliding speeds, under isothermal conditions, the variation in apparent viscosity of the oil with pressure and temperature has been found. The variation with temperature at high pressure was exponential with an index similar to that at low pressure. The variation with pressure showed a striking reduction in the rate of increase with pressure in the high pressure region (> 105 lbf/in2). At high sliding speeds the traction coefficient was found to approach a common ‘ceiling’, which was largely independent of contact pressure, rolling speed and disc temperature. The ceiling appears to be a function of sliding speed only; it falls from 0.07 at 5 in/s to 0.04 at 60 in/s. Using the measurements of apparent viscosity obtained at low rolling speed, it has been shown conclusively that the limitation (or ceiling) in traction at intermediate sliding speeds cannot be explained by Crook's theory of a reduction in Newtonian viscosity by frictional heating. Alternative explanations based upon plastic shear of the lubricant when a critical shear stress is reached are much more consistent with the observations. But further work is necessary to elucidate fully the behaviour of E.H.L. films in sliding.
An Analysis of the Geometry of Gear Hobbing
Authors: Hannam R. G. , Andrew C. 
Published: October 2007

This paper describes an analytical examination of chip formation in the hobbing of spur gears. The process is analysed by considering relative rather than absolute motion, and is reduced to a two-dimensional problem. The mathematics were carried out on a digital computer. The analysis shows the number of hob teeth engaged in forming a gear tooth space, the shapes of the chips and the volume of metal removed. The analysis is applied to a given hob and gear and the results indicate that: the flanks of the hob teeth remove a greater volume of metal than the tips, but the tips accomplish their metal removal in fewer cuts and are therefore loaded more severely; the volumes of metal removed by, and hence the wear on, the two flanks of a hob tooth are unequal; the machining forces exert a fluctuating and reversing torque on the worktable.
Some Recent Research in Turbo-Machinery
Authors: Horlock J. H. 
Published: October 2007

Research on turbo-machinery carried out at Liverpool University in the period 1958-66 is reviewed. The work described includes: (1) The accurate determination of two-dimensional incompressible flow in cascades; and an assessment of the effects of contraction of the mainstream. (2) A study of the nature of the flow on the end walls of compressor cascades, including the prediction of the laminar and turbulent boundary layer development on these walls. The interaction of these boundary layers with flows due to tip clearance is discussed. The effect of separation of the flow from the end walls upon the contraction of mainstream and the stalling performance of the blading is important and is strongly dependent on the aspect ratio of the cascades. (3) A series of experiments on rotating machines. The performance of compressor blading in stationary cascades and in the blade rows of an axial compressor is compared and the effect of aspect ratio on compressor stage performance is determined. A number of observations are made on the stalling of compressor stages and calculations of the three-dimensional flow in turbo-machines are reported.
Boundary Layer Effects in the Turbulent Spiral Vortex Flow of a Compressible Fluid
Authors: Scott B. F. 
Published: October 2007

Because of the characteristically narrow impeller tip width in a proposed supersonic centrifugal compressor design, boundary layer effects in the vortex chamber are likely to be significant. The radial pressure gradient in the chambers sweeps retarded fluid towards the centre of curvature of the streamlines, thereby creating a ‘cross-flow’ in the boundary layer which is three-dimensional. Although the flow geometry has axial symmetry, the cross-flow is not independent of the streamwise flow. The momentum—integral method is adopted, together with assumptions concerning the velocity profiles; the energy equation is solved with the assumption of an adiabatic wall. Simultaneous solution of the free stream and boundary layer equations yields results emphasizing the critical dependence of the transverse deflection and growth of the boundary layer on the whirl component of the velocity. Separation cannot be predicted, but effects in the free stream can be estimated when the perturbations are small. Although the results are related to compressor performance, the method is generally applicable in situations where the idealizing assumption of spiral vortex flow is acceptable.
Commissioning of Medium-Scale Chemical Process Plant
Authors: Kingsley R. J. , Kneale M. , Schwartz E. 
Published: October 2007

The commissioning procedures and philosophies applicable to a medium-scale company are outlined. Project information is channelled through research and pilot-plant reports, design circulars, and relevant committees. Lists of commissioning preparations are given, including inspection, testing, process simulation, manuals and operating documents, training of staff, control procedures, safety, and maintenance preparations. The philosophy of the commissioning organization is indicated, emphasizing the position of the Chief Technologist. Many common start-up difficulties are described, with particular reference to personnel and human problems. A favourable commercial climate is very important: company and commissioning policies must be integrated. Criteria are given for terminating the commissioning effort and the setting up of the subsequent Plant Development Committee. The paper concludes with commissioning experiences abroad.
Basic Factors in the Design of Hydraulic Circuits
Authors: Kibble J. D. 
Published: October 2007

This paper is concerned with the design of hydraulic systems of the type containing one or more rams or rotary motors driven by a pump having a relief valve or other means of controlling the flow so as to limit the pressure. The choice of working pressure is discussed and it is concluded that there is no inherent advantage in the use of high pressures analogous with that of high voltages for electrical power transmission. The other factor investigated is the selection of pipe and valve sizes. The customary use of a standard flow velocity as a guide for this purpose can give very unsatisfactory results. As a better basis, an estimate of the allowable pressure loss is recommended, this being obtained from considerations of efficiency or from a novel parameter, ‘hydraulic regulation’. The latter is the ratio of the pressure loss at full working speed to the maximum pressure, and is a measure of the extent to which a system slows down under heavy loads.
Stresses in Oil Lubricated Bearings
Authors: Ibrahim S. M. , Mccallion H. 
Published: October 2007

Stresses in a bimetal strip of white metal bonded to steel, to simulate a journal bearing shell or a thrust bearing ring, have been calculated for various loading conditions. The stresses arose from: fluid pressure loading on the bearing surface whilst the back was supported on a complete rigid surface; locating and holding forces, e.g. compression due to nipping-up the bearing; elastic deformation of the bearing housing; differential thermal expansion and temperature gradients, and incomplete support of the bearing shell when subjected to fluid pressure on its bearing surface. Points at which fatigue damage is likely to originate are apparent. The stresses were calculated numerically from displacements which were found, by an iterative method, to satisfy a finite difference analogue of the governing differential equations.