bluuebunny/crossref_metadata_2025 huggingface dataset:
The Development of Gas Turbine Power Plants for Traction Purposes in Germany
Authors: Bright R. H.
Published: October 2007

The simpler and cheaper construction, and the prospect of using fuel of low quality and of considerably increasing the power-to-weight and power-to-volume ratios of the power unit, led the Germans towards the end of the war to investigate the possibility of using gas turbines for land traction units. It was expected by them that they would be able to employ this new type of power plant for a variety of ground traction purposes, but, owing to their total national mobilization, the most important immediate applications they had in mind were for war purposes. It is considered that the information obtained and given in this paper may prove a useful background when considering the possibilities of future development of gas turbine power plants.

The various arrangements possible, using either one single turbine, or separate turbines to drive the compressor and provide the output of useful work, were considered by the Germans and a résumé is therefore made of the characteristics of each. In addition, the salient features of the components—compressor, turbines, and combustion chamber—and their development for the purposes which the Germans had in mind, are given.
The Measurement of Errors in Gears for Turbine Reduction Drives
Authors: Timms C.
Published: October 2007

The paper forms a review of the work carried out during the past six years at the National Physical Laboratory in connexion with the development of methods for measuring the errors of large gears for turbine reduction drives by means of a series of portable instruments. The relationship between these errors and the inaccuracies of gear-hobbing machines and gear-cutting hobs is discussed. Methods of determining these inaccuracies are described, together with information showing the improvements which have taken place in the accuracy of these machines and cutting tools resulting from the applications of the methods of testing.
Radiology of Joints in Welded Piping for Power Plants
Authors: Thomas E.
Published: October 2007

The type of equipment needed for the examination by radiology of joints in welded piping may vary considerably, especially when the work is carried out both in the shops and on the installation site.

Portable X-ray equipment should be robust and improvements in present equipment could be made. The portability of gamma-ray apparatus is a great advantage, but it has disadvantages in its inferior absorption factor.

The examination of large and of small pipes calls for different procedure as do also the methods of assessing the radiographs.

The determination of the size of fine cracks is largely dependent upon the film-screen combination and there is a need for high-speed fine-grain film. Care should be taken on length of exposure and good facilities should be available for processing work. The location of large faults can be accurately obtained by a technique of double exposure. Of the various types of penetrameters, the “postage stamp” type is considered to be the most suitable for the examination of the welds of pipes.
The Norwich Heat Pump
Authors: Sumner J. A.
Published: October 2007

The paper provides the history and constructional details and working results of what is believed to be the first large heat pump used for building heating in Great Britain. This machine was constructed and installed as an experimental machine for heating a large block of municipal buildings in Norwich.

A brief explanation indicating the principle upon which the heat pump works is given. Reference is also made to the differences between the reversed heat engine when working as a refrigerator and when working as a heat pump. In the latter case there is a deliberate increase in the final temperature T1, from approximately 85 deg. F. to temperatures which may be of the order of 150–200 deg. F. The unsuitability of the term “coefficient of performance”—normally used as a criterion of refrigerator performance—when used as a coefficient relating to the heat pump is pointed out; and the use of a new, alternative term is suggested.

The results are shown of operating the Norwich Heat Pump for two winter heating seasons. When using an unsuitable compressor the heat delivered to the building was found to be 3·45 times greater than the equivalent heat (electric) energy required to operate the machine, averaged over the 1945–6 winter heating season. With a more efficient compressor, installed later in 1946, a still better performance is anticipated. The actual costs of heating the building, with coal-fired boilers and a heat pump respectively, are shown in the form of a table. Conclusions indicated are that the heat pump can show a financial saving, as compared with the use of coal-fired boilers, and that it is practicable to use the heat pump in Great Britain for building heating throughout normal English winters.
The Prospects of the Steam Cycle in the Central Power Station
Authors: Martin G. H.
Published: October 2007

The advent of the gas turbine and its effect on the position of the steam turbine for the central power station is briefly discussed. In the opinion of the author the steam turbine will hold the field for large power generation for many years to come, and there is no immediate prospect of any other form of prime mover becoming a serious competitor for the generation of electricity in the central power station.

Data are given indicating the gain in thermal efficiency that can be expected from increased steam conditions up to 2,000 lb. per sq. in., and 1,000 deg. F. with and without reheating.

The advantages of reheating as a means of obtaining higher efficiency are strongly emphasized. Methods of operation to enable quick starting are discussed.

Some of the principal constructional problems created by high steam conditions are briefly discussed and methods of overcoming the difficulties are indicated.

