bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some Technical Aspects of High-Pressure Boiler Design
Authors: Davis R. F. , Timmins A. L. 
Published: October 2007

In introducing the subject the authors suggest a classification of boilers on a pressure basis. Alternative methods of drum construction are reviewed, leading to an investigation of the effects of higher saturated steam temperatures on the physical characteristics of the metal and the factor of safety. Attention is paid to the analysis of stresses induced in the drums of large high-pressure installations, with comments on the limitations of standard design rules and formulae. Similar treatment of the subject of boiler tubes follows, attention being directed particularly to the combined effects of temperature and stress. The importance of accurate estimation of furnace exit temperature, especially in relation to superheat, and the effects of modern designs of water-cooled furnaces are then discussed. The influence of radiant heat emission from non-luminous gases in the convection passes is emphasized. A simple graphical method for determining the rate of natural circulation is outlined and the retarding influence of high pressure is discussed. Orthodox designs of high-pressure boilers, the relative merits of which are compared, present no serious difficulty in operation, providing adequate attention is paid to feed water treatment, some aspects of which are discussed. Further developments are contingent upon the economic extension of the range of commercial heat-resisting metals; the adoption of more logical and adequate rules and regulations governing design; and closer investigation into the behaviour of tubes, etc., under high pressures and temperatures and subject to the conditions prevailing in a boiler when in service.
The Mechanics of Electrical Switchgear
Authors: Trencham H. 
Published: October 2007

The importance of mechanics in the design of switchgear is emphasized, and attention is drawn to the desirability of applying to switchgear the best that mechanical science has to offer. The functions of switching apparatus are set out in detail and the forms usually taken by the devices for performing these functions, and their relationships to each other, are described. The following are instanced as typical mechanical problems in switchgear design: the strength of complex enclosures against internal pressure; oil-tight joints with insulators; the use of Portland cement with insulators; mechanisms for operating circuit breakers, including internal linkages and external actuating devices; the design of contacts. Essential and arbitrary variations in switchgear design are considered, the former including voltage, amperage, frequency, breaking capacity, and location; and the latter, evolution, economic pressure, safety requirements, and individual preference. The incidence of the causes of variation is indicated and some attempt is made to describe their range of action. A short summary is given of the effects of the wide variety in demand, and the expected course of future progress is indicated. Appendixes are given exemplifying the application of simple mechanical calculations to circuit breaker mechanisms, and the usual loadings on various forms of contacts are tabulated.
Gas Works Practice
Authors: Birks F. M. 
Published: October 2007

Gas manufacture is generally carried out in either horizontal, continuous vertical, or intermittent vertical retorts supplemented by carburetted water-gas plant. At the present time a certain amount of gas from coke oven plants is purchased, but only one such installation is at present in use on a gas works primarily for the production of gas. All four types of carbonizing plant, together with the carburetted water-gas plant, are described briefly, and a table is put forward to show the results obtainable from them. Four thermal balance diagrams demonstrate the possibility of heat recovery from the waste flue gases, hot coke, and the hot coal gas by the generation of steam. A brief description of the various ancillary plant employed is given, whilst the production and use of steam is discussed more fully. The use of back-pressure steam is advocated and a table shows the variation of power requirements in six works, two each of the three main types of carbonizing plant. A brief description of the recently reconstructed Brentford works of the Gas Light and Coke Company shows the extent to which mechanical handling of material has been adopted.
The Operating Temperatures of Cast Iron and Aluminium Pistons in a 12-Inch Bore Oil Engine
Authors: Baker H. Wright 
Published: October 2007

The engine used for these tests is of the single-cylinder vertical Diesel type, having a 12-inch bore and 18¼-inch stroke and running at 250 r.p.m. Temperatures have been measured at nineteen points on a ribbed “jam pot” cast iron piston, at twenty-three points on a “mushroom” type aluminium piston, and at fourteen points on a cast iron piston with a conical head support. Temperatures have also been measured at eight points on the cylinder liner. A description is given of the pistons and special testing apparatus. The influence of subsidiary junctions in the thermocouple leads, which led to some discussion following Dr. Mucklow's recent paper on piston temperatures,† has been studied. Errors, varying with engine output and amounting to as much as 29 deg. C., have been measured where no compensator was used. The effects of the temperature of the liner and of the jacket water outlet on the pistons have been measured, and are discussed. The conclusions are in general agreement with those of Dr. Mucklow except such as apply to the central portions of the heads, where the great differences of area exposed to flame lead to remarkably divergent results. The temperature distributions throughout the pistons are considered, and a quantitative estimate is made of the value of the neck, ribs, etc., when these are considered as heat channels. The radial temperature differences recorded for the aluminium and cast iron pistons and for the piston tested by Dr. Mucklow, are roughly in the ratio of 1/5½/19. The effect of varying the engine output has been studied, also the time required to warm up the pistons, the light alloy reaching its maximum temperature in approximately half the time required by the cast iron. A decrease in the number of rings from five to three is shown to have very little effect except in reducing the fuel consumption, while rings of forged “Y” metal slightly reduce the temperature of the piston. The effect of totally enclosing the piston shows that only some 2 per cent of the heat received is normally lost to the air circulating within it.
Force Fits and Shrinkage Fits in Crank Webs and Locomotive Driving Wheels
Authors: Coker E. G. , Levi Miss R. 
Published: October 2007

