bluuebunny/crossref_metadata_2025 huggingface dataset:
Hot-Starting Trials on Reheat Generating Units at Ferrybridge ‘B’ and Northfleet Power Stations
Authors:   Steam Plant Group, Austin P. E. , Beck J. S. , Dixon P. , Evans H. M. , Kalderon D. , Mathews H. L. , Parish A. H. , Payton E. J. , Weatherson J.
Published: October 2007

The paper summarizes the results of a number of starting tests, after unit shutdowns of 6 and 36 hours respectively, conducted collaboratively by the manufacturers of the principal generating plant and the C.E.G.B. on a 100-MW reheat unit, in October-November 1959, and on a 120-MW reheat unit in June-July 1961.

The units were extensively instrumented for the tests and many steam and metal temperature measurements on the boiler, pipework and turbine were taken at regular short intervals to determine the thermal condition of the unit during the shutdown and starting operation.

The tests were conducted on the basis of carefully planned and agreed operational procedures, within the framework of the working limits recommended by the manufacturers of the principal generating plant.

It was demonstrated that the units could be satisfactorily and quickly started up to full load with a drainage loss of about 22 000 lb, after a 6-h shutdown, and with a drainage loss of approximately 20 000 lb, and 52 000 lb, after a 36-h shutdown, for the 120-MW and 100-MW unit respectively, without exceeding the recommended limits.

It was possible to operate the 100-MW unit at full load in 64 min, and 120-MW unit in 51 min from lighting the boiler, after a 6-h shutdown. The minimum turbo-generator loading times were 25 and 11 1/2 min respectively.

After a 36-h shutdown the 100-MW unit was brought up to full load in about 200 min and the 120-MW unit brought up to full load in about 170 min from lighting the boiler. The corresponding loading times were 110 and 55 1/2 min respectively.

Information obtained from the tests has been used in designing new plant.

The paper includes descriptions of the plant installed, instrumentation used, and the development of the tests. The recommended procedures for two-shift operation of these units are also given, based on the results obtained.
Steam-Water Critical Flow through Pipes
Authors:   Thermodynamics and Fluid Mechanics Group, James Russell
Published: October 2007

Steam and steam-water flashing flow were used to obtain critical† discharge pressures for pipes over the stagnation enthalpy range 230 to 1200 Btu/lb and for the critical pressure range 14 to 64 lb/in2 abs.

Pipe sizes used were 3, 6 and 8 in. in diameter. The following empirical equation covers the data with an accuracy of ±3 per cent:

where G is mass-velocity, lb/sec.ft2, h is specific stagnation enthalpy, Btu/lb, and P is the critical discharge pressure, lb/in2 abs.

It is also shown that the amount of energy flowing along a pipe can be obtained accurately to within ±10 per cent if the critical pressure only is known; that is, the stagnation enthalpy is not known.
Heat Exchange in Profound Hypothermia: Heat Exchanger Design for Blood during External Circulation
Authors:   Thermodynamics and Fluid Mechanics Group, Shore D. T.
Published: October 2007

Profound hypothermia involves the cooling of a patient from 37°C to 13-15°C, using the patient's own blood as a secondary heat transfer medium.

The problem presented is one of heat transfer in viscous flow, demanding apparatus of absolute reliability and ensuring thermal and hydrodynamic conditions which would in no way damage blood cells. Apparatus must be easily sterilized and all blood contact surfaces readily examined. The paper presents a solution using an annular heat exchanger design capable of cooling a patient weighing 10 stone in a period of 30 minutes, the same heat exchanger being suitable for body weights of between 8 and 186 lb. The heat transfer theory presented compares published work in this field, in particular the Graetz result for viscous flow. In the paper it is suggested that measurement of local heat transfer coefficients under similar conditions of both heat flux and velocity gradients gives a better approximation for design than lengthy arithmetic analysis of theoretical equations.

Blood is a complex non-Newtonian fluid and consideration is given to viscosity variations with both temperature and rate of shear.

Finally, there is a description of automatic controls installed with the heat exchanger unit now operating at the Westminster Hospital.
A Thermocouple for the Measurement of Gas Temperatures up to 2000°C
Authors:   Thermodynamics and Fluid Mechanics Group, Bertodo R. J.
Published: October 2007

The present paper reviews the principal aspects of some work carried out between 1958 and 1961 to obtain a thermocouple capable of operating in the range of 1200-2000°C in the combustion chamber and reheat tailpipes of advanced turbojet aero-engines with an inherent accuracy of about ± 1 per cent.

The work of previous experimenters is reviewed and a consideration of existing thermocouple combinations indicates that oxidation-resistant refractories might be well suited to the applications envisaged. A number of refractories and high-temperature metals and alloys were selected for evaluation on an oxidation-resistance basis, and their thermoelectric output against EY4 graphite (Morgan Crucible nomenclature) is presented. Thermocouple pairs were selected on the basis of the above tests and complete assemblies were evaluated in the laboratory and on test-bed engines, a total of over 1000 hours being accumulated for the final design. Such factors as repeatability, stability and response time are presented.