The essence of the paper is to examine, in as simple a manner as possible, the means available for improving the efficiency of the central power station; and in an effort to achieve this, detailed methods of calculation are not included, as it is considered they would detract from a clear appreciation of the results. The minimum of assumptions have been made, so that the curves represent a true picture of the actual gains that could be obtained in practice.
The Gas Turbine as Applied to Marine Propulsion
Authors: Crowe T. A.
Published: October 2007

The paper commences with an historical survey of gas-turbine development, and deals briefly with the constant-volume and constant-pressure principles. Under the latter are included the open, closed, and semi-closed cycles. Notes are added on air heaters and heat exchangers, materials required for gas-turbine components, and systems of control.

The latter portion of the paper covers the application to marine purposes, and describes some current marine-turbine installations. In view of the small number of the moving parts, gas turbines should eventually prove as reliable as older forms of propulsion machinery. Life should not be less than 100,000 hours at full load and temperature, but, as creep tests of this duration are impracticable, the designer must at present base his calculation on rather meagre data. Up-keep costs should, once the initial difficulties have been overcome, compare favourably with those of other forms. A gas turbine of 5,000-10,000 s.h.p. per shaft can be constructed to give a fuel consumption of 0·44-0·46 lb. per s.h.p.-hr. (giving a thermal efficiency of more than 30 per cent on the gross calorific value of the fuel), and the figure should improve to 0·38 lb. (comparable with the Diesel consumption) when metallurgical developments allow the initial air temperature to be raised by 150 deg. F. It should be able to burn the cheaper grades of boiler oil. The gas turbine is lighter in weight and occupies less space than the corresponding steam-turbine or Diesel installation.

The author concludes that it will earn a fundamental place in marine propulsion during the course of the next few years.
Modern Applications of Photo-Elasticity
Authors: Heywood R. B.
Published: October 2007

It has long been known that polarized light may be employed to analyse the stresses occurring in engineering parts. Recent modifications have simplified the apparatus required, so giving a wider scope to the application of photo-elasticity to engineering. The method of preparing transparent models for stress analysis is discussed, and the significance of the photo-elastic fringes is explained. Only the boundary stresses in the model are considered, and their importance is demonstrated by means of examples, such as the modification of the design of aero-engine parts so that a substantial increase in strength is attained. The procedure for evolving the best shape of fillet for a particular set of conditions is given.

The three-dimensional “freezing” technique is described, a technique which enables the boundary stresses in parts of complicated shape to be determined, and has the further advantage that an assessment of the elastic distortions may be made. Examples of the application of photo-elasticity include a connecting rod, crankshaft, poppet valve, and gear wheel.
A Theoretical Discussion of Pitting Failures in Gears
Authors: Beeching R. , Nicholls W.
Published: October 2007

This paper is primarily concerned with the theoretical consideration of the stresses that cause surface failure of gear teeth.

Methods of calculating the permissible line load between contacting cylindrical surfaces for static or cyclic conditions are considered, and the probable effects of friction are discussed qualitatively.

Maximum permissible case thicknesses are suggested for case-hardened steel components of varying core strength when subjected to contact stresses of the type encountered in gears, rollers, and cams.

In the Appendix is given an account of the derivation (from Hertz's general solution) of expressions for the principal stresses at any point in the neighbourhood of the zone of contact between parallel cylinders. These expressions, which lend themselves to ready computation, reduce to the same form as those derived by Thomas and Hoersch for stresses in the plane of symmetry, but they are more widely applicable.
Thrusts and Stresses in Two-Dimensional Pipe Expansion Bends
Authors: Finniecome J. R.
Published: October 2007

The primary aim of the paper is to present the fundamental theory on the thrusts and stresses of two-dimensional pipe expansion bends incorporating the Karman flexibility factor. The application of this theory to a series of typical expansion bends is demonstrated for three well-established methods of fixing the ends: fixed at one end and free at the other, fixed at one end and guided at the other, and fixed at both ends. A series of tables summarizes the formulae and data on the expansions, thrusts, and bending stresses for 90 deg. bends, 180 deg. U-bends, and 45 deg. lyre expansion-bends for the three methods of fixing the ends indicated above.

The importance of the methods of fixing the ends of expansion bends on the thrusts and bending stresses for four typical cases is indicated in a table that gives the ratio of the resultant thrusts and maximum bending stresses due to expansion for bends fixed at one end and guided at the other end, and for those fixed at both ends, in relation to the corresponding amounts for bends fixed at one end and free at the other.

The detailed analysis for typical cases shows distinctly that the thrusts and bending stresses are greatly increased for a pipe bend fixed at both ends or fixed at one end and guided at the other, as compared with those fixed at one end and free at the other.
Basic Principles of Automatic Control Systems
Authors: Porter A.
Published: October 2007

The importance of automatic control systems in a wide field of industrial and military applications has been accentuated during the past few years. The object of this paper is to review some of the basic principles of the subject, with special reference to automatic regulating systems.