This experimental investigation relates to a general method of measuring stress distribution when force fits and shrinkage fits of the plane stress type are employed in engineering practice. Important cases occur in the webs of built-up crankshafts for locomotives and Diesel engines. When the latter are of high power and short stroke, so that crankshaft and crankpins are large and relatively close together, the initial constructional stresses are shown to attain high values. More complicated cases, from an experimental point of view, occur in the driving wheels of locomotives with a tyre shrunk over a wheel centre having a crank and balance weight integral therewith, while the main axle and crankpin are forced or shrunk in. Such a case is examined with reference to a driving wheel of the London Midland and Scottish Railway locomotive Royal Scot, and the stress distributions measured in various parts of a model of it are described in detail.
Bauer-Wach Exhaust Steam Turbines
Authors: Crossley E. 
Published: October 2007

In 1927–8 two cargo ships of roughly 11,000 tons displacement were built by Messrs. R. and W. Hawthorn, Leslie and Company for the Booth Steamship Company of Liverpool. Originally of identical design, the plans of S.S. Boniface were altered during construction to include a Bauer-Wach exhaust steam turbine, whilst S.S. Basil was built as originally designed with a triple-expansion engine only. Builders' trials on S.S. Boniface proved the turbine to give a reduction in coal consumption of 24·5 per cent. The paper adds to the facts already known about this type of installation some information regarding reliability and economy in actual service. Following a general description of the propelling machinery and auxiliaries of the two ships, and a more detailed description of the exhaust steam turbine, gearing, hydraulic coupling, and control system of S.S. Boniface, notes are made regarding the general running and the troubles experienced with the extra equipment. Particulars of two trials at sea under normal conditions on S.S. Boniface are given, and finally, a coal consumption comparison on a yearly basis between the two ships is shown to give a saving of 15·9 per cent in favour of S.S. Boniface at the age of four years.
Air Swirl in Oil Engines
Authors: Alcock J. F. 
Published: October 2007

Swirl, or rotation of the air charge, is increasingly popular as an aid to fuel distribution in Diesel engines, but as yet little is on record as to the principles of its production and use. On certain types of engine it is possible to mount a “swirl meter” or freely rotating vane within the combustion chamber, and thus by motoring the engine to obtain a measure of the swirl rate. From such experiments and from theoretical considerations, one can draw certain conclusions, and although these are directly established only as regards one particular combustion system, indirect evidence suggests that they have a much wider application. The most important conclusion is this, that with the combustion system in question there is an optimum “swirl ratio,” or number of revolutions of the vane per minute divided by the number of revolutions of the engine per minute which gives the best performance, whatever the engine size, speed, or load, and which is, in fact, characteristic of that combustion system. It seems probable that the same rule applies to other swirl systems. In most cases the “swirl ratio“ is roughly constant over a wide speed range. This means that if this ratio is made correct at one speed, it will not be far wrong at any speed within the working range, a fact which accounts for the popularity of swirl type engines in vehicle and other variable-speed services. The primary effect of swirl is that of winnowing the fuel spray, blowing away fine spray and burnt gas, and giving the heavier particles access to fresh air. There are, however, important secondary effects of which the causes are not known with certainty.
Piston Temperatures in a Sleeve Valve Oil Engine
Authors: Baker H. Wright 
Published: October 2007

The paper describes tests on a Mirrlees-Ricardo sleeve valve engine of inches bore, running at speeds up to 1,400 r.p.m. The pistons used were: (1) a simple piston of cast iron; (2) a piston with tapered head section, cast in “L8” alloy; and (3) a heavily ribbed and strutted piston of “Y” alloy. A robust form of thermocouple gear which has been devised is described in the paper, and the probable errors are discussed. The temperatures attained by a number of points in each piston are shown for various conditions. The effect of the sleeve is much less than might be expected. The rates of heat reception by the central and outer portions of the piston head differ considerably owing to the vortex type of combustion chamber used. Values of these rates have been estimated for different loads and speeds. The alloy pistons become warm in about half the time required by the cast iron piston. Piston temperature appears to be a linear function of engine speed, the alloy pistons showing an increase of 42 deg. C. at the centre when the speed was increased from 800 to 1,400 r.p.m. at constant brake mean effective pressure. The temperatures of the lower edges of ribs of moderate depth were only 10–18 deg. C. cooler than the under surface of an unribbed piston. Distortion of the pin seatings due to the expansion of the struts must be very slight. With normal water circulation and a constant temperature of water supply, piston temperatures in this engine are almost independent of the final temperature of the water.
Ventilation with Air Conditioning in Modern Buildings
Authors: Dolby E. R. 
Published: October 2007