It is concluded that in order to obtain adequate response times only refractories having a high thermal conductivity are suitable. Greater immersions are therefore required in order to avoid excessive cooling of the hot junction by conduction. This in turn requires greater strength in the thermocouple in view of increased stresses due to gas loading. As a result a refractory thermocouple will be dimensionally larger than conventional thermocouples, but the thermoelectric output will be one magnitude greater. By stringent control during sintering or hot moulding and subsequent selection, adequate accuracy may be maintained and repeatability achieved. Some limitations exist as regards shape and size in view of the difficulty in obtaining sintered or hot-moulded bodies of high length/diameter ratio. In view of the fact that the thermocouple impedance could be less than 10 Ω in conjunction with thermoelectric outputs of 200 mV or more, the possibilities of power generation are considered.
The Thirty-Fifth Thomas Lowe Gray Lecture: Design and Construction of Large Tankers in Japan
Authors: Yoshiki Masao
Published: October 2007

This lecture first presents an outline of research work by which many troublesome problems in the design and construction of large tankers were solved, and secondly introduces the largest tanker ever built in Japan, the Nissho Maru, of 130 000 deadweight tonnage.

With regard to design of such tankers, two points, that is,

(1) reduction in length of ship ( L), and (2) increase in depth ( D),

should be taken into account from the standpoint of weight saving and of easy fabrication.

Researches into structural problems of tank parts and into the dynamic pressure of cargo oil tank, due to ship motions, are described briefly, and show that the maximum impulsive pressure in model tests may be up to 5 times the static fluid pressure and may be observed at the tank top when the natural period of fluid in the tank is resonant with the oscillation period of the ship.

Special care should be taken in the detailed design of longitudinals, struts and so on, otherwise cracks will initiate easily at the point of stress concentration.

As regards hull construction practices in such large tankers, there seem to be no special problems except in the fabrication and welding of very thick plate of up to 50 mm thickness. Very thick plates thus offer several problems to be solved such as groove shapes, application of ‘Unionmelt’, doubling plate, weld cracking, and back-wave welding technique, etc. Brief discussion and some test results on these problems are included and mention is made of the superiority of KZ-type groove for automatic single-pass submerged-arc welding and of ‘Uranami’ welding electrode (which offers a perfect one-side welding without backing plate).

Finally, construction methods for large tankers are briefly introduced to give an idea of the hull construction of such large tankers in the building berth.
Faults in Cast Components for High-Pressure, High-Temperature Service
Authors: Rogers J. A. , Brewer R. C.
Published: October 2007

The operating conditions to which some castings are subjected are much more severe than they were a quarter of a century ago, and are likely to become more severe in the future. Castings which were acceptable in the past are often considered unsuitable for present-day working and great cost is involved in achieving cast components which can be used in modern equipment. These costs are often incurred in correcting the castings. By changing designs, production methods and inspection and testing techniques the cost of the castings should in the long run be reduced, and the challenge of future conditions will be met.
Teaching Design to Sandwich Course Students
Authors: Pullman W. A.
Published: October 2007

The ‘Feilden report’ has drawn attention to the shortcomings of the design tuition received by engineers, and there has been much discussion of what can be done about this in a university course. In this paper are described experiments in teaching design to students taking a sandwich course for the Diploma in Technology at one college. It is believed that an exchange of ideas on this particular aspect of the problem is worthwhile, particularly when thought is being given to the inclusion of design as a subject in examinations of the Institution.
Second Paper: Deep Drawing and Free Forming Using a Water Hammer Technique
Authors: Vafiadakis A. P. , Johnson W. , Donaldson I. S.
Published: October 2007

Earlier work on a water-hammer technique for high-rate forming of sheet metal has been extended to include work on deep drawing using lead plugs. A study of the pressure-time history of a deforming blank during its initial movement is reported.

An assessment of the overall efficiency of the process has been made and is found to be about 50 per cent; this is an order of magnitude better than that found with comparable electro-hydraulic and explosive methods.
Experience in the Use of a Digital Computer for Predicting Steam-Turbine Performance
Authors: McCrae R. U. , Montague A. , Douglass M.
Published: October 2007

This paper describes a number of programmes for digital computers that have been developed by the authors' firm to eliminate many of the tedious hand calculations which are encountered in the preliminary stages of steam-turbine and condenser design.

By their use a considerable amount of the designers' time is saved and fatigue is reduced. These programmes also eliminate mistakes and inaccuracies which may occur in long calculations made by hand.

