bluuebunny/crossref_metadata_2025 huggingface dataset:
Vortex Formation near the Intakes to Turbomachinery and Duct Systems
Authors: Swainston M. J. C.
Published: October 2007

Experimental results are presented which show vortex formations occurring within a model marine gas-turbine downtake. The basic phenomenon of vortex formation is discussed and the boundary-layer-potential-flow interaction identified as the cause. Further experiments on a model gas-turbine test stand are reported in which the vortex strength was assessed. On this basis, a simplified theory for the occurrence and strength of vortex formations is presented which agrees qualitatively with the principal experimental findings. The formation of air-entraining vortices in hydraulic installations is briefly examined in the light of the explanations previously advanced. Although a number of possible vortex formation mechanisms are identified, it is concluded that further research is required in this area.
Using the Finite Element Method to Determine Temperature Distributions in Orthogonal Machining
Authors: Tay A. O. , Stevenson M. G. , De Vahl Davis G.
Published: October 2007

Temperature distributions for typical cases of orthogonal machining with a continuous chip were obtained numerically by solving the steady two-dimensional energy equation using the finite element method. The distribution of heat sources in both the primary and secondary zones was calculated from the strain-rate and flow stress distributions. Strain, strain-rate and velocity distributions were calculated from deformed grid patterns obtained from quick-stop experiments. Flow stress was considered as a function of strain, strain-rate and temperature. The chip, workpiece and tool (actual shape and size) were treated as one system and material properties such as density, specific heat and thermal conductivity were considered as functions of temperature.
Low-Cycle Fatigue under Biaxial Stress
Authors: Parsons M. W. , Pascoe K. J.
Published: October 2007

The low-cycle fatigue behaviour of a ferritic and an austenitic steel have been studied under various conditions of reversed biaxial strain. These cyclically softened and hardened respectively. In all cases, relationships of the form

were found between total strain range Δε t and life Nf for lives in the range 102−105 cycles, with an abrupt change of β at intermediate lives. Variation of state of strain affected both β and κ.

Various theories for the correlation of fatigue behaviour under multi-axial loading have been reviewed and compared with these results. None was found to account adequately for the effect of straining régime with the materials tested.
Two- and Three-Dimensional Analyses of Surfaces According to the E-System
Authors: Shunmugam M. S. , Radhakrishnan V.
Published: October 2007

The E-system of roughness measurement can be used either for a two-dimensional or a three-dimensional assessment of surface roughness. The procedure for computing the two- and three-dimensional envelopes from digitized profiles is briefly explained. This method will be useful for verifying the results obtained by practical instruments. The filtering characteristic of the E-system, when used for two- and three-dimensional roughness measurement, is analysed with reference to theoretical profiles. Various skid configurations are studied using a doubly curved skid simulated by a computer.
Safety Motorcycle
Authors: Westcott J. S.
Published: October 2007

To discover what happens to a motorcycle in a variety of collisions, a model about 24 in long was constructed with a dummy figure fitted, all contained in a travelling cage moving down a sloping runway. The dimensions, velocities, etc. of the components are related by the principle of dimensional similarity so that relative motions and velocities remain as those of a full-sized machine. This enables the ultimate effect on the dummy to be photographed after the accident and from this can be built up a design for a safety motorcycle that will withstand the collisions met in practice.
Experimental Model Techniques for the Investigation of the Dispersion of Chimney Plumes
Authors: Robins A. G.
Published: October 2007

The use of wind tunnels for the study of flue-gas dispersion, the scaling criteria appropriate to the modelling of the motion of buoyant plumes in turbulent boundary layers, and an experimental technique for measuring mean concentration levels are presented and discussed. Two examples of wind-tunnel experiments are used to demonstrate the techniques and to illustrate the implications of the scaling criteria. Both experiments were performed at ***1 300 scale in a simulated neutrally stable atmospheric boundary layer. Finally, the present limitations of wind-tunnel studies are considered and possible future developments are discussed.
A Costing System Suitable for Use in the Teaching of Design
Authors: Henry T. A.
Published: October 2007

A system for costing the manufacture of engineering components is described. The system, which has been tested in an undergraduate course in design, covers casting, forming, machining, heat and surface treatment, and welding, and takes account of material cost and accuracy of finish. Three examples are given to demonstrate that, although the method is simple and rapid in use, cost comparisons between methods of manufacture and actual costs are realistic.
The Role of the Mechanical Engineer in the Environmental Problems of a Developing Technological Society
Authors: Crossland B.
Published: October 2007

The lecture briefly reviews the current fears for the future of civilization as we know it. It considers in greater detail the problems of the population explosion, the exhaustion of energy supplies, the exhaustion of raw materials and the pollution of our environment. It refers briefly to the study of pollution problems, or the whole world problem, by the creation of models and application of system dynamics to them as a method which may ultimately be able to provide predictive guidance to the most appropriate courses of action.

