bluuebunny/crossref_metadata_2025 huggingface dataset:
A Three-Dimensional Simulation for Non-Isothermal Forging of a Steam Turbine Blade by the Thermoviscoplastic Finite Element Method
Authors: Cho J-R , Lee N-K , Yang D-Y
Published: February 2007

The study is concerned with the three-dimensional analysis for non-isothermal forging of a steam turbine blade by the thermoviscoplastic finite element method. The analysis includes deformation of the workpiece and heat transfer of the workpiece and the die. In the transient heat-transfer analysis, the finite element method is adopted for the workpiece, while the boundary element method is adopted for the die.

The non-isothermal analysis is compared with the isothermal analysis as well as with the experimental results. The length of the forged blade increases by 20 per cent as compared to the initial billet, as confirmed by the deformed configuration of both the computation and experiment. The prediction for non-isothermal forging has been shown to be in good agreement with the experimental results from forging load, temperature and geometrical configurations. It has also been shown that consideration of nonisothermal conditions renders a better prediction of forging load.
Closed-Loop Vibration Control of Flexible Rotors—An Experimental Study
Authors: Burrows C R , Keogh P S , Tasaltin R
Published: February 2007

An experimental study has been made for the synchronous vibration control of a rotor-bearing system using a magnetic actuator to supply the control forces. Both open- and closed-loop strategies were implemented using measured displacement signals from various transducer configurations.

Model reduction based on dominant mode methods was used to aid the design of the closed-loop strategies. These were based on pole placement techniques. It was shown that state feedback, without co-location of sensors and actuator, can be used to suppress critical speed responses without encountering spillover problems. The robustness of the strategies was also assessed by deleting selected feedback paths.
Nematic Liquid Crystals as the Working Liquid in Hydrokinetic Devices
Authors: Sokalska D
Published: February 2007

Low-power hydrokinetic devices with nematic liquid crystals as the working liquid are presented. Continuous change of the effective viscosity of the nematic liquid crystals caused by application of the electric field allows for the continuous control of the coupling constant of the hydrokinetic devices.
Operation of a Two-Motor Robot Wrist to Achieve Three-Dimensional Manoeuvres with Minimum Total Rotation
Authors: Stammers C W
Published: February 2007

By use of a friction drive, two motors can be used alternately to reproduce a three-degree-of-freedom wrist manoeuvre. The algorithms required to achieve this are developed. In particular the efficiency of the resolution of the desired rotation is defined and simple approximations are derived for optimum operation, that is for which the total rotation required by the two motors for a given manoeuvre is minimized.

Results are presented of optimum resolution for a wide range of manoeuvres. The time for calculation is also studied. Resolution time is insignificant on a mainframe computer, but for a 286 PC the approximate analysis would have to be used unless the manoeuvres were preprogrammed or a rapid response was not needed, as in a rehabilitation application.
Steady-flow Cf-Nre Correlation for the Wire Gauze Regenerator Inferred from Linear Wave Analysis
Authors: Organ A J
Published: February 2007

Linear wave analysis of unsteady flow in the wire mesh regenerator is extended to account for viscous losses (shear at the wall and abrupt change in the free-flow area). As a test of relevance to the Stirling gas circuit, the standard, unsteady-flow momentum equation is re-expressed in terms of the algebra [admittance ratios, pressure ratios) of the linear wave approach. This permits the steady-flow friction factor, Cf, to be extracted and plotted as a function of Reynolds number, Ntc. The resulting correlation is found to correspond closely to the experimentally determined counterpart. An explanation is found for the discrepancy noted between computed and observed pressure drops in the Stirling cycle machine.
Elastohvdrodvnamic Lubrication of Elliptical Contacts with Pure Spin
Authors: Dowson D , Taylor C M , Xu H
Published: February 2007

In a lubricated, non-conformal conjunction piezoviscous effects associated with the lubricant and elastic distortion of the bounding surfaces can have a significant influence upon the generation of the lubricant film and consequently upon the oil pressure distribution. In many widely studied cases which have been concerned with surface motions of rolling/sliding, it has been shown that these effects enhance the load-generating capability of the oil-film. However, some machine elements experience more complicated bearing surface motions. For example, spinning as well as entraining occurs in the elliptical contact regions of angular contact bearings and some forms of continuously variable speed drives. In this paper, results from a study on the elastohydrodynamic lubrication of elliptical contacts with pure spin are reported. In contrast to the former situation, an unfavourable influence of the surface deflection upon the generation of the fluid film has been observed. Comparison with experimental observation demonstrated encouraging agreement.
Flow Structures and Their Relevance to Passive Scalar Transport in Fume Cupboards
Authors: Özdemir İB , Whitelaw J H , Biçen A F
Published: February 2007

