bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Measuring Force, Stylus Radius, and Surface Finish on the Accuracy of Measurement of Work-Pieces by a Comparator
Authors:   Industrial Administration and Engineering Production Group, Nickols L. W. , Oakley T. R. J.
Published: October 2007

An investigation is described which was undertaken to determine the effect of the measuring force and stylus radius of the comparator on the measured sizes of work-pieces made of the materials and having the machined finishes commonly used in engineering. The information was required to enable recommendations to be made concerning the performance and certain features of engineers' measuring instruments. The sizes of the work-pieces were measured using styluses of different radii under successively increased measuring forces. It was found that the sizes obtained at any one point were influenced mainly by alterations in the measuring force, and that the effect of the surface finish was relatively small. The relation between the measuring force and the magnitude of the deformation at the contacting surfaces of a solid stylus and a work-piece followed a law similar to that derived by Hertz from theoretical consideration of elastic deformation, despite the appreciable plastic deformation of the work-pieces that occurred in some instances. Variations in the measured sizes over an area of a work-piece were influenced more by the surface texture of the work-piece than by the radius of the stylus used.
Inspection of Primary Circuits and Reactor Pressure Vessels of Nuclear Power Plant
Authors: Pemberton H. N. , Crossley E.
Published: October 2007

In this context inspection relates to the acceptance of design and construction, and of components that have been in service. Inspection details of the pressure parts of British gas-cooled power reactors is outlined and discussed. Reference is also made to steel containment pressure vessels.

The main problems presented by reactor pressure parts are associated with the large size and also site fabrication. Periodic inspection of plant is restricted to date to those parts that do not emit dangerous radiations. While contamination of the other parts by radioactive dusts introduces another limitation, experience over four years at Calder Hall has shown that components on the heat-exchanger side of the stop valve can be efficiently examined. The need for extension of periodic inspection to the remaining circuit components of gas-cooled nuclear-power plants is emphasized. Reference is made to the need for radical improvement in leak tightness of circuits. Also of the desirability of maintaining simplicity and including essentials only in new specifications or codes of practice for reactor pressure-vessels and circuit components.
Considerations of the Lubrication of Free-Piston Gas Generators
Authors: Hosie R. M. , Barrett G. M.
Published: October 2007

The paper reviews very briefly the development of the Pescara free-piston engine and outlines the general constructional features of the GS 34 design of free-piston gas generator. The arrangements for the application of lubricants are described, illustrating the total loss and circulating oil systems. The requirements of lubricants are discussed together with some operating troubles associated with lubrication. The paper concludes with the contention that the individual efforts of the engine and petroleum industries will find their best return in co-operative action at all stages of further development.
A Comparison of Materials for Use as Unlubricated Journal Bearings
Authors:   Lubrication and Wear Group, Simpson F. F.
Published: October 2007

A number of materials have been run as unlubricated plain journal bearings, against mild-steel journals, at a number of combinations of load P and speed v sufficient to cause failure within 100 hours. For each material the bearing life for various values of P and v giving the same product were similar, but the materials differed greatly in the P and v value which resulted in similar bearing lives.

Polytetrafluoroethylene (P.T.F.E.)-lead-bronze appeared to be outstanding, supporting Pv values as much as 30 times greater than those that resulted in a similar life for other materials and surface treatments commonly used as unlubricated bearings.

The performance characteristics of the various materials are commented on.
Performance of Forging Presses
Authors:   Hydraulic Plant And Machinery Group: Industrial Administration And Engineering Production Group, Stern H. , Green J. I. T.
Published: October 2007

After briefly sketching the history of performance trials conducted by the authors' organization, the importance of making forging presses fast acting at minimum capital cost is established. Extracts from trial results taken on presses with direct, steam-intensifier, and accumulator drive are included and discussed. Inherent features particular to each of these drives are distinguished from those common to all, or applying to particular presses only. Of the three kinds of drive considered, the steam-intensifier drive is deemed obsolescent. The advantages and disadvantages of the other two types of drive are reviewed, with special reference to performance. It is concluded that the full benefits of fast-acting presses can only be realized by parallel improvement in manipulation and the development of position control.
Design of Irradiation Experiments
Authors:   Nuclear Energy Group, Atkinson J. R. , Rigg S.
Published: October 2007