The most serious problem is still the population explosion. The lecture discusses the contributions of engineers in providing solutions to the problems of energy and materials utilization and in overcoming pollution problems, and emphasizes the essential need for a much stronger professional body for engineers. Finally, it points to the need to introduce engineering students to these problems and the desirability of an ethical code which includes reference to the necessity of conserving energy and materials and avoiding unnecessary pollution.
The Automatic Vertical Steering of a Longwall Coal-Cutting Machine—An Experimental Investigation
Authors: Bogdadi W. A. , Edwards J. B.
Published: October 2007

Although there exist mathematical descriptions of the process by which a longwall coal-cutting system is steered vertically through an undulating coal seam, numerous factors neglected in such idealized models cause significant discrepancies between predicted and actual performance and cast some doubt on the adequacy of control systems designed on a purely theoretical basis. These factors are examined in detail and the design requirements for a 1/4-scale mechanical model are given together with details of its instrumentation and interfacing to the controlling computer for the purpose of exhaustive laboratory trials.
The Use of Accident Data in Studying Vehicle Handling Performance
Authors: Jones I. S.
Published: October 2007

A study to establish the relation between vehicle handling performance and accident causation. Since deficiencies in handling are likely to be associated with accidents involving loss of control, measures of handling which are likely to express proneness to loss of control are first suggested; emphasis is placed on simplicity of measurement to allow as many different models of car as possible to be included in the study. Accident rates for the various types of accident which are likely to be influenced by these parameters are then determined by model of car. The effect of other factors, such as variation in driver characteristics between different models of car on these rates is then assessed so that the relation between handling characteristics and accident frequency can be defined. Finally, the relative importance of the various measures of handling suggested are assessed.

The results suggest that there is a definite relation between handling performance and accident causation although it is relatively small when compared to driver effects. In explaining the variation in the accident rate between different models of car, driver effects account for as much as 70 per cent; if driver effects are removed from the accident rate then handling parameters explain between 35 and 40 per cent of the remaining variation between models of car. The important parameters appear to be weight, a measure of the change in understeer as a function of lateral acceleration and power to weight ratio.
Prediction of the Coefficient of Friction for Pneumatic Tyres on Hard Pavement
Authors: Kant Shri , Rao D. L. Prasanna , Munjal M. L.
Published: October 2007

The relationship between the coefficient of friction and the slip of a flexible wheel, such as the pneumatic tyre, plays a major role in the design of refined braking systems for vehicles. The available data being partly empirical in nature, it was desirable to be able to predict this relationship. In this paper an attempt is made to explain the mechanism defining this relationship for a pneumatic tyre operating on a hard pavement. The distinct roles of the flexibility of the tyre and the sliding of the wheel are identified and utilized in predicting the curve. A model of the tyre is proposed to explain the role of flexibility of the tyre. It is shown that the procedure suggested here can clearly bring out the effects of some of the operating paramenters of the vehicle, such as speed of the vehicle, presence of contaminants in the contact patch, stiffness of the tyre, and vertical load on the wheel.
Friction Reduction in Journal Bearings by High-Molecular-Weight Polymers
Authors: Hampson L. G. , Naylor H.
Published: October 2007

The effect of high-molecular-weight polymer drag-reducing agents on the performance of a plain hydrodynamic journal bearing operating under turbulent flow conditions has been studied. Reduction of the frictional torque by up to 45 per cent was observed for polymer concentrations in the range 5–200 μg/g using solutions in water of Polyox WSR 301 of molecular weight 4 times 105.*** The polymer solutions had a stabilizing effect against half-speed oil-film whirl. Degradation of the polymer by mechanical shear was fairly rapid.
The Glancing Collision of Two Shock Waves in a Branched Duct
Authors: Deckker B. E. L. , Yang A. W.
Published: October 2007

The collision of two shock waves of different strengths and initially at right angles to each other at the junction of a branched duct has been followed by schlieren photography and by numerical analysis using a finite difference scheme and also a hybrid method comprising finite elements and finite differences. Because of cost, analyses of the wave patterns have been confined to times that are less than that required for wave action to completely cease in the junction of two ducts. However, it is during the early stages that wave action is important and, therefore, provides a critical test of the numerical methods. The results obtained by both methods have been satisfactory. On the other hand, the sequences of schlieren photographs extend to the time when flow in the junction is steady. Because shock waves of different initial strengths in the two branches have been used there are interesting differences in flow behaviour.
Fundamental Equations Governing Pressure Surge Phenomena in Pipes of Rectangular Cross-Section
Authors: Thorley A. R. D. , Guymer C.
Published: October 2007

