bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-Dimensional Geometric Analysis of the Plunge Centreless Grinding Process
Authors: Udupa N G Subramanya , Shunmugam M S , Radhakrishnan V
Published: February 2007

The grinding action and the rounding mechanism are highly complex in centreless grinding. The axis of the workpiece not only moves laterally but also tilts during the grinding process. Rowe and Barash have developed a two-dimensional model for an infeed centreless grinding neglecting the tilt of the workpiece.

In this paper, an attempt has been made to develop a simulation model which incorporates the tilt of the workpiece. The theoretical and experimental investigations have been carried out with workpieces having specific geometries and the results are discussed.
A Study of Vortex Throttles Part 2: Viscid Flow Analysis
Authors: Priestman G H
Published: February 2007

A simple viscid flow model has been developed to describe the effects of geometry and fluid properties on the performance of vortex throttles. The semi-empirical model can be used as a basis for design of certain types of vortex throttle. Within defined limits, the equations predict the performance of throttles of various geometries operating over a range of Reynolds number, for non-cavitating incompressible and subsonic compressible flow. Friction losses are accounted for by using a theoretical velocity recovery factor and a semi-empirical overall circulation factor. The model indicates a change in performance of the throttles over a certain Reynolds number range which is interpreted as transition from turbulent to predominantly laminar flow within the chamber. Predictions are made of optimum throttle design at various Reynolds numbers.
A Correlation between Aerofoil Theory and Euler's Equation for Calculating the Head of a Constant-Pitch Axial-Flow Inducer
Authors: Yedidiah S
Published: February 2007

This study indicates that the aerofoil theory of an impeller blade is not interchangeable with Euler's equation. Instead, these two approaches are supplementary to each other. The conclusion is well supported by observations from practice.
Natural-Convective Heat Exchanger with Vertical Rectangular Fins and Base: Design Criteria
Authors: Leung C W , Probert S D
Published: February 2007

Steady state rates of free-convective, conductive and radiative heat transfer from a polished, duralumin and extended-plate, heat exchanger through air have been measured. When its vertical base was maintained at 40.0 (±0.2) K above the local air temperature (=15.5 ± 0.4°C) in the laboratory, optimal values of the vertical-fin array's geometrical parameters, corresponding to achieving maximum rates of heat loss, were deduced. For a base of width 190 mm and length 250 mm, the optimal uniform separation between 3 mm thick fins rose from 9.5 to 11.1 mm as the fin protrusion was decreased from 90 to 30 mm: it was almost independent of temperature within the range considered. For a base of width 190 mm and length 500 mm, the optimal uniform thickness for fins of 60 mm protrusion rose from 1.5 to 3.6 mm as the fin separation was increased from 15 to 55 mm, the optimal fin thickness being almost invariant with respect to changes in the fins' base temperature.

No generalized quantitative recommendations emerge from the present investigation with respect to the optimal values for the fins' length or fins' protrusion. These would have to be evaluated, by making additional due allowances for the weight and cost of material involved in each proposed heat exchanger, according to each particular application envisaged. Nevertheless, it can be concluded that the use of two separated heat exchangers of the considered type, rather than a single one of similar design but whose length is the sum of the lengths of the previous two, should be considered when attempting to enhance the heat-transfer performance.
Thermodynamic Analysis of the Stirling Cycle Machine—A Review of the Literature
Authors: Organ A J
Published: February 2007

There is no agreed approach to the analysis of the practical Stirling cycle. Consequently there is no method of any generality for thermodynamic design and no established yardstick for assessing candidate design methods. The author therefore presents a vision of Stirling cycle analysis as it might be. Salient contributions to the literature are reviewed with this as background. The prospects are discussed for use of theoretical analysis in the optimization of thermodynamic performance.
Alleviating Thermal Resistances of Thermally Distorted Pressed Contacts
Authors: O'Callaghan P W , Probert S D
Published: February 2007

A suite of interactive computer codes, described previously, for simulating the heat-transfer behaviours of pressed contacts between dissimilar materials has been used to examine how thermal contact resistances may be minimized by:

(a) optimizing the roughnesses of the contacting faces, (b) introducing appropriate interfacial fillers, (c) suitably pre-machining (under isothermal room-temperature conditions) the surfaces which will subsequently be pressed together.