The programmes described have been chosen as being representative of the range of programmes used in preliminary turbine design and optimization and are as follows:

a programme to enable steam properties to be calculated, based on the formulae given in the Keenan and Keyes Steam Tables;

a programme which can be used to determine the efficiency of small industrial turbines;

a feed-heating programme which will carry out the calculations necessary to determine the preliminary energy balance for a feed-heating cycle;

a detailed energy-balance programme incorporating turbine-efficiency calculations;

a condenser-optimization programme for determination of the ideal parameters to be used in the design of a condenser.

The programmes are arranged so that unskilled operators can run them on the computer without the help of an experienced programmer. Facilities are also made available for writing programmes in a simplified form called ‘autocode’ which can be used by an engineer after the briefest of trainings.

Some programmes are described in considerable detail to assist others who may wish to write a similar programme or to compare them with programmes of their own.

All these programmes have been in regular use for more than three years and have greatly enlarged the scope of investigations which may be carried out in the project stage of the design of a steam-turbine generator and associated power-station equipment.
Development of a Small Single- and Two-Shaft Gas Turbine for Military Applications
Authors: Petrie K.
Published: October 2007

In the last two decades there has been a progressive increase in the scope of small gas turbine development and application, both in commercial and military fields. Technological advances in the military field have created demands for prime movers able to meet more stringent operational requirements.

An environment now exists in the U.S. Armed Forces conducive to the acceptance and use of small gas turbines that can be adapted to the many specialized applications demanding distinctive physical characteristics.

In 1957, the U.S. Bureau of Naval Weapons entered into a contract with Solar, a Division of International Harvester Company, for the design and development of a small, lightweight, single-shaft gas turbine engine to power a one-man helicopter. Rated at 55 s.h.p. for 100°F ambient conditions, the engine design requirements were based on simplicity of operation and maintenance, low production cost, and a short development time. These factors were considered more important than optimum specific power, fuel consumption and weight. A two-shaft version of this engine was also required to power a one-man flying platform. To facilitate the required low engine airflow, weight and rugged characteristics, a single-stage centrifugal compressor and radial inflow turbine, mounted back to back, were selected. A unique feature of the two-shaft engine was the simple method of achieving two-shaft capability by using the exducer portion of the radial turbine as a power turbine. This design resulted in both engines having the same nominal performance, weight and envelope dimensions, with maximum component interchangeability.

A comprehensive aerodynamic development programme was undertaken to improve component efficiencies and various aspects of this programme are discussed.

Based on favourable results from this programme, the building and development of an uprated engine was undertaken. By incorporating a modified compressor, a 38 per cent increase in s.h.p. and a 6 per cent decrease in specific fuel consumption (s.f.c.) was obtained.

Probably the most important factor in the choice of a small gas turbine for military applications is its ability to develop more power, per unit weight and volume, than other engine types. In general, the specific weight of reciprocating engines, in the same power class as the subject gas turbine, average about 10–15 lb/hp with specific volumes ranging from 0.220 to 0.30 fr3/hp, compared to values of 0.53 lb/hp and 0.027 ft3/hp for the turbine.

Over 20 different variations of this engine have been produced for such diverse applications as small aircraft and boat prime movers, aircraft and helicopter auxiliary power plants, mobile generator sets, and ‘winterization’ kits for U.S. Army field service.

Intensive efforts are being made by companies on both sides of the Atlantic to develop the small gas turbine for a variety of applications. It seems reasonable to predict that these efforts will ultimately lead to the development of units with improved performance and lower initial cost.
The Effect of Hydrostatic Pressure on the Plastic Flow and Fracture of Metals
Authors: Pugh H. Ll. D. , Green D.
Published: October 2007

A description is given of an apparatus for carrying out tension tests under hydrostatic pressures of 60 ton/in2 or more. The results of an investigation of the effect of hydrostatic pressure on the tensile properties of a number of metals are given. It was found necessary to protect cast materials with a rubber sleeve. The fracture strain increased with hydrostatic pressure, but this increase was not linear but varied with the crystal structure of the metal. In zinc and Mazak a sudden transition from brittle to completely ductile behaviour occurred at a critical pressure; this was probably due to a flat stress/strain curve.

It was found in tension tests under pressure that specimens could deform and neck in a characteristic tensile manner, even though all the stresses were compressive. Fracture also could occur when the axial stress was compressive.