A major difficulty at present is the lack of standardization of the terminology associated with automatic control systems; in this paper an attempt has been made to co-ordinate, albeit on a small scale, generally recognized industrial usage with the recommendations of the Ministry of Supply Servo Nomenclature Panel. It is convenient, for example, to consider an automatic regulator system as a special type of servo-system. In order to present the nomenclature in a manner which may be readily assimilated, the operation of a simple automatic speed regulator is described in detail.

The performance of an automatic control system is usually assessed by ( a) the speed of response of the system subsequent to a sudden disturbance, ( b) the nature of the response, and ( c) the magnitude of the steady-state errors. In the case of complex control systems, such as fire-control systems, it is sometimes desirable to study, in addition, the frequency response characteristics of each main element, and to determine the overall performance of the system by the application of vector methods. The latter have been used widely in the solution of acoustical problems, and in the design of electronic feed-back amplifiers, and their adaptation to the analogous problems of servo-system design has considerably facilitated progress.

The stabilization of automatic control systems, and the elimination of steady-state errors can often be achieved by the incorporation of subsidiary feed-back loops. For example, a comparison of the basic operation of a typical position control servo-system with that of a typical automatic regulator shows that certain lags in the operation of the latter can be short-circuited by introducing “disturbance feed-back”. This approach to the problem of improving the performance of these systems does not appear to have been treated extensively in the literature. Its value is demonstrated in the paper by comparing the responses of certain idealized automatic thermal regulating systems, some incorporating “disturbance feed-back”, and others with straightforward controllers.
An Electrical Potential Analyser
Authors: Redshaw S. C.
Published: October 2007

The electrical potential analyser provides, in effect, an electrical analogy to the solution of Poisson's and Laplace's equations when expressed in finite difference form. The principal object in designing the instrument was to provide an experimental alternative to the “relaxation” technique which, although invaluable in the solution of many problems, is often very lengthy and tedious.

The potential analyser consists essentially of a square mesh, the nodal points of which are interconnected by low value wire resistances, and a base. Corresponding nodes on the mesh and base are connected through high value resistances. A current is applied in such a manner that an electrical potential is provided, as required, to points on the mesh and the mesh boundary; the base being either used or discarded according to the nature of the problem. Readings of potential at each mesh node are recorded by a suitable galvanometer circuit.

An analyser having a square mesh, such that the mesh separation is 1/12 the side length, has been constructed and encouraging results have been obtained with its use. The instrument is easily operated and results are rapidly obtained.

The use of the analyser is not limited to the solution of Poisson's and Laplace's equations. By a suitable interchange of network resistances, other equations which can be expressed in finite difference form may be solved and solutions to problems involving irregular boundaries present no undue difficulty.
A Comparison of Some Carbon Molybdenum Steels on the Basis of Various Creep Limits
Authors: Johnson A. E. , Tapsell H. J.
Published: October 2007

A previous report gave the results of an experimental study of the relationship between short-time and long-time creep limits of a number of carbon steels. Certain conclusions were drawn which it was realized were not necessarily applicable to other types of steel. Similar experimental work has since been carried out on six carbon molybdenum steels, and the results obtained indicate similar limitations in the applicability of short-time creep limits to estimation of design stresses for long-time service, as were disclosed by the prior tests on carbon steels. There is not, at first sight, any reason why short-time and long-time creep limits should correlate, since with most engineering materials metallurgical changes occur during prolonged heating.
The Prospects of Land and Marine Gas Turbines
Authors: Constant Hayne
Published: October 2007

At the end of the 1939–45 war, the rapid developments that had taken place in the aeronautical gas turbine during the previous decade became generally known to engineers, and the advent of this turbine naturally turned their minds to its possible application to other forms of power production. In his lecture the author considers the world conditions under which the gas turbine for land and sea use is being developed, and attempts to assess its prospects. If some of the problems remaining to be solved are overcome, it is possible to foresee a wide field of usefulness for this prime mover. When the present world-shortage of liquid fuel is eased, the gas-turbine locomotive will become a strong competitor to the steam locomotive, and, whatever the liquid-fuel position, it will shortly be able to meet the Diesel-electric locomotive on more than equal terms. The prospects for marine use turn on its ability to burn heavy residual oils. For base-load power stations, its widespread use is dependent on the practicability of its being linked to a district heating system, so that the best use can be made of its waste heat.
Heat Flow in the Gas Turbine
Authors: Smith A. G.
Published: October 2007

In this lecture experimental data are presented on turbine-blade heat transfer, which is an important factor in the design of high-temperature turbines. Blade stagger has a considerable effect on blade Nusselt number and on the rate of variation of Nusselt number with Reynolds number. For nozzleblades, theoretical and experimental values of the Nusselt number agree fairly well. A method is proposed for the approximate estimation of Nusselt number by Keynolds analogy. The experimental data are used in the calculation of heat flow in blades cooled at the root, and in internally air-cooled blades.