It has been shown that an inexpensive means of eliminating the component of the macroscopic constrictional resistance, which would arise from thermal distortions of the contacting materials in the presence of a temperature gradient, can be achieved by selecting optimal surface roughnesses.
Medium Friction Non-Metallic Composition Brake Shoes as Direct Replacement for Cast Iron Brake Shoes on Rolling Stock
Authors: Mercer C I
Published: February 2007

The results of tests on medium friction composition brake shoes by the Peruvian National Railways has produced a viable alternative to the locally made cast iron shoes which were proving to be dangerous. The composition brake shoes performed better than the cast iron ones in all aspects, the uniform friction characteristics ensuring safe braking at speeds not possible previously. As they also proved to be more reliable, with longer life and less wear, cost benefits actually accrued, bringing the project to a successful conclusion.
An Advanced Engine Control System Using Combustion Pressure Sensors
Authors: Sasayama T , Suzuki S , Amano M , Kuribara N , Sakamoto S , Suda S
Published: February 2007

While investigating high-efficiency responsive driveability accompanied by low exhaust emissions, a new concept in engine control has been developed. The method is based on the direct monitoring and controlling of combustion conditions in engines, using a newly developed combustion pressure sensor. Fibre-optic technology is adapted to this sensor to produce a high noise immunity and a simple structure that facilitates applications in automotive engines. A sensing method to obtain information on engine output, knocking or detonation and the combustion temperature from the signal of the combustion pressure sensor has been proposed. A control system for the engine and powertrain control using this sensing method has been put forth to provide a remarkable improvement in engine and powertrain characteristics.
The Roll-Centre Concept in Vehicle Handling Dynamics
Authors: Dixon J c
Published: February 2007

The roll-centre concept has been in use since the 1930s, but did not have its source in a single definitive paper. Although it is defined by the SAE in terms of forces, many authors introduce the concept as a kinematic one. The kinematic and force roll-centres are really diyerent points, and should be distinguished. The kinematic roll-centre is a difficult concept when the underlying principles are considered, and is only really comprehensible if the vehicle is considered to move with small lateral acceleration. The force roll-centre may be developed using force analysis only, and is comprehensible for high lateral acceleration. A new definition of the roll-centre is proposed. The incremental roll-centre is defined. The various approximations involved in the standard constructions are considered, which are different for the two types of roll-centre, these only being equivalent for an idealized mechanism. Some difficulties in the experimental measurement of the force roll-centre are considered, especially for significant roll angles. The geometric constructions for the roll-centres of various types of suspension are discussed.
A New Look at the Analysis of Coast-Down Test Results
Authors: Lucas G G , Lucas G G , Emtage A L
Published: February 2007

A new look is taken at the analytical procedure for reducing the results of the coast-down test. A three-degree-of-freedom model is discussed, and a derivative-based correction algorithm is shown to account for changes in ambient conditions. A parameter optimization technique for coeficient extraction is described, but not validated, due to deficiencies in the available data. The calculation of the standard errors in the extracted coeficients provides the basis for a statistical analysis of coast-down tests. This type of analysis is applied to simulated coast-down data that contain artificial pseudo-random errors, and this leads to a discussion of the accuracy requirements of the coast-down test.
The Development of a Theoretical Technique for Rail Vehicle Structural Crashworthiness
Authors: Scott G A
Published: February 2007

The development of a theoretical technique, based on the finite element method, is described from initial conception through to a production design tool, together with its application to typical vehicle structures.
Aluminium Alloy Body Structures for Future Vehicles
Authors: Kewley D
Published: February 2007

This paper describes a vehicle design concept concomitant with weight saving and the dominating role of the vehicle body leading to the use of aluminium and polymer composites.
The Bentley Turbo R
Authors: Dunn M R
Published: February 2007

This paper describes briefly the sporting background of Bentley motor cars and the early development of the Mulsanne Turbo. Following the decision to produce an improved version which would be fully worthy of its sporting heritage the Turbo R was produced by development of the car which derives from the long-lived Shadow and Spirit series. The development of the Turbo R chassis is described as is the extensive work on the engine and its installation to incorporate fuel injection and meet ECE 15.04 exhaust emission levels with improvements in performance and fuel economy.
Railway Passenger Vehicle Design Loads and Structural Crashworthiness
Authors: Scholes A
Published: February 2007

The loading specifications to which passenger vehicle body structures are designed seek to fulfil two basic requirements. Firstly, normal service loads experienced over the life of the vehicle must be met without loss of serviceability. Secondly, passengers and crew must be afforded protection against loads outside the normal service experience. In the specifications used in Europe and the United States there is an emphasis on ‘proof’ loading, that is loading which causes no permanent deformation. This requirement is in conflict with the absorption of energy which is necessary to cushion passengers and crew involved in an accident. The author examines UK accident statistics and proposes alternative ways in which the basic aims of structural crashworthiness can be met.
The Quantification and Reduction of Piston Slap Noise
Authors: Richmond J W , Parker D A
Published: February 2007

Recent advances by engine and vehicle manufacturers in the reduction of overall noise levels have resulted in piston slap noise becoming more intrusive and its reduction increasingly important.