It is only comparatively recently that the realization of the desirability of a supply of pure air in buildings has been put into practice. In the early attempts to improve the air conditions in buildings it was thought that the mere admission of external air in sufficient quantity might suffice, but that was soon found to be inadequate. The ideal condition of the air suggested by the author is a temperature of 60 deg. F., a relative humidity of 50 per cent, and not more than 6 or 7 parts per 10,000 by volume of carbon dioxide. The air treated should also have dust, fog, and deleterious gases removed. The author describes mechanical means for air conditioning and indicates the method of calculating the amount of conditioned air required in any given case. Examples of some typical installations are also illustrated. Filters for the removal of dust are of special importance in certain industries. Dry filters are very effective, but are expensive. In most cases the use of a viscous filter suffices. The paper concludes with descriptions of various types of instruments for measuring humidity, a special type of centrifugal refrigerator for cooling the air delivered into buildings which uses dichloromethane as a refrigerant, and apparatus for ozonizing the air supply.
Shoe Machinery
Authors: Cooper B. P. 
Published: October 2007

Shoemaking is a very ancient craft, but it is rather less than a century since machinery was first used for the purpose, though in 1810, when the need arose for large quantities of boots for the troops engaged in the Napoleonic Wars, the elder Brunei invented the first riveting machines, which attached the uppers to the soles by nails which were driven and clenched. A number of methods of construction are commonly employed, and the Goodyear welted process is described in the paper in some detail. Attention is then directed to some of the mechanical problems which have been solved in the design of the various machines used. These include a single-revolution clutch capable of stopping the machine with an accuracy of a few degrees of a revolution, and devices for selecting, separating, and feeding such loose articles as tacks, nails, and eyelets. The outsole lockstitch machine is described in detail as an example of what has been accomplished by way of speed and quality of the product. The machine sews at the rate of 1,000 r.p.m. The automatic edge setting machine is also dealt with in detail on account of the arresting feature which might be called its “sense of touch”.
Friction and Heat Transmission Coefficients
Authors: Cope W. F. 
Published: October 2007

The work described in the paper was carried out to determine simultaneously the friction and heat transmission coefficients of metal pipes of various cross-sections. A technique has been worked out and apparatus constructed for the simultaneous determination of the friction and heat transmission coefficients of the central portion of a pipe through which a fluid is flowing. With this apparatus, and with water as the working fluid, tests have been carried out upon a series of drawn copper pipes whose cross-sections varied from circular through square, to rectangular with sides in the ratio of 8/1; in addition two drawn brass pipes, one of which had had its internal surface artificially roughened, have been tested. The extreme values of velocity and Reynolds number are in the ratio of about 300/1; the maximum values being about 340 cm. per sec. (11 ft. per sec.) and 30,000 respectively. The friction coefficient of the rough pipe under isothermal conditions has been determined for values of the Reynolds number up to 50,000, using air as the working fluid. The observations made have been reduced by the method of dimensional analysis and the following conclusions drawn:— (1) That the results of the heat transmission tests on the various pipes can be correlated on the basis of the hydraulic diameter. (2) That an increase in friction coefficient is not necessarily accompanied by an increase in heat transmission coefficient. (3) That the friction coefficient under heat transmission conditions is the same as that under isothermal conditions if the viscosity in the former case is that pertaining to the wall temperature of the pipe.
Exhaust Systems of Two-Stroke Engines
Authors: Farmer H. O. 
Published: October 2007

Crankcase-scavenge two-stroke engines have always been fitted with a large expansion chamber immediately outside the exhaust ports, but this is by no means essential, as such engines will operate very satisfactorily with a plain exhaust pipe. The length of this pipe is most important and has a controlling influence on the scavenging of the cylinder and the performance of the engine. Even when an expansion chamber is used in the exhaust system, the length of exhaust pipe still has a very marked effect on engine performance. It has been found that certain arrangements of this combination of expansion chamber and pipes completely upset the performance of the engine, whilst others improve the performance, but it is possible to calculate the “equivalent length” of any system of this nature, and so arrange matters that the exhaust system is a help rather than a hindrance to the engine. Though certain results have not been satisfactorily explained, the tests carried out do give a fairly clear indication of the way in which the engine performance is affected by the variations in pressure in the exhaust system. The concluding section gives a description of the principle on which the self-induction engine works, and indicates how use is made of the pressure variations or oscillations in the exhaust pipe to scavenge the engine cylinder, resulting in the complete elimination of the air pump on a two-stroke engine.
Engineering Problems Associated with the Improvement of Temperature and Humidity Conditions of the Atmosphere in Mines at Great Depths
Authors: Dobson J. H. , Walker W. J. 
Published: October 2007