The two fundamental principles, momentum and continuity, which govern the behaviour of pressure surge phenomena, are developed for pipes of rectangular cross section. A theoretical relation for the velocity of propagation of a pressure surge in such pipes is also obtained. It is represented in a chart for various pipe-wall materials, and comparisons made with experimental data. In addition, the deflection of the wall of a square section pipe is examined, theoretically and experimentally.
An Experimental Investigation into the Relative Contribution of Potential Flow and Wake Interaction to Discrete Frequency Sound Pressure Generation in Axial Flow Fans
Authors: Watson J. F.
Published: October 2007

The development of an experimental technique to enable the separate contributions of potential flow interaction and wake interaction to the total sound pressure level generated adjacent to the interacting blade rows to be determined. The physical situation considered was that of a row of rotating blades preceded by a single inlet guide vane similar to that investigated by Fincher (1)†.
The Assessment and Assurance of Pressure Vessel Reliability
Authors: Nichols R. W.
Published: October 2007

The factors involved in assessing the reliability of pressure vessels drawing extensively upon the developments which have arisen from applications in the nuclear industry. Existing assessments of reliability and operational behaviour highlight some improvements which could result from more detailed design assessments especially with respect to stress analysis, stress transients and the significance of defects. Additionally the contributions to reliability made by fabrication and materials technology, inspection and quality assurance and post operational surveillance are critically examined. The use of such data in synthesizing a reliability assessment is discussed noting the problems of establishing statistical confidence levels and highlighting those areas where further evidence would produce significant advances in quantifying reliability assessments.
Dynamic Analysis of an Industrial Refrigeration System to Investigate Capacity Control
Authors: Marshall S. A. , James R. W.
Published: October 2007

The paper is concerned with the development of a mathematical model which describes the behaviour of a quick freezing plant and its refrigeration system and its use in designing a capacity control system. The model is represented by sets of non-linear algebraic and differential equations which were derived using a ‘stirred tank’ approach on each section of the plant, in conjunction with conservation laws concerned with mass and energy balances, and with momentum equations relating force and flow rate. The capacity control system developed was based upon the measurement of initial and final product temperatures and product mass flow rate. This system showed an improvement in the operation of the plant over the existing control system. Problems of implementation are also discussed.
The Influence of Exhaust Poppet Valve Gas Flow on Reciprocating Engine Noise
Authors: Williams T. J. , Cox J. B.
Published: October 2007

The far field noise generated by cold air flowing through stationary and reciprocating exhaust poppet valves into a cylindrical duct or pipe has been investigated. A method of predicting the intensity and frequency spectrum of the noise generated in such circumstances in terms of the known or assumed geometry and flow characteristics of the valves is presented. Comparisons of the predicted frequency spectra with measured values show good agreement for steady gas flows through stationary valves and for unsteady flow through a simplified exhaust system of a motored single cylinder internal combustion engine.
A Whole-Life Approach to the Engineering Support of Equipment
Authors: McKay A. M.
Published: October 2007

The cost of maintaining equipment throughout its service life attracts increasing interest as the growing complexity of equipment and plant, exploiting the advances made in engineering technologies, adds impetus to the search for ways and means of containing the effort required for its maintenance. Reliability and maintainability are key factors affecting maintenance workloads, and these are principally determined during design and development. This paper describes the contribution made by the Corps of Royal Electrical and Mechanical Engineers (R.E.M.E.) towards improving the reliability and maintainability of Army equipment, based on knowledge of its intended operating environment and on the Corps' whole-life approach to the provision of engineering support. The paper develops the theme of the James Clayton Lecture Achieving quality and reliability, presented by Professor A. D. S. Carter on 15th May 1974, concerning the paramount need for matching equipment design to the user's requirements.
Performance Prediction for Automotive Turbocharger Compressors
Authors: Whitfield A. , Wallace F. J.
Published: October 2007

A procedure to predict the complete performance map of turbocharger centrifugal compressors is presented. This is based on a one-dimensional flow analysis using existing published loss correlations that were available and thermodynamic models to describe the incidence loss and slip factor variation at flow rates which differ from the design point. To predict the losses within the complete compressor stage using a one-dimensional flow procedure, it is necessary to introduce a number of empirical parameters. The uncertainty associated with these empirical parameters is assessed by studying the effect of varying them upon the individual losses and upon the overall predicted performance.
Rope in the Marine Environment
Authors: Sharp D. M.
Published: October 2007

Rope has always been an important item in the marine environment. The transition from one type of construction to another, notoriously slow: for example, rope of both wire and fibre supplied to the S.S. ‘Great Britain’, launched in 1843 was of a similar type and quality to that which would be equally familiar to our mariners a century later.

Many having experience in this latter period might recognize some similarity with the rope in use today but there have been substantial changes, and these changes have occurred not specifically because of any major breakthrough in rope design and production, although there have been very substantial advances in these sectors but because the detail of today's and tomorrow's applications have themselves changed.