The effect of in-pile irradiation on fissile and non-fissile materials is discussed briefly, distinction being drawn between the effects of neutrons, β particles and γ rays. It is the purpose of this paper to discuss the design of experimental equipment needed to investigate these effects. The eight phases of an irradiation experiment are discussed and attention is drawn to the importance of the initial specifications. Methods for determining the fluxes and heat generation in test rigs are given. Five experiments are described in some detail. The description of the carbon dioxide semi-static experiment gives a method of controlling the non-fissile specimen temperature in-pile. The graphite-carbon dioxide dynamic mass transfer experiment is designed to investigate the transfer mechanism in graphite-moderated carbon-dioxide-cooled reactors. The liquid metal mass transfer experiment poses special problems of safety. The description of the water-cooled fuel specimen experiment shows how the temperature of the specimen is maintained constant even during pile shut-down. The advanced gas-cooled reactor (A.G.R.) fuel cluster experiment is described to show the difficulty of simulating operating reactor conditions in a materials-testing reactor. The paper is concluded by a brief reference to the philosophy or thinking of irradiation experiments.
Blade Profiles for Axial-Flow Fans, Pumps, Compressors, Etc.
Authors:   Applied Mechanics Group, Carter A. D. S.
Published: October 2007

In this paper the basic factors controlling blade-section performance are first examined. It is shown that substantial differences in performance may be expected from profiles having different fluid surface velocity distributions. Thus some distributions favour a wide working range while another may be more suitable for very high-speed operation, and so on. A desired velocity distribution may be achieved by appropriately selecting the various physical parameters, such as maximum thickness, position of maximum thickness, position of maximum camber, etc. which define the blade profile. Thus if a particular performance in terms of inlet angle, deflection, Mach number, and incidence and Mach number range, is specified, there will be a particular blade profile to do the job. These conditions will have been determined by the overall design considerations, and the various features which the profile designer can then choose to meet them are fully discussed in the second part of the paper.

In the final section the requirements of some illustrative applications are discussed. It is shown that, on the basis of the earlier parts of this paper, certain applications demand significantly different blade profiles. Evidence is given that substantial gains have been achieved by using the appropriate blade profile for some duties, from which it is concluded that proper attention to the selection of profiles for all duties must lead to an all-round improvement in the performance of these machines.
Effects of Impeller Design and Surface Roughness on the Performance of Centrifugal Pumps
Authors: Varley F. A.
Published: October 2007

Conventional methods of designing centrifugal pump impellers are based on the ideal velocity triangles and the Euler head equation. Empirical modifications derived from the performance of previous successful designs are used to correct for departures from these ideals, and design procedure becomes a matter of extrapolating from past experience.

More fundamental studies of the flow conditions inside a centrifugal pump have been made, but these have generally required simplifications of the impeller geometry or other expedients in order to render the problem amenable to analysis. In consequence, the results have found only limited application for the complex pumps and real fluids met in practice.

In the paper the author attempts to reconcile these different approaches by presenting data on the effects of the various impeller design elements on the performance of a 2-in. double-entry pump. The decisive parameters determining the performance of the impeller are shown to be the number of blades and their outlet angle. The inlet angle and the blade profile are of relatively minor importance. Roughness of the impeller surfaces, both internally and on the outside of the shrouds, decreases the pump's efficiency but increases its output.

Analysis of the test results with artificially roughened impellers demonstrates that current conceptions of disc friction and the energy balance sheet for a pump are untenable.
A New Apparatus for the Precise Location of an Inaccessible Point, with Applications to Deep Surgery
Authors: Harrison J. Y. , Willis A. H.
Published: October 2007

A stereotactic apparatus is a device used to guide a needle to a chosen point in the brain. The position of the point, relative to the skull or to any artificial reference system fastened to the skull, is determined by radiographic means.

Many types of stereotax exist and are in present-day use; several of these are referred to in the text. Certain disadvantages are associated with existing instruments, and in developing the stereotax under discussion, specific design objectives were kept in mind, the more important of these being the elimination of excessive weight, the elimination of any form of calculation, and the need for reasonable accuracy.

The basic theory and a general description of the apparatus are given, together with photographs of X-ray films taken during the course of an operation.
Behaviour of Compound Steel Cylinders Subjected to Internal Pressure
Authors:   Applied Mechanics Group, Crossland B. , Burns D. J.
Published: October 2007

In this paper the literature on the strength of compound cylinders subjected to internal pressure is reviewed. The theoretical treatment is briefly discussed and a theory for the pressure-expansion curve for a partially plastic duplex or two-component vessel is given. Pressure tests on two duplex vessels are reported, one made of Vibrac steel and having an overall diameter ratio of 2, and the other made of 0.15 per cent carbon steel and having an overall diameter ratio of 5.86.

It is concluded that considerable and unpredictable axial stresses are set up when the two-component cylinders are shrunk together. Apparently, however, these do not seriously influence the yield pressure computed on the assumption that no axial stresses are induced during shrinking. In the partially plastic region there is good agreement between the experimental values and the theoretical pressure-expansion curve. The ultimate pressure and experimental pressure-expansion curves at large strains are in good agreement with values predicted for monobloc cylinders of the same overall diameter ratio.
Some Aspects of Feed Heater Design
Authors: Finlay L. C.
Published: October 2007

Thermodynamics dictate that ideally the process of heat transfer obtaining within a feed heater should be reversible. Modern high-pressure feed heaters are, however, costly units and so it is also important that they should be economically efficient heat exchangers.