At AE an essential part of a larger programme aimed at achieving this objective has been to develop a technique to assess piston noise in gasoline engines. The paper describes this technique and its application to investigate the effect of piston clearance and bore ovality. The technique may be applied to engines in development without recourse to internal instrumentation and correlates well with the result of listening panels.
And now…for Something Rather Different
Authors: Casey M V
Published: February 2007

The 1987 Railway Division Chairman reviews the changes that have taken place on the railways since his first early association with British Railways. He describes a programme of continual development and change, from the introduction of the first diesel locomotive to electrification, and the important part new technology has played in the changes.
Climatic Simulation in a Purpose-Built Wind Tunnel
Authors: Cumberpatch D C
Published: February 2007

The necessity to engineer motor vehicles for operation in extremes of temperature has long been acknowledged. The classical solution utilizes road testing in the environment. Shortcomings, however, exist and it is because of these that Gaydon Technology invested in a purpose-built wind tunnel for climatic simulation.
Limit Steady State Vehicle Handling
Authors: Dixon J C
Published: February 2007

Previously, limit steady state handling has always been restricted to the qualitative statement that a vehicle has final understeer or final oversteer; it cannot be analysed by the conventional understeer gradient concept. A specific proposal is made for quantification of final understeer or oversteer. This is called the understeer number, and is defned by Nu = (ArAf)-1, where Af and Ar are the lateral acceleration capabilities of the front and rear axles. Thus Nu is non-dimensional, is zero for a notional final neutral vehicle, positive for final understeer and negative for final oversteer. A typical value is 0.150 (rear drive) or 0.220 (front). The various design parameters that influence the understeer number are investigated, and equations are obtained and quantified, including centre of mass position, lateral load transfer distribution, longitudinal load transfer, traction, the components of aerodynamic forces and moments, the effect of non-free differentials and the effect of load increments. The effect of turning radius and slopes is also investigated. Thus the limit state of handling is subject to a quantitative assessment, showing the degree of a vehicle's commitment to final understeer or oversteer.
Industrial Combined Heat and Power: Investment, Savings and Decision-Making
Authors: Gurney J D , Hyde R G F , Pickering S J , Shute M
Published: February 2007

The economics of industrial combined heat and power (CHP) schemes are complex and require careful evaluation. A method of assessing CHP schemes by computer, which has been found to give good results, is described which enables the most cost effective CHP plant configuration to be determined as an aid to decision-making and investment.
The Integration of Noise Control in Plant Design—A Review
Authors: Lyle C D
Published: February 2007

Adequate control of industrial noise is essential to ensure that local residents are not subjected to nuisance and that people on site are not exposed to noise levels which cause hearing impairment.

Noise control engineering should be an integral part of the design process. This paper explains what noise limits must be met and how the noise control requirements should be incorporated in the project. It is shown how noise control interacts with other engineering disciplines to achieve the optimum cost effective design. This is contrasted with the situations which could arise if noise control were considered an add-on feature which is included after the overall design has been completed, or, worse still, after commissioning.

It is concluded that involving a noise control engineer from the early planning of a project, through the design stage and ultimately carrying out a post-commissioning noise survey, ensures that noise control engineering expertise is used effectively, technical feedback is maximized and the right standard of noise control is achieved at minimum cost.
Non-Metallic Asbestos-Free Gaskets
Authors: Childs P
Published: February 2007

With the increasing concern over asbestos, more companies are considering the possibility of changing to asbestos-free, non-metallic gaskets. However, caution should be exercised when adopting alternative materials because their applicational requirements are significantly different. Specifically, when compared with premium quality compressed asbestos fibre grades, the calendered asbestos-free grades generally have: lower temperature and pressure ratings, temperature and pressure ratings which do not co-exist (that is as the temperature increases, the maximum internal pressure sealable decreases), higher minimum surface stress requirements, lower maximum surface stress values, lower creep resistance, different chemical resistance, poorer performance in steam and less tolerance to the deleterious effects of jointing compounds.

This paper attempts to demonstrate why this new group of materials should not be considered as a direct replacement for compressed asbestos fibre but rather as a limited substitute. It also offers some hope for the future with the prediction of the development of a calendered asbestos-free grade with similar properties to the best traditional asbestos-based grades but without the large cost penalty involved in selecting exfoliated graphite.
A Review of the Development of Safety and Relief Valve Silencers for Steam Discharge
Authors: Crawford C J
Published: February 2007

The paper outlines the progress made by the Central Electricity Generating Board (CEGB) in the development of silencers for the control of boiler safety valve and relief valve noise.

System noise sources and the formulation of environmental noise criteria are discussed; the silencer design philosophy adopted by the CEGB is described and the progressive improvements are charted to demonstrate the advances made over earlier practices.