The paper examines a number of the major applications involving rope in the marine environment, and shows how rope characteristics must be recognised and wedded to the duty parameters if optimum performance is to be achieved.
Problems in the Design and Operation of Limpet Coil Vessels
Authors: Barrass A. , Walter G. H. , Kitching R. , Moore M. A.
Published: October 2007

SYNOPSIS Failures in a limpet coil vessel arising due to thermally induced stresses are discussed. A method of presenting design information on stresses due to pressure in part circular limpet coils is given for a range of parameters. Analytical and experimental work on a rectangular limpet coil vessel is also described.
Tyne and Wear Metro—A Modern Rapid Transit System
Authors: Howard D. F.
Published: October 2007

The paper outlines the processes which gave rise to the rapid transit proposals for Tyneside, and the development of these into the Tyne and Wear Metro. The concept of a fully integrated public transport system, capable of making a significant contribution to local movement and land use is explained, and the feasibility of introducing Metro over a significant part of the existing British Rail network detailed. A technical description of the Metro includes civil engineering, signalling and communications, and electrification. The rolling stock is described in detail. The paper concludes with sections on finance and organisation.
A Comparison between Experimental and Analytical Transient Test Results for a Turbocharged Diesel Engine
Authors: Winterbone D.E. , Benson R.S. , Closs G.D. , Mortimer A.G.
Published: October 2007

SYNOPSIS A computer controlled diesel engine test-bed is described. The system is capable of excursions into regions of very low air-fuel ratio operation without damage to the engine; this enables the engine “steady-state” characteristics to be measured for off-design operating conditions. A computer-based data acquisition system was developed to acquire test-bed results under engine transient operating conditions. An analogue computer model of the engine was constructed using the steady-state characteristics of the engine as obtained from on- and off-design. This model operated in real-time and was suitable for both studies of engine control systems and the testing of control hardware. Results obtained from the test-bed and the model are compared. It is shown that good agreement can be achieved by minor modifications to the model based on steady state results.
The Use of Skiving Cuts to Obtain Data on Cutting Forces and Some Predictions of Workpiece Geometry and Force Variation for Skiving
Authors: Duggan C.K. , Stokes R.J. , Stone B.J.
Published: October 2007

SYNOPSIS An analysis of orthogonal skiving is presented which includes the previously omitted effects of machine deflections and non-circular final geometry. Also the skiving process is shown to be a useful method for the rapid accumulation of data on cutting forces. The method uses fewer tests than would be required using conventional methods and the data are shown to agree well with those obtained by such conventional methods. Finally predictions are made of force variations during a skiving cut and also of the final geometry of the workpiece and these are found to agree well with experimental results.
Part 2: Behaviour of a 1 Cr Mo V Steel Subject to Combinations of Fatigue and Creep under Strain Control
Authors: Ellison E.G. , Paterson A.J.F.
Published: October 2007

A 1 Cr Mo V steel has been studied at 565 °C under a cyclic strain axial mode with various combinations of tensile and compressive dwell periods. Compared with the continuously cycled data, the presence of a tension only dwell caused a considerable decrease in the number of cycles to failure. The addition of a compressive dwell to the cycle already containing a tensile dwell tended to reduce or eliminate the harmful effects of the latter. Metallographic evidence suggests that the compressive dwell reduced the incidence of internal intergranular cracking. A ratchetting grain boundary damage model to account for this is proposed.
Acoustic Aspects of Railway Vehicle Design
Authors: Eade P. W. , Stanworth C. G.
Published: October 2007

SYNOPSIS The paper describes the present acoustic environment in railway passenger vehicles, and discusses the various mechanisms leading to this. The factors providing a basis for an internal noise criterion are stated, and suitable criteria for different classes of stock suggested. A more detailed discussion is presented of various problems encountered during investigation, and of the experiments and analytical techniques evolved during their solution. It is pointed out where the experience gained in this work can be applied, and also where gaps still remain to be filled by future investigation.
Aspects of Car Rear Suspension
Authors: Bastow D.
Published: October 2007

SYNOPSIS Various considerations which need to be kept in mind when making a choice between and designing rear axles and independent rear suspensions are listed and explored, so that a sensible compromise related to the vehicle type and desired characteristics can more easily be achieved or approximated at the design stage. Methods of avoiding standing height and bounce frequency variation between one-up and fully laden are described and illustrated with reference to optional extra and initially incorporated systems. Accepting the desirability of maintaining the same relationship to critical damping over the load range, different ways of achieving it are described.
Computer-Aided Synthesis of Linkages—A Motorcycle Design Study
Authors: Oldham K. , Fawcett J.N.
Published: October 2007

SYNOPSIS The geometry of current motorcycle rear suspension systems is such that the centre distance between the gearbox output sprocket and the rear wheel sprocket varies as the suspension deflects.
The Price of Safety
Authors: McNaughton I. K. A.
Published: October 2007

The author shows how railway safety has developed, usually in reponse to public opinion, to the high standard of today. He traces the significant improvements in safety that have been achieved during the past 15 years and discusses the extent to which further improvements might be justified.

