bluuebunny/crossref_metadata_2025 huggingface dataset:
Pneumatic Transportation of Coal and Ash in Industrial Boiler Plant-Design of the System
Authors: Hunter J.
Published: October 2007

A general theory of pneumatically transporting industrial coals through pipework is proposed based on an adaptation of Hinkle's general equation for solids flow in pipework. The theory is suggested as an overall mathematical framework for designing systems for industrial and power station coal-fired plant and possibly for general transportation systems. Results are given for trials on a test rig based on three industrial coals—singles, dry/untreated and wet/washed smalls coal—and their fit with results predicted by the theory. In the design of the system, I propose the concept of dividing the system into three basic sections: (1) the clean-air section; (2) the coal-transportation section; and (3) the ash-transportation section. Equations are given for designing sections (1) and (2) and empirical data for section (3). Curves are given for the coal transportation section showing the effect of the coal concentration in the pipework, the pipework diameter and length and the verticality of the pipework on the dependent variables—pressure loss, coal quality, power requirements, energy consumption, flow rate and average pressure in the section. Important general conclusions are drawn from this work and practical information is given based on my experience. It is finally suggested that there is an urgent need for new concepts in the design of automatic systems for all types of coal-fired plant if coal is to assert its natural place in the current explosion in demand for world energy. I suggest that automatic systems are the best way of achieving this.
Low-Cycle Fatigue Behaviour of Gas Turbine Alloys
Authors: Evans W. J. , Tilly G. P.
Published: October 2007

The low-cycle fatigue characteristics of an 11 per cent chromium steel, two nickel alloys and two titanium alloys have been studied in the range 20° to 500°C. For repeated-tension stress tests on all the materials, there was a sharp break in the stress-endurance curve between 103 and 104 cycles. The high stress failures were attributed to cyclic creep contributing to the development of internal cavities. At lower stresses, failures occurred through the growth of fatigue cracks initiated at the material surface. The whole fatigue curve could be represented by an expression developed from linear damage assumptions.

Data for different temperatures and types of stress concentration were correlated by expressing stress as a fraction of the static strength. Repeated-tensile strain cycling data were represented on a stress-endurance diagram and it was shown that they correlated with push-pull stress cycles at high stresses and repeated-tension at low stresses. In general, the compressive phase tended to accentuate cyclic creep so that ductile failures occurred at proportionally lower stresses. Changes in frequency from 1 to 100 cycle/min were shown to have no significant effect on low-cycle fatigue behaviour.
Investigation of Bearing Misalignment Problems in a 500 Mw Turbo-Generator Set
Authors: Ettles C. , Wells D. E. , Stokes M. , Matthew J. C.
Published: October 2007

An elasticity analysis to calculate the distribution of all bearing loads in a turbo-generator set is presented from first principles. It is shown that the movement of bearing pedestals caused by the thermal distortion of the foundation can cause considerable changes of load distribution between bearings with consequent problems of oil film instability and shaft whip. Acute misalignment encountered in practice can cause some bearings to take a negative load. The development of a computer programme is described, which can be used to investigate a range of possible cold re-alignments.

A separate analysis of the particular type of bearings used shows that the load capacity is completely adequate in the downwards direction, but greatly reduced in the upwards direction. Upwards loads of static or dynamic origin should be avoided with the type of journal bearing design considered here.
Surface Roughness of Graphite and Its Effect on Friction Factor
Authors: Warburton C.
Published: October 2007

Experimental results are presented for friction factor and surface finish measurements on eight graphite tubes machined to give a range of surface finishes from smooth up to the maximum roughness likely to occur in a reactor.

Correlations are given which allow estimation of friction factor from graphite surface finish measurements.

The results are compared with those obtained by Nikuradse in his sand-grain roughness tests. Except at low values of es+, agreement is good, enabling the heat transfer similarity law of Dipprey and Sabersky to be used to predict any increases in Stanton number due to surface roughness.
Mixed Lubrication and Surface Topography of Rolling Contacts
Authors: Leaver R. H. , Sayles R. S. , Thomas T. R.
Published: October 2007

Measurements of friction torque in a tapered roller bearing are made over a range of axial loads at low rotational speeds. Under these conditions considerable metallic contact between surface asperities occurs. Experimental and theoretical values of no-contact time are compared. The usually adopted ratio of calculated film thickness to gross surface r.m.s. value is shown to be a less meaningful measure of the quality of lubrication than one based on the r.m.s. after filtering out contributions due to asperities of wavelength greater than twice the Hertzian width. An analysis of the statistical properties of worn and unworn surfaces is made. Digital filtering of the power spectrum reveals differences that are not apparent in the unfiltered data. Asperities of long and very short wavelengths, compared with the Hertzian width, are shown to be little affected during running-in whilst those of intermediate size are removed.
Bulge-Forming in a Pressurized Atmosphere
Authors: Kular G. S. , Hillier M. J.
Published: October 2007