The results of this work are design concepts which provide silencers which are suitable for application to any of the CEGB's steam valve vent systems and are capable of meeting stringent neighbourhood noise criteria.
The Theory of Thin Shell Structures 1888–1988
Authors: Calladine C R
Published: February 2007

This paper commemorates the publication in 1888 of A.E.H. Love's paper on thin elastic shells. It discusses Love's relationship with Rayleigh and others, and assesses the historical significance of the work.
Perception of Plant Design
Authors: Thompson G
Published: February 2007

The case is argued that true mechanical engineering designers in the process industries are often underutilized due to certain constraints placed upon their work. Creative thought is suppressed if designers are employed in the wrong environment. There are some activities, often referred to as design, that in fact have no design characteristics and are essentially solely analytical excercises. However, opportunities do exist for designers to practice their talents to the full, so enabling them to make a greater contribution to their company's business than has hitherto been possible. Some examples are presented where designers may be gainfully employed, and a reappraisal of the role of engineering designers is called for.
Diesel Emissions Reduction Using a Catalyst and Water Scrubber for Underground Mine Applications
Authors: Andrews G E , Everest R , Jepson D , Pang S W
Published: February 2007

BS 6680 requires the efficiency of coalmine diesel engine exhaust pollution-reduction devices to be determined. The efficiency of an Englehard PTX catalyst and water scubber for both particulate and gaseous emissions reduction was determined using a 533 cc single-cylinder Petter AVI direct injection diesel engine. The separate and combined influence of the two exhaust devices was determined. The water scrubber acted as aflame trap as well as an exhaust particulate trap. The catalyst gave a substantial reduction in CO and UHC gaseous emissions and particulate SOF emissions for exhaust temperatures above 250°C. However, the high MW particulate SOF, including the PAH, had a 70 per cent reduction for catalyst temperatures as low as 200°C. The water scrubber was the dominant particulate removal device, although the catalyst removal efficiency was significant for temperatures above 250° C. The scrubber also had a significant influence on the reduction in NOx emissions, with a 30 per cent removal at high exhaust temperatures.
On the Optimum Utilization of Water Hammer
Authors: Azoury P H , Baasiri M , Najm H
Published: February 2007

The computerized method of characteristics was used to analyse, for a single pipeline discharging into the atmosphere, the effects of valve-closure schedule and pipe length on optimum water-hammer strength. It was found that the criteria of optimum water-hammer utilization are a non-linear inherent valve schedule in which the bulk of the pressure surge occurs near the beginning or towards the end of valve closure, together with as small a value of dimensionless valve-closure time and as high a value of wide-open valve area as is consistent with cavitation-free operation. Also, a comparison of the results with hydraulic ram test data suggests that optimum drive pipe length may be based solely on optimum water-hammer strength, in the light of the relative effects of pipe friction and dimensionless valve-closure time. In general, optimum pipe length is not highly sensitive to inherent valve-closure schedule, water-hammer strength, pipe size or reservoir head.
Estimating the Performance of Gas Turbine Heat-Recovery Boilers Off-Design
Authors: Weir C D
Published: February 2007

In installations where a gas turbine is coupled to a steam prime mover through an exhaust heat steam generator, the need may arise to estimate the behaviour of the latter away from its specified design conditions. For example, the performance of the steam generator when the gas turbine is operating away from its design conditions may be of fundamental importance in relation to the economics of a proposed coupled installation. In particular, it determines inter alia the extent to which supplementary firing may be required.

A question closely related to that of the off-design performance of a given exhaust heat steam generator is that of evaluating the comparative merits as regards thermal performance of designs differing in the layout and configuration of the heat-transfer surfaces when tendered for the same specified duty. (The need for such assessments frequently arises in the examination of competitive tenders.)

The paper discusses briefly procedures allowing the influences of the interrelated heat balances of the heat-transfer surfaces, of the heat-transfer surface geometry and of the steam and gas physical properties to be analysed separately and integrated into a computational procedure permitting their combined effect on performance to be determined with sufficient accuracy.
Integrating Universities and Industry—A German Approach
Authors: Winter H
Published: February 2007

Starting from a list of topics which were suggested by the Institution of Mechanical Engineers this paper surveys the situation at German technical universities in the field of mechanical engineering. The details of teaching and research activities described here refer to the Institute for Machine Elements, Technical University of Munich, but the principles of the organization and the structure are mostly comparable with corresponding institutes at other universities in the Federal Republic of Germany. The following subjects will be discussed: 1. The organization of German technical universities, in particular the Institute's structure of a Faculty of Mechanical Engineering. 2. Undergraduate courses in engineering based on ‘vocational’ education; the means to ensure an education of approximately equal academic standard at different universities. 3. Machine element teaching at undergraduate level; efforts to ensure an equal level of knowledge in this field. 4. The structure and funding of postgraduate engineering research centres and institutes. For example the relationship between the Gear Research Centre (FZG) and the gearing and transmission industry in Germany will be discussed. 5. A summary of the research carried out at the FZG (gears, clutches, tribology)
Project Management—A Personal View
Authors: Toft L A
Published: February 2007