Other methods of cooling have been proposed, including partial admission of cold air or liquid through the nozzle ring; the theoretically advantageous “sweat” cooling by exuding coolant air through a porous skin, or the injection of coolant air through slits; root cooling might include modifications, such as effective increase of blade conductivity by tubes of liquid embedded in the blade or reduction, by an insulating layer, of the amount of heat conducted to the blades; internal liquid cooling by forced or convective circulation is a possible alternative to internal air-cooling. Some of these methods have been successfully used-for example, internal air-cooling of hollow blades in German jet engines; internal liquid-cooling in an experimental German turbine; and a certain degree of “root” cooling in British aircraft turbines. Theoretical analysis of the problem of turbine cooling has been rendered difficult, in the past, by absence of data on blade heat-transfer coefficients.

For root-cooled blades of heat-resisting alloy the cooled region is small, but it would be satisfactorily large for nozzle blades of high-conductivity material. Internal air-cooling needs only small quantities of coolant, provided a high internal blade conductance is achieved by subdividing the internal flow passage. The effectiveness of root-cooling diminishes with increase of scale; on the other hand, the relative cooling air quantity necessary to cool a blade internally diminishes with increase of scale.

The heat exchanger is a bulky and expensive component of most “plant” gas-turbine systems, and with the aim of size reduction “regenerative” type exchangers have been investigated for some time as an alternative to the bulky recuperative type. The lecture deals with the advantage in bulk of the regenerator, and gives some relevant data on heat-transfer in laminar flow
Large-Scale Torsional Fatigue Testing of Marine Shafting
Authors: Dorey S. F.
Published: October 2007

The paper describes the design and construction of a new type of torsional fatigue testing machine of the resonance type capable of generating a reversed harmonic torque of up to ±3 × 106 lb.-in. in a stationary test shaft, at a frequency of approximately 2,500 vibrations per minute. Reference is made to a specially developed electronic method of speed control capable of regulating the nominal stress in the specimen to within one per cent.

The paper includes the results of a number of fatigue tests carried out on 9 3/4-inch diameter mild steel shafts, and also on “Meehanite” cast-iron specimens of 6 inches diameter, and concludes with some remarks on scale effect, based on results from 1/2-inch diameter specimens subjected to reversed torsional fatigue tests carried out on a combined-stress fatigue testing machine at the National Physical Laboratory.
Crankshaft Damping
Authors: Draminsky P.
Published: October 2007

The author attempts to give a correct physical explanation of natural damping by torsional vibrations, and also to obtain approximate formulae for pre-calculation of the damping in any given case.

The paper describes experimental work with a single-cylinder engine driven by external power, and excited to torsional vibrations by a spring-loaded cam disk. In this way the damping from the moving parts could be investigated separately, and it was found that the damping was almost entirely due to hysteresis in the crankshaft, and oil damping, due to lateral shaft movements in the main and crankpin bearings, which was directly proportional to the bearing clearance.

The paper also gives a simple and practical method for the calculation of damped vibrations in arbitrary elastic systems, and the calculation of hysteresis and bearing damping in a single-cylinder engine. Formulae are given for the total damping in multi-cylinder engines, with or without heavy flywheels, and the results are compared with the measured damping of oil engines in service.
Graticule Ruling in Australia
Authors: Shaw Mansergh
Published: October 2007

The problems of precision manufacture in Australia, arising chiefly from her geographic isolation, are first discussed. The paper then takes one particular problem from the field of optical manufacture and shows how it was solved for the conditions prevailing in the Dominion. The problem discussed is the production of graticules, or reticles, for range-finders, predictors, gun sights, telescopes, binoculars, microscopes, collimators, and many other such instruments.

The first part of the paper deals briefly with methods used in reproducing the pattern, particularly the ruling and etching process. The second, and much the larger, part of the paper deals with the design of the high precision machines which were made for ruling the glass disks preparatory to etching the pattern into the glass. Two such machines were developed, one generating the pattern from the movements of the machine itself, the other, a pantograph, by copying the pattern from master plates. A series of self-checking tests is described by which the accuracy of the generating machine could rapidly be tested to an accuracy of much better than 0·0001 inch. A brief survey of the complete process, from glass blank to finished graticule, is made in the Appendix.
Control of Production
Authors: Lister S. W.
Published: October 2007

The author sets out to describe the basic principles of production control, and after a brief analysis of the nature of the problem, administrative set-up is described, and reference made to the work of Taylor. The importance of apportioning material before it is issued from the store is emphasized, and the fundamentals of stores accountancy are stated.

