bluuebunny/crossref_metadata_2025 huggingface dataset:
Paper 22: Experimental Studies on the Role of the Basal Ganglia in the Control of Movement
Authors: Sedgwick E. M.
Published: June 2010

When the basal ganglia are damaged by disease processes in man, various disorders of movement occur. In order to control movement the basal ganglia must have a sensory input and in the absence of direct connections to motoneurones or motor cortex they must act through intermediate structures.

The experiments, on cats, demonstrate: (1) which sensory inputs reach the caudate nucleus and how they influence activity of the neurones there; (2) the effect of the output from the caudate nucleus and globus pallidus on the neurones of the inferior olive and reticular formation. The results are discussed with respect to the control of movement.
Paper 6: The Higher National and College Diploma
Authors: Butler C. T.
Published: June 2010

For many years the H.N.D. has provided a route to professional status for the more able students emerging from the O.N.C. course, and in recent years there has been a growing practice on the part of colleges to offer a post-H.N.D. course leading to a diploma or associateship of the college concerned. The College Diploma course cannot be divorced from the H.N.D. course of which it is the culmination, and in this paper the course will be considered as an entity. The historical development will be reviewed and this will be followed by an analysis of typical course structures, including entry conditions, syllabus content, and patterns of industrial and college periods. The advantages of retaining such a pattern will be outlined while the problem of the setting and maintenance of academic standards through the tutorial system and external examiners will also be discussed and a comparison made with other courses, e.g. degree courses. In particular, the problem of the relationship of the H.N.D. with C.N.A.A. degree courses will be examined and the case for C.E.I. recognition of appropriate College Diploma courses will be argued.
Paper 8: Degrees outside Universities
Authors: Brosan G. S.
Published: June 2010

This paper discusses the various types of engineering activity and their corresponding types of education, within broad definitions. The danger of stating an over-rigid definition of purposes is discussed, and methods of preventing this hazard are considered. The general trend of systems adopted by educational establishments is given, together with extracts from recent reports on engineering education. Some comments are also presented on an American summary of the future requirements for the engineering industry there.

The paper gives some recommendations that may be considered in an attempt to produce a clearer definition of the objectives envisaged for any particular engineering course.
Paper 11: Regenerators for High Temperature Gas Turbine Engines
Authors: Penny R. N.
Published: June 2010

In various companies throughout the world a first generation of production vehicle gas turbine engines are being engineered. A vital component involved is the regenerative heat exchanger.

The relative merits of the rotary regenerative and static recuperative heat exchanger are compared.

Thermal efficiency and competitive initial cost are the two vital issues involved in the design of small gas turbines for the commercial establishment of gas turbine vehicles.

The selection of a material for the rotary regenerator is essentially related to resolving the two vital issues of future small gas turbines and is, therefore, analysed.

The account of the pioneering work involved in engineering the glass ceramic and other non-metal rotary regenerators includes a complete failure analysis based on running experience with over 200 ceramic regenerators.

The problems of sealing, supporting and manufacturing the glass ceramic rotary generator are discussed and future practical regenerative designs are outlined.

Heat exchange theory applied to small gas turbines is also reviewed.
Paper 15: The Design of Tubular Gas Turbine Combustion Chambers for Optimum Mixing Performance
Authors: Lefebvre A. H. , Norster E. R.
Published: June 2010

A method is presented for determining the ideal ratio of flame-tube diameter to air-casing diameter, and the optimum number and size of dilution holes, for the attainment of a well-mixed primary combustion zone and the most uniform distribution of exhaust gas temperature for tubular gas turbine combustion chambers. The method employs data accumulated from a series of experimental investigations carried out on the flow and mixing characteristics of cold air jets when injected into a hot gas stream. Graphs are included to facilitate the design procedure and to illustrate the relative importance to mixing performance of various factors such as overall pressure loss, airflow distribution and diffuser pressure loss coefficient.
Paper 1: Trends in the Design of Highly Rated Steam Turbines
Authors: Mitchell J. M.
Published: June 2010

This paper discusses briefly the concept of a highly rated steam turbine, making use of the well-known laws of dynamic similarity, and demonstrates the economic advantages of using highly rated machines in appropriate circumstances. A number of design and constructional features of highly rated modern turbines are described and illustrated, together with examples of complete machines. Operational and control aspects and solutions to a number of special problems are discussed.
Paper 12: Review of a Modern Marine Boiler
Authors: Disley K. T.
Published: June 2010

In recent years the operating conditions and power requirements of ships have led to rapid developments in marine boiler design. Up to 1949 steam pressures and temperatures had been fairly moderate. Since then steam temperatures and pressures have gradually increased and now the majority of modern boilers are operating at 850 lb and 950°F. In addition to the changes in steam conditions the development of the large tanker and fast container ship and the requirements of passenger liners have led to considerable changes in boiler design. The object of this paper will be to outline the development of marine boilers over the years and to indicate the reasons that have led to the changes illustrated and to comment on the type of boiler that will be coming into operation in the 1970s.
Effects of Some Hydraulic Fluid Lubricants on the Fatigue Lives of Rolling Bearings
Authors: Hobbs R. A. , Mullett G. W.
Published: June 2010

Hydraulic equipment operating in potentially explosive or inflammable atmospheres (e.g. pumps in mines) has to use special fluids which are fire-resistant. Frequently the equipment design is such that the same fluid is used to lubricate rolling bearings. It is already known that some fluids, particularly those containing water, cause a serious reduction in the fatigue lives of the bearings.