This paper sets out a series of precepts which the author has found to be useful when managing substantial capital projects in the heavy chemical plant field. The importance of a thorough understanding of the design background to the plant on the part of the project manager is considered to be very necessary for the effective management of contracts for new works. The importance of detailed knowledge, leadership and team motivation in minimizing risks arising from both human fallibility and events beyond the manager's control is also stressed. Finally the necessity for foresight and the means used by the author for forward prediction are set out.
Prediction of the System Efficiency of Balanced Automatic Transfer Lines
Authors: Ma X , Kochhar A K
Published: February 2007

This paper presents a simulation study of the system efficiency, in terms of production rate, of automatic transfer lines. A particular type of system, referred to as balanced automatic transfer lines, is considered in the study. In such a balanced automatic transfer line, the stations are considered identical in terms of availability and the buffers are uniformly allocated, and only four system design parameters are involved, namely the number of stations, the identical failure and repair rates, and the uniform buffer capacity.

Based upon simulation results, an empirical production rate equation is established by using available optimization techniques for fitting non-linear functions. The empirical relationship is validated using further experimental results. It is shown that this empirical equation can be simply used, with a high enough accuracy in many practical applications, to predict production rates of balanced automatic transfer lines with reasonably wide ranges of system design parameters.
Engineering for Quality
Authors: Manton S M
Published: February 2007

Through continual improvement in the satisfaction of customer needs and expectations, Japanese manufacturers have set new standards in product specification, quality, and reliability and nowhere more so than in the international automotive markets where there is recognition of best-in-world status. In response to the challenge, manufacturing companies in the West and in particular those with international market perspectives, have initiated a process of change that commits to a different approach to quality. The reinforcement of quality control procedures driven by design specifications to which all manufacturing processes must be made to conform, is being displaced by the need for change in the operation of all functions within the company, including those less obviously associated with quality in the end product. Total quality is a philosophy that lays the ground for revisions to the management of the entire production process and creates the conditions for the establishment of a common purpose.
Making Finite Element Analysis Available to Designers at the Concept Stage
Authors: Clarke R B
Published: February 2007

Too often in the past, ‘computer aided design’ has really meant ‘computer aided draughting’. It has been assumed implicitly that the creative input has been made, and subsequent efforts are concentrated on streamlining and on making downstream processes more efficient. This has been the traditional development path of CADCAM applications, but it underrates the vital importance of a sound design concept in the first place since it is true to say that all the fundamental costs etc. of a product are built in at the design stage. More sophisticated tools are required for the designer working at the concept stage to help ensure the quality of his scheme and to avoid potential problems downstream during detailing etc. This paper will make these points and describe and illustrate a basic system created at the University of Ulster to allow designers to use finite element analysis effectively in certain situations without the degree of skill normally required of an analyst.
The Design and Development of a Non-Contact Printer for Product Coding
Authors: King D , Luk R , Massingberd-Mundy P , Sendell A , Holmes R
Published: February 2007

This paper is concerned with the design and development of a low-cost system for applying product information to a target area on the top of a carton passing through a cartoning machine at, typically, 60 cartons a minute. A prototype was designed and built which prints high-quality preprogrammed characters on to a range of carton sizes, can be adjusted in the x, y and z planes and can be fitted to a variety of existing packaging machines.
The Cambridge Phenomenon—Lessons for Manufacturing
Authors: Gregory M J
Published: February 2007

This paper reviews the development of ‘high tech’ companies in the Cambridge area and examines some of the factors which are believed to have encouraged these developments. It identifies the characteristics which attract able young engineers to work for these companies and points to some lessons which manufacturing industry may learn from the ‘Cambridge phenomenon’.
The Management of Product Quality: A Study
Authors: Duncalf A J , Dale B G
Published: February 2007

This paper reports on an investigation based on manufacturing companies in the United Kingdom. The investigation examined various ways in which companies manage their product quality. In carrying out the study three different pieces of work have been undertaken: namely, case studies, two separate postal questionnaire surveys, and the development and testing of a method for helping organizations to focus on their quality-related decisions. The method developed enables an organization to identify the strengths and weaknesses of their approach to quality management.