Clamped aluminum circular blanks, having approximately planar isotropy, were bulge-formed by an oil pressure differential against hydrostatic back pressures of up to 69 MN/m2. Both generalized strain-hardening and the onset of necking were found to be virtually independent of back pressure. Theoretical calculations of the maximum pressure differential agreed closely with experiment. Theory underestimates the critical generalized strain at necking.
Four-Cylinder, Four-Cycle Engine with Two Reciprocating Components
Authors: Baker A. J. S. , Cross M. E.
Published: October 2007

Without introducing novel technology, the advantages of the Cross cool-combustion chamber have been combined in a compact engine form. This has enabled a practical engine to be developed in a comparably smaller envelope than would be possible with a conventional arrangement. An eccentric crank mechanism is used, which eliminates swinging connecting rods and thus generates simple harmonic motion at the pistons.

The Cross rotary valve enables the bore-stroke ratio to be reduced significantly without combustion penalty and a bore-stroke ratio of 1:7 has been chosen for a prototype. The practical development of this engine is described, together with the rationale of its conception.

In the present climate of fuel shortage, it is anticipated that low fuel consumption and octane requirement, which have been well demonstrated for the Cross combustion chamber, will be of considerable importance, while the compactness of the complete engine should offer significant installational advantages.
The National Centre of Tribology—Some Experiences of Services to Industry since 1968
Authors: Roberts W. H.
Published: October 2007

N.C.T. has dealt with virtually every industry. An analysis is presented of the use made of its consultancy and R&D services by equipment manufacturers and by plant users; and by large and small companies. Examples are given to illustrate the great diversity of problems encountered, both in application and scale. It is concluded that there is a need for tribological help to industry and that there is a demand for such a service on commercial terms.
The Corps of Royal Electrical and Mechanical Engineers—An Engineering System Supporting the Army'S Vehicles and Equipment
Authors: Hughes T. J. A.
Published: October 2007

A review of the Corps of Royal Electrical and Mechanical Engineers—a brief history introduces a description of the present day engineering support provided to the British Army by REME.
The Vane Bearing—A Self-Pressurizing Journal Bearing
Authors: Ettles C.
Published: October 2007

If the shaft of a journal bearing could be made to have a number of pressure sources which travel with the shaft, the load capacity of the oil film could be greatly enhanced. This paper describes the development of a concept in which the pressure sources arise from a positive displacement effect due to the eccentricity of the shaft within the bearing. The configuration has similarities to the rotor of a vane pump in which the entry port is open and the exit port closed. The bearing could be described as a hybrid hydrodynamic-hydrostatic bearing where the hydrostatic supply is self-contained and self-generated.

A number of methods of causing this self-pressurization are discussed. A theoretical analysis shows that load (or Sommerfeld) number improvement factors in the range 3–10 are quite feasible at the expense of an increased flow and power requirement.
Viscous Dissipation Effects on Developing Laminar Flow in Adiabatic and Heated Tubes
Authors: Collins M. W.
Published: October 2007

A finite-difference solution is presented for the problem of laminar developing flow in a circular tube, allowing for viscous dissipation and viscosity variation with temperature. Predictions of temperature and pressure under adiabatic conditions compare reasonably with published experimental and analytical results. Polak's postulation of a hot slip zone is considered. Heat transfer, with constant wall heat flux, is also studied and it is concluded, with reference to some recent experimental data, that it is not necessary to postulate viscous dissipation as being a substantial aiding effect. Predicted Nusselt numbers are, in fact, reduced by allowing for the effect.
Computerized Analysis of Dynamic Pressure Exchanger Scavenge Processes
Authors: Azoury P. H. , Hai S. M.
Published: October 2007

The present work supplements a previous analysis by Azoury of the basic wave processes in a d.p.e. (dynamic pressure exchanger) cell. A hybrid computerized method of integrating the differential equations of unsteady one-dimensional ideal gas flow is used to analyse the component scavenge processes of the d.p.e. in a looped arrangement. These processes are employed to investigate the effect of the relative nature of the interacting gases on d.p.e. performance. A criterion of high performance is proposed in terms of the overall strength of the interface between the gases and their relative specific heat ratios. The criterion gives good agreement with theory when tested with experimental results obtained on two d.p.e. test units.
The Application of Double Conical Journal Bearings in High Speed Centrifugal Pumps — Parts 1 and 2
Authors: Ettles C. , Svoboda O.
Published: October 2007

Conical bearings can in principle support a combination of radial and axial load. Their application to centrifugal pumps is considered, which allows the thrust bearing of the conventional arrangement to be dispensed with. It is shown that with low pressure oil lubrication, the axial load of this type of bearing is limited to the ratio (axial load/radial load)=Tan A, where A is the half angle of the cone. Methods of avoiding this limitation are considered.

