bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Operation of a Large Heat Transfer Installation
Authors: Brearley N. 
Published: October 2007

Jacketing by a transfer medium of the condensing vapour kind is a suitable method for heating many process units to temperatures of about 300 deg. C. (572 deg. F.) when fine control is necessary. The mixture of diphenyl and diphenyl oxide known as Dowtherm “A” has a good relation between vapour pressure and temperature for such a purpose. In the paper the other relevant properties are discussed. The principle of operation of a circulating system and the design of an installation of vaporizing and auxiliary equipment having a rated output of 11,000,000 B.Th.U. per hr. are described with reference to the special problems presented by Dowtherm owing to its inflammability, high freezing point, searching nature, scouring properties, and possibility of degradation. Preliminary work on two possible alternative materials with lower freezing points and less propensity to leakage is briefly mentioned.
The Mechanism of Work-hardening of Metals
Authors: Mott N. F. 
Published: October 2007

The most striking feature of the deformation of metals is the formation of slip lines. Recent investigations suggest that, when formed at low temperatures, each slip line is the result of a displacement of the material along a single lattice plane through a distance of about a thousand atomic diameters. Moreover, there is much evidence that the steps on the surface which appear as slip bands attain their full height in a small fraction of a second, though their length may thereafter increase slowly. At higher temperatures and at slow rates of strain the slip bands appear, under the electron microscope, as clusters of lines about a hundred atomic diameters apart. The origin of slip lines, the reason for this clustering and the cause of work-hardening are discussed. The two conceptions used in the discussion are the dislocation line and the vacant lattice site. Slip lines are believed to have their origin in a certain arrangement of dislocation lines of frequent occurrence in the interior of the crystal. These are known as Frank-Read sources; their relation to recent work on the growth of crystals is shown. Where a slip line terminates dislocations must remain in the crystal; to the internal strains round these is ascribed work-hardening, much as in Taylor's theory of 1934†. It is now, however, possible to explain what it is that stabilizes the dislocations and prevents them from moving back when the stress is released. Finally, vacant lattice sites are shown to be formed in a cold-worked material. If the temperature is high enough for them to diffuse, they soften the material round the slip band and allow the observed clusters to form. They also play a part in producing the observed “fragmentation” of cold-worked material.
Effects of Inertia on Flow of Steam through Nozzles and Blading of Axial-flow Turbines
Authors: Kearton W. J. 
Published: October 2007

A method is given for calculating the radial distribution of pressure in a steam turbine with long blades, the conditions for radial equilibrium, for continuity, and for energy balance being satisfied simultaneously. An example, illustrating the application of the method, shows that if there is pure impulse at the root of the blade, an appreciable degree of reaction may be reached at the outer end of the blade. It is shown that if the steam flow is to be parallel to the axis of the turbine then the variation of nozzle outlet angle with change of radius depends on the steam velocity at the inner radius. An alternative theoretical analysis of the problem is given which yields quickly the radial distribution of pressure where the nozzle outlet angle is uniform. This analysis is extended to give the degree of reaction at the blade tip in terms of that at the blade root. The paper concludes with a brief note showing that in geometrically similar turbines operating with the same blade speed, but different speeds of rotation, the radial distribution of pressure is the same.
The Design and Operation of Dunston “B” Generating Station with Particular Reference to 50-megawatt Turbo-alternators Unitized with Reheater Boilers
Authors: Howell A. , Jackson J. B. 
Published: October 2007

Two 50-megawatt turbo-alternators unitized with reheater boilers were commissioned at Dunston “B” generating station towards the end of the year 1950, and ranked as the most efficient generating plant owned by the British Electricity Authority during the year 1951. In Part I of the paper are shown the changes in design compared with the original plant which was commissioned seventeen years previously. In Part II plant staffing and staff training are discussed and details of operating experience are given, including methods adopted for overcoming the initial plant troubles and the procedure eventually evolved for starting-up and shutting-down, and, in particular, the method adopted to permit full load to be achieved in hours from starting-up. Performance and “outage” figures for 1951 are discussed and analysed and results of tests are tabulated, including load throw-off tests and monthly performance tests for the two Units 5 and 6. It is concluded that unitized generating plant can be controlled so closely as to achieve test conditions and performance in commercial operation, but that attention needs to be drawn to detailed improvements in design and workmanship. In particular, the need is stressed for more care in making joints and tightening bolts for high-pressure work. Future economies and improvements proposed as a result of experience are mentioned.
Contemporary Methods of Watch Production
Authors: Fell R. A. , Indermuhle P. 
Published: October 2007