It was found that the present results on tension, and previous results in torsion on cast iron, conformed either to a criterion that fracture occurred when the largest tensile stress reached a critical value which decreased as the volumetric compressive stress increased, or to a maximum deviatoric stress criterion, the critical value increasing with volumetric stress.
Reducing Condenser Tube Corrosion at Kincardine Generating Station with Ferrous Sulphate
Authors: Lockhart A. M.
Published: October 2007

The successful operation of high-pressure steam generating plant depends on many factors, one of which is the maintenance of a high standard of purity in the feed water. Contamination of the feed water by ingress of hardness salts from condenser tube failures is therefore serious. Early in the operational life of the three 120 MW units at Kincardine it was found that aluminium brass was an unsuitable alloy for the condenser tubes: corrosion was widespread and tube failures were a regular occurrence. The investigations made to determine the cause of failure and to provide a more suitable alloy for tube replacement are described. However, it was impractical to retube the condensers completely. Aluminium brass tubes which have given satisfactory service are generally found to have protective films rich in iron oxides. The condenser tubes at Kincardine did not have an iron oxide film nor did the cooling water contain any appreciable iron. Ferrous sulphate was added to the cooling water to provide iron and the effects and cost of conditioning are described.
Structural Model Techniques and Their Application to Oil Engine Design
Authors: Morland G. W. , Ganguly S. , Atkin K.
Published: October 2007

The design of oil engines for strength and stiffness has, in recent years, become much more stringent than before the 1939–45 war. This is due to the need to meet more competitive market conditions by increasing power/weight ratio without incurring mechanical unreliability. Many engine components are inherently most difficult to analyse by theoretical approaches. The adoption of model techniques for experimental stress analysis can show great savings in cost compared with the use of prototype full-scale testing for proving mechanical strength. The advantages of model techniques for prediction of stresses due to mechanical loading are discussed in the paper, and some applications, using plastic, rubber, cardboard and aluminium models are described together with a full account of the experimental techniques, results and limitations.
Design Study of a Forge Cogging Unit
Authors: Hutson C. , Knowles K.
Published: October 2007

Modern developments in forging equipment and techniques are combining to make the dimensional accuracy and surface quality of forged stock comparable with that of rolled products. The output of a conventional press forge, employed on the cogging of alloy steels, is comparatively modest, being of the order of 10 000 tons/annum, as compared with a rolling mill installation which has a capacity in the range 500 000 to 1 000 000 tons/annum. It follows that, for production requirements between these two extremes, a high productivity cogging forge unit costing substantially less than a cogging mill should prove to be a worthwhile investment for many alloy steel producers.

This paper contains an account of a design study of a forging machine with an output of 50 000 tons/annum capable of cogging alloy steel ingots down to billets or bars. The performance is based on current industrial requirements and the design concept calls for a machine in which the forging and manipulative functions are fully integrated and controlled. To achieve this, new features in press design and manipulative equipment have been evolved.

It is concluded that a specialized high productivity cogging unit is a practical and economic proposition for the range and quality of steels considered.
Railway Overhead Contact Systems: First Paper: An Experimental Study of the Overhead Contact System for Electric Traction at 25 kV
Authors: Sell R. G. , Prince G. E. , Twine D.
Published: October 2007

Increasing train speeds and the use of multiple pantographs have emphasized some of the problems of ensuring good current collection from the light overhead contact system used for railway electrification at 25 kV in Britain and overseas. The development, in Britain, of instrumentation and test methods is described, and the problems which arise as a result of ‘hard spots' and resonance effects are referred to.

Experimental investigation has shown that greatly improved current collection can be obtained, by suitable modifications, even at speeds exceeding 100 mile/h, and under features such as bridges with minimum clearance. The main principle employed, which has been called ‘stiffness grading’, is to ensure a smooth transition of stiffness, or compliance of the overhead contact system through such features. These are, of necessity, considerably stiffer than normal open route equipment because of the strictly limited electrical clearances. The result is achieved primarily by modifications to the geometry of the equipment.

It has been shown that such modifications can reduce appreciably the tendency of the system to build up oscillations of large amplitude, particularly in sequences of spans of approximately equal lengths. This tendency is much more marked where multiple pantographs are used, especially at certain spacings. Such phenomena can be remedied even more effectively by introduction of damping into the system and this can be achieved more conveniently by use of viscous dampers on the pantograph rather than on the overhead contact system. Appendix I describes recent test results which show that modified simple catenary equipment may be suitable for British Railways ‡ requirements if a smooth pantograph trajectory is ensured by suitable control of contact wire profile. This can be achieved by the use of mid-span sag. It will give an appreciable reduction of cost.
The Scientific Investigation of Aircraft Accidents
Authors: Walker P. B.
Published: October 2007

Aircraft accident investigation is here treated as a problem in detection, calling for observation and deduction, and sometimes for scientific experiments to test tentative explanations. After consideration of preliminaries, such as the discovery and retrieval of the wreckage and its reconstruction as a jig-saw puzzle, most of the principal methods for ascertaining the cause of an accident are described under separate heads. It is shown how the different lines of investigation may proceed more or less simultaneously, and may substantiate each other. They include the analysis of fractures and the study of scratches, marks and indentations. Disruption of mechanical and electrical components is considered and also the evidence of eye-witnesses. Consideration is also given to methods that can be used even when no wreckage is available.