The lecture also raises the possibility thai, for certain lines, some relaxation of the current safety requirements, with consequent cost savings, might be made without a significant lowering of safety standards.
Recent Developments in the Use of Municipal Refuse as a Fuel
Authors: Burnett J. M.
Published: October 2007

The increase in the price of fuel since the Near East war of 1973 has led to renewed interest in refuse as a fuel, starting with more accurate knowledge of its calorific value. No further large power plant has been built but there have been incinerators supplying steam for heating purposes. The use of refuse as supplementary fuel for boiler plant and for cement production and as fuel for burning sewage sludge. Experiments are in progress on refuse in pelletised form for general sale and on pyrolysis and hydrolysis. In the USA there is interest in gas production from refuse landfills.
Adapter Errors in Indicator Diagrams of Combustion Engines
Authors: Van Aken C.
Published: October 2007

A comprehensive experimental study of the distortion and resonance in adapters is made on a special test rig and on combustion engines. A theoretical treatment of the phenomenon is made, using simple simulation models and the method of characteristics.
Design and Performance of Transpiration-Cooled Combustion Systems
Authors: Bayley F. J. , Cornforth J. W.
Published: October 2007

This report describes a comprehensive experimental investigation of a gas turbine combustion system incorporating a porous, transpiration-cooled flame tube. The effectiveness of this system of cooling is demonstrated and the general performance of the chamber reported. From the observations of distributions of pressure and temperature, and hence coolant flows, heat fluxes are derived and compared with theoretical predictions. On the basis of these comparisons a design method is proposed for advanced combustion systems in which transpiration cooling can be employed to reduce cooling air requirements by a factor of four compared with conventional systems.
Temperature Distributions and Thermal Distortions of Brake Drums
Authors: Ashworth R. J. , El-Sherbiny M. , Newcomb T. P.
Published: October 2007

This paper presents calculated results of transient temperature distributions and the resulting drum distortions when band contact occurs between the rubbing surfaces during operation of a brake. The finite element method is used to compute the thermal distortion in drums when incomplete contact arising from previous distortion, manufacturing tolerances or shoe misalignment occurs. The results are compared with those obtained when there is complete contact between lining and drum. Both single and repeated brake applications made at regular intervals with convective cooling are considered.
The Professional's Dilemma — Engineer or Ingeneer?
Authors: Ford Hugh
Published: October 2007

Most people, I suppose, have wished at some time in their lives that, having a burning desire to get something off their chest, they had a captive audience with no chance of escape and no right to answer back. The Presidency of this Institution provides the President not only the great honour of representing for a year the mechanical engineering profession but also gives him just such a captive audience. But I have to admit to a certain diffidence now that I am facing you all. Having so often felt an urge to get many things off my chest, I now find it is much more difficult than I had thought. We have come to expect from the President both some insight into what brought him to this important responsibility and also a profession of faith or at least an apologia for what he did or did not do in his engineering career.
Motivating Engineering Undergraduates to Learn
Authors: Hannam R. G.
Published: October 2007

An approach to educating mechanical engineers is presented which is based on the observations of behavioural scientists who have examined what motivates people to work. Behavioural scientists' work has been widely adopted by industry and it is also relevant to education. The methods described are based on satisfying those factors in a student's character which are motivating factors on the reasonable assumption that well-motivated students work well. The methods relate to material presentation rather than to syllabuses and they are shown to have advantages which will benefit the whole profession in the long term.
Design and Performance of an Automatic Control System for Fastener Tightening
Authors: Boys J. T. , Wallace P. W.
Published: October 2007

Methods of controlling the tightness of bolted assemblies by presetting the torque or bolt rotation are reviewed. It is shown that these produce either inaccurate clamp loads or excessive elongation of the fastener. As a result the tightening operation is often the weakest link in obtaining a reliable assembly.