This paper describes a ball bearing rig and the test conditions under which several fire-resistant fluids were evaluated. It compares the fatigue lives obtained with the lives obtained when using mineral oil lubrication. Factors by which bearing capacities should be reduced when using these fluids are suggested.

The fatigue testing of batches of bearings is time-consuming and the fluids are continually undergoing development. There is thus some difficulty in keeping up-to-date. However, the capacity factors given are indicative of the magnitudes of the effects that fire-resistant fluids can have on bearing lives.
Load-Carrying Properties of Metal Dialkyl Dithiophosphates: Application of Electron Probe Microanalysis
Authors: Forbes E. S. , Allum K. G. , Silver H. B.
Published: June 2010

The surface topography and the nature of the surface layer of wear scars obtained with Bi(III), Pb(II), Cd(II), Ni(ll), and Zn(II) di-(4-methylpentyl-2) dithiophosphates, using the four-ball machine, have been studied using an electron probe microanalysis (EPMA) technique. The results show that the nature of the dithiophosphate markedly affects the surface topography, element content, and distribution of the wear scar in both the extreme pressure and mixed lubrication or antiwear regions. The implication of these EPMA results on the load-carrying mechanism of metal dialkyl dithiophosphates is discussed.
Non-Linear Transient Vibrations in Journal Bearings
Authors: Jakobsen K. , Christensen H.
Published: June 2010

A journal under constant external loading will, when released from a position different from its equilibrium position, execute a damped vibration motion, since the journal mass, together with the non-linear damping and elastic fluid forces, will constitute a vibrating system. The journal centre locus is calculated for various journal masses and starting positions.
Formation of Tin Oxides on White-Metal Bearings
Authors: Lloyd K. A. , Wilson R. W.
Published: June 2010

This paper describes a laboratory investigation of the factors governing the formation of hard layers of mixed tin oxides on tin-base white-metal bearing surfaces in marine power units. A galvanic corrosion cell has been developed which produces hard black layers identical with those found on failed bearings. The influence of temperature, of oil and electrolyte composition, and of the composition of the bearing metal and its substrate on this anodic oxidation has been investigated.
Film Thicknesses in Elastohydrodynamic Lubrication at High Slide/Roll Ratios
Authors: Dyson A. , Wilson A. R.
Published: June 2010

The thicknesses of the films of lubricant formed between two steel discs in rolling and sliding contact have been estimated from measurements of the electrical capacity between the two discs. As the slide/roll ratio increased above a certain level the experimental values of the film thickness became progressively greater than the values predicted by conventional isothermal elastohydrodynamic theory. Ultimately the discs were operated satisfactorily with equal and opposite peripheral velocities, although the conventional theory would then predict the complete absence of a hydrodynamic film.

These discrepancies are observed when the peripheral velocities of the discs are in opposite directions and they are explained in principle by the effect of the variation of the temperature of the oil across the film in the inlet zone. The conventional theory of film thickness in elastohydrodynamic lubrication has been modified to take this effect into account.

It was not possible to obtain an exact theory for the general case but two extreme conditions could be defined and exact solutions found for them. Most of the experimental film thicknesses fell within the range of these extremes, and the variation with conditions of the position of the experimental points was approximately as expected on general grounds.

One of the consequences of these general considerations was that film thicknesses should increase with load at constant disc speed and surface temperature, and this was confirmed by direct measurement.
Performance of a Short Multi-Grooved Capillary Compensated Hydrostatic Journal Bearing
Authors: Patrick J. K. , Chen N. N. S.
Published: June 2010

This paper presents the results of an extensive experimental investigation into the performance of a short multi-grooved bearing subjected to a range of static and alternating loads. Lubricating oil was supplied, at pressures of up to 2000 lb/in2, to capillary type restrictors connected to 10 closed-end axial grooves in the bearing. The bearing had a length/diameter ratio of 1/3 and operated with a journal speed and load frequency of 327 c/min.

Measured load capacity, stiffness, and flow characteristics indicate that bearings of this type have a significant load-carrying capacity at zero journal speed and that the load capacity is increased by journal rotation. A feature of the journal behaviour under alternating loads is the movement of the journal centre along a straight line coincident with the load plane.