The treatment is essentially practical as it proceeds from one specific example to another, with several photographs taken from actual cases. The paper concludes with a few remarks on modern trends, which do not appear likely to upset any of the basic principles here described.
Internal Aerodynamics of Turbo-Machines
Authors: Lewis R. I.
Published: October 2007

In this paper it is shown how principles which are fundamental to external aerodynamics have been applied to study the internal aerodynamics of turbo-machines.

Mention is made of aerofoil cascade, radial equilibrium, and actuator disc theories. Results are also presented of a number of supporting experimental investigations.
Electromagnetic Metal Forming
Authors: Baines K. , Duncan J. L. , Johnson W.
Published: October 2007

Some results of an experimental and theoretical investigation of the dynamic forming of thin-walled tubes and flat circular diaphragms by the electromagnetic metal forming process are given. The paper is divided into two parts.

Part 1—The magnetic forming process is described and its use as a production technique is discussed. The process is a high strain-rate technique suitable for forming relatively light gauge material; the forces causing deformation result from the interaction of the current in specially constructed coils and the resulting eddy currents induced in the workpiece. The source of energy is a capacitor bank which can be discharged rapidly through the work-coil. The experiments described were performed using a specially constructed 16 kj discharge unit. The method of constructing work-coils and the failures experienced with these coils in service are described.

Thin-walled copper and aluminium tubes were expanded by means of internal solenoidal work-coils of various lengths. The strain distribution and forming efficiency is presented, together with results showing the variation of process efficiency with changes in the primary circuit parameters. The strain distribution for a circular aluminium alloy diaphragm bulged by means of a flat spiral coil is given.

Typical primary current waveforms are given and the changes in waveform and discharge current frequency due to different workpiece materials and changes in primary circuit parameters are indicated.

Part 2—An attempt is made to determine theoretically the forces acting on one of the aluminium alloy tubes expanded and described in the work of Part 1. The currents in the work-coil and workpiece are calculated using the experimentally determined current waveform and the calculated value of workpiece inductance. A rudimentary method is developed for relating pressure on the workpiece to the primary and secondary currents and, using this, the radial motion of the tube is predicted. Although the analysis involves the use of a number of simplifications and approximations, the theoretical results obtained are of the same magnitude as would be expected by reference to other high-rate forming processes.
Burst Strength of Rotating Discs
Authors: Waldren N. E. , Percy M. J. , Mellor P. B.
Published: October 2007

The rotating discs in the aircraft gas turbine engine are components in which the requirement for high strength/weight ratio and the complex stress produced by rotation have a significant influence on material strength and ductility and the study of material behaviour under these conditions has been the subject of numerous investigations. The opportunity to examine the most promising theories for predicting the plastic deformation and fracture of rotating discs arose when a large number of model discs in vacuum melted steel, having near uniform properties, became available for evaluation by burst testing.

Fully ductile behaviour of a rotating disc is manifested in the instability phenomenon and correlation between theory and experiment shows that the rotational speed at which instability occurs may be predicted from a knowledge of the true stress-strain curve for the material in simple tension using the Hencky deformation theory. However, due to complex stress resulting from centrifugal loading, fracture in a rotating disc may precede the instability condition and it is not possible to assume fully ductile behaviour in a real material.

The plastic stress analysis of model discs in which burst has resulted from fracture prior to instability shows that the materials tested favour a maximum principal stress criterion of fracture and good correlation has been achieved with the maximum true stress at fracture in the tensile test piece.

The important influence of strain-hardening on the strength of a rotating disc is demonstrated by the theoretical analysis and by the burst results. For materials exhibiting low strain-hardening the average tangential burst stress in a disc agrees reasonably well with the tensile strength of the material and confirms the simple burst criterion. High strain-hardening materials, however, may be required to exhibit exceptional ductility to allow a disc to achieve a burst strength consistent with the tensile strength and in practical examples relatively low burst strengths have resulted.
The Mechanics of the Screw Feeder
Authors: Metcalf J. R.
Published: October 2007

The screw feeder is considered as a measuring device for dry fragmental materials. Expressions are obtained for volume delivered and torque required, in terms of the dimensions and coefficients of friction involved. Limited confirmation has been obtained in experiments using coal. The cases where the tube is eccentric to the screw axis and where fine material can pass the wing-tip are examined. Improvement in screw feeder design appears possible.
Dynamic Indentation of Copper and an Aluminium Alloy with a Conical Projectile at Elevated Temperatures
Authors: Mahtab F. U. , Johnson W. , Slater R. A. C.
Published: October 2007

The dynamic indentation of copper (B.S. 1433) and an aluminium alloy (B.S. 1476 HE 10) has been investigated, using cylindro-conical projectiles fired from an air-actuated gun. The experiments were performed with impact velocities varying between 1000 and 2500 in/s and at elevated temperatures up to 600°C for the copper and 550°C for the aluminium alloy. The magnitude of the corresponding range of mean strain rate was then 103-104/s, depending upon the material; impact velocity and temperature (see Appendix I).