Accurate and exact planning is the keystone of good production control, and the consecutive processes to which each part must be subjected in the planning department are described. One of the most important of these is the difficult job of estimating standard times of manufacture; records of past performance are useful, but the only really reliable method is time study, the principles of which are very briefly mentioned.

No plan of manufacture will work to schedule without a good scheme of incentives for the workers. The guiding principles which have to be kept in mind when preparing a bonus scheme are discussed, and the use of standard minutes applied to individuals and groups is considered.

The general lines of procedure on which production control in the works should operate are given in a consecutive form, from the actual booking of an order to the processing of parts through the plant, and the collection afterwards of records of performance. The requirements of production control are then listed under ten headings, and the paper concludes with a few of the more practical points which occur, in firms of various sizes, where parts are being processed to a pre-arranged plan.
The Full Journal Bearing
Authors: Cameron A. , Wood W. L.
Published: October 2007

The basic mathematics of the full journal bearing have been known since 1904 when Sommerfeld‡ made the complete solution, for the infinite journal, of Reynolds theory of 1886. The detailed application of the theory has not been possible owing to the uncertainty in the choice of boundary conditions. In this paper the Reynolds condition that p = 0 at θ = 0 and p = ∂ p/∂θ = 0 at θ = π + α is shown to follow for the infinite bearing from a consideration of continuity of flow and, equally important, from the shaft stability condition, first put forward by Swift in 1933. It is claimed that this is the final answer to the question of correct boundary conditions.

The Reynolds equation for the infinitely wide bearing was solved using these conditions. Assuming the viscosity is constant all round the bearing, the coefficient of friction-load criterion curve has the same slope as experimentally determined curves.

The Mathematics Division, N.P.L., computed, by Southwell's relaxation methods (1946), the figures for finite bearings of diameter length ratios of 4, 2, and 1. The theoretical figures for eccentricity ratio-load criterion are satisfactorily compared with some of Nücker's experimental results, and the coefficient of friction, load criterion, figures explain the apparent intercept found by McKee and McKee.

A diagram is given allowing the eccentricity ratio c, to be obtained from the load criterion for any bearing of diameter/length ratio from 0 to 4, and this enables the minimum film thickness, which equals (1 — c) x radial clearance, to be calculated.
Producer Gas for Road Transport
Authors: Hurley T. F. , Fitton A.
Published: October 2007

Immediately before, and during the 1939–45 war a considerable amount of research and development work on the use of producer gas for road transport was carried out by the Fuel Research Station, in close co-operation with several other interested organizations.

Road tests showed that none of the existing commercial producers was entirely satisfactory with the fuels most readily available in this country. A new dry-blast cross-draught producer, known later as the Government Emergency Producer, capable of using either anthracite or low-temperature coke, was therefore developed. At the same time the effect of variations in the quality of the fuel was examined and a specification for transport producer fuel was prepared.

A survey of potential fuel supplies revealed that the output of fuel complying with the specification, although considerable, was insufficient for general use. Accordingly a modified Emergency Producer—known as the Government Utility Producer—was developed, and this was capable of using coke prepared under special conditions in “high temperature” retorts, thus greatly extending the amount of available fuel. “Activation” of the fuel with sodium carbonate effected a further extension. The serious problem of engine wear was solved by the development of new types of filter to remove dust from the gas.

The present position is that, although producer gas is a poor substitute for petrol in a converted petrol-driven vehicle, there is no doubt that transport could be operated on a large scale on producer gas should the necessity arise.
Some Operating Experiences with High-Pressure Steam Power Plant
Authors: Clinch W. N. C.
Published: October 2007

Between the years 1938 and 1944 the Northmet Power Company placed in commission four high-pressure steam power plant installations comprising 50 and 60 megawatt units at Brimsdown “A” and “B” Power Stations respectively, operating on the 1,900 lb. per sq. in., 930 deg. F. reheat cycle, and two 32 megawatt non-reheating units at Willesden Power Station, operating at 1,300 lb. per sq. in. and 950 deg. F.

These cycles were selected for the respective sites from considerations of coal cost and of circulating water make-up facilities, both stations relying upon rail-borne coal supplies and operating with cooling towers. The capacity and design of the plant were largely determined by the available space, existing buildings being utilized to accommodate most of the new machines and auxiliaries.