The development of a system of tightening control that overcomes these problems is described. It operates by sensing the gradient of the torque-rotation characteristic, thus detecting the yield point of the fastener. In principle it requires no preset control torques or rotation angles. Comparative results show that the system increases bolt clamp loads and reduces their scatter very significantly.
Control of Welding Standards: Construction of Locomotives and Rolling Stock
Authors: Hurst J. K.
Published: October 2007

Welding has become an extensively used method of construction of structures for locomotives, rolling stock, plant and equipment. This paper describes the methods and practices adopted to overcome the many problems associated with fabrication of welded structures. It is not the intention to discuss the causes of weld failures in specific cases nor the particular remedies adopted, but rather to describe the general approach in terms of training and education, in welding and technology, the adoption of detailed specifications and procedure controls used for the control of welding standards.
Energy and Environment
Authors: Barrere M.
Published: October 2007

Energy problems will play a fundamental role in the near future and it is necessary that researchers, engineers, economists, ecologists start working together, before it is too late, in order to increase the existing non-fossil energy sources, to develop new sources or new technologies using less energy without polluting the environment. This situation may lead in some cases to conflicting actions, and therefore the engineer's task is to find the optimal solutions. The problem is considered from both the national and international points of view.
Heat Transfer to a Pvd Rotor Blade at High Subsonic Passage Throat Mach Numbers
Authors: Martin B. W. , Brown A. , Garrett S. E.
Published: October 2007

This paper reports heat-transfer measurements round a PVD rotor blade using a transient method. Instrumented syndanio-asbestos blades forming part of a cascade are suddenly introduced into a heated air stream, the temperature-time response of surface thermocouples attached to copper inserts in the blades then being used to determine local heat-transfer coefficients for (a) passage throat Mach numbers between 0.79 and 0.94 (b) turbulence intensities from 4.15 to 9.05 per cent (c) blade chord Reynolds numbers from 7.8 times 105 to 8.9 times 105.

Measured transition lengths on the suction surface, over which the heat transfer nearly trebles, are somewhat short in relation to other measurements. The onset of transition, which is downstream of predictions for the higher Reynolds numbers but accords with the trends of existing correlations, is little influenced by turbulence intensity variations in the above range. Over the pressure surface the heat transfer is less than for a fully-turbulent boundary layer. Comparisons with other high Mach-number measurements suggest that much further work is needed before the effects of scale of turbulence are fully understood.
Brake Test Dynamometer Programming
Authors: Hatch D. , Moore M.W.
Published: October 2007

In testing, conflict often arises between adequate simulation of interacting variables and the need to achieve precise repeatability. The development of a control system is described in which firstly an X-Y plotter and later a punched chart is used to programme an inertia dynamometer. Simultaneously a continuous plot of material behaviour is obtained. Friction and wear data from both disc brakes and large commercial vehicle drum brakes are shown, and demonstrate the comprehensive assessment of material behaviour. The standard deviations between tests for wear and for coefficient of friction are 0.005mm (0.0002 in) and 0.003 respectively.
The Engineering of Reliability into Waste Heat Boiler Systems
Authors: Hinchley P.
Published: October 2007

Waste heat boiler systems are often a weak link in process plants and some failures have caused severe losses. The author considers that this situation can be avoided in future plants by following the guidelines laid down in the paper.

The paper begins with a general description of a waste heat boiler system which is applicable to all processes. The evolution of the flowsheet for a typical plant is described and it is shown how the early involvement of engineering specialists can influence the choice of steam conditions and the positioning of items of equipment in the flowstreams, so as to ensure that reliable equipment can be designed and purchased. The early development of a computer model of the system is recommended since it frequently demonstrates how the duties of individual items deviate markedly from normal, under start-up, part-load and trip conditions.

The various items of plant are described, potential problems are mentioned and methods of avoiding them given. In the case of boilers heated by process gas, reference is made to some of the special designs that have been developed for specific processes. The need to acquaint the equipment supplier of the special problems of a particular process is stressed, as is the importance of close attention to detailed design, fabrication and quality control. The main pre-commissioning steps are described. In operation, water quality is vital and continuous analysers are advocated in specified locations, with some linked to automatic trips which prevent contaminated condensate or feedwater from entering the treated water storage tank or deaerator.
The Relative Thickness of Grease and Oil Films in Rolling Bearings
Authors: Wilson A. R.
Published: October 2007

A method for measuring the thickness of grease films between the rollers and rings of rolling bearings is described. Measurements in two designs of bearing show that a grease can initially form thicker films than can its base oil but that, without frequent relubrication, the grease films become slightly the thinner with time. The thinning of grease films, which is attributed to partial starvation, is accompanied by a reduction in viscous friction. Except in critical applications, where the thickest films are required, the consequences of partial starvation associated with grease lubrication can be advantageous.
Compressible Flow through a Butterfly Throttle Valve in a Pipe
Authors: Woods W. A. , Goh G. K.
Published: October 2007

This work is put in perspective by mentioning some of the applications of butterfly throttle valves and explaining how the next tests are complementary to other work (1). The present tests examine the flow characteristics of a butterfly throttle valve in relation to valve opening, pressure ratio and circumferential and axial location of the pressure tappings.

The paper gives results of a comprehensive series of steady flow tests and, also, results of a limited number of unsteady flow tests. In the latter, the butterfly throttle valve was located in the intake system of a single cylinder diesel engine.