For the range of impact velocities investigated no consequential transition temperature † was encountered. The dynamic temperature coefficient† thus remained constant throughout the test temperature range for each material. This dynamic temperature coefficient was found to be equal to the static temperature coefficient corresponding to the sub-transitional temperature range for the respective materials.

The mean effective dynamic indentation pressure is shown to decrease with temperature but the ratio of this dynamic pressure to the static indentation pressure increases with temperature.

Strain rate effects for both materials were negligible for sub-transitional temperatures but become important at super-transitional temperatures. It was observed that the parameters on which the strain rate effect depends are in some way related to the absolute melting point of a pure metal.
On the Dynamics of Large Turbo-Generator Rotors
Authors: Morton P. G.
Published: October 2007

It would be desirable to be able to predict the running characteristics of turbo-generators at the design stage. The paper describes tests on production generators and their component parts, directed at evaluating the relative contributions of these components to the dynamic behaviour of the complete system. Tests have shown that the contribution of the rotor alone may be estimated with some confidence, but that the present state of knowledge regarding the rotor supports, whose characteristics are shown to have a profound effect on the running behaviour of the machine, is inadequate. Theoretical techniques are presented which should rigorously solve any practical configuration provided the correct parameters are available.
A Platform with Six Degrees of Freedom
Authors: Stewart D.
Published: October 2007

This paper describes a mechanism which has six degrees of freedom, controlled in any combination by six motors, each having a ground abutment. It is considered that by its particular arrangement, this mechanism may form an elegant design for simulating flight conditions in the training of pilots. Unlike most simulators, it has no fixed axes relative to the ground, and therefore within the limits of amplitude of the design it can truly simulate the conditions of banking by carrying the simulation of control surfaces into the axes of the new attitude.

Variations in control arrangements are described and their respective design merits considered.

Other possible uses for this mechanism are mentioned, including automation of production.
An Introduction to the Dynamic Pressure Exchanger
Authors: Azoury P. H.
Published: October 2007

The historical background and operational principle of the Dynamic Pressure Exchanger (DPE) are outlined. The basic aerodynamic processes of cell-emptying and cell-filling are analysed by the ‘method of characteristics’ for air and for no temperature discontinuities in the unsteady flow pattern. The results of the analysis are then used to generalize performance qualitatively for overall pressure ratios up to the sonic threshold. It is shown that, for pressure wave effects to be fully utilized, a DPE rotor should run such that 8 is of the order of or less than 0.5, where δ is the ratio of the time taken to open or close a cell to the time taken for a sound wave to travel a cell length at the thermodynamic stagnation state of the primary or secondary fluid. In the case where the thermodynamic properties of the fluids vary considerably, it is suggested that 8 be referred to the gas which yields the highest sonic speed. In general, the extent to which the performance is affected by a change in δ, within the range 0 < δ < 0.5, is inappreciable. It is also shown that the use of a transfer passage may be expected to yield a significant improvement in performance and an increased range in overall pressure ratio.

A number of applications are described and some recent developments are reviewed. It is also indicated that the main sources of loss can be incorporated within the method of characteristics used in the prediction of performance.
Oil Whirl of a Rigid Rotor in 360° Journal Bearings: Further Characteristics
Authors: Mitchell J. R. , Holmes R. , Byrne J.
Published: October 2007

In an earlier paper (1)† the oil whirl of a rigid rotor was considered theoretically and compared with limited experimental findings. In this paper the comparison is taken further as a result of a fuller theoretical and experimental investigation.
The Performance and Quality Control of Diesel Engine Components
Authors: Towell R.
Published: October 2007

This paper outlines methods developed to control the quality of incoming materials and finished components with emphasis on the performance that is ultimately required from them. The examples given are taken from diesel engineering but the basic ideas apply to all industries whose final products consist of an assembly of components which are complete in themselves.

The quality control of materials and components fills an important role in ensuring that the technical requirements written into a specification by a designer are met by suppliers. The author outlines various techniques developed in his company to achieve this.

The paper has two main sections: ( a) quality control of incoming materials, and ( b) performance control of components.

The first part deals with the controls established for cast-iron components of various sizes ranging from bedplates and columns weighing about 20 tons to piston rings weighing less than one pound. Ultrasonic testing is briefly discussed as also is the material specification for white metal bearings.