This paper describes an experimental investigation of air flow patterns and related passive scalar transport inside an open-fronted containment facility, with emphasis on the interaction with the laboratory environment. Time-averaged and instantaneous structures of the turbulent flow were examined by visualization and local measurements inside the enclosure and at the front aperture of 1200 mm × 500 mm cross-section. The cabinet was scavenged at an extract flowrate of 0.310 m3/s with 95 per cent of the air passing through the front aperture at a spatially averaged air velocity of 0.5 m/s and 5 per cent supplied through an auxiliary aperture of 1200 mm × 15 mm cross-section located at the front edge of the ceiling of the enclosure. Sulphur hexafluoride was used to mark the flow and the distributions of its time-averaged concentration over the front aperture and inside the cabinet were used to deduce the degree of mixing and passive scalar transport.

The geometrical features of the cabinet provided a flow field with a spanwise vortex at the upper frontal part of the enclosure, whose cross-sectional dimension was larger close to the side walls where the velocity of the inflowing air was lower than in the central region. The spanwise vortex implemented to improve capture efficiency at low inflowing air velocities can be detrimental to the stability of the inflowing air stream along the sash handle, leading to severe leakage of the passive scalar encapsulated within the vortex itself. Without external disturbances, the leakage from the vortex occurs with the periodic bursts generated by the oscillations at the periphery of the spanwise vortex, but these oscillations become more random with the cross-draught. The structure and the orientation of the vortex were vulnerable to external disturbances in that the vortex was tilted and pushed below the sash level on one side, resulting in asymmetrical leakage.
Flow in the Stirling Regenerator Characterized in Terms of Complex Admittance Part 1: Theoretical Development
Authors: Organ A J
Published: February 2007

A wire mesh regenerator is studied, with one end closed and the other subject to a harmonic variation of flow. The methods of linear wave analysis are used to determine acomplex input admittance, Y, for the system. Y is the ratio of volume flow to pressure excess for a given frequency, and permits piston face pressure waveform to be determined directly in terms of prescribed velocity waveform. A computational procedure is developed for finding the pressure waveform at the closed end. Computed waveforms are presented and discussed. Energy dissipated per cycle is calculated.
For the Growth of 3 Inch D-Shaped GaAs Crystals by a Modified Horizontal Bridgman Process
Authors: Hsieh M H , Chieng C C , Lie K H , Guo Y D
Published: February 2007

Doped with silicon or zinc, 3 inch D-shaped GaAs crystals were grown by the modified two-temperature horizontal Bridgman (M2T-HB) technique. Then (1&10) wafers were sliced axially from the chunk of silicon-doped 3 inch GaAs crystals and chemically etched to reveal the growth striations of solid/liquid interfaces. Three-dimensional, numerical simulations of the solidification process for growing 3 inch crystals by the M2T-HB system were performed and compared with the etched (110) wafers from experiments. The heat- and mass-transfer mechanism through the melt is the combination of convection, conduction and radiation. The finite volume approach and the continuum model are employed to determine the position and shape of the interface of the solid/melt, dopant concentration and the temperature field in the crystal and melt. Two methods for computing the dopant concentration are (a) solving the transport equation of full mass concentration and (b) using the simplified model of equilibrium. The computed solidification fronts and the dopant distributions agree successfully with the experimental data, and the axial distribution of dopant concentration as well as flow and temperature fields are computed for information of the crystal quality.
Influence of Local Imperfections on the Collapse Strength of Domed End Closures
Authors: Blachut J , Galletly G D
Published: February 2007

The influence of localized shape imperfections on the elastic buckling of torispheres is discussed in this paper. Perfect and imperfect injection-moulded torispheres were manufactured from ABS plastic and tested under vacuum. The models were made in five batches of thirty and all had the same basic geometry. One series was near-perfect and the other four had single localized increased-radius (‘flat patch’) imperfections in them. The centres of the imperfections were all located 12° from the axis of symmetry and the four series differed only in the size of the imperfection. This specific positioning of the imperfection was influenced by some unusual results which were published recently (1).

The agreement between the experimental results and the numerical predictions, based on the BOSOR 4 and ABAQUS codes, was very good. In particular, the validity of the lower-bound curve of collapse pressure versus size of the imperfection was confirmed experimentally. The predicted buckling strength was also not influenced by the location of the flattening (that is whether on-axis or 12° off-axis) and the numerical results were confirmed by experiment.