The findings reveal the many different opinions, structures and functions relative to the approaches of manufacturing companies to quality management. Due to the multitude of factors which influence the way a company goes about managing the task it was impossible to identify a general approach. It was, however, possible to evolve a method based on a quality-related decision-making approach, which provides a means for manufacturing companies to assess their ongoing management of quality and relate this to their specific needs.
Adventuring in Industry
Authors: Ashton E W S
Published: February 2007

The interplay between the capability of a company, the pull of a market for its product, and its profitability, is examined on a catastrophe ‘cusp’ diagram.
The Development of Production Monitoring Systems
Authors: Ososanya E T , Franks I T
Published: February 2007

Computer technology has given manufacturers the opportunity to monitor, on-line and in real-time, a wide variety of manufacturing systems. Such monitoring systems have considerable potential for expansion and development but need to take account of the special characteristics of particular manufacturing systems and how the information is to be used to best effect. This paper outlines the use of monitoring in the broad context of manufacturing plant operations and describes the design of a development system that will facilitate research into the effective application and improvement of monitoring systems.
The Effect of Billet Location on Completely Closed Cavity Die Forging
Authors: Ibhadode A O A , Dean T A
Published: February 2007

The effect of the accuracy of location of cylindrical billets in completely closed cavity dies, on forging loads and product accuracy has been investigated.

Aluminium billets with various off-centre locations were forged at room temperature on a 3000 kN hydraulic testing machine. The results indicate that inaccuracies in billet location significantly affect forging load requirements and dimensional accuracy of forgings. An energy method solution is presented to provide accurate load predictions for relatively small off-centre locations of billets.
Elimination of Parcel Damage from Conveyor Systems
Authors: MacMillan C G
Published: February 2007

The development techniques for gently transferring bulk mail from one conveyor to another is described in a previous paper (1). This paper describes the further development of those techniques, and a method of establishing specific designs.
Film Thicknesses in Circular Elastohydrodynamic Contacts
Authors: Greenwood J A
Published: February 2007

A new elastohydrodynamic film thickness chart is introduced, with advantages over the Johnson chart for the true elastohydrodynamic regime. Collected results of point-contact calculations from different sources are plotted, and show excellent agreement, but do not fit an obvious power law formula.
Three-Dimensional Thermoelastohydrodynamic Analysis of Pivoted Pad Thrust Bearings Part 1: Treatment of Bearing Deflections and Fluid Film Flow and Heat Transfer
Authors: El-Saie Y M H Ali , Fenner R T
Published: February 2007

A computational method is described for predicting the performance of pivoted pad thrust bearings. The model used allows for heat generation and transfer in the oil film and also heat conduction in the pad and other solid parts of the bearing. Pad deflections due to both temperature variations and oil film pressures are calculated, and an overall solution procedure developed which allows all of these effects to interact.
Identification of Small Amplitude Resonances in Rotary Digital Systems
Authors: Smith J D
Published: February 2007

A method is described for determination of amplitudes of high-frequency vibrations of a system when the level of vibration is less than the discrimination of the system. This allows identification of torsional resonances in rotary encoders used to measure gear vibrations.
A Thermodynamic Design Simulation for Stirling Cycle Machines Using a Lagrangian Formulation
Authors: Rix D H
Published: February 2007

This paper describes a one-dimensional simulation of the Stirling cycle machine. A Lagrangian coordinate system is used in conjunction with an implicit solution scheme.

The detailed formulation of the conservation equations is set out, including the heat transfer and fluid friction correlations used. The regenerator model includes the use of a spline function to represent the axial temperature distribution. The means of increasing the rate at which the solution attains its final steady state value is outlined.

The choice of working fluid subdivision size and number is investigated along with the equation integration time increment. It is shown that optimum values exist for both. Finally, a favourable comparison is made of predicted and experimental results for the pressure-time variations and heat transfers to and from the compression and expansion spaces of a heat pump. The problems of using air as the working fluid are discussed.
An Evaluation of Eight-Node Quadrilateral Finite Elements for the Analysis of a Dynamically Loaded Hydrodynamic Journal Bearing
Authors: McIvor J D C , Fenner D N
Published: February 2007

A comparative study is presented for the finite element analysis of a dynamically loaded journal bearing showing the improvement in solution accuracy and decrease in computer time achieved when using eight-node quadilateral, rather than three-node triangular, elements. Results are presented for medium size diesel engine big end bearings using a wide variety of mesh gradings.
Computation of Decoupling Precompensators for Linear Multi-Variable System Models
Authors: Whalley R
Published: February 2007

In this paper system models which are stable, linear, multi-variable and time invariant, expressed in the form of a transfer matrix in the Laplace variable, will be considered. The spectral form of the transfer matrix will be used to show that if the number of coupled right-hand plane zeros is less than or equal to the number of inputs to the system then proper, stable, realizable decoupling precompensators for the system exist. Thereafter algorithms which give the number of decoupling realizations in the set are derived and demonstrations of the wide range of options afforded by these variations to the system designer are presented. To emphasize the flexibility and generality of the result the decoupling precompensators for a simple multi-variable system are computed together with the resulting non-interacting system/compensator combination. Selection of the ‘best’ configuration is then made on the basis of the pole-zero pattern associated with each interfaced system. Finally, the design may be completed by way of the Nyquist array method using the preferred decoupling precompensator as a starting point in the search for a low-order realization, producing diagonal dominance rather than non-interacting characteristics.
A Revised Philosophy of Surface Measuring Systems
Authors: Whitehouse D J
Published: February 2007