The second part of the paper gives examples of performance testing of a number of diesel engine components together with brief details of some of the test rigs that have been developed to carry out the tests. Some of the components discussed in this section are piston rings, crankshafts, camshafts, cams, and fuel injection equipment.
The Large Signal Response of a Loaded High-Pressure Hydraulic Servomechanism
Authors: Nikiforuk P. N. , Westlund D. R.
Published: October 2007

This paper describes the closed-loop response of a loaded, valve-controlled, high-pressure, hydraulic servo-mechanism to large-amplitude sinusoidal and transient input signals. Oil compressibility and leakage are included in the analysis. The system is of conventional constant-supply-pressure, d.c, position-control configuration. It consists of an electronic amplifier, a two-stage electrohydraulic transfer valve, and a ram-type actuator. The load is comprised of a mass, viscous damping, and Coulomb friction. Load loci and the describing- function technique are used to evaluate the closed-loop frequency response. Load loci and piecewise linearization are used to determine the closed-loop transient response.

Experimental verification of the analytical work is included.
Elevated Temperature Yield and 0·2 per cent Proof Stress Properties of Carbon Steel Plates, with Particular Reference to the Values Specified in B.S. 1501: 1964
Authors: Glen J. , Johnson R. F.
Published: October 2007

The results of some 5000 elevated temperature yield or proof stress tests on steels conforming to the new series of B.S. 1501 carbon steel plate specifications are reported. The data are discussed in relation to the levels of yield and proof stress specified in B.S. 1501: 1964 and the various factors causing variations in the elevated temperature properties are outlined.

The effect of differences in testing technique and in methods of deriving ‘guaranteed’ properties (i.e. minimum values which the steel in question will always meet) are considered in relation to the draft International Boiler Code and it is suggested that discrepancies in design thicknesses of approximately 10 per cent can arise owing to these differences.
The Balancing of Flexible Turbine and Generator Rotors
Authors: Last B. P.
Published: October 2007

The paper covers the factors which make balancing operations necessary, and outlines the principles and several methods of balancing used in factory practice. Some of the problems arising during balancing are mentioned, and methods used in overcoming them are given.
Mechanical Engineering in the Industries of the North-East
Authors: Campbell W. W.
Published: October 2007

The industries of the North-east, to which mechanical engineering contributes so much, are to be seen against their historical background. Much of the developmental impetus came originally from the needs of the coal industry but the transformations wrought by technology have led to the present wide spread of industries among which coal, though vital, is no longer dominant. Notwithstanding the introduction of lighter industries, the mechanical engineer in the North-east is still mainly concerned with the heavier industries though in an almost unlimited variety of forms.
Oil Hydraulic Spool Valve Operating Times
Authors: Lorenz M. H. , Stringer J. D.
Published: October 2007

This paper concerns oil hydraulic spool valves of the on-off type and describes an investigation into the time taken for such valves to open or to close. Operating times depend upon the forces acting on a spool as it slides along the bore and the balance of these axial forces has been both analysed and studied experimentally.

Operating times were first estimated from a simplified equation neglecting forces due to fluid flow. Experiments were then made on two solenoid operated valves to measure actual times and to discover the reasons for differences between calculated and measured values.

Measurements of the sliding friction force between spool and bore indicated that the spools were never concentric in their bores but were displaced radially at all times.

Measurements and analyses were also made of the forces due to fluid flow through the test valves. These suggested that it is important to take account not only of momentum changes (1)† and fluid acceleration effects (2) but also of fluid friction in the valve chamber. The influence of fluid flow on operating times was found to be significant unless flow rates were small.

Another equation incorporating flow effects was then developed and shown to give a realistic indication of the behaviour of a valve. It is concluded that a simple form of equation may be adequate for approximate predictions of valve operating times, but that a more satisfactory method is to use the complete equation based on the work reported in this paper.
Analysis of the Rigidity of the Grinding Wheel-Workpiece-Grinding Machine System
Authors: Kaliszer H. , Singbal P. D.
Published: October 2007

The purpose of the paper is to establish a relationship between the vibration marks generated on the work-piece periphery and the rigidities of the grinding wheel-workpiece-grinding machine systems. To investigate the problem several static and dynamic methods of determining the rigidity are analysed.

Based on experimental results the grinding machine is assumed to consist of two separate sub-systems: the wheel-head-body system and the workpiece holding system, both coupled together by the grinding wheel.

To check the correlation between various methods of determining rigidity, differential equations of motion have been introduced and solved with the aid of a digital computer. In order to consider all forces taking part during grinding an effective force factor has been analytically defined and applied to determine the rigidities. To find the relationship between rigidity established in static conditions and during grinding, coefficients of static and dynamic rigidity have been proposed.
First Paper: An Analytical Study of the Tilting Pad Gas Lubricated Journal Bearing
Authors: Pitts G.
Published: October 2007

Presented in this paper is an analytical method of producing design curves for tilting pad gas journal bearings, with dimensionless parameters chosen in such a way that a single set of curves may be used for any size of bearing with any length to diameter ratio.