These demands are in conflict and, in an effort to achieve highest thermal efficiency with lowest capital cost, the conditions for optimum design, the heat transfer and thermodynamic aspects must be a matter of compromise. It is essential, therefore, that the designer should have to hand means of readily determining the effects that changes in operating conditions, in processes within the system, will have on the efficiency and cost of the proposed plant.

First, the thermodynamic aspects are dealt with; the ideals of regenerative feed-heating systems are briefly outlined. The ‘availability’ concept is suggested as a means of readily determining the effects that changes in operating conditions have on the efficiency of the plant as a whole.

Generalized equations governing the heat-transfer processes obtaining within a desuperheating-type feed heater are next formulated. The large number of dependent variables operating in these equations, together with the range of possible boundary conditions, render any optimization process an exceedingly laborious task, involving as it must much repetitive computation. This is the type of problem most advantageous for solution on a digital computer and, without entering into the field of computer programming, an effort has been made in the paper to present the problem and its solution in generalized terms.
Pneumatic Gauging: A Technique for Special Applications
Authors: Gorski W.
Published: October 2007

The paper describes the principles and characteristics of pneumatic gauges together with some items of equipment, A number of illustrative examples are considered in detail. A mathematical appendix and list of references are included.
Lubricants for Nuclear Reactors
Authors:   Lubrication and Wear Group, Vaile P. E. B.
Published: October 2007

The earlier British carbon-dioxide-cooled, graphite-moderated power reactors were designed to operate without lubrication. This was necessitated by lack of knowledge of the effects of radiation and other reactor operating conditions on lubricants, and of the degree of compatibility of lubricants with reactor materials

Investigations carried out over the past few years of the effects of nuclear radiation on many types of lubricant have shown that it is possible to produce materials capable of lubricating some reactor components. In order to further the development of such lubricants the U.K.A.E.A. and the nuclear manufacturing groups have co-operated in providing lubricant manufacturers with details of design and operating conditions of reactor components which it is desirable to lubricate

In this paper is described the range of operating conditions which lubricants are expected to encounter in different reactors, with particular emphasis on the C02-cooled, graphite-moderated reactor. Nuclear lubricant requirements proposed by the U.K.A.E.A. to cater for many applications are also discussed

With this information available it is now possible to assess realistically the types of test facility necessary for the evaluation of nuclear lubricants. Such test facilities are described. They include irradiation sources, a test rig for running under irradiation conditions, various test rigs to simulate reactor operating conditions for testing products both before and after static irradiation, and other specialized equipment

The effect of radiation on both conventional and nuclear lubricants is described and the use of ‘anti-rads’ illustrated. Attention is drawn to other desirable properties of nuclear lubricants such as temperature stability, low volatility and compatibility with reactor and fuel-can materials

Designers of reactor machinery have taken, and will increasingly continue to take, advantage of the developments in lubricants but, while still further advances in lubricant quality will be made, some components, particularly of the more advanced types of reactor, will probably continue of necessity to be operated without lubrication
Flow Measurement of Solid-Liquid Mixtures Using Venturi and Other Meters
Authors:   Hydraulic Plant and Machinery Group, Brook N.
Published: October 2007

Test results for a non-standard type of venturi meter with a wide throat metering a mixture of water and crushed bakelite or water and basalt chippings are presented. In addition, results using a 90° bend as a flow meter are given, and a ‘vertical counterflow meter’ is described, which measures both mixture velocity and concentration
Lubricating-Oil Filter Testing
Authors:   Lubrication and Wear Group, Buckman K. E. , Kemp S. W.
Published: October 2007

A review of existing test methods and apparatus as applied to full-flow lubricating-oil filter testing including, where applicable, notes on functional operation which need to be considered in testing and in the ultimate interpretation of test results. Reference is also made to the desirability of a future standard test procedure and performance specification
Effect on the Performance of a Small Air-Cooled Compression-Ignition Engine of Variations in the Ambient Atmospheric Conditions
Authors:   Internal Combustion Engines Group, Pattenden R. F. S.
Published: October 2007

In this paper consideration is given to the effect upon the performance of small compression-ignition engines of variations in ambient atmospheric conditions. The validity of some correction and derating formulae when applied to such engines is discussed, and an experimental investigation is described in which two small air-cooled compression-ignition engines were run at constant speed in atmospheric conditions which could be controlled at values ranging from the normal to those widely different from normal conditions. Some conclusions relating to corrections for deviation from standard conditions are drawn from these test results and a comparison is given of the correction of experimental results by a number of correction or derating formulae, which are described in Appendix I
Applications of Automatic Control to Pressurized Oil Film Bearings
Authors:   Lubrication and Wear Group, Royle J. K. , Howarth R. B. , Caseley-Hayford A. L.
Published: October 2007