The feasibility of water lubricated inclined journal bearings for centrifugal pumps is analysed. A ‘Vee’ configuration double conical journal bearing is considered with a central high pressure feed from the pump outlet. Although the enhancement of viscosity due to turbulence is not as great as anticipated, the bearing is shown to have an adequate axial and radial load capacity.

It is shown that flow compensation or restriction to each side of the bearing is necessary to maintain the escaped flow at an acceptable level. The limits of bearing operation are set by acceptable film thickness rather than excessive temperature rise. For this reason, the correct choice of bearing materials to run under thin film or no film conditions in the presence of dirt is probably more important than correct hydrodynamic design.
An Investigation of the Concentration of Chemical Contaminants in a 4 2 MPa Once-Through Boiler Using a Full-Scale Part Model
Authors: Gill G. M. , Norris W. T. , Parry D. J. , Tyldesley J. D.
Published: October 2007

A scanning gamma-ray detector located deposits of radio-labelled magnetite and sodium and bromine salt contaminants in water fed to an electrically heated serpentine tube replicating one of those in the boilers of Wylfa Nuclear Power Station. Magnetite deposited mainly in the economiser and evaporator initially near the entrance but later spreading further into the boiler. Soluble salts were found mostly in the dryout zone but also in the superheater and, under certain conditions, in parts of the evaporator. Sodium salts were carried through stoichiometrically, but with magnesium salts the anion was carried through in excess. Disodium phosphate added in suitable quantities was found to suppress internal corrosion.
Human Aspects of R and D Organization
Authors: Parker R. C.
Published: October 2007

The organisation structure of an R&D Division should seek to establish conditions in which creative ideas flourish. The nature of the R&D activity and needs of its staff must be clearly understood. The essential core of the organisation should comprise a number of commercial target groups around which lie a flexible array of disciplinary and service groups. It is essential that group managers are seen to be scientists or engineers of distinctive competence. There should not be more than three tiers of management.
Turbulent Boundary Layer Flow on the End Wall of a Cylindrical Vortex Chamber
Authors: Kotas T. J.
Published: October 2007

A presentation of some measurements of velocities in the turbulent boundary layer on the end wall of a vortex chamber. These show that the boundary layer flow is three-dimensional with large inward radial velocities. Consequently, most of the fluid entering the vortex chamber passes into the central region through the boundary layers on the end walls rather than the main space of the vortex chamber. A momentum integral solution is used to obtain an estimate of the radial flow through the end-wall boundary layers. A comparison of the theoretical curves with the experimental results gives support to the main assumptions used in the solutions.
A Numerical Simulation of the Diaphragm Stepped Thrust Bearing
Authors: Tieu A. K.
Published: October 2007

The diaphragm stepped thrust pad (l)† operating at low rotor surface speeds is simulated on the PDP-6 digital computer according to a numerical procedure involving the solution of the Reynolds equation and the elasticity equation respectively by the finite element method and the finite difference method. The computed results compare very well with the experimental results. Multiple regression analysis is then applied to the computed data of the simulated pad to obtain design relationships between parameters affecting the performance of the pad.
A Theoretical Investigation of the Effect of Initial Velocity and Temperature Lag on the Flow of a Gas-Solid Suspension through a Convergent-Divergent Nozzle
Authors: Mobbs F. R. , Baum M. R. , Cole B. N.
Published: October 2007

The effects of initial velocity and temperature lags between the solid particles and the gas in the high speed flow of a gas-solid mixture through a convergent-divergent nozzle are investigated. The results are interpreted physically in terms of the relative importance of heat, momentum, and kinetic energy transfer between the solid particles and the gas, and nozzle area variation.

The influences of solids loading, solids specific heat, solids density and particle diameter on the flow process are also examined.
Nucleation Studies in Flowing High-Pressure Steam
Authors: Bakhtar F. , Ryley D. J. , Tubman K. A. , Young J. B.
Published: October 2007

A description is given of a theoretical treatment of nucleation in flowing steam employing an equation of state based on the second virial coefficient. Comparison is made with experimental observations of reversion in the pressure range 2–35 bars of steam in a convergent-divergent nozzle of expansion rate P = 104 s-1. The agreement obtained is moderate.
The Rotary Fuel-Injection Pump as a Source of Cyclic Variation in Diesel Engines, and its Effect on Nitric Oxide Emissions
Authors: Wing R. D.
Published: October 2007

Cyclic combustion variations have been demonstrated to exist in a direct injection Diesel engine to a surprisingly large extent. With the aid of an on-line computer engine-test facility statistical and correlation analyses were carried out to verify a strong relationship between the cyclic combustion variations and variations in the timing of fuel injection. The importance of these cyclic variations in the reduction of nitric oxide emissions from the engine is shown by experimental results and computer combustion model predictions.