There is at present no written matter in the English language on watch production, the industry having died out in Britain some thirty years ago. The aim of this paper is to provide the engineer who is not a specialist in the subject with a background knowledge of the methods used in the production of watch components and the special difficulties encountered in watch manufacture. In the first part of the paper the historical development of the watch and the general principles of design are briefly reviewed. A fifteen-jewelled man's wrist-watch with lever escapement is taken as a typical example, in which the features commonly encountered are examined in more detail and the small size of the pinions and pivots is emphasized. The latter part of the paper is devoted to the techniques used in the production of the components (the plates and bridges, turned parts, wheels and pinions, escapement, and balance); their final assembly; and the oiling, springing, and timing, of the finished watch. A general note on the three main categories of watches is amplified by figures illustrating the performance actually attained by a wrist-watch of the highest grade.
The Problem of Fuel-oil Ash Deposition in Open-cycle Gas Turbines
Authors: Bowden A. T. , Draper P. , Rowling H. 
Published: October 2007

The loss of power due to the deposition of fuel-oil ash on the turbine blades at present limits the use of boiler fuels in open-cycle gas turbines, and therefore prevents the more widespread application of this form of prime mover in the marine and industrial fields. The nature and occurrence of the ash-forming constituents are discussed, followed by consideration of the possibilities of removal of these from the oil. There appears to be no solution along these lines nor by removal of the ash from the gas stream. The basic factors controlling deposition of ash are still not fully understood and therefore further experimental work is required. However, a method which gives a considerable reduction in deposition has been discovered. In this, combustion of the fuel droplets is controlled so that each droplet burns down and leaves the combustion chamber as a hard, dry, carbon particle containing an appreciable proportion of the ash. The combustion loss due to this unburnt carbon is less than 1 per cent. Long-term engine tests are now required to assess the practical use of the method. Another means of reducing deposition which appears to offer considerable promise is the use of various additives to the fuel or gas stream. Of those tested the oxides of silicon, zinc, and magnesium were the most effective.
Design of Precision Grinding Machines
Authors: Asbridge G. H. 
Published: October 2007

In this paper are put forward the basic principles under which all grinding machines, irrespective of size or type, must be constructed. The chief problems facing the designer of precision grinding machines are discussed, together with the essential elements and physical components. The choice of solutions which seem to offer the most promising future developments is suggested. The factors affecting the design of grinding machines—cost, ease of maintenance, and the influence of the user—and the essential elements—rigidity, accuracy, and constancy, are discussed. Mechanical and hydraulic traverse mechanisms are compared and a brief description is given of a typical hydraulic system. Although mechanical methods of traverse have been giving way to hydraulic systems, the author considers that with the improved electrical control gear available there may be a reversion to mechanical traverse mechanisms on account of their simplicity and reliability. The influences of the wheel-head and wheel-head spindles are discussed. The two lines of approach that wheel-head design and wheel-head speeds will follow during the next few years is suggested. Work-head and work-head drive arrangements are described; followed by the main features of universal machines and machines arranged for automatic operation. Finally, methods and mechanisms are described for obtaining concave and convex camber with roll-grinding machines.
Nuclear Reactors and Power Production
Authors: Hinton Christopher 
Published: October 2007

This lecture deals with the design and construction of nuclear reactors, and particularly of types suitable for the generation of power. To introduce this a detailed description is given of the British Experimental Pile (BEPO) at Harwell. This is a typical ‘thermal’ reactor on a small scale, using natural uranium as fuel and graphite as moderator; it is air-cooled and the shielding and control arrangements illustrate general practice. There follows an account of some of the engineering and construction problems met in the erection of the Windscale piles, and the solutions achieved. The problems involved in designing power-producing reactors are discussed. The choice of materials in the reacting core is restricted by nuclear physical considerations; large absorbers of neutrons cannot be used. There is a conflict between the demand for high temperatures to give satisfactory thermal efficiency and the limitations imposed by the metallurgical properties of the fuel elements and by the coolants employable. The safety aspect of design is considered and the influence of the coolant described; certain types of reactor can be designed to be inherently safe even in the event of a coolant failure but with others there is the risk of reaching a supercritical condition, and the effect of this is discussed. The possible reactors may be divided into two groups: those which use ‘thermal’ neutrons and are similar in principle to BEPO, and those which use ‘intermediate’ or ‘fast’ neutrons and have a much smaller core size. Within each group are alternatives provided by differences in fuel, moderator, and coolant. A number of these are reviewed with general indications of their size, and some of the more detailed problems associated with their design are considered. The large reduction in core size resulting from the use of ‘fast’ neutrons leads to acute problems of heat transfer and, though the fuel investment is much less, the fissile material content of the fuel used must be much higher. One or two possibilities for the more distant future are briefly mentioned. Prospects for the large-scale development of nuclear power are discussed, and it is argued that the replacement of coal-fired boilers by nuclear reactors as the heat source at power stations should, before many years have passed, be economically sound and is further justifiable as it would help to reduce the recurrent shortage of coal. A possible national scheme is outlined in which thermal reactors would be built in the first stage; these would produce supplies of fissile material as well as power, and this material would later be used in ‘breeder’ or ‘converter’ reactors in the second stage; these reactors should be self-sustaining in fuel after the initial charge. An Appendix is included which gives a simple explanation of the underlying theory of atomic energy and of the terms used in the lecture.
Corrosion Aspects of the Vanadium Problem in Gas Turbines
Authors: Frederick S. H. , Eden T. F. 
Published: October 2007