The pressure and temperature conditions involved consideration of creep characteristics in selecting suitable alloy steels for the pressure parts, and their mechanical properties were closely investigated before contracts were placed. Welding was extensively employed in boiler and pipework construction, and preliminary tests and subsequent radiographic examination presented many interesting problems.

Early performance figures promised the achievement of the thermal efficiency to be expected from the cycles, and subsequent experience shows that, as indicated by theoretical considerations, the 1,300 lb. per sq. in. cycle is capable of equal or greater economy than the higher pressure with the reheating arrangements.

Certain difficulties in operation have been encountered—not all inherently associated with high-pressure working. The paper gives an account of these difficulties and of the steps taken to surmount them.

In the light of these operating experiences, the future of high-pressure steam power generation is discussed with comments on features which are considered essential to a successful design of plant. The initial ventures are felt to have been justified by results and by the contribution made to mechanical engineering in general. The present and future urgent need for coal for international barter calls for the fuller development of the use of high-pressure cycles, and experience to date warrants a continued advance toward their more general application.
The Use of Plumber's Resin to Determine the Occurrence of Yield
Authors: Blair J. S.
Published: October 2007

Brittle lacquers used for the determination of elastic stress have a number of disadvantages, particularly in connexion with the technique of applying them and the need for careful calibration in each case. They are not generally applicable to the whole of very large specimens such as bridges.

Plumber's resin provides much the same information more readily and needs only a simple technique. It has, however, the disadvantage that it is necessary to stress the specimen slightly beyond the yield point. The technique of applying it, which is described in detail, consists in little more than the essential point that the resin must be applied hot without the use of a solvent.

After the specimen has been stressed beyond the yield point, Lüders' lines are shown by the resin at those points which have yielded. Thus, not only is the ratio of applied load to yield point obtained—and hence the relationship between stress and load in the elastic range, but the most highly stressed parts are immediately indicated on even the most complicated structure, and the Lüders' line pattern gives information as to the type and direction of stress.
A Single-Cycle Test Apparatus for Studying “Loop Scavenging” in a Two-Stroke Engine
Authors: Sammons H.
Published: October 2007

An apparatus is described for studying the process of scavenging the cylinders of loop-scavenged two-stroke engines. This consists essentially of a full-scale single-cylinder model of the engine with means for driving it for a single porting cycle.

Tests upon the apparatus are made at atmospheric temperature and different gases are used at appropriate pressures to simulate the correct densities of the engine air charge and exhaust gas. The choice of suitable gases permits an easy analysis of the trapped charge for the determination of the efficiency of the scavenging process.

Some experimental results and conclusions are presented, including the effects of operating with high charge densities and exhaust back pressures.

A method is developed of expressing, from the experimental results, the scavenging performance of a given design of ports. This takes the form of curves relating the volumetric total charge supplied and the charging efficiency with the pressure ratio across the ports. These relationships are otherwise independent of the mass charge, the intake density, the exhaust back pressure, and the pressure loss across the cylinder.

The influence of crankshaft speed is examined, as also are some causes of lost efficiency.
Research on the Compression-Ignition Engine and its Fuels
Authors: Vaile P. E. B.
Published: October 2007

This paper, an abstract of the original, is intended to provide information concerning the present status of Diesel fuel research.

The paper is divided into two parts, the first of which concerns the types of fuel in use, describing briefly their sources and properties. A short account is also given of the existing fuel situation and how this may influence future research.

Part II deals with the effects of fuel characteristics on engine performance, wear, and fouling. The methods of overcoming any deleterious effects caused by the fuel are discussed, and particular reference is made to the beneficial effects of lubricating oil additives.

It must be emphasized that most of the work described refers to the high-speed Diesel engine, owing to the unsuitability of large units for laboratory testing. However, this is beneficial since the high-speed Diesel is most sensitive to fuel characteristics, and it serves to disclose the majority of defects that can arise in a Diesel engine.
The Thermal Efficiency of a Hand-Fired Natural-Draught Lancashire Boiler
Authors: Hurley T. F. , Sparkes W. J.
Published: October 2007

Following the development of the Fuel Research Station “smoke eliminator” fire doors for hand-fired, natural-draught Lancashire boilers, a series of trials was carried out to obtain figures for their performance under a variety of conditions. Most of the trials were made with one or other of two sizes (”singles” and “smalls”) of a Northumberland coal, which was chosen because of its tendency to make heavy smoke; similar results were obtained with both sizes. The figures obtained during these trials, together with those of a few supplementary trials, are used to illustrate the effects of certain variables upon the performance of a boiler of that type. The information presented includes (1) the correlation of smoke intensity with the composition of the flue gases and with thermal efficiency, (2) the use of secondary air and suitable methods of firing to reduce the heat losses caused by incomplete combustion, (3) the effect of too little and of too much excess air upon efficiency, and (4) the effect of load upon efficiency.