The overall effect on nitric oxide emissions is, however, small over most of the operating range of the engine.
Skin Friction and Form Pressure Loss in Tube Bank Condensers
Authors: Morsy M. G.
Published: October 2007

In this paper, the effect of condensation on both skin friction and form pressure loss in staggered tube bank have been studied. Skin friction distributions on cylinders in different positions within the bank have been measured by a newly developed technique. Form pressure losses were calculated from the measured static pressure distributions “round bank cylinders. Condensation was simulated by homogeneous suction of air through cylinder wall, and the effect of suction rate on both skin friction and form losses was studied. The results show that condensation favourably modifies both skin friction and form losses in the bank.
Engine Induction Developments - Economic and Reduced Exhaust Emissions: Fuel Vapourization - Economy with Reduced Exhaust Emission
Authors: Hughes D. W. , Goulburn J. R.
Published: October 2007

SYNOPSIS This paper describes a simple system of controlling exhaust emissions from gasoline engined vehicles, using a coolant-heated fuel vaporiser in the inlet system. The object of complete vaporisation of the fuel is to create a homogeneous inlet charge, giving improved cylinder-to-cylinder distribution and permitting operation with very lean mixtures. This leads to low exhaust emissions of Carbon Monoxide, Hydrocarbons and Nitric Oxides. The effects of vaporisation on the lean limit of operation, exhaust emissions, power output, fuel consumption and optimum spark ignition timing have been investigated, and are discussed in the paper. Results of tests on a 1.6 litre car are also presented. It was found that exhaust emissions were effectively controlled, while vehicle driveability remained acceptable. Engine power was reduced by 25-30%, although fuel consumption was not increased.
Some thoughts on the Training and Career Development of the Chartered Engineer in the Railway Industry
Authors: Hardy R.H.N. , Howard H. , Withey J. A.
Published: October 2007

SYNOPSIS Training and career development of the Chartered Engineer in the Railway Industry has changed greatly in the last fifteen years. A degree or its equivalent is now obligatory as a basis for Chartered status. Industrial experience has to be condensed and carefully executed and the development of a young man's career must be given greater attention than in the past. Much has been done in recent years, more remains to be done if the right balance in training and development is to be achieved. The authors, experienced managers in the Industry, have drawn on their experience to write a paper in which some of the answers are given, which should provoke discussion and which it is hoped will be practical and useful.
Dynamic Behaviour of a Road Vehicle with Rear Wheel Adaptive Braking Control
Authors: Earles S. W. E. , Aurora B. R.
Published: October 2007

SYNOPSIS Initially the vehicle response during braking is investigated with the aid of a mathematical model having a realistic road input. Using an integrated hybrid computer, the road-tyre characteristics are simulated by generating non-linear functions on the digital computer, while the mathematical model is described on the analogue computer with parallel logic facility. An adaptive braking control system is proposed which measures and processes the rear-wheel motion. Activation of the system occurs when the wheel deceleration and a quasi wheel slip reach given reference values. The adaptive system as developed and optimised on the hybrid computer is implemented on the rear wheels of the test vehicle. The predicted values of wheel speed, brake-pressure modulation, stopping distance and vehicle yaw are shown to compare favourably with the test results.
The Effect of Sizing, Specific Gravity and Concentration on the Performance of Centrifugal Slurry Pumps
Authors: Burgess K. E. , Reizes J. A.
Published: October 2007

Experiments were carried out to ascertain the effects of a slurry on the pump characteristics. The performance of the pump depended mainly on the sizing, specific gravity and concentration of solids in the slurry. A method has been developed for predicting the characteristics of a pump when pumping a slurry, from the clear water performance of the pump and a knowledge of the characteristics of the slurry.
Crack Separation Energy Rates in Elastic-Plastic Fracture Mechanics
Authors: Kfouri A. P. , Miller K. J.
Published: October 2007

SYNOPSIS The application of Griffith energy concepts to Elastic-Plastic Fracture Mechanics (EPFM) is investigated. An elastic-plastic finite element program is used to calculate the values of the Crack Separation Energy Rate, GΔ, corresponding to a variety of biaxial stress-strain states. The effect of the size of the crack tip plastic zone on the fracture stress is investigated and a relation is established between two non-dimensional parameters φ and ψ . The first parameter φ gives a measure of the ductility of the material while the second parameter ψ is related to the applied stress when brittle fracture occurs. The character of the φ, ψ dependence suggests that when a certain value of the ductility parameter φ is exceeded, brittle crack growth is no longer possible and the mode of crack extension must change to one of a ductile nature. The theoretical predictions of fracture toughness are favourably compared with the results of experiments. Calculated values of GΔ, the stress intensity factor, K, and Rice's path independent integral J are also compared and the applicability of these parameters to brittle, quasi-brittle and ductile fracture is critically discussed.
The Unit Strength Concept in the Interpretation of Beam Test Results for Brittle Materials
Authors: Stanley P. , Fessler H. , Sivill A. D.
Published: October 2007

SYNOPSIS

Brittle materials are usually characterised in terms of the “modulus of rupture” obtained from the results of fracture tests on beam specimens. This is not a fundamental quantity. Alternative quantities (the mean strength of unit volume and of unit area) are introduced which are independent of the size of the specimen and the form of test, which allow the correlation of results from different tests, and which may be validly used in design calculations. After an outline of the necessary theory, the derivation of the two “unit strengths” and their use in correlating test results are illustrated using fracture data from a series of reaction-bonded silicon nitride beams. Minimum values obtained are:- mean uniaxial fracture stress of unit volume, 140 N/mm2 per cm3; mean uniaxial fracture stress of unit surface area, 180 N/mm2 per cm2.