Surfaces have been measured for many years yet there are still many factors which have not been optimized both for the contacting methods and non-contacting methods. In this paper the philosophy of optimization for both types of system is examined and rules established for improvement of system fidelity. In particular, ways are suggested of increasing the speed of measurement. This new philosophy has implications when consideration is being given to improving the performance of the modern generation of surface measuring instruments. These include not only those measuring geometry such as the scanning tunnelling microscope but also devices for measuring force and friction.
Experimental and Theoretical Investigation of Mixed and Stratified Hot Water Storage Tanks
Authors: Votsis P P , Tassou S A , Wilson D R , Marquand C J
Published: February 2007

This paper investigates the performance of a 1.1 m3 stratified hot water storage tank coupled to a vapour compression heat pump system. A comprehensive data acquisition system has been used to obtain the experimental data from a series of static and dynamic tests. In the static experiments a well-defined thermocline has been achieved and the effects of insulation and tank wall thickness on the preservation of the thermocline have been determined. The results indicate that thermal losses in stratified tanks are about 22 per cent higher than the losses in fully mixed tanks. The dynamic experiments have been conducted with an upward-moving thermocline and the major factors influencing its stability have been correlated in terms of the Archimedes number (Gr/Re2). It has been found that good stratification performance can be maintained with Archimedes numbers in the range between 35000 and 55000. A simplified one-dimensional model of the storage tank has been developed and validated against experimental results. The model will be linked to dynamic models of the heat pump and the building to simulate the performance of a heat store/heat pump energy management system.
Combustion Oscillations in Dump Combustors with a Constricted Exit
Authors: Sivasegaram S , Whitelaw J H
Published: February 2007

Combustion oscillations in axisymmetric dump combustors have been examined in terms of amplitude and frequency characteristics for two dump-plane area ratios and as a function of combustor length, exit constriction, diameter, flowrate, equivalence ratio and swirl. The flammability limits are similar to those previously determined in disc- and dump-stabilized flames without a constricted exit, but the stability limits are not. Rough combustion, characterized by radiated sound levels more than 12 dB above that in smooth combustion, was observed at equivalence ratios close to the flammability limits for values of swirl number less than 0.2 and was associated with the bulk-mode frequency. With swirl numbers in the range from 0.2 to 0.4, rough combustion was not encountered and, for higher values, existed in a range of equivalence ratios from around 0.8 to 1.4, provided the combustor length and flowrate led to half-wave frequencies less than around 800 Hz. In those ranges of equivalance ratio where the combustion was smooth, discrete frequencies corresponding to the bk-mode and half-wave were observed. The amplitude of the discrete frequency increased when it coincided with the shedding frequency of the shear layer.
History Dependence in Two-Disc Scuffing Tests
Authors: Williams P A , Finnis M P , Kelly D A
Published: February 2007

Salient features are described of a two-disc machine and its use to monitor friction, resistance drop count rate, surface roughness and disc bulk temperature in scuffing tests on mineral oil lubricated, case-hardened En 36A steel. Tests with two different load sequences and three oil supply temperatures are reported. Results for two extreme-pressure-additive oils are compared with earlier results for a non-additive oil and shown to support the validity of a recent hypothetical model by Baglin for the onset of microelastohydrodynamic lubrication.

Compared to the non-additive oil, the additive oils gave higher disc bulk temperature rises, greater running-in and more severe conditions at scuffing when tested at sliding and rolling speeds of 6 m/s. Nevertheless, these scuffing conditions were not so severe as those for the non-additive oil tested at a sliding speed of 3 m/s and a rolling speed of 4.5 m/s.
The Growing Pains of Ceramics Processing
Authors: Charnah R M
Published: February 2007

Recent advances in ceramics and in particular their processing have led to a re-evaluation of how and where they can be used. The lecture discusses some of the recently introduced processing techniques for ceramics and the new materials derived from them. The processes are used to illustrate where engineers can apply ceramics, including ceramic composites, and how they can tackle the challenges posed by the materials themselves and by the changes implicit in using them rather than, or in conjunction with, traditional engineering materials.
Thermal Analysis of a Spur Gearbox Part 2: Transient State Finite Element Analysis of the Gearbox Casing
Authors: Joule D , Hinduja S , Ashton J N
Published: February 2007