With the special fire doors, the admission of secondary air over the fire could easily be controlled and a simple method of firing could be employed. In consequence, the efficiency of combustion was maintained at a consistently high level without calling for exceptional skill or effort on the part of the fireman. Maximum efficiency was obtained when the quantity of secondary air was just sufficient to eliminate smoke: decreasing the percentage of excess air by a small amount below the optimum had as bad an effect upon efficiency as a considerable increase. Varying the load also affected efficiency, the maximum being reached well below rated load, but the variation in efficiency between 40 and 100 per cent of full load was comparatively small.
The Influence of Certain Factors on the Performance of a Lancashire Boiler
Authors: Ritchie E. G. , Kirov N. Y.
Published: October 2007

The paper summarizes results obtained in a programme of research carried out by the British Coal Utilisation Research Association, under the guidance of the Shell-type Boiler and Firing Equipment Committee, an advisory committee convened by the Association in 1943.

In this country, 70–80 million tons of coal are consumed per annum in shell boilers of different types or burnt in industrial and heating furnaces in which mechanical firing is, or might be, employed. It is probable that 45–50 million tons per annum are used for steam raising in Lancashire boilers and it is more specifically with this type of boiler that the paper deals.

Excess air admitted through or in the neighbourhood of the fuel bed in a boiler represents, perhaps, the most important source of inefficiency, owing to the fact that it results in a substantial increase in gas temperature at the boiler exit. The experiments quoted show that, in terms of fuel consumption per pound of steam produced, increase in exit-gas temperature is responsible for approximately 50 per cent of the total effect of excess air. The elimination of excess air entering the furnace tubes of a Lancashire boiler represents one of the most important possibilities of effecting fuel economy on a large scale.

The rate of evaporation in relation to the normal rating of a boiler is another important factor. The investigations described show that, over a wide range of conditions, the heat absorption efficiency of a Lancashire boiler—without an economizer—decreases by 2 per cent for each 1,000 lb. per hr. increase in evaporation. The corresponding figure for the complete plant—boiler and economizer—is 1·8 per cent. It is suggested that the most efficient rate of evaporation with this type of boiler is approximately 70 per cent of normal rating. Under these conditions, with modern equipment and suitable fuel, operating efficiencies up to 80–85 per cent should be practicable.

Brief reference is made to “unaccounted” heat loss as an important item in the testing of a boiler and to the influence of boiler and stoker type and the effect of fuel characteristics on efficiency. Many of the points mentioned in the paper are being further investigated in the steam engineering laboratories of the British Coal Utilisation Research Association.
The “Lost Wax” Process of Precision Casting
Authors: Turnbull J. S.
Published: October 2007

The paper describes a casting process which differs from standard foundry practice in that it uses a wax pattern in a high refractory one-piece mould to produce metal castings with a good surface finish to an accuracy of ±0·002 inch.

The process involves making a master pattern in either hard wood or metal, relating it to a soft metal die by precision casting technique, and then the production of wax patterns from the die on an injection machine. Finally, the wax patterns are invested in refractory moulds, the wax is melted out, the mould baked, and the metal component is cast.

The “lost wax” process is advantageous in cases where ( a) the metal is unmachinable, or ( b) where the component is of an unmachinable shape, or ( c) where production by other methods takes too long. One of the most common applications is in the manufacture of gas-turbine blades.

The tool costs are relatively low compared to the costs involved in alternative methods of manufacture, the die cost being a function of the number of castings required.

The production of cheap castings is necessarily dependent on the scrap percentage being kept to a minimum; at present the scrap from the manufacture of gas-turbine blades is less than 30 per cent, and the author surmises that it would not be unreasonable to expect it to be less than 10 per cent in two years' time.
Simplification Creates New Problems for Top-Management
Authors: Merritt H. E.
Published: October 2007

The reports of the Lemon Committee and of the Anglo-American Council on Productivity draw timely distinctions between the terms “standardization”, “simplification”, and “specialization”. This paper discusses simplification, with special reference to complex proprietary engineering products.

The problems examined are those of determining and controlling a range of simplified products; the determination of domestic standards, classified as “manufacturing standards” and “constructional standards” for the components of those products; the need for, and effect of, more refined manufacturing standards with increasing volume of production; the possibility of obtaining varieties of end-product by alternative assemblies of simplified components, through what is here tentatively termed “rationalized construction”; and the increased complexity of the technical problems which the development of those products entails.