The effect of V2O5 and mixtures of V2O5 and Na2SO4 on turbine fouling and corrosion is discussed. Laboratory tests have shown that none of the commercially available alloys is immune from attack when these mixtures are molten, that is, at temperatures above 650 deg. C. Nickel base heat resisting alloys of the Nimonic type offer higher resistance to attack than the austenitic steels and some degree of protection is afforded by electro-deposited coatings of chromium. Steels and heat resisting alloys are not attacked to any significant extent at temperatures below the melting point of the ash, but copper base alloys suffer considerable corrosion at temperatures as low as 500 deg. C. A detailed investigation of the effect of additives on the corrosion rate of V2O5-Na2SO4 ashes indicates that corrosion can be considerably reduced, and that such a method of approach is promising. Suitable additions may be made by a mixture of oil or water soluble materials with the fuel, by suspension in the fuel, or by separate injection into the combustion chamber with the object of reducing corrosion and deposition. Laboratory corrosion tests, using ash additives such as ZnO, Al2O3, and kieselguhr, have shown that the rate of attack can be greatly accelerated if the additive is present in certain critical proportions, but when this is exceeded, corrosion is considerably reduced. With MgO, however, no such increase in attack was noted. Rig tests have confirmed some of the beneficial effect of additives.
Measurement and Analysis of Rolling Loads in a Large Hot Plate Mill
Authors: Stewartson R. 
Published: October 2007

Instruments for measuring rolling loads have been constructed for insertion between the screw and the top bearing chocks of a heavy plate mill. They have been accommodated in a limited space and designed to attempt the measurement of non-uniformly applied loads. The load indications during the rolling of a varied programme for plates of different size have been analysed and compared with three roll-load formulae. That due to Sims seems to give the best agreement, and the majority of the calculations for reductions over 10 per cent lie within ±25 per cent of the measurements, whereas the other formulae show discrepancies often exceeding 50 per cent. For reductions less than 10 per cent all three formulae show similar trends, giving values in general very much lower than those obtained with the instruments. Although the instruments have proved satisfactory for short trials, certain features will be modified in models which are now being designed with a view to more permanent installation.
Practical Training in Industry for the Graduate in Mechanical Engineering: Part IV
Authors: Pope J. A. 
Published: October 2007

Engineering is not only a science but also an art. With the ever-increasing scientific content of an engineering graduate's training, less and less time is devoted to workshop practice, machine drawing, and design. The engineering graduate leaving the university today is much less an engineer than his counterpart was in 1910. In fact, universities do not produce engineers, they train students in engineering science and it is left to industry to complete the graduate's training. The common pattern of training for the graduate engineer is direct from school to the university for three years followed, after graduation, by two years' practical training. The author suggests an alternative scheme of one year in industry after leaving school to be followed by three years in a university, the graduate's training being completed by a further year's training in industry. The scheme is called ‘the thick sandwich’. Its main advantages are that (1) the undergraduate knows what engineering is when he joins a university, (2) it will tend to produce men with a stronger bias towards the production side of the industry, and (3) men who commence their training in the shops will be, after graduation, more acceptable to the personnel of the engineering industry.
Technical Features of the New British Standard System of Limits and Fits
Authors: Conway H. G. 
Published: October 2007