In Part 1 of this paper measured and computed steady state temperatures for a spur gearbox casing have been compared, and the approach to determining the thermal boundary conditions is presented. In Part 2 this approach is extended to two different transient problems. The first is for continuous running from start-up until the steady state conditions are attained, and the second is for a start-stop-restart cycle in an attempt to simulate intermittent running. The finite element (FE) results and derivation of the boundary conditions are both described.
The Elastic—Plastic Contact of Rough Surfaces and its Relevance in the Study of Wear
Authors: Halling J , Arnell R D , Nuri K A
Published: February 2007

In a recent paper it was shown that the limit of elastic behaviour of rough surfaces could be defined by a unique relationship between the plasticity index and the nominal pressure. Specific experimental evidence suggested that the best theoretical model was one when the asperity height probability distribution was assumed Gaussian with a truncation of 3 σ. This paper extends this argument by showing that for a given ratio of plastic-elastic area of real contact, similar unique relations exist between the plasticity index and nominal pressure. It is assumed that the maximum non-dimensional elastic deformation is given by the inverse of the square of the plasticity index, and this is supported by experimental results. It is also shown that the model proposed is in error at higher pressures, due to the interaction of the deformations of adjacent asperities.
Flows Through Round Sudden Contractions
Authors: Khezzar L , Whitelaw J H
Published: February 2007

Measurements of the mean axial and radial components of velocity, the r.m.s. of the corresponding fluctuations and the wall static pressure are reported for flows through round sudden axi- and asymmetric contractions with an area ratio of 2.5 and were obtained at a Reynolds number of 40 000 based on the bulk velocity in the upstream pipe. In the axisymmetric case, the main changes in the approach velocity profiles occurred within a distance of one-half diameter upstream of the contraction, and the velocity profiles suggested that the flow separates at the entrance to the smaller diameter pipe. The wall static pressures revealed the presence of a vena-contracta downstream of the contraction plane. In the asymmetric case, the velocity profiles were very three-dimensional but regained symmetry by 9.5 diameters from the contraction plane.
Estimation of Daily Inclined Surface Solar Irradiation—an Anisotropic Model
Authors: Muneer T , Saluja G S
Published: February 2007

The validity of an isotropic model for predicting daily irradiation on inclined surfaces was tested by using one-year measured data on a horizontal, an inclined and four vertical surfaces for Easthampstead (51.4°N, 0.8°W) and Lerwick (60.2°N, 1.2°W) in the United Kingdom. As a consequence an anisotropic model has been developed. The proposed model treats south-, north- and east/west-facing surfaces differently. The accuracy of the proposed model is compared with that of the isotropic model by employing a simple technique of error analysis. The usefulness of a good daily inclined surface irradiation model is outlined.
Evaluation of Cavitation Damage Characteristics Using a Profilometer
Authors: Balachandar R , Ranganathan Y , Ramamurthy A S
Published: February 2007

The ability to make quantitative statements concerning cavitation damage should involve appropriate measurements of both material loss and material damage. This study investigates the extent to which surface profilometry techniques can be used to determine cavitation damage characteristics by obtaining the surface profiles of test specimens before and after cavitation. Based on the maximum depth of penetration obtained from the surface profiles, the velocity exponent for maximum damage is determined. This value of the exponent agrees favourably with previously published values obtained from weight loss measurements.
The Mapping of Metallic Sliding Wear
Authors: Childs T H C
Published: February 2007

Mechanisms of machining (abrasive), fatigue and transfer wear are reviewed in the context of the interfacial shear stress (adhesive) and surface roughness (deformation) conditions in which they occur. In the first part it is shown how model predictions of surface flow, friction and wear may be mapped on to a field with surface shear strength and roughness slope as its coordinates and in the second part the response of real metals to these variables is considered. The main attention is given to abrasive wear, with a review of lubricant, geometry, bulk mechanical and microstructural effects on abrasive wear resistance; but briefer reviews of fatigue and transfer wear are also given. Any overview of metallic wear requires consideration to be given to wear not of the metal but by removal of surface reaction films (usually oxides): regimes of oxidational wear do not plot on to a map of surface shear strength and slope but on to a map of nominal contact pressure and sliding speed. The need is argued for two sorts of map on which to classify wear phenomena.
Vibratory Conveying by Non-Sinusoidal Excitation
Authors: Srinath K , Karmakar R
Published: February 2007

A vibratory conveyor is essentially an inclined plane which is subjected to an acceleration cycle, conventionally sinusoidal. It is used to transport components or material. Usually rapid upward motion is desired. This paper presents the results of an investigation on the performance of a vibratory conveyor excited by two in-phase non-sinusoidal displacement cycles composed of the first two harmonics along the trough and perpendicular to it. Mean conveying velocity is found to be considerably larger than that of conventional vibratory conveyers if the proper amplitudes of the second harmonics are chosen.