A means of allowing for the effects of contact friction in the analysis of beam fracture test data is presented. The ignoring of these effects may result in a significant over-estimate of strength. The measured coefficient of friction decreased with increased load intensity.
Translational Energy Exchanged between an Oil Film and a Cyclically Loaded Journal — A Theoretical Study
Authors: Mccallion H. , Wales D. R.
Published: October 2007

SYNOPSIS Predicting the stability of rotating systems at intermediate and large whirl amplitudes is costly. This paper suggests a cheaper' approximate method based upon an overall energy balance.

By representing the force exerted on the bearings as combinations of constant forces and cyclically varying forces, the influence of bearing geometry, and other factors on the magnitude and direction of the energy flow between oil film and rotor for a complete cycle was investigated and found significant.

It is suggested that designers should check stability of intermediate or large amplitude whirls by an overall energy balance.
A Proposed System for Desalination
Authors: Morsy M. G.
Published: October 2007

Despite the fact that the world's need for fresh water is becoming more urgent, the ability to desalinate economically on a large scale still remains a goal rather than a reality. Distillation systems are by far the most widely employed systems for sea water desalination. However, the relatively high costs of these systems' products limits their competence with natural water resources, particularly for agricultural use. In this paper a distillation system is proposed. The system gives high performance ratios at low flashing ranges, which leads to a substantial saving in the distillation plants running costs. The analyses showed that the system has big thermodynamic potentialities.
Methods for Determination of Composition and Thermodynamic Properties of Combustion Products for Internal Combustion Engine Calculations
Authors: Way R. J. B.
Published: October 2007

SYNOPSIS

Two alternative methods are described for the calculation of gas composition. These are:- 1. Complete chemical equilibrium; 2. A combination of chemical rate equations for some slower reactions with partial equilibrium for faster reactions. Some calculated results are given in the form of comparisons between the two methods, showing the changes in gas composition caused by a temperature rise and fall with a constant rate of change of temperature. Equations are also given for the thermodynamic properties of individual species which may be used together with the appropriate gas composition to obtain properties of the gas mixture.
The Failure of Elastohydrodynamic Lubrication of Circumferentially Ground Discs
Authors: Dyson A.
Published: October 2007

SYNOPSIS A new theory is developed in an attempt to explain the scuffing failure of circumferentially ground discs. The characteristics of the surfaces of a particular pair of such discs just before scuffing took place have been analysed in detail. The roughness of the surfaces has been taken into account in the treatment both of the hydrodynamics and of the contact mechanics of the system.

The disc bulk temperature at which high hydrodynamic pressures just fail to be generated shows a reasonable agreement with the temperature observed just before scuffing. The implications for the mechanism of scuffing are discussed.
The Rolling Wheel — The Development of the Pneumatic Tyre
Authors: Shearer G. R.
Published: October 2007

A review of the early development of the pneumatic tyre for the cycle industry, followed by an examination of the progress made towards the requirements of comfort, durability and safety for the automobile.
Fundamental and Practical Aspects of Crack Growth under Corrosion Fatigue Conditions
Authors: Schijve J.
Published: October 2007

The crack growth mechanism is dependent on environment, frequency and temperature as shown by some examples. Two cracking modes are observed in aluminium alloys: the tensile mode and the shear mode. Examples show that inert environments promote the shear mode whereas aggressive environments promote the tensile mode. Information from constant-amplitude tests need not be applicable to service loading conditions as illustrated by an example. Significant environmental effects on crack growths are observed in aircraft flight-simulation tests. Growth delays induced by severe flights occur in all environments. As a consequence the truncation of the load spectrum at the high level end is a difficult question. The problem of producing relevant information in the laboratory is discussed.
The Evolution of the CSV Water Tender and its Safety Cab
Authors: Rose R.A.L.
Published: October 2007

The current commercial situation, the Home Office standards, and the trends in water tender design are outlined. The aims of a fire appliance cab designer are examined and the reasons for the decision to develop a 6 man crew safety cab are explained. The current and proposed commercial vehicle and bus legislation was examined and found to be not directly relevant to Water Tenders. A series of fundamental safety standards were evolved and the CSV cab was designed to meet these standards. The non-structural aspects of the cab design are discussed. The successful cab testing programme is described.
The Design of Drivers' CABS
Authors: Powell A. J. , Cartwright A.
Published: October 2007