A finite element case study of an imperfect hemisphere with an on-axis and a 12° off-axis flat patch was also carried out. Once again, the location of the localized imperfection did not affect the buckling strength of the shell. This finding is at variance with a prediction made recently by other investigators of this problem.
A Systematic Formulation for Dynamics of Flexible Multi-Body Systems Using the Velocity Transformation Technique
Authors: Lee B H , Yoo W S , Kwak B M
Published: February 2007

An efficient and systematic formulation for dynamics of spatial multi-body systems with flexible bodies is presented using the velocity transformation technique. The Cartesian variables are expressed in terms of the relative and elastic variables. Using the resulting kinemtic relationships, the velocity and acceleration transformation equations are derived and used to transform the equations of motion from the Cartesian coordinate space to the relative coordinate space. In order to reduce the number of elastic coordinates, elastic deformations are represented by the vibration normal modes obtained from the finite element analysis. The Euler parameters are used as the rotational coordinates since they are convenient for algebraic manipulation and have no singular condition. The formulation is illustrated by means of two numerical examples.
A Technique for the Calculation of the Location of a Vibration Source
Authors: Shippen J M
Published: February 2007

A study was undertaken to assess the feasibility of identifying the location of a point of excitation acting on an elastic structure based on information obtained from remote transducers. This process was deemed significant as the technique would have applications in identifying machinery in a large, complex plant that was producing spurious forcing conditions, for example out-of-balance or shaft misalignment. A pattern recognition strategy was adopted using the Kohonen network. The Kohonen array was subsequently labelled using both multi-layer perceptrons and Gaussian labelling. The former was found to be computationally inefficient and hence the latter is implemented. It was found that using the system described it is possible to identify a single frequency source of vibration.
Robotic Peg-Hole Insertion Operations using a Six-Component Force Sensor
Authors: Qiao H , Dalay B S , Parkin R M
Published: February 2007

Peg-hole insertion is a widely used industrial robot process. For precise insertion it is common to use force sensors to obtain the deviation between the peg and the hole. In this paper, several examples of six-component force sensors, which are designed to measure the forces and torques in all directions, are reviewed. The problem of how to obtain the deviation between the peg and the hole from the measurement of the forces and the torques exerted on the sensors is then discussed. It is shown that the angle between the peg and the hole and the roughness of the contact surfaces (the end surface of the peg and the surface surrounding the hole) would significantly influence the identification of deviation, no matter how small they are. Two measures to address these phenomena are introduced. A novel strategy of the high-precision chamferless peg-hole insertion with a wrist force sensor is presented and verified experimentally. This strategy is constructed:

to obtain the relationship between the peg and hole from the force sensor signal when angular misalignment and the defects of the contact surfaces are present to reduce the angular and lateral errors and to achieve precise chamferless robotic peg-hole insertion.

In this paper, it is shown that the insertion can be effected with a reasonably large range of initial conditions. The principle is to move and rotate the peg from an area having many geometric uncertainties to a new area, where the deviation of the peg and hole can be obtained.
SUCCA3D—An Alternative Scheme to Reduce False Diffusion in Three-Dimensional Flows
Authors: Scanlon T J , Carey C , Fraser S M
Published: February 2007

An alternative flow-oriented convection algorithm is presented which acts as a replacement for the first-order accurate UPWIND scheme in three-dimensional scalar transport. The scheme, formally titled SUCCA3D (skew upwind corner convection algorithm 3D), attempts to follow local streamlines, thus directly reducing the multi-dimensional false diffusion of the conserved scalar. In a standard benchmark test of pure convection across a three-dimensional cavity the SUCCA3D scheme was found to compare favourably with alternative schemes such as UPWIND and the higher-order QUICK scheme. The results highlight the potential of the SUCCA3D code for the reduction of three-dimensional false diffusion of a scalar variable in convection-dominated flows.
Kinematic Synthesis of RRSS Spatial Motion Generators using Euler Parameters and Quaternion Algebra
Authors: Lee K-W , Yoon Y-S
Published: February 2007

This study proposes a new method using Euler parameters and quaternion algebra for the kinematic synthesis of an RRSS spatial motion generator. The proposed method is compared with the other method using rotation angles for two-position and three-position motion guide problems.

It is found that the proposed method provides solutions better in most cases tested here because the synthesis equations in the method include no trigonometric functions. The solutions converge more easily than in the other method as well as avoiding rotational singularity problems encountered otherwise.
Reducing the Vibrations Caused by a Marine Diesel Generator Set
Authors: Day M J , Randall R J , Ratcliffe C P , Rider E
Published: February 2007

This paper details work undertaken to investigate the use of pneumatically controlled vibration absorbers to reduce the vibrations caused by a G&M/Perkins six-cylinder diesel generator (DG) set. The DG set had a mass of approximately 1 tonne and reductions in vibration levels near the engine mounts of about 10 dB were achieved using four absorbers with a total active mass of 18 kg.