Expressions for the load-carrying capacity, stiffness and damping rate of pressurized oil film bearings are derived and expressed in terms of the variables available to the designer

By adding a simple automatic flow valve, operated by pressure feed-back, the pressurized oil film exhibits infinite stiffness to steady normal loads. The method can be adapted for a system, embodying pilot pad control of a main bearing pad, in which the pilot pad slides on a flat strip and the film thickness of the main pad is varied to compensate for undulations in the main slideway

A further experimental and theoretical investigation is described in which feed-back control is used to support concentrically the shaft of a journal bearing. With a shaft diameter of 2 in. and a radial clearance of 0002 in. the eccentricity is generally not greater than 2 × 10-5 in., as inferred from the pressure measurements, for loads exceeding 300 lb and rotational speeds up to 1200 rev/min. It is argued that much greater loads and higher rotational speeds can be attained with virtually no eccentricity
Design and Operation of a Once-Through Supercritical Steam Pressure Boiler Installation
Authors:   Steam Plant Group, Cooke G.
Published: October 2007

The paper describes the first super-critical once-through boiler to be installed in Great Britain. The unit is designed as a topping installation working in conjunction with a back pressure turbine exhausting into a medium pressure steam system

Reasons for the choice of critical pressure are given, followed by a note on the fuels used and their effect on design. The boiler and its auxiliary plant are then described together with the control system; a note is included on feed water

The operation of the boiler, including the method of starting up and shutting down, as well as some difficulties with tube faults, is described

The paper concludes with a statement that the boiler has fulfilled its purpose since it is extremely flexible in response to load changes, and is also capable of operation below the designed pressure and temperature, if required to do so.
Critical Conditions for Hydrodynamic Lubrication of Porous Metal Bearings
Authors:   Lubrication and Wear Group, Cameron A. , Morgan V. T. , Stainsby A. E.
Published: October 2007

The theory of the operation of porous metal bearings as given in the 1957 Conference on Lubrication and Wear has now been extended. The analysis of a 360° porous bearing leads to a critical value of the Sommerfeld reciprocal 1/δ below which full fluid lubrication cannot be obtained. The magnitude of this critical value 1/Δc is found to vary only with the length to diameter ratio of the bearing L/D, and with the design variable Ψ, a dimensionless parameter dependent upon the Darcy permeability Φ, wall thickness H, and radial clearance c, and defined as + = Φ H/c3. In the absence of a full computed solution of the modified Reynolds equation, variation of the L/D ratio has been allowed for by applying the same correction factors that apply to non-porous bearings. Experimental work has been carried out using + values varying from 1.95 × 10-4 to 2.91 × 10-2 (a factor of 150) and within this range good agreement with the theory was obtained.
Performance of Two-Stroke Compression Ignition Engines in Combination with Compressors and Turbines
Authors:   Internal Combustion Engines Group, Wallace F. J.
Published: October 2007

Several papers (1)-(5)† have been written in recent years dealing with various aspects of the performance of turbocharged two-stroke compression ignition engines. None of these, however, provides a general method of performance prediction for a given engine-turbocharger combination over the complete range of load and speed, in terms of given design operating conditions and given compressor and turbine characteristics. Such calculations are complicated further by the inclusion in the system of a mechanically driven scavenge blower, usually in series with the turbocompressor.

The paper provides a complete solution of this complex problem on the basis of certain necessary simplifying assumptions relating primarily to the engine cycle.

Since the gas generator and compound engine have been recognized in recent years as, in certain circumstances, superior alternatives to the turbocharged engine, the method is extended to cover also these two cases. In all three cases the engine is assumed to be of the opposed-piston type, which is now recognized as being particularly suitable for high-pressure supercharging (6).

The paper may be considered supplementary to a recent paper by Chatterton (6), in which the turbocharged, gas generator and compound cycles are compared purely on a basis of design point operating conditions.
Case-Carburization and Other Surface-Hardening and Residual Stress Treatments in Relation to Fatigue Strength in Torsion
Authors:   Applied Mechanics Group, Benham P. P.
Published: October 2007

Uni-directional torsion fatigue tests were carried out on heat-treated En 36A (nickel-chromium) alloy steel which had been given various surface treatments. Recarburization raised fatigue strength relative to the scaled and decarburized condition by 160 per cent. Pre-strained, polished or shot-peened surfaces produced increases in strength ranging from 16 to 60 per cent. The effects of hardening and residual stress are discussed.
Contact Stress Distributions on Elliptical Contact Surfaces Subjected to Radial and Tangential Forces
Authors:   Lubrication and Wear Group, Haines D. J. , Ollerton E.
Published: October 2007

The problem of Hertzian bodies in rolling contact and supporting radial and shearing forces in the rolling direction is considered.