This paper discusses the new British Standard for limits and fits for Engineering (B.S. 1916), outlining in particular the technical features and explaining how the system has been built up. A brief historical review of other systems is made, their faults being referred to. The prospects of adoption of an equivalent system by the United States and a corresponding decision already taken by Canada are mentioned. The paper goes on to discuss the theoretical requirements of a good tolerance system and then compares the new standard with the theoretical desiderata. The technical reason for each particular diameter step, tolerance value, or shaft or hole allowance is given, supplementing the necessarily bare data given in the standard itself. Indications are given of the future extensions of the system which are likely to be made following international discussions in relation to tolerances for small diameters as used in the horological industry, tolerances for precision fits and fine quality gauges, and tolerances for large diameters up to about 6 feet. The practical difficulties in determining and using tolerances in diameters above 20 inches are considered in some detail, and a plea is made for discussion and information on this matter.
The Practical Application of the New British Standard System of Limits and Fits
Authors: Pearmain G. J. 
Published: October 2007

This paper suggests methods by which the new British Standard system for limits and fits can be most efficiently applied in industry, and proposes a method of approach by which series of fits for various purposes can be selected from those shown in the British Standard. It refers particularly to Part II of the Standard which gives data on the application of various types of fit. The choice of tolerances is discussed in relation to machine capabilities and fit requirements, and a series of fits for general engineering requirements is proposed. Methods of assisting the correct application of tolerances and fits in the design stage of a piece of equipment are suggested, and the use of methods of selective assembly is shown to be practicable, using standard limits. Assembly fits for ball and roller bearings are discussed, and it is suggested that a standard series of such assembly fits should be established.
An Experimental Investigation into the Effect of Fuel Addition to Intake Air on the Performance of a Compression-ignition Engine
Authors: Lyn W. T. 
Published: October 2007

The investigation arose from a programme of research into the means of reducing combustion noise and engine roughness in a compression-ignition engine. Information on pre-flame reactions in spark-ignition engines from published literature indicates that these reactions, which yield active partial products of combustion that finally lead to the auto-ignition of the end gas, or ‘knock’, may reduce the ignition delay in a compression-ignition engine and contribute to the smooth running of the engine. Preliminary tests with part of the fuel introduced with the intake air in the form of spray confirmed such a view. They showed how, by slow oxidation of the aspirated fuel, the compression pressure is increased and the ignition delay of the main fuel is reduced with consequent smoothing of the pressure diagram and elimination of combustion noise. The effects on combustion and performance under various loads and speeds are presented, it being found that overall thermal efficiency is improved at high load but made worse at low load. Further investigations were then carried out on the various factors that may have effects on the result of introducing fuel with the intake air. Among these were the types of fuel used for the aspirated as well as the main charge, combustion chamber design, compression ratio, and timing of both parts of the charge. An analysis is made of the processes of combustion under such conditions and a theory advanced to account for the phenomena observed. It is concluded that the lean aspirated mixture does not proceed to complete combustion. The use of intake spray was found particularly effective when the main fuel was of low ignition quality. The technique of using the slow oxidation of the aspirated fuel was then applied to study the ignition of various hydrocarbons in a compression-ignition engine. It is shown that the differences in ignition delay of various fuels lie chiefly in the chemical part of the delay while the physical part remains essentially constant in spite of widely different physical properties of the fuel. It is shown also that with the use of intake spray, the compression-ignition engine can run on any fuel irrespective of its cetane number and with only small differences in thermal efficiency. Finally, the effect of some additives on the reactions of the aspirated fuel and the ignition of the main fuel were studied. The results showed that the reactions were suppressed by the addition of formaldehyde and tetraethyl lead and slightly accelerated by nitrogen peroxides. The indication was that the reaction is of the ‘low-temperature’ mode. This is discussed in relation to the recently published works on oxidation of hydrocarbons in general and the reactions leading to knock in the spark-ignition engine.
The Impact of Development and Research on Production and Design
Authors: Leedham L. H. 
Published: October 2007

The paper deals with some technical activities which are of particular importance in relation to production, but which are not always recognized as having a direct bearing thereon. Simplification of product, functional development and production research provide means by which existing facilities may be made to yield greater output, that is, to increase production efficiency. They also make it certain that industry will in the future employ those processes which ensure the maximum economic gain. The attitude of the mechanical engineer to production techniques as a part of design also receives consideration, together with the desirability of infusing designers and draughtsmen with a greater interest in new methods. The responsibility of industry in affording training for this purpose is also discussed. The lack of adequate support for production research is emphasized, while attention is drawn to the difficulties of small firms in benefiting from the results of research and development work on new processes.