The paper highlights the importance of the position of pressure tappings when pressure measurements are used to estimate flow rates. The results of the present study show that when suitable precautions are taken the quasi-steady flow method may be used to predict the flow rates under pulsating conditions.
Youth Unemployment and the Roles of Engineering Education and Training in the UK
Authors: Jackson R. A.
Published: October 2007

The paper looks at some of the interrelationships between youth unemployment and education and training in the UK at the present time. This leads on to suggesting, within a context of engineering education and training, how the existing arrangements might be improved and what additional measures should be considered for the immediate future.
Analogue and Digital Modelling in the Design of a Hydraulic Vehicular Transmission
Authors: Svoboda J. V.
Published: October 2007

This paper is concerned with the design and development of a hydraulic hybrid urban vehicle power plant using a small internal combustion engine prime mover, a hydraulic transmission, and a hydraulic accumulator as a small energy store. The driver controls the vehicle velocity by operating the swashplate of the axial-piston variable-displacement hydraulic motor. The remaining system inputs, i.e., the engine throttle and swashplate of the axial-piston variable-displacement hydraulic pump, are governed by a multiloop electronic controller via electro-hydraulic servo-actuators.

The system aims to achieve a high overall efficiency by utilizing the hydraulic accumulator to maintain optimal loading of the prime mover and to provide regenerative braking.

The design was aided by an analogue simulation implemented on an EAI 690 hybrid computer. For the final quantitative evaluation of the system, a digital simulation program was written using the MIMIC processor. Realistic modelling was attained in both cases by using manufacturers' data for commercially available components to define the dynamic response and efficiency of the individual elements of the overall system.

The simulation model was subjected to accelerator/decelerator step input signals under various road conditions. ‘Drives’ through the standard LA-4 and EPA standard urban cycles were performed. The simulation results showed high system stability, satisfactory acceleration and deceleration performance and a good overall efficiency.
Observations on the Influence of Rotation on Heat Transfer in the Coolant Channels of Gas Turbine Rotor Blades
Authors: Morris W. D. , Ayhan T.
Published: October 2007

This paper reports the results of an experimental study of the combined influence of Coriolis acceleration and centripetal buoyancy on heat transfer in a cylindrical tube which rotates about an axis orthogonal to its axis of symmetry. It is demonstrated that for a radially outward flow, Coriolis acceleration tends to improve heat transfer. However the Coriolis-induced improvement to heat transfer may be nullified and reversed due to centripetal buoyancy and this is demonstrated. Proposals are made which permit an overall assessment of these two interacting effects to be made. The implications of the results reported in relation to the design of conventionally cooled turbine rotor blades are discussed.
Performance of N2O4 Gas Cycles for Solar Power Applications
Authors: Angelino G.
Published: October 2007

The use of N2O4 as the working fluid in gas turbine power cycles is recognized as a potential instrument for improving cycle efficiency at moderate top temperatures while maintaining the technical advantages connected with the waste heat rejection at a comparatively high average temperature. Solar central receiver power stations, whose economic effectiveness is very sensitive to cycle efficiency and which must often reject their waste heat into the atmosphere, could usefully adopt this fluid. The thermodynamic reasons which explain the peculiar behaviour of N2O4 as the Brayton cycle working fluid are discussed. With respect to inert gas cycles, N2O4 permits, for a given efficiency, a reduction in turbine inlet temperature by 200-250°C. At a given turbine inlet temperature, the dissociating character of N2O4 allows overall efficiencies similar to those of steam cycles (at least for moderate plant capacities and provided N2O4 and steam cycles reject their waste heat at comparable temperatures). The relatively long relaxation time of the second step of the N2O4 dissociation can represent a problem mainly for the regenerator. A cycle is presented where regeneration at a pressure higher than the compressor inlet pressure can alleviate this problem.
Hot Wire Measurements at the Exit of a Centrifugal Compressor Impeller
Authors: Goulas A. , Baker R. C.
Published: October 2007

Hot wire measurements at the exit of a small centrifugal compressor impeller are reported. Three different hot wire readings were obtained and stored on a magnetic tape for each point by gating the analogue hot wire signal with a pulse which indicated circumferential position. The combination of the three readings yielded the mean velocity and some Reynolds stresses at each point. The measurements show a ‘jet-wake’ profile towards the shroud and ‘isentropic’ flow near the hub.
The Steady State Hydrothermal and Chemical Environment of a Once-Through Boiler Operating at 14.5 MPa
Authors: Crow I. G. , Greene J. C. , Tyldesley J. D. , Walker M. A.
Published: October 2007

The chemical, thermal and hydrodynamic conditions present on the waterside of a once-through nuclear boiler operating under steady conditions at a pressure of 14.5 MPa have been studied in a recirculating test loop operating at plant relevant conditions. By means of a highly sensitive scanning gamma-ray detector system and the use of radio-labelled sodium chloride, together with conventional hydrothermal instrumentation a comprehensive description of the waterside environment has been obtained.