A modified form of the conventional photoelastic frozen stress technique has been used to study the particular case of flat elliptical contact surfaces. Existing theories are reviewed and new theories are presented which permit the analysis of the frozen stress results. The dependence of the measured stresses on the hysteresis of rolling is studied.
Turbocharged Loop Scavenge Diesel Engine
Authors:   Internal Combustion Engines Group, Henshall S. H.
Published: October 2007

This paper describes the application of turbocharging to the loop scavenge diesel engine.

The first part is concerned with the important effects on the practicability of the cycle of the turbocharger efficiency, scavenge air pressure and temperature, exhaust pressure and temperature, and the pulses in the exhaust, the allowable maximum pressure in the cylinders, the pressure drop across them in relation to the air flow and the air utilization of the engine. It then goes on to a discussion of the way in which these many factors may be arranged to result in a practical engine of high efficiency and utmost reliability. Reasons are given for preferring, in the present state of knowledge, to retain the crankshaft-driven scavenge pump and the merits of series and parallel arrangements are discussed together with the possibilities of cooling during the compression stages.

The application of these considerations to the development of a range of engines is described. Results of tests on the berth and in service are given together with some details of the mechanical design and construction.
Nominated Lecture: Special Requirements for the Design of Nuclear Power Stations to Withstand Earthquakes
Authors:   Nuclear Energy Group, Muto Kiyoshi , Bailey R. W. , Mitchell K. J.
Published: October 2007

The aseismic design specification to which the Tokai plant was designed is summarized and explanations of certain of its requirements are given. A general review of the main features of the plant, with particular reference to aseismic problems, follows. Finally, certain elements of the design are selected for more detailed explanations of how their earthquake resistance was developed and demonstrated.
Mechanizing the Postal Service
Authors:   Manipulative and Mechanical Handling Machinery Group, Phillips R. S. , Davison G. N.
Published: October 2007

The paper describes briefly the mechanical aids that have been brought into use in the various fields of postal work; the public office counter, collection and delivery of mail and the sorting operations. The major part of the paper., however, is devoted to details of segregation, facing, sorting and coding of letter mail.
Nominated Lecture: The Mechanics of Instrumentation
Authors: Boiten R. G.
Published: October 2007

In this lecture instrumentation will be interpreted as the ways and means to transport and modify signals so as to make them suitable for the input channels of human beings and automatic controllers.

A difference may be made between measuring and control systems; the first present the value of the measured quantity in an appropriate way, the second also formulate and execute command signals. Modern control theory and techniques have an increasing influence on the arts of instrumentation.

An important part of all instrumentation systems is the transducers, which convert the value of the signal to be measured to another physical dimension, more suited for transport or evaluation. Typical are the conversions to electric voltages, pneumatic or hydraulic pressures. The main requirements for the design of a transducer are a low energy consumption from the measuring source, fast response and low susceptibility to disturbing signals and noise.

At the input there exist besides the value of the signal to be measured xm an associate signal ym, such that xmym has the dimension of energy W (watt). The generalized impedance Z is defined as Z = xm/ym, so that W = xm2/ Z. In general W should be small, requiring Z being large, sometimes approaching infinity. On the other hand, examples will be given where Z must have a certain specified value. A low value of W can be obtained either by using a very sensitive primary sensor and applying sufficient signal amplification afterwards or by using feedback techniques. Most of the primary sensors transfer the measured quantity into a displacement or elongation of the measuring element. A fast response requires small moving parts and a high stiffness. This lowers the sensitivity and efficiency of the signal conversion. Feedback techniques make it possible to increase the high-frequency response without undue miniaturization of the mechanical parts.

The shape and the way of loading of the measuring elements have great influence on the efficiency of signal conversion and a figure of merit will be defined and applied to a number of common elements.

An instrumentation system should be insensitive to disturbing signals and noise. This requires no, or a non-changing, interaction between adjacent components. Further the design should be such that such disturbances as temperature and barometric changes, accelerations, vibrations and gravity have no influence on the output. The first step is to make the design as insensitive as possible for these errors and thereafter by means of series—or parallel-compensation techniques—the remaining effects can be reduced to the required values.
Lubrication and Wear Group: Oil-Whirl Characteristics of a Rigid Rotor in 360° Journal Bearings
Authors: Holmes R.
Published: October 2007

An insight into the mechanism of oil whirl is obtained by investigating theoretically and experimentally its two main characteristics, frequency and amplitude. It is shown that the ratio of steady oil-whirl vibrational frequency to shaft speed may be predicted qualitatively by a linear treatment and some conclusions of a nonlinear treatment are also given. It is also concluded that oil-whirl amplitude can be restricted by the oil supply pressure.