The extensive oil film pressure surveys indicate for the first time the pressure distribution within narrow hydrostatic bearings and provide a basis for a realistic theoretical analysis of this type of bearing.
Lubrication at Elliptical Contacts
Authors: Snidle R. W. , Archard J. F.
Published: June 2010

The classical hydrodynamic theory for point contacts is extended to cover the general case where the resolved hydrodynamic velocity is not directed along either of the axes of the ellipse of contact. Isobar plots of deduced values of the non-dimensional reduced pressure, q, are shown for some of these cases. A first approximation to an elastohydrodynamic film thickness equation is derived, for this general case, by equating the maximum reduced pressure generated between undeformed bodies to the inverse of the pressure coefficient of viscosity, α.

The theory is applicable to the contact conditions that exist between the teeth of hypoid gears, and the variation of lubricant film thickness with pinion offset and gear ratio for a range of hypoid gear sets has been deduced. Experiments have been performed on a crossed cylinders machine, the results of which demonstrate the general validity of the theory.
Optimum Design of a Spiral Groove Bearing
Authors: Fernlund L. M. I. , Kellström E. M.
Published: June 2010

A new bearing system, consisting of a combination of a flat spiral groove bearing and rolling bearings, has been analysed in respect of temperature distribution under different operating conditions with the aid of a computer programme universally applicable to different design parameters. This programme, in combination with another for the optimization of a function which varies with certain auxiliary conditions, has also been used for the design of the spiral groove bearing in order to obtain maximum film thickness or minimum power loss.
The Chemical Behaviour of Chlorinated Additives under Medium Range Temperature Conditions
Authors: Jemmett A. E.
Published: June 2010

The chemical behaviour of chlorinated e.p. additives has been examined at elevated temperatures and their failure to form a ferrous chloride surface layer is noted. Their method of adhesion has also been examined by infrared spectroscopy.
A Study of the Low-Speed Oscillating Sliding of Unlubricated En 1A Steel Surfaces
Authors: Powell D. G.
Published: June 2010

The apparatus allows a pin to rub on an oscillating disc whilst friction force and pin wear are recorded continuously. Tests have been performed over the load range 0–4·5 kgf at a constant speed of oscillation (8 c/min) and a constant amplitude (approximately 5·0 cm). Transitions are observed in the ‘friction force-load’ and ‘average wear rate–load’ relationships, the slope of the latter changing by a factor of about 30 at a critical load. The wear debris has been studied using the X-ray diffraction technique, and the rubbed surfaces have been examined using a Talysurf instrument and optical and electron microscopy.
Factors Affecting Laboratory Accelerated Testing of Materials for Rolling Elements
Authors: Scott D. , Blackwell J.
Published: June 2010

Although laboratory tests simulating service conditions place materials and lubricants in the same order as full-scale bearing tests, considerable variation can occur between results from machines of the same type. Alignment and elimination of vibration of rolling four-ball type machines and specimen flatness of washer-type machines are important to obtain reproducible results. Results from reference materials are used to illustrate the various factors.
Paper 3: Turbo-Charged Diesel Engines in Production
Authors: Soule G. E.
Published: June 2010

This paper describes some of the practical problems encountered and the resolutions applied during the design and development of a turbo-charged derivative of a production engine. Some further problems are described which were met when the prototype designs were manufactured in the production area. A very brief summary of the reasons for turbo-charging, and the performance results, are also included. The base engine was a 6-litre direct injection dry-linered diesel engine with a rated speed of 2800 rev/min in its naturally aspirated form, used for commercial vehicle propulsion plus industrial and marine purposes.
Paper 14: The Application of Electric Motors in Vehicles
Authors: Barr H. N.
Published: June 2010

The use of electric drive for motor vehicle ancillaries is questioned when adequate power is available from the vehicle's own source of motive power. The term ‘motor’ is extended to include any electromagnetic device which converts electrical energy to mechanical energy. Reference is made to one of the earliest and best-known applications of an electric motor, i.e. the starter motor. Rotating machine construction and performance characteristics are outlined in some detail, and reference is made to applications appropriate to the machine characteristics. Simple control systems are mentioned to show their interdependence with motors as part of the application. The background and current status of the ‘disc’ motor is presented showing the advances made and the problem to be solved in the context of the motor vehicle industry. Machine rating based on the thermal stability of the insulation system with time is discussed. Life, reliability, and cost as major industry objectives receive mention at appropriate points in the text. A typical application is dissected to illustrate the process and some of the details taken into account by a designer before any calculations are made. Reasons are given to show that the application of an electric motor to a motor vehicle is almost wholly a mechanical engineering function with the basic electrical design taking an essential but minor role in the process from demand through to supply.
Paper 5: Power Assistance Pumps for Steering
Authors: Martin K. C.
Published: June 2010