The paper examines the operational role of the driver and the environmental requirements if he is to fulfil this role successfully. It then looks at the state-of-the-art, with particular reference to Great Britain, in the fields of structure, visibility, environment, controls and instrumentation, and concludes by suggesting the basic characteristics of an optimum cab layout.
A Comparison of Methods for Measuring the Frequency Response of Mechanical Structures with Particular Reference to Machine Tools
Authors: Taylor H.R.
Published: October 2007

The measurement of the frequency responses of machine tool structures is necessary because of the association between frequency response and chatter with consequent limitation of productivity. Various alternative techniques have been suggested. The paper describes comparative measurements of the frequency response of two systems using several techniques. The techniques examined were

(1) Sinuoidal excitation with digital analysis, frequency incremented manually.

(2) Slowly swept sinusoidal excitation with analogue analysis. (Traditional method).

(3) Fast swept sinusoidal excitation with digital analysis.

(4) Impulse excitation with digital analysis.

(5) Band-limited random excitation with digital analysis.

The results show the fast swept sinusoidal and impulse methods to be the most satisfactory.
The Influence of Lubrication on Tooth-Roller Impacts in Chain Drives
Authors: Fawcett J. N. , Nicol S. W.
Published: October 2007

In a roller chain drive an impulsive load occurs each time a roller is picked up by the driving sprocket from the chain span. These impulsive loads cause high frequency sprocket angular accelerations of large amplitude, and are the source of high frequency chain noise.

Measurements of sprocket acceleration immediately after impact have been made to demonstrate the effects of different methods of lubrication on the magnitude of the impulse. Oil drip, oil jet and oil bath lubrication have been investigated for normal machine oil and very high viscosity oil. The results show considerable variations in acceleration amplitude.
Flexural Effects in Disc Brake Pads
Authors: Harding P. R. J. , Wintle B. J.
Published: October 2007

Details of the automobile disc brake are outlined, leading to the flexural requirements and construction of friction pad assemblies. A theoretical treatment of these is given, introducing the concept of a critical length which influences pressure distribution and reliability. A simple experiment which illustrates the critical length effect is described, with details of the experimental and theoretical correlation. The finite element technique is applied in a computer study of the structural behaviour of pad assemblies when subjected to various loads. Effects of load distribution, pad compression and backplate rigidity are discussed in the context of specific operational problems.
An Investigation of the Sources of Blowby in Single-Cylinder Supercharged Diesel Engines
Authors: Bull B. , Voisey M. A.
Published: October 2007

Measurements of carbon dioxide concentrations in the exhaust and in the crankcase of two different types of single-cylinder, supercharged diesel engines have been used to determine the amount of exhaust gas reaching the crankcase as piston ring blowby and as leakage through the exhaust valve stem-to-guide clearance. Over a wide range of operating conditions in both engines the carbon dioxide concentration was found to be more dependent on engine fuelling rate per hour than on fuel input per stroke. It was established that blowby through the exhaust valve guide was a major contributor to crankcase contamination. A simple method has been devised, requiring only minor modifications to the engine, that permits the blowby through the piston ring pack and the exhaust valve guides to be determined separately in turbocharged production engines.
The Development, Application and Experimental Evaluation of a Design Procedure for Centrifugal Compressors
Authors: Came P. M.
Published: October 2007

A computer-based centrifugal compressor design procedure developed at the National Gas Turbine Establishment is described. The impeller design package includes a geometry modelling procedure, aerodynamic analysis, stress analysis, and the direct generation of data for manufacture by numerical control. The method of diffuser design incorporates analyses of the flow in the vaneless space and ‘semi-vaneless’ space adapted from a new performance prediction technique; published diffuser pressure recovery data are used in the selection of the diffuser channel geometry.

The application of these methods to the design of a 6.5 pressure ratio centrifugal compressor stage is described. The experimental rig testing of this compressor has been used to evaluate the advantages offered by the new design procedure. By comparing the measured performance with that of an earlier compressor designed with less advanced techniques for the same aerodynamic duty, the advantages of the new design procedure are established.
Environmental Control for a Rapid Transit System in a Tropical Climate
Authors: Kibblewhite G. G.
Published: October 2007

The need for rapid transit systems in tropical cities has brought into focus the problem of giving acceptable conditions underground when the ambient temperature is elevated and coupled with high levels of humidity. It is an economic problem to set reasonable comfort levels. The amount of power liberated within a tropical underground system is discussed and the size of air conditioning plant required for trains if these are used. Three general systems of dealing with the overall problem are discussed, together with the effect on the systems arising from the speed of the trains and the special problems created when stationary within the tunnels. The conclusions indicate that for tropical conditions a closed system underground is to be preferred without air conditioning on the trains. The use of power to achieve acceptable conditions is one of economics rather than a technical question, but cooling is expensive in energy for any underground system in the tropics.
Axisymmetric Flow in a Motored Reciprocating Engine
Authors: Gosman A. D. , Melling A. , Whitelaw J. H. , Watkins P.
Published: October 2007