An analytical solution to the compressible Reynolds equation, based on the linearization by Ausman, is presented in detail. Comparisons are made between the analytical results, numerical results, and experimental findings on the author's rig at Southampton University.

Included in the paper is a sample design curve, together with equations for constructing additional curves. The author concludes by briefly outlining his proposed extension of this work.
First Paper: Further Investigations of the Mechanics of Roller Bearings
Authors: Garnell P.
Published: October 2007

An earlier paper (1)† investigated roller and cage motion, friction torque, film thickness, and electrical resistance of a roller bearing. Further friction-torque measurements are presented and an analysis of friction losses in a roller bearing is made. Additional measurements of resistance are discussed.
Identification of Mechanical Sources of Noise in a Diesel Engine: Sound Emitted from the Valve Mechanism
Authors: Fielding B. J. , Skorecki J.
Published: October 2007

The sound emitted from the valve mechanism of a diesel engine was investigated by standard methods of sound and vibration analysis augmented by correlation of incidence of individual transient components. This latter technique makes use of information obtained from the tuned output of the noise signal focusing attention on the incidence of single-frequency transients. Three distinct sources of noise were exposed: valve-gear transmission mechanism, valve impact, and the flow of air through the valve gaps. The characteristics, relative contributions, and effects of these sources are discussed in detail, and insight is gained into the mechanism of noise generation and radiation.
The Use of Numerical Methods for the Investigation of Flow in Water Pump Impellers
Authors: Wood M. D. , Marlow A. V.
Published: October 2007

The paper describes the development of a digital computer method for predicting the streamlines and vane surface velocities in mixed flow impellers. The flow is assumed to be axisymmetric and reversible. However, even with these simplified assumptions, it is shown by examples that valuable information can be obtained for design purposes.

No attempt is made to describe computer flow diagrams or to list machine orders. The paper is concerned rather with the fundamental and practical difficulties encountered in getting the program to work and with the techniques finally devised to produce meaningful numerical results.
The Thirty-Ninth Thomas Lowe Gray Lecture: Offshore Drilling, with Particular Reference to the North Sea and the ‘Sea Quest’
Authors: Avery R. G. S.
Published: October 2007

The origins of offshore drilling work and the development of structures used at sea are traced. Comparison of the various types illustrates the advantages and disadvantages of each. Tables show the numbers in operation, being built, and the apparent liability of each type to damage.

Typical bore-hole structures are illustrated, the need for undersea well-heads explained and their development into a sea-bed completion is discussed. Much more research is necessary before this can be considered a practical proposition.

The design of drilling barge equipment is compared with typical land rigs and the development of drilling equipment, including the sophisticated electric drive and turbo-drill, discussed.

Rigs in various types of barge are compared. Fire precautions and other safety equipment are described. The problems associated with control by the driller lead to complications of motive power layout.

The lecture describes in some detail the design of the semi-submersible drilling barge Sea Quest, illustrates the weight problems and their effect on floating stability and indicates the need for management decisions on the degree of resistance to damage. This is measured by the variable deck load of drilling equipment that can be held on board and the degree of weather deterioration that can be tolerated before disengaging the drill from the hole.

The need for, and extent of, diving is discussed, with some comparison between diving vehicles. Weather too is an essential factor of work in the North Sea and both pre-surveys and day-to-day reporting are described.
The Third John Player Lecture: Progress in the Manufacture of Large Forgings
Authors: Sully A. H.
Published: October 2007

Difficulties in the production of large steel forgings stem from the metallurgical and physical heterogeneity of large ingots, the extent of which increases with the size of ingot.

The production of large forgings will be discussed with special reference to the manufacture of large mono-bloc rotor forgings for electrical generating plant, the size of which has increased progressively. These rotors are required to meet extremely high standards and must have uniform mechanical and creep properties.

Manufacturing processes are reviewed in relation to steelmaking (the advantages of vacuum treatment of the liquid steel are discussed), forging (involving upsetting operations in a forging press of very large capacity), metallurgical control of properties in components of great metal thickness; and in relation to inspection, involving refined ultrasonic techniques. Recent developments and improved techniques offer the possibility of producing sound unbored rotors with guaranteed creep properties and consequent design advantages to turbine engineers.

Future developments in the production of large forgings are speculated on, and the significance is discussed of the influence of electroslag welding which opens up new possibilities through its ability to join sections of large thickness.
Graphical Analysis of the Step Response of Hydraulic Servomechanisms
Authors: McCloy D.
Published: October 2007

The closed loop hydraulic servomechanism is analysed graphically. The fluid is assumed to be incompressible.

Electrical and mechanical feedbacks are considered and the effect of feedback on the system step response is demonstrated. Viscous and Coloumb friction forces and inertia and spring loads are considered. A non-linear valve area-displacement characteristic is shown to have a considerable effect on the response.