This paper discusses the pump output problems peculiar to power assisted steering, together with the need for the flow control valve. A description of a basic combined flow control and pressure relief valve is given, and the adaptation of the flow control valve to the requirements of power assisted steering is detailed. The pump construction and operation are mentioned, with a description of a typical pump with reference to the special features incorporated for quiet operation. Some changes in design, in an attempt to keep pace with higher pressure demands, are described. The paper also presents the various types of installations and measures adopted to minimize transmitted noise, and concludes with a brief survey of pump types.
Paper 4: Electron Optical Techniques of Failure Investigation
Authors: Scott D. , Loy B. , McCallum R. , Mills G. H.
Published: June 2010

Fractography, the study of fracture surfaces, is useful in failure investigations as the topography and characteristic markings of such surfaces are indicative of the mechanism of fracture which operated during the initiation of failure and crack propagation. Owing to the low depth of focus of the optical microscope, interpretation of some fracture surfaces may be difficult. The microscopic topography, and its relation to the causes and basic mechanisms of fracture, may be conveniently studied by electron microfractography using non-destructive replica methods. Replicas may be taken from selected areas of the fracture surface of large, unwieldy engineering components. Complementary electron optical techniques such as electron diffraction, scanning electron microscopy, and extraction replicas are used where possible to obtain additional fine-scale information of use in the elucidation of failure mechanisms. An explanation of the various techniques and examples of their use in the work of the National Engineering Laboratory in failure investigations is given. The investigations involve fatigue, brittle fracture, corrosion fatigue, stress corrosion, welding problems, and surface phenomena.
Paper 7: Designing to Prevent Fatigue Failures in Service
Authors: Frost N. E. , Marsh K. J.
Published: June 2010

Despite intensive research, failures in service still occur too frequently, and in normal environments most service failures are caused by metal fatigue of some component. The basic mechanism of fatigue failure is examined, indicating that in many cases the failure of a component is dependent more on the cyclic stress required to grow a fatigue crack than on that required to initiate a crack. In such cases, the plain fatigue strength of a material alone may be of little use to the designer, and additional knowledge is required to effect the efficient design of a real component or structure. The problems of variable-amplitude stress cycles and service loadings, notches, crack propagation characteristics, fretting, joints and environment are discussed in some detail, and the concept of designing for a flawed material is proposed.
Paper 9: Fretting Fatigue in Keyed Dovetail Root Fixings
Authors: Morton P. G. , Goodman P. J. , Kawecki Z. M.
Published: June 2010

Dovetail pole root fixings, consolidated by tapered keys, are a feature of many large-diameter salient pole alternator rotors. This paper describes an investigation into the failure in service of such a fixing; the failure being ascribed to fretting fatigue and resulting from a combination of tensile centrifugal loadings and superimposed oscillatory loading.

The failures were reproduced on a series of full-scale joint sections and the design of a special rig, capable of applying typical oscillatory forcing superimposed upon a steady tensile load of 100 tons, is described. The rig was used to assess quantitatively the effect of various measures taken to eliminate the cause of failure.

The test specimens were hand fitted to normal manufacturing methods and, despite the inevitable variations in fit, failed in a consistent manner. The results of the tests provide a practical example of fretting fatigue, and are generally in line with the findings of a fundamental investigation using small specimens and published in 1967 by Field and Waters. The dramatic improvement resulting from relatively minor geometrical changes is clearly demonstrated.
Paper 12: Reliability of Solenoid Valves
Authors: Mercer J. R.
Published: June 2010

The reliability of solenoid valves is of increasing importance, and a comparison is made between electronic components and solenoid valves. Various types of failure are defined and the user's influence in defining failure is explained. Factors influencing failure of a simple solenoid valve are tabulated and the high cost of obtaining data about interaction between factors is described.

The importance of a statistical design approach and the value of test or field experience are emphasized, and mention is made of the problem of obtaining field failure data. The paper also explains the difficulties of detecting component differences which lead to early failure, and the importance of using inspection and production experience to modify designs.
Paper 14: Vehicle Defects as a Contributory Cause of Road Accidents
Authors: Perring H.
Published: June 2010

Frequence of accidents due to mechanical defects is examined, and in addition the ways in which designers can learn details of failures.

Relatively few accidents are fully investigated for mechanical failures, therefore designers must rely mainly on manufacturer's warranty claims for their information about failures which occur in service. These defects have usually not caused the accidents which might have resulted from them.

Certain accidents are investigated by police teams, the Road Research Laboratory, accident hospitals, and Ministry of Transport vehicle examiners; and from these bodies information on mechanical defects is supplied to the manufacturers.