Experiments involving the use of a rigid rotor supported on two fully lubricated 360° journal bearings are described and ratios of steady oil-whirl frequency to shaft speed as low as 0.37 reported.
Some Problems in the Design and Operation of Jet Ejectors
Authors:   Steam Plant Group Thermodynamics and Fluid Mechanics Group, Engel M. O.
Published: October 2007

The author presents some of the more recent ejector design theories and compares them with experimental data, and he describes the operation of a few different types of ejector used at present in industry. He also gives a short survey of the relevant literature.

The design theory developed in the first part of the paper is based on the momentum exchange between motive and suction fluid and the assumption that entrainment occurs at constant pressure and mixing at constant area. The equations in which the use of experimental coefficients is kept to a minimum give the motive-to-suction mass-flow ratio in terms of the pressure ratio and certain velocity ratios, as well as the required entry and mixing tube lengths and profiles. Optimization of the ejector for fixed pressure levels enabled the best ejector geometry to be determined with regard to nozzle position, mixing tube entry profile, and mixing tube length. The nozzle was in its optimum position when it reached up to the mixing tube. For this condition the optimum mixing tube length was seven tube diameters and the entry profile did not affect the operation. Although the theory is developed in more detail for an ejector using liquids the methods necessary for calculating gas ejectors and multi-phase and multi-component ejectors are outlined.

The operating characteristics given in the second part of the paper emphasize the limitations of the jet pump but it is pointed out that both efficiency and compression ratio can be improved by the use of multistage designs. A particular application for a turbine condenser is discussed.
Determination of the Optimum Level of a Steam Power Station Turbine House from Hydraulic and Constructional Considerations
Authors:   Hydraulic Plant and Machinery Group, Dartnell L. M.
Published: October 2007

The time taken to construct large-capacity thermal power stations is becoming increasingly important and demands close attention. During the constructional period large capital sums are invested without return and as the demand for electricity is ever increasing early availability of generating plant is of consequence.

Subject always to satisfactory load-bearing conditions the level of a coastal or esturine power station turbine house is hydraulically related to sea level. An investigation has been made into the economical depth of excavation for the turbine house as plant erection cannot commence until basic building work is complete.

The investigation shows that the optimum level of a turbine house is amenable to calculation and two methods of establishing the level are described. The first method involves equating the financial value of lost generation to the savings in civil engineering consequent upon reduced excavation. The second method balances generation lost at low water with increased generation at high water.

The results demonstrate that acceptance of periodic small reductions in electrical generation reduce excavation depth, construction time, capital cost or operating cost. The study involves variation in sea level with moon phase, cooling-water pump flow, hydraulic gradients, condenser vacuum and turbine power.

Extension in coverage of the conclusions permits power station design engineers to select an optimum turbine house level, subject to consideration of relevant civil engineering factors, in the early design stages.
On the Isolation of Modes in the Balancing of Flexible Shafts
Authors:   Applied Mechanics Group, Bishop R. E. D. , Parkinson A. G.
Published: October 2007

A method of balancing axially-symmetric flexible shafts has been given previously. The process of balancing requires the distortion to be magnified in successive modes so that each may be considered singly near its corresponding critical speed. It may be impossible to isolate a mode with sufficient purity when the shaft has a gross component defect (of bend or unbalance) in an adjacent mode or when critical speeds happen not to be widely spaced apart. Methods are suggested for overcoming the difficulty and the results of an experimental investigation of these proposals are included. The experiments were carried out both on a laboratory scale and on a large industrial rotor.
Engineering Aspects of Extracorporeal Blood Circulation
Authors:   Thermodynamics and Fluid Mechanics Group, Lucas B. G. B. , Montgomery S. R.
Published: October 2007

The operation of the heart and of the human circulation system is described and the flow properties of blood are considered in relation to an artificial pumping and oxygenation system. The requirements of such a system are described and discussed with particular reference to their practical operation, including the requirements for a simple and reliable control system. Some ideas are presented on the future trends of such machines.
Disposal of Flue Dust from a Large Generating Station
Authors:   Steam Plant Group, Nicholson G. , White E. G.
Published: October 2007

The paper presents an example of the practical application of the principles of controlled long distance pumping of a mixture of flue dust and water, at comparatively high concentration and low velocity, based on recent research into the hydraulic transportation of solid materials. Precise hydraulic theory is not discussed as this has been dealt with in detail elsewhere.