A study was made of axisymmetric, laminar and turbulent flow in a motored reciprocating engine with flow through a cylinder head port. Measurements were obtained by laser-Doppler anemometry and predictions for the laminar case were generated by finite-difference means. Agreement between calculated and measured results is good for the main features of the flow field, but significant small scale differences exist, due partly to uncertainties in the inlet velocity distribution. The measurements show, for example, that the mean velocity field is influenced more strongly by the engine geometry than by the speed.

In general, the results confirm that the calculation method can be used to represent the flow characteristics of motored reciprocating engines without compression and suggest that extensions to include compression and combustion are within reach.
A Simple Method for the Selection of Axial Fan Blade Profiles
Authors: Hay N. , Metcalfe R. , Reizes J. A.
Published: October 2007

Existing data on aerofoil sections suitable for axial flow fans are replotted on axes of angle of incidence against camber angle. The carpet plots so obtained permit the best operating conditions for each type of aerofoil to be immediately identified and thus the most suitable section can be easily selected for a given specification. A design method based on the use of these carpet plots is proposed and illustrated with a numerical example.
On the Continuous Monitoring of Oil-Film Thickness in an Engine Bearing
Authors: Goodwin G. , Holmes R.
Published: October 2007

This paper describes research involving the measurement of oil-film thickness in a large end bearing of a medium-sized medium-speed marine diesel engine. The design of the transducer and its novel signal conditioning circuitry is discussed. Comparisons are made between the measured results and numerical predictions.
High Speed Train - Fleet Operation
Authors: Power S. R. D.
Published: October 2007

In October 1976 British Rail introduced its first 200 km/h service on the London-Bristol and London-South Wales services. This followed several years of design work and extensive testing of a prototype train. The increase in passenger traffic on these routes, during the first two years of high speed operation, clearly indicates that there is a demand for such a service and that the train itself fully meets the need from the passenger viewpoint.

Unlike some railway administrations, who have built separate lines dedicated to high speed services, it is British Rail policy to operate these units on the existing network, sharing it with passenger and freight trains running at conventional speeds. Because of this policy the designer is constrained by track impact force limitations specified by the Civil Engineer and he must also ensure that the train can be operated safely within the existing signalling arrangements.

Bearing in mind the extent of technical innovation it is not surprising that a number of problems have arisen. However, as a result of prompt and effective action on the part of both the railway and the railway supply industries, modifications have soon been introduced to eliminate the problems.

The paper starts with a brief description of the train and the facilities provided to ensure adequate maintenance resources both within regional depots and railway workshops. This is followed by a review of experience to date and the paper concludes with a forecast about future trends in high speed operation.
A Review of Reports of Failures
Authors: Wearne S. H.
Published: October 2007

Despite the general reduction in the incidence of serious technical failures in industry, the failures that do occur are attracting greater public concern. Some reports of inquiries into failures have included statements that engineers should be more broadly educated. Other reports appear to indicate the opposite. This paper is an attempt to review the evidence available from the inquiries of failures in order to define the implications for the education and training of engineers and of managers.
The Trrl Quiet Heavy Vehicle Project
Authors: Tyler J. W.
Published: October 2007

This paper describes a co-operative programme sponsored by TRRL which has produced heavy diesel engined articulated vehicles having considerably lower external and internal noise levels than vehicles in current operation. The other organizations involved were Fodens Limited, Rolls-Royce Motors Limited, Leyland Vehicles, MIRA, ISVR and NEL. The work was directed at reducing the noise levels from the engine, exhaust and cooling systems, tyre-road surface interaction, and the transmission of noise into the cab. The environmental background to the project and its relation to future legislation on vehicle noise is considered as well as the bases for the technical solutions evolved.
Design and Development of the New 75 Tonne High Capacity Rail Cranes
Authors: Robinson P. J. , Baker S. M. , Hind J.
Published: October 2007

British Rail are taking delivery of six high capacity rail cranes. They are the first cranes of this capacity to be purchased for eighteen years and represent significant advances over previous designs. This paper gives background information on the choosing of specification requirements and the design concept and gives details of the design development for the ‘as made’ crane.
Die Casting of Major Engine Components
Authors: Nakashima W. , Ebisawa M.
Published: October 2007

‘Aluminum and automobiles’ are closely linked to the progress and development of the automobile industry. Moreover, at this time when energy conservation is the prime requisite, manufacturers are compelled aggressively to pursue weight reduction and compactness in designs of future automobiles. As a result, lightweight alloys, in particular aluminum and magnesium, are in ever increasing use as materials for automobile components.