Designers should apply lessons learnt from vehicles in service to designs on the board.
Paper 15: Causes of Unreliability or Failure: Component Defects
Authors: Holmes P. M.
Published: June 2010

The reliability of a component is interpreted as depending upon the accuracy with which it is possible to predict its standard of performance such that an acceptable working condition is sustained up to the point when maintenance or replacement is scheduled. Possible causes of component defects of a magnitude sufficient to give rise to unreliability are discussed from the viewpoint of a user of components, and particularly as obtaining in the mining industry. The discussion of the subject ranges from the pre-design investigation and specification stages to the means by which defects may be determined or their effect minimized during use.
Paper 19: Stress Analysis in the Design of Flawed Structures
Authors: Turner C. E.
Published: June 2010

Sophisticated structures with severe operating conditions may provide a potentially serious safety hazard if failure were to occur. The conventional margins of safety of the nominally perfect structure may be inadequate as a basis for discussing the real strength because flaws will probably exist in the materials from fabrication, or by development during service from fatigue or corrosion. The role of linear elastic and yielding fracture mechanics for assessing the strength of flawed structures is reviewed for static, impact fatigue, and environmental conditions. It is concluded that for those problems that warrant such treatment, the basic knowledge exists whereby the initiation, and particularly the propagation, of cracks on the macroscale can be studied near quantitatively during the design process.
Paper 25: Reliance on Statistics
Authors: Cox H. L. , Fenner A. J.
Published: June 2010

This paper reviews the probable characteristics of the populations the engineer is likely to encounter, and considers the dangers inherent in reliance upon analysis based on a characteristic not truly representative of the population. For comparison between two or more samples, an inappropriate choice of population characteristic may not matter a great deal; but any estimate of extreme values must depend vitally upon our confidence, on grounds quite independent of the samples themselves, that the samples are indeed drawn from populations having the same general characteristic, albeit one different from that on which the comparison is based.
Paper 26: Techniques of Improvement
Authors: Nixon F.
Published: June 2010

Management's task is to ensure that the enterprise will deliver products which will satisfy the customer. A main requirement is reliability of performance and hence freedom from unexpected failure. To achieve this, management must deploy adequate engineering resources throughout all the activities concerned with the evolution of the product from concept to satisfactory service.

An engineering background helps management to preserve the wider viewpoint that is often lacking in specialist areas. It is essential that there shall be effective communication and collaboration between all departments, a need that is well described today as ‘systems engineering’. The paper also examines prevailing difficulties and suggests remedies.
Paper 31: Major Causes of Failure—Civil Aircraft Structure
Authors: Williams J. K.
Published: June 2010

This paper deals with failures of structural components of civil aircraft which have resulted in fatal accidents or serious incidents during the past twenty years.

Fatigue failure of components has been the most significant contribution to the major structural failures of civil aircraft. As a result, the attack on the fatigue problem has had the greatest effect on changes in structural design concepts, substantiating tests and operational maintenance and inspection procedures.

Today, with the ‘fail safe’ concept of structural design, combined with complete airframe fatigue testing, a very great advance has been made towards ensuring the safety standard of civil aircraft structures.
Paper 33: The Choice of Fail Safe and Safe Life Fatigue Philosophies in Aircraft Design
Authors: Ward A. P. , Parish H. E.
Published: June 2010

This paper considers the current fatigue design process and the means of establishing safe lives. The alternative philosophies are discussed together with the required scatter factors. Methods of achieving fail safe designs and the application of crack propagation data are reviewed. Also, since some fatigue designed members will be loaded in a cracked or flawed condition, the theory of fracture mechanics is mentioned. Finally, alternative designs are compared on a weight basis, these leading to different conclusions, depending on the particular function of the structure.
Velocity of Sound and Critical Discharge Pressure in Annular Two-Phase Flow
Authors: White R. F. , D'Arcy D. F.
Published: June 2010

The effects of a rapid loss of coolant caused, for example, by the fracture of a pipe in the primary coolant circuit play an important part in the safety assessment of a water-cooled nuclear reactor. In particular, it is essential to know the rate of decrease of coolant density in the core and the rate of discharge of coolant into the containment space. It is uneconomic to obtain this information from experiments on each new reactor. Consequently computational methods, supported by experiments on basic elements of a coolant circuit, are being developed which will be applicable to a wide variety of reactors.

An experiment is described in which fundamental information on fluid flow dynamics was obtained. In the experiment, a flow of two-phase water at high pressure was established in a straight pipe 15 ft long and 0–621 in i.d. At the downstream end of the pipe a rupture disc was suddenly burst. The pressure versus time histories at three locations along the pipe were recorded, using fast response pressure transducers and a multichannel oscilloscope. Experimental results are given for pre-blowdown pressures of 500 and 1000 lb/in2 (abs.) and steam qualities of 10–30 per cent. The mass flux was 0·6 times 106 lb/ft2 h, and the flow regime was annular.