Finally, attention is directed towards the new problems and responsibilities with which simplification confronts top-management, partly in the closer control of line of products, but chiefly in the integration of the design, production, and marketing functions.
High-Pressure Vessels in the Chemical Industry
Authors: Granville J. J.
Published: October 2007

The development of high-pressure processes (200–1,500 atm.) in the chemical industry in recent years, often carried out at high temperatures, has helped considerably to cheapen the production of basic materials, such as ammonia and methanol, and has opened up entirely new fields, particularly in the manufacture of important plastic materials, in coal hydrogenation, and in oil-cracking operations, calling for special equipment and novel techniques.

This paper deals with the mechanical requirements for high-pressure vessels, and traces progressive changes in their construction during the last thirty years, from cast autoclaves to forged vessels and to modern composite designs, having due regard to the volume-to-weight ratio, construction, inspection, cost, and maintenance.

Stress distributions in the cylinder wall, suitable closure mechanisms, the effects of temperature, chemical and physical attacks, and the provisions for stirring, heating, and cooling are discussed.

A brief account of the control mechanisms involved and of the necessary vital safety precautions is given.
Mechanical Engineering in the Midlands, 1925–1950
Authors: Everard F. Vincent
Published: October 2007

Developments of popular interest that have taken place in the mechanical engineering industry in Birmingham and the surrounding districts by the year 1950, which is not only twenty-three years since the Institution last met there but also is the turn of the half century, are briefly surveyed. Power plant, incorporating steam boilers, steam turbines, oil engines, and gas turbines, is discussed, with special reference to the development of the oil engine and its adaptation for special usage in the 1939–45 war.

Changes in public and private road transport engines are traced up to the first turbine-engined private motor car.

Improvements in the design of machine tools from practical and aesthetic aspects are touched upon. Mass production and its effect on the craftsman, and advances that have been made in factory management, amenities, and the prevention and treatment of accidents are mentioned, as also is the rehabilitation of workmen, with special reference to the work carried on by the Birmingham Accident Hospital. In processes, the hydroblast method of cleaning castings and the automatic rustproofing of car bodies are described.
Education and Training in Engineering Management
Authors: Nelson H. G.
Published: October 2007

The paper reviews some of the facilities for management training now available, under the headings Education (in reference to courses), Practice (in reference to engineering apprenticeships), and Experience (in reference to interdepartmental experience gained after apprenticeship, and to the exchange of experience in discussion on management problems at professional institutions).

The term “management” connotes anything from top-management to junior supervision, and the problems and treatment differ according to the nature of the firm and the level of management considered. Discussion should indicate clearly, therefore, which type of management is under review and, with respect to educational schemes, for what kind of personnel (apprentice, post-graduate apprentice, or post-apprenticeship) the schemes are intended.

Some important considerations dealt with individually in the paper include: the provision of facilities for training by individual firms; education in leadership; selection of personnel for management training; the first position of responsibility; and the dangers of over-emphasis on management training.
The Practical Application of Frequency Response Analysis to Automatic Process Control
Authors: Rutherford C. I.
Published: October 2007

The paper shows how the basic principles of frequency response analysis may be applied to automatic process control without the introduction of any of the mathematics which are used in the servomechanism field of study, and which have in the past discouraged its use in the process field.

It is shown how the frequency response of any part of an automatic control system may be represented graphically, how the response of any simple element of a system may be calculated, and how the response of the individual elements thus obtained may easily be combined to give the characteristics of the whole plant. Alternatively, the frequency response of the plant may be plotted experimentally without interrupting its operation.

By reference to a typical example, it is shown that all proprietary “three-term” controllers do not necessarily function as simple theoretical controllers, but that their performance may often be represented as that of an effective theoretical controller, and may, in any case, be shown as a frequency response diagram from which the necessary information is available to match the controller to any particular process.

The method introduced is shown to give a convenient measure of plant controllability, and by means of plant analysis on this basis, it is suggested how automatic control may often be improved by better design of the process rather than of the controller.

The design of automatic controllers is also treated, and it is shown how various design features may be compared in the light of their frequency response characteristics. It is suggested that future controllers should be designed to give a specified frequency response.
The Particle Size Analysis of Crushed Products
Authors: Ratcliffe A.
Published: October 2007

An examination is made of two particle size analyses which are typical of two categories of crushed products. One example represents material reduced in a hammer mill; subjected to indiscriminate reduction, it contains a preponderance of smaller sizes, and this is characteristic also of ball mill products and the small particles in the products of jaw, gyratory, and roll crushers. The second example illustrates the influence of the sizing action which occurs in the latter machines and results in a closer grading of the coarse particle fraction.

These characteristic features are illustrated by graphs, and a mathematical basis is given for Gaudin's law of particle size distribution.