General details of the main features of the generating station, its location, the reasons for choosing hydraulic transportation, and the arrangements for ultimate storage of the flue dust are described. Brief details are given of design parameters, plant arrangement, test results, running costs and operating experience.
The Development of the Large Assisted-Circulation Boiler in England
Authors:   Steam Plant Group, Davis R. F.
Published: October 2007

The principle of assisted circulation and the reasons for its adoption for large high-pressure boilers. The process of development that has taken place in the designs for High Marnham 200 MW, Thorpe Marsh 550 MW, and West Burton 500 MW boiler units. Improvements in compactness achieved without sacrifice in operating efficiency. (Reference is made to the firing system and the heat-recovery plant.) The use of flow models. Operating experience with the High Marnham units. Some subsequent modifications. Possible future developments in the light of foreseeable limitations.
Mechanical Aids to Permanent Way Engineering
Authors:   Railway Engineering Group, Conran D. A. S.
Published: October 2007

The paper describes equipment which is used to assist in the maintenance of the permanent way and deals particularly with changing methods and the effects of new designs of track components.

Powered plant is employed on all sections of this work on British Railways. In depots and for day-to-day maintenance on the line small machines such as rail saws, nut runners, mechanical hoes, hedge trimmers and welding machines are used.

The cleaning of ballast is done by special machines and pockets of deep clay are removed by excavators. Track is renewed in pre-assembled lengths by purpose-designed track-laying machines, and rails are welded into continuous lengths. The ballast is consolidated and levelled by powered tampers with levelling equipment and track-recording trolleys are used to pin-point any unevenness which would prevent smooth running.

The limitations imposed on plant design are stressed, since equipment must be within the loading gauge—an onerous condition in Britain—and must cause as little interruption as possible to traffic. Consequently plant must travel rapidly and be quickly set up and disengaged. Plant must have a high speed of operation, and also be extremely reliable.
Plastic Flow in Rollers Loaded above the Yield Point
Authors:   Applied Mechanics Group, Hamilton G. M.
Published: October 2007

The plastic flow which occurs when two cylinders are rolled in line contact at loads exceeding the yield point has been examined. It has been found to consist of a circumferential movement of the surface in the rolling direction accompanied in some circumstances by radial corrugation. The resistance to rolling and distribution of pressure in the contact have been measured and the results are compared with the theoretical predictions of Merwin and Johnson in their accompanying paper (1)†.
An Analysis of Plastic Deformation in Rolling Contact
Authors:   Applied Mechanics Group, Merwin J. E. , Johnson K. L.
Published: October 2007

When two metal cylinders roll together under a contact pressure sufficient to cause yielding, a surprising mode of plastic deformation occurs. The surface of each cylinder is progressively displaced in the forward direction of rotation relative to the core by plastic shearing in a thin subsurface layer. This phenomenon was first observed by Crook (6) in 1957 and the results of a more complete experimental investigation are reported by Hamilton (9) in an accompanying paper. In this paper an attempt is made to explain the mechanism of ‘forward flow’ by an approximate numerical analysis of the elastic-plastic stress cycles to which the material is subject in repeated rolling contact. On the basis of an idealized material which is elasticperfectly plastic and isotropic, it is shown that a forward displacement of the surface would be expected as a result of the complex cycle of stress and strain encountered in rolling. It is also shown that residual compressive stresses are introduced into the immediately subsurface layers during the first few cycles of the load. If the load does not exceed the elastic limiting load by more than 66 per cent further plastic deformation would then cease. At higher loads a steady pattern of plastic deformation is predicted which in its principal features is consistent with the observed behaviour.
On the Teaching of Design in Universities
Authors:   Education and Training Group, Bishop R. E. D.
Published: October 2007

An attempt is made to identify the main points that the teaching of design in a university seems to raise. Despite the existence of a large literature, this still appears to be an essential preliminary to an objective discussion. Following on from this attempted clarification, a tentative suggestion is made as to a particular form that such teaching might profitably be given.
Comparative Experiments on Surge Tank Performance
Authors:   Hydraulic Plant and Machinery Group, Pearsall I. S.
Published: October 2007

The dual function of a surge tank is to reduce water-hammer waves in power station piping systems and to act as a rate-of-flow equalizer, from which immediate water or storage requirements following turbine load changes can be met.

Design requirements are based on predictions of surging in the tank. Experimental performance figures from model and full-scale tanks are compared with various theoretical methods.

Experimental investigations include comparison between the simple, widened, conical, throttled, differential and twin-type tanks, showing their uses and respective advantages. The effects of modifications of design are also examined.