From the recorded pressure traces, the speed of the head of the rarefaction wave travelling upstream into the fluid was measured and also the pressure at critical flow conditions as functions of the pre-blowdown conditions. These measurements are compared with values calculated from steam tables.
Equipment and Techniques for Studying the Deposition of Sub-Micron Particles on Turbine Blades
Authors: Parker G. J. , Ryley D. J.
Published: June 2010

The equipment and techniques for an investigation into the mechanisms which deposit sub-micron particles on to turbine blades are described, with particular reference to the deposition of fog within the low-pressure steam turbine. The experimental studies were centred around a cascade of blades in an open-circuit low-speed wind tunnel. Deposition on the blades of small solid uranine particles entrained in the main air flow was detected and measured using the fluorescent properties of the particles. Some results from preliminary deposition tests are given.
Local Heat-Transfer Measurements during Forced-Convection Boiling in a Helically Coiled Tube
Authors: Bell K. J. , Owhadi A.
Published: June 2010

Forced-convection boiling heat transfer to water at atmospheric pressure was studied in two helically coiled tubes. Temperature measurements were made at four positions round the tube at each of nine stations along the tube, permitting calculation of the local heat-transfer coefficient at each point. The local coefficients are correlated by the Lockhart-Martinelli parameters for two-phase flow, using the Seban-McLaughlin correlation for liquid phase heat transfer in coiled tubes. The curves for each of the four peripheral positions, compared to that previously obtained for the peripheral mean coefficient, are consistent with a flow structure having a vapour core with a strong secondary flow serving to distribute the liquid over the entire surface of the tube. The correlation and its interpretation in terms of flow structure may fail at high pressures as a result of the much smaller change in the radial acceleration in systems with small density difference between liquid and vapour.
An Investigation of Electrostatic Charging Effects in High-Speed Gas-Solids Pipe Flows
Authors: Cole B. N. , Baum M. R. , Mobbs F. R.
Published: June 2010

A comparison is made between the pressure distributions in identical brass and nylon pipe-lines conveying polystyrene powder, showing that electrostatic charging of the solid particles has a negligible effect on highspeed, gas-solids pipe flow.

A theory is presented for the prediction of the electrostatic charging rate of the solid particles. It is predicted and confirmed experimentally that the current to earth from electrically isolated sections of the brass pipe and from aluminium foil wrapped on a length of the nylon pipe varies linearly with the solids loading.
Effect of By-Pass Characteristics on Parallel-Channel Flow Instabilities
Authors: Carver M. B.
Published: June 2010

Experiments on parallel-channel hydrodynamic stability frequently use one heated channel operating in parallel with an unheated by-pass. This arrangement is designed to simulate the operation of a particular channel in a boiling water reactor; the by-pass providing the essentially constant pressure drop which the remaining channels impose on the channel in question.

If the ratio of by-pass flow to channel flow is large the changes in channel flow do not significantly affect the overall pressure drop; however, particularly in experiments using full-scale reactor fuel channels, loop capacity may limit this by-pass ratio. In this case the pressure drop is no longer constant.

This paper shows, analytically, that a low by-pass ratio, resulting in a variable overall pressure drop, significantly affects the dynamic behaviour of the heated channel. Both the power at threshold of flow oscillation and the natural frequency of the system are shown to depend on by-pass characteristics. In particular, a heated channel operating with a low by-pass ratio is normally stable to much higher powers than it is with a high by-pass ratio.

A linearized analysis is presented which illustrates the effect of by-pass resistance and inertia on the threshold power and natural frequency of flow oscillations. The analysis is incorporated in a computer code, and resulting threshold powers and oscillation frequencies are compared to data from experiments using a full-scale simulated reactor channel in parallel with a by-pass.

It is concluded that the finite unheated by-pass does not accurately simulate the dynamic effect of the remaining reactor channels on a particular channel. However, the methods of this paper should prove useful in interpreting results from a flow-limited test loop and extrapolating to the full reactor case.
Adiabatic Flashing Flow of Water in Tubes
Authors: Dickson A. N. , Markham V. B.
Published: June 2010

A report is given of some studies of adiabatic flashing flow of water in tubes; it forms an extension of the work reported in reference (1). The work, which is supported by a grant from the Science Research Council, is part of a programme of research directed towards the flash distillation process. The principal phenomena governing this type of flow are discussed, including, in particular, the local rate of formation of vapour, because it is this which determines the non-equilibrium character of flashing flow. Equations are developed to describe the problem, and numerical solutions are compared with experimental results. Experimental technique is discussed, including the measurement of density by a ‘one-shot’ gamma-ray method.
Current Design Activities on British Railways
Authors: Thring J. F.
Published: June 2010

With the identification of profitable freight areas and the selection of growth traffics for development has come the need to review in detail the running gear and, in particular, the suspensions of both 4-wheeled and bogie vehicles. This design review has been aimed at ensuring a high-speed capability for all new freight vehicles coupled with safety at all times, low maintenance costs, and maximum availability.