A previously unsuspected form of sodium hold-up in the test-section has been observed and attributed to an adsorption process. The amount of sodium adsorbed has been found to be dependent upon the dry area of the tube available, the temperature of the metal and the ratio of sodium chloride to hydrogen chloride in the working fluid.
Variable Amplitude Fatigue in Relation to Highway Bridges
Authors: Tilly G. P. , Nunn D. E.
Published: October 2007

With the introduction of welded construction in highway bridges it has become necessary to assess designs for fatigue. Current methods of calculating endurances involve constant amplitude data and assumption that the Palmgren-Miner law can be used to sum the damage caused by different stresses. In order to investigate the efficacy of this method laboratory tests have been conducted on representative welded connections using variable amplitude loading at endurances of up to 415 × 106 cycles.

Using a Rayleigh spectrum of stresses it is shown that for endurances relevant to bridge service, the role of stresses below the constant amplitude fatigue limit is critically important. If they are ignored, calculated endurances can be many times too optimistic. An accurate allowance for the effects of low stresses can be made by representing the constant amplitude data by a curve having a higher stress exponent for stresses below the fatigue limit. At the longest endurance tested, only about 0.25 per cent of the stresses exceeded the fatigue limit and these caused 9 per cent of the calculated damage.

Under an axle load spectrum, endurances were six times longer than calculated. This was found to be due to an interactive effect caused by small numbers of high stresses which effectively retard the rate of crack propagation. In practice, shapes of stress spectra differ from axle load spectra and situations in which measured stresses involve small numbers of high values are rare.

In all cases, conservative endurances were estimated using the method given in the British Standard for bridge design.
An Automated Mobile Laboratory for Continuous Monitoring of Atmospheric Pollutants
Authors: Harrison R. M. , McCartney H. A.
Published: October 2007

The construction and operation of an automated mobile laboratory for continuous air pollutant monitoring are described. The gaseous pollutants sulphur dioxide, nitric oxide, nitrogen dioxide and ozone are monitored continuously, whilst particulate pollutants are collected for subsequent wet chemical analysis. Gaseous pollutant concentrations together with measurements of wind direction and speed and solar radiation are recorded continuously in both analogue and digital form. The problems inherent in siting and operating the mobile laboratory are discussed and the analysis of monitoring data is illustrated with reference to a recent survey carried out in the vicinity of an ammonium nitrate fertilizer works.
Prototype Class 210 Diesel-Electric Multiple Unit Trains for British Railways
Authors: Goldfinch A J
Published: October 2007

Most of the diesel multiple unit trains operated by British Railways were built between the years 1956 and 1960 and many will need to be replaced during the next decade. The paper describes in detail two diesel-electric multiple unit trains which are being constructed to test their technical and commercial suitability for services which are relatively heavily used but which are not electrified. The business requirements are outlined, and the design options available and decisions reached are discussed.
The Implementation of NC Plant in Functional and Cellular Groupings
Authors: Rathmill K , Sackett P J , Littlefield T
Published: October 2007

In this work the subject of NC (numerically controlled) machine tool investment is viewed in the context of two quite different manufacturing systems. The selection of an NC plant is examined in a study exemplifying a highly profitable and traditional functionally organized plant; here the machine selection process itself is examined and particular reference is made to the data requirements met in the company considered. A second duty is then used to demonstrate the operational implications of NC plant when implemented as a successful cellular system.
The Effect of Irreversibility on the Capacity of a Turbine Blade Row
Authors: Fielding L
Published: October 2007

If the assumption is made that the process followed by the expansion of a gas in a converging blade row is isentropic, thermodynamic analysis leads to the result that the attainment of maximum mass flow, for a given flow area and predetermined inlet pressure and temperature, occurs when sonic velocity is reached at the throat. If, however, as in practice, the expansion proceeds with internal frictional losses, and if certain common assumptions are made regarding these losses, then, assuming adiabatic flow, thermodynamic analysis shows that the maximum flow will occur at a Mach number less than unity. If this paradox is not noticed, it may lead to an appreciable underestimate of the mass flow passed by a blade row for a given set of inlet conditions. This paper examines the relationship between blade row losses and boundary layer characteristics in an attempt to rationalize the calculation of the capacity of a turbine as modified by irreversibility.
Evolution of the Lipe Hydraseal Self Contained Fluid Clutch
Authors: Linn D F , Yanko J P
Published: October 2007

The Lipe Hydraseal is a new fluid clutch concept to transmit engine torque to the transmission more efficiently than previously existing methods. It can be applied to various types of vehicle from passenger cars to large heavy duty trucks or off-road equipment. It offers the smooth coupling, long life and efficiencies of an oil spray clutch without the inherent installation difficulties.