A very good example of the extent of lightweight alloys used in automobiles was very evident at the 1976 international conference on aluminum and the motor car held in West Germany. On display were aluminum bumpers, truck cabs, door panels, bonnets, steering columns and numerous other parts, indicating the rapid trend toward weight savings by broadening the use of aluminum materials. However, even though great strides have been achieved in weight savings through design, a full market acceptance cannot be realized unless products of stable quality and low manufactured cost can be made available.

Discussed herein is the approach being taken by Honda Motor Company to cope with this subject. The focal points to be discussed are the existing production line which produces the large engine cylinder block die casting, and future development of aluminum die casting.
Measurement of Flame Velocity and Entrained Velocity from High Speed Photographs in the SI Engine
Authors: Rashidi M.
Published: October 2007

The paper describes the measurement of combustion parameters which are required for the theoretical models such as Blizard and Keck (4). Quantitative analysis is performed on high speed photographs of flame propagation in a transparent piston engine with a typical combustion chamber design. From the measurements, the flame velocity, the flame radius and the volume burnt are determined directly. Then using a simple model of flame propagation the gas velocity just ahead of the flame is calculated, and then the entrained velocity is obtained. The entrained velocity which mainly remains constant, decreases towards the end of the flame propagation; this is believed to be due to the reduction in the eddy length scale and decay of the turbulence energy caused by the compression of the eddies.
Computer Analysis of Three-Dimensional Turbulent Flows around Ships' Hulls
Authors: Markatos N. C. , Malin M. R. , Tatchell D. G.
Published: October 2007

This paper describes a general solution method for three-dimensional, steady, turbulent flows around long, smoothly-shaped bodies, of arbitrary and varying cross-sectional shape. The particular example considered here concerns the flow around the hull of a ship, but the method can equally well be applied to other, similarly shaped bodies such as an aircraft fuselage, or a submarine. Moreover, the basic non-orthogonal grid method described can also be applied to internal flows in irregular shaped passages, or to the prediction of flows around bodies in ducts.

The mathematical model consists of the partial differential equations for continuity and three components of momentum, along with a two-equation model of turbulence, and proper modelling of the ship's hull.

The solution method utilizes a non-orthogonal coordinate system in the plane normal to the axis of the body, which has one coordinate surface coinciding with the hull surface. This coordinate system is flexible and is easily modified to enable the calculation procedure to handle bulbous ships' hulls, which are of great importance in modern ship design.

The differential equations involved are solved numerically after provision of the proper boundary and initial conditions. The solution procedure is a unique one, called ‘partially-parabolic’, as first used by Pratap and Spalding (1). Solutions are presented for flow around ships' hulls, which demonstrate the physical realism of the achieved results and the potential of the present method.
Unsteady Airflows in Rapid Transit Systems
Authors: Vardy A. E.
Published: October 2007

The principal aerodynamic effects in a rapid transit system are predicted by use of a computer program. Account is taken of the influence of cross-passages, ventilation shafts, cross-overs and stations, etc. on the airflows generated by any number of trains travelling along any routes with any speed histories. Very few empirical coefficients are needed to obtain satisfactory correlations with experimental data.

The program is used to investigate the relative influence of important system parameters, and skin friction is found to have a particularly strong effect. It is shown that the tunnel system can be considerably simplified in the numerical simulation without serious loss of accuracy, but that account must be taken of local cross-passages and ventilation shafts.
Corrosion Protection Methods on Rolls-Royce Motor Cars
Authors: Creer T. F.
Published: October 2007

The need for a high level of corrosion resistance in motor cars continues to increase. In the view of Rolls-Royce Motors it can only be achieved by careful application of suitable systems and an appreciation of the processes by the designers.

For components and assemblies in critical areas, tests have been developed to ensure the limitations of corrosion protection methods over long service periods are understood, particularly for parts operating in close proximity.

Promising developments to achieve weight saving and environmental improvements without sacrificing corrosion resistance are under investigation.
Computer Aided Calibration of the Geometric Errors of Multi-Axis Coordinate Measuring Machines
Authors: Burdekin M , Voutsadopoulos C
Published: October 2007

The concept of a rapid calibration method for obtaining the individual components of the geometric error of CMM (coordinate measuring machines) is applied to the case of the two-dimensional (in-plane) error. Analysis of the geometrical model of the structure which can be easily obtained from first principles for any specific kinematic design of multi-axis coordinate measuring machines reveals which individual components have to be measured and how they combine. The analysis is extended to include weight deformation effects. Computer controlled calibration with the use of laser interferometer allows continuous sampling ‘on the fly’ of the target points for the efficient, automatic measurement of the positioning, straightness and squareness and angular motion errors. The systematic, random and hysteretic elements in each error component are evaluated. Interactive software programs offer versatility and choice of variables and appropriate fixturing is used to reduce the set-up time, so that a realistic overall time scale is achievable.