The subject is very complex and a great deal of research has been devoted to it on account of its great economic importance. The magnitude of the problems involved is shown by reviewing underground conditions on the Witwatersrand goldfields. Consideration of the limiting air conditions underground enables a specified mine-cooling problem to be enunciated. The final section of the paper reviews the various methods that have been tried for cooling the air in deep mines; some have been wholly or partially given up and some have survived. In particular, the possibilities of meeting requirements on a large scale have been analysed. Reference is made to cooling schemes which have been inaugurated on the Witwatersrand goldfields during the past two or three years. An analysis sets forth the relative merits of water, brine, and air as media for cooling deep mines, and a comparison of cooling plant performances and costs is made on the basis of: (1) vapour refrigerating plants on the surface and underground, using air and water respectively as cooling media, and (2) compressed air refrigeration.
The Design and Operation of a Modern Blooming Mill
Authors: Cartwright W. F. 
Published: October 2007

As an introduction to the visit of the members of the Institution to the Cardiff Works of Messrs. Guest Keen Baldwins, Ltd., the paper has been written to describe the blooming mill, and to indicate some of the reasons governing the adoption of this particular layout. It refers to some of the troubles experienced in operation and how they were overcome. Rapid output of blooms is the result of several factors, ample heating furnaces close to the mill, good roller gear and manipulators, rapid reversal and screw-down gear, good shears, and the general robust construction of the mill —all of which are dealt with in detail in the paper.
The Effect of Certain Factors on the Izod Value of Weld Metal
Authors: Schuster L. W. 
Published: October 2007

This research was carried out to obtain data on the application of the Izod test to non-alloyed weld metal. In general it was found that a good-grade refined weld metal, owing to its fine grain structure, behaves on Izod test much as an alloy steel hardened and tempered at say 650 deg. C. The extent to which the Izod value of such a weld is lowered by the presence of unrefined metal of any given depth was studied. To allow the start of the crack to be nearer than usual to the surface of the specimen, experiments were made on specimens with the notch depth reduced from 2 to 1 mm., the height of specimen required to give an equivalent result being determined for a good-grade refined metal. Results from specimens, both longitudinal and transverse, with notches at the various sides were compared, also the results from square and round specimens. A form of representative all-weld-metal specimen was devised that allowed the Izod results to be more truly representative of a test on a welded joint. The effect on the test result of varying the plate thickness, as well as the interval of time between the laying of the runs, was studied, also the effect of constraining the joint while being welded, some additional comparative experiments being made on rigidly constrained massive welds, chilled with water during deposition. The effect of a low-temperature annealing treatment on the Izod value was determined for several good-grade metals. To obtain data on the liability for results to vary according to the temperature of the test house, tests were made on chosen grades of weld metal, completely refined and completely unrefined, in each of two states of heat treatment.
Identification of the Source of Deposited Matter
Authors: Owens J. S. 
Published: October 2007

When complaints of a smoke nuisance arise it is very important to be able to identify the source. The aim of the paper is to indicate possible methods of overcoming the difficulties of correct identification. Consideration is given to the rate of settlement and the terminal velocity of dust particles, and the application of the physical laws governing deposition. The author has used successfully a method of measurement involving the arrangement of series of gauges in rows extending radially from the suspected source, observations being made with due regard to the prevailing winds. Another method is particularly applicable to the measurement of dust emitted from pulverized coal furnaces, and is based on the tendency of the particles emitted from such furnaces to fuse whilst suspended in the furnace during combustion. Directional deposit gauges have been tried, but so far have not been very successful. The basic idea is to provide a gauge which will separate the deposits from different directions, and various forms have been experimented with.
Second Report of the Pipe Flanges Research Committee
Authors: Tapsell H. J. 
Published: October 2007

The research † has continued to follow the main lines of the programme originally laid down by the Committee, with an important addition, namely that relating to the study of the creep relaxation of model flanges. Some sections of the work are still incomplete; in such cases the data so far obtained are recorded and discussed, but final conclusions must be postponed until the research is terminated. The present report deals with the following sections of work:—(I) an investigation of conditions on the joint under which tightness is maintained at room temperature (p. 433); (II) an investigation of the behaviour of compressed asbestos packing materials under certain conditions of loading and temperature (p. 437); (III) the completion of the examination of the properties of the materials used in the bolt assembly tests (p. 439); (IV) experiments on full-scale bolted flange joints under conditions of high temperature and pressure (p. 441); and (V) creep relaxation tests on model flanges (p. 453).