After reviewing traditional suspensions, in wide use, with reference to their known strengths and weaknesses, the paper discusses in some detail the philosophy now being applied in B.R. design offices to new freight running gear, for both 4-wheeled and bogie vehicles, to ensure satisfactory achievement of technical objectives.

Examples of new developments are provided, together with comments on progress to date.
A Study of the Fluid Flow in the Stator of an Electrical Machine
Authors: Latto B. , Galloway L.
Published: June 2010

This paper describes an experimental study of the air flow behaviour in the ventilating ducts in the stators of electric motors and/or generators of a conventional design. The objective of the research was to facilitate the prediction of the local heat transfer coefficients in the ventilating ducts. Various flow phenomena were observed and compared with theoretical predictions. Although the theory usually used for similar cases was found to be inapplicable, a related theory was found that checked well with experimental results. A stall phenomenon was observed under certain identified conditions. Useful relationships for predicting the flow details were obtained, and suggestions for future improvement in duct designs are proposed.
Non-Steady State Thermal Performance of Electrical Machines
Authors: Preston S. B. , Thomas M. A. , Pennington G. A.
Published: June 2010

Because the ratings of electrical machines continue to increase, there is a growing need to be able to predict their thermal performance under the transient conditions caused by overloading or stop-start operation. The design of electrical machines is often too complex to make an analytic solution feasible, but a general numerical method has been developed to predict component temperatures at the drawing-board stage. The problem to be solved is represented by a thermal resistance-capacitance network, the resulting set of simultaneous equations being solved by a digital computer employing a step-by-step procedure. The number of network nodal points at which the temperature can be calculated is at present restricted by computer storage space to 150, therefore the fully three-dimensional problems which can be solved are of limited complexity. However, the majority of electrical machines can be simplified by assuming axial symmetry, which permits a large variety of problems to fall within the capabilities of this technique.
A Summary of Research into the Basic Principles of Flameproof Enclosure
Authors: Phillips H.
Published: June 2010

The flameproof enclosure of electrical machines relies on the ability of small gaps between flanges to prevent the transmission of an explosion from inside an enclosure to a flammable atmosphere outside. Obstructions to the free flow of gas from the gaps may sometimes seriously reduce the size of the critical gap for ignition. The mechanism of ignition is explained as being dependent on heat transfer within the flange gap, and on mixing and combustion within the jet of combustion products emerging from the gap. From the theory the sizes of safe flange gaps can be predicted and the effect of obstacles can be explained
Flow Distribution and Pressure Drop in Salient Pole Electrical Machines
Authors: Carew N. J.
Published: June 2010

These machines generally have a volumetric flow distribution, which although symmetrical about the core centre-line, increases from the end of the machine to maximum in the middle. The rise of volumetric flow is attributed to an axial increase of interpolar static pressure caused by change of kinetic to potential energy due to air bleed-off through the core ducts. Equations predicting the pressure losses for the rotor/stator combination are itemized, together with an expression for head generation by the salient poles. A comparison is made between predicted volumetric flow distribution and a machine test result.
The Solution of the Heat Flow Equations in Large Electrical Machines
Authors: Roberts T. J.
Published: June 2010

To ensure that the materials used in the construction of a rotating electrical machine are utilized economically it is necessary to be able to predict the temperature distribution within the machine.

A resistance network analogue representation of the stator core and windings is derived, based on the finite difference approximation to the heat flow equations. A solution of the analogue is achieved by matrix methods on a digital computer. The advantages of this particular analogue representation are that the effects of axial heat flow in the copper and changes in the air temperature in the radial air ducts are taken into account. The validity and accuracy of the analogue representation are checked by comparing the results with those obtained from detailed temperature measurements on a production machine. It is shown that the present standard methods of measuring winding temperature are inadequate for determining the actual copper temperature.

Under certain circumstances high temperatures can be obtained in the endwinding region of a machine. These temperatures are undetected by the standard method of temperature measurement and are shown to be due to the low value of endwinding insulation thermal conductivity.
Determination of the Thermal Constants of the Heat Flow Equations of Electrical Machines
Authors: Roberts T. J.
Published: June 2010

One of the major problems in obtaining accurate predictions of temperature distribution within an electrical machine is the values of the thermal constants used in the solution of the heat flow equations. A line source method is developed for anisotropic materials and is used to determine the thermal conductivity of sheet steel laminations. Results are given for three typical sheet steels showing the effect of varying core clamping pressure. The thermal conductivity of high-voltage insulation is obtained from tests on production machine coils and values are given for typical insulation systems.