Finally, experimental results are presented which show the variation of water-hammer pressures with the different types of tank and system arrangement.
The Contribution of a Research Laboratory to Prime Mover Development
Authors: Edmunds H. G.
Published: October 2007

In the past decade or two the pace of technical development has accelerated sharply, and for the technological industries research and advanced technology are now essential both to support and stimulate the advance. By brief descriptions of selected projects, it is shown that one industrial research laboratory finds its function in the support of product divisions by: (1) providing a background of expert knowledge to support and stimulate a rapid rate of technical advance, (2) increasing design potential by the application of advanced philosophies of design and analysis, (3) reducing the labour and cost of designing and tendering by the application of advanced technological tools and providing a consulting service.
The Avon Aircraft Engine and Its Industrial Power Applications
Authors: Fletcher A. Holmes
Published: October 2007

A brief description is given of the situation leading to the introduction of aero jet engines as power units for emergency generating plant to be put into service in Great Britain by the Central Electricity Generating Board. The characteristics and economics of these power units are discussed, in comparison with those of more orthodox types of prime mover. An examination is then made of statistics relating to the world market for gas turbines and sales to date, with a commentary on future prospects in which the aero turbine is expected to take an important place.
An Experimental Impact-Extrusion Machine Driven by a Linear Induction Motor
Authors: Johnson W. , Laithwaite E. R. , Slater R. A. C.
Published: October 2007

The linear induction motor as a planar development of the conventional rotary machine is described and the fundamental differences between it and the conventional machine are discussed.

The effects of the discontinuities which occur in the linear machine, either in the stator as ‘short-stator’ effects or in the ‘translator’ as ‘short-translator’ effects, are discussed. The secondary member of the linear machine is referred to as a ‘translator’ in order to distinguish it from the rotor of the conventional rotary counterpart. The exploitation of the double-sided stator system is also briefly discussed.

A linear induction motor has been constructed as an accelerator specifically for axi-symmetric impact extrusion. Some elements of design employed in the construction, together with a description of the model impact-extrusion machine, are given. The linear induction motor consists of a twin arrangement of double-sided stator systems, side by side, and in the same plane. The kinetic energy possessed by a mass accelerated in guides between the two stator systems is used for impact extrusion and the mass is propelled by the force exerted on a single-plate ‘dual translator’. The linear induction motor functions as a ‘short-translator’ machine.

Experimental results presented show the nature of the accelerated motion of the mass, the force-slip characteristic, and how the overall energy efficiency of the linear induction motor is related to the root mean square phase voltage.

Impact forward extrusions were performed for which \ in and 1 in diameter billets of pure lead and 1/2 in diameter billets of tellurium lead and super-pure aluminium were used. Some evidence is presented to show the limitations of impact extrusion.
High-Rate Forming: First Paper: Experiments on Clamped Circular Blanks Subject to an Underwater Explosive Charge
Authors: Johnson W. , Sowerby R.
Published: October 2007

The results of experiments on the dynamic free stretch forming of peripherally clamped circular blanks of brass and mild steel subject to an underwater explosive charge are given for use in connection with studies on explosive metal forming. The results are presented in six parts.

part 1: Some results for the effect of hydrostatic head above the charge on the polar deflection suffered by a blank are given and it is shown that for some otherwise fixed sets of parameters, at a depth of about 18 in below the free water surface the polar deflection is greatest. Illustrations of how strain distribution and the plastic work done on a blank vary with hydrostatic head are also given. In particular it is shown that the energy received from an explosive charge by a blank may greatly exceed the fraction expected by reference to the solid angle subtended by the blank at the point charge. With the aid of some blank speed measurements an attempt is made to relate the kinetic energy acquired by the blank to the plastic work done on them.

part 2: The measured maximum speed of deformation over the central portion of blanks is shown to be less than 300 ft/sec (rupture excluded). For some circumstances that two phases of motion exist is incontrovertible, and the mechanism responsible for these, we believe, is as follows. In the first phase the speed is dependent upon stand-off distance and is a consequence of the primary shock wave and subsequent cavitation and diffraction effects that occur as a result of the shock wave impinging on the blank. The second phase (arising only with the larger stand-off distances) occurs some time later and may be accompanied by a greater deformation velocity; it is thought to be due to a water hammer or similar effect.

part 3: An attempt is made to present generalized results for the maximum polar deflection incurred as a function of both charge weight and hydrostatic head.

part 4: This shows how the density of a curtain of air-bubbles, measured by aerator pressure, inserted at the walls of the confining tank reduces the polar deflection or damage a blank may sustain.

part 5: A short empty cardboard cylinder (sealed at each end with a layer of polythene) inserted between the blank and charge leads to increased polar deflection, other things remaining the same.

part 6: Deals with gas-bubble pulsation and generally confirms the Willis formula, namely, that for charges not too near a free water surface or an underwater blank, the period of oscillation is proportional to (charge weight)1/3 and (the ambient pressure at the charge)−5/6.