A model test is described for the evaluation of the heat transfer coefficients from the cooling surfaces of the radial air ducts, based on the assumption of a uniform distribution of air across the duct entrance. The heat transfer coefficients from the other cooled surfaces within the machine are determined from full-scale temperature measurements on production machines. The limitation of this latter method of determination of heat transfer coefficient is evaluated.
Heat Transfer Considerations in Superconducting Machines
Authors: Tinlin F.
Published: June 2010

Problems of cryogenic heat transfer are discussed with particular reference to the IRD prototype superconducting motor. Experimental work on heat transfer in the nucleate boiling régime of liquid helium is described and the application to the design of a superconducting field coil is outlined.

The design of gas-cooled high-current leads in a cryogenic environment is discussed and the practical solution is compared with the theoretically ideal design. Other heat transfer problems encountered in the machine design are those associated with the thermal isolation of the field coil from the environment. An assessment is given of the various heat loads due to conduction and radiation which make up the total refrigeration requirement of the machine.
Film Thicknesses in Elastohydrodynamic Lubrication of Rollers by Greases
Authors: Dyson A. , Wilson A. R.
Published: June 2010

The object of this work was to measure the thickness of the films formed by greases under conditions of elastohydrodynamic lubrication. The thicknesses of the films were estimated from measurements of the electrical capacity between two discs. In general, the mineral oils from which the greases were made formed films whose thickness did not vary with time. The films formed by the greases were initially thicker than those formed by the corresponding base oils but, after continuous running, became thinner than the oil films. Evidence is offered that the differences observed between oils and greases are related to the viscoelastic properties of the lubricants.
Greases as Lubricants for Metal and Plastic-Lined Plain Bearings
Authors: Sallis J. G. M. , Wilson W. H.
Published: June 2010

Compared with data on oil-lubricated plain bearing materials, very little has been published about the performance of conventional plain bearing materials with grease lubrication. This paper presents the results of wear tests on bushes as a guide for designers to the selection of suitable materials and types of grease. Marked differences were shown between the relative performance of different metals lubricated with grease compared with those lubricated with oil. Good mechanical and chemical stability are most important for greases used to lubricate plastic bearings. To stimulate constructive comment, a suggested ideal grease specification for plain bearings is mooted.
Paper 4: An Investigation of Shock Wave Behaviour in Ducts with a Gradual or Sudden Enlargement in Cross-Sectional Area
Authors: Deckker B. E. L. , Gururaja J.
Published: June 2010

This paper details some investigations relating to non-stationary wave interactions and their effects on the propagation of finite amplitude waves in ducts with either a gradual or sudden change in cross-section. The influence of the angle of divergence on the wave-front and the perturbed flow behind it has been examined in different diffuser configurations using Schlieren spark photography.

The variation with incident pressure of the net pressure (superimposition pressure) and the transmitted pressure are presented for incident pressure ratios up to 3·4. The results have been compared with a quasi-steady one-dimensional analysis and with the theory of Chisnell. Differences between measured and predicted results are attributed to the failure of the theories to account for the wave interactions. A complete analytical solution does not appear possible in view of the complexities of the flow and wave action, and numerical methods have to be employed.
Paper 1: Relation between Blade Row Spacing and Potential Flow Interaction Effects in Turbomachines
Authors: Parker R.
Published: June 2010

This paper develops a simple relationship between distance upstream and downstream of a row of blades and the velocity disturbances created by the passage of those blades. The relationship is compared with values obtained by numerical computation and measurement in an experimental axial flow compressor rig. The magnitude of vibration exciting forces and/or noise radiation sources due to potential flow interaction on a stationary row of blades is directly related to the magnitude of these velocity fluctuations. The analysis is therefore a basis ( a) for estimating the inter-row spacings for a turbomachine such that potential flow interactions are reduced below the levels of other forms of interaction, and ( b) of translating practical experience of noise and/or vibration excitation in existing machines to give reliable predictions for future designs.

It is found that while potential flow interaction effects drop rapidly with increasing blade row spacing for low-speed machines, this is not the case for high speeds and very large spacings may, in fact, be required where the rotor blade speed is equivalent to a high value of Mach number. It is also found that the rate of decrease in effect is related to the circumferential wavelength of the disturbance, and comparisons between machines based on blade chords (as is the present normal practice) are meaningless unless the ratio pitch/chord is constant.
Paper 13: The Performance of Turbojet Engines during the ‘Thermal Soak' Transient
Authors: Maccallum N. R. L.
Published: June 2010

The changes are considered which might be present within a jet engine during the ‘thermal soak’ transient to cause the engine's performance to differ from the equilibrium performance. The effects of known values of these changes are given for a simple jet engine over a wide range of engine pressure ratios. Values of these changes are then predicted for a typical engine, and the observed loss in thrust of 1·7 per cent is satisfactorily explained. Two of the major factors giving loss of thrust in the simple jet engine were heat absorption in the turbine metal and heat absorption in the compressor metal. The effects of known values of these two factors on the performance of a typical high by-pass turbofan engine are given. For similar fractional heat absorptions, the losses in thrust of the turbofan engine are roughly double those of the simple jet engine.