The absorbers incorporated air springs which have the advantage of a variable stiffness depending on the contained air pressure within the springs. The ability to continuously tune to a target frequency was offset by the non-linear stiffness of the air springs, which makes control of the absorbers more complicated. For the work reported in this paper, the absorbers were manually tuned to the desired operating frequencies. Sensitivity trials for absorbers detuned from the optimum frequency are also reported.
Dynamics of Liquid Sloshing in Horizontal Cylindrical Road Containers
Authors: Popov G , Sankar S , Sankar T S , Vatistas G H
Published: February 2007

A study of the liquid behaviour in horizontal cylindrical road containers undergoing a steady turning manoeuvre is presented and discussed. The steady state solutions are derived analytically from the hydrostatic equations. The transient solutions are obtained by numerical integration of the Navier-Stokes, continuity and free-surface equations. The non-dimensional governing equations are solved in primitive variables by using a modified marker-and-cell technique which involves the interpolation-reflection type boundary conditions developed for this investigation. The mathematical model of the liquid motion includes all essential non-linear effects and allows the damped natural frequencies of liquid vibrations to be obtained as well as the magnitudes of the liquid slosh loads. This study also enables the coupled directional dynamics of the ‘vehicle-liquid tank’ system undergoing different road manoeuvres to be investigated by integrating the non-linear fluid slosh model and an appropriate vehicle model simultaneously.
Heat Transfer from Hanging Radiation Panels
Authors: Novak M H
Published: February 2007

This paper deals with energy-saving radiation heating realized by hanging radiation panels. In comparison with the classical convection heating the use of radiation panels limits heat losses by ventilation and significantly saves energy. To express the relationships between the radiation heat flux to the heated space and the basic radiation sheet geometry, a simple mathematical model is proposed and analysed using the small parameter method. To verify the accuracy of the solution the governing equation was also solved numerically and laboratory experiments were conducted. The experimental results agree very well with the analytical solution. For panel design, recommendations are made.
A New Approach to Predicting Annulus Wall Boundary Layers in Axial Compressors
Authors: Dunham J
Published: February 2007

This paper introduces a new phenomenological approach to modelling the end-wall effects. It is based on explicit calculations of the annulus wall boundary layers by Hirsch and de Ruyck's method, with significant changes to allow tip clearance effects to be represented, together with explicit calculations of the secondary flows outside the boundary layers using Marsh's equations. To achieve this, the secondary vorticity is computed throughout the compressor. A new simple model for the tip clearance vorticity is added. It is shown, by comparison with Salvage's cascade measurements and Inoue's isolated rotor measurements at varying tip clearance, that the method is capable of satisfactory predictions of the pitchwise-average local deviation and loss near the end-walls. The model is only accurate, however, when there is no significant end-wall flow separation. Two examples of complete multistage low-speed compressors are given. It is concluded that a promising foundation has been presented for a more satisfactory and more accurate way of predicting the end-wall effects than any published purely empirical scheme.
A Graphical Solution for Compressed Air Flow through a Spool Valve Using Combined Characteristics of Orifices in Series
Authors: Mo J P T
Published: February 2007

This note describes a graphical method for analysing compressed air flow through a spool valve by establishing a set of modified choked flow curves from two intersecting combined choked flow surfaces of the individual flow streams through the valve. The computation using intersection of planes and lines is found to be much easier than the hybrid method used in an earlier flow node model.
Factors Affecting Car Fuel Consumption
Authors: Redsell M , Lucas G G , Ashford N J
Published: February 2007

This paper describes a programme of statistical analyses on test data conducted to investigate the effects of a number of factors on car fuel consumption. The data used for the analyses were obtained from a comparative study of the fuel economy of petrol and diesel cars, conducted at the Department of Transport Technology, Loughborough University, on behalf of the Transport and Road Research Laboratory (TRRL). Three Vauxhall Cavalier cars (1300 cc, 1600 cc petrol and 1600 cc diesel models) and six drivers, categorized by sex and age, participated in the tests. Each test was completed over an extensive test route on public roads encompassing all types of driving environments.

Factor analysis was used to determine the underlying relationships between a number of measured variables and fuel consumption. Under the ‘free-flowing’ environment of the motorway route section, fuel consumption was primarily influenced by ambient pressure, vehicle speed and frequency of gear change. In suburban conditions, only throttle velocity made any significant contribution to fuel consumption. In the tests over urban sections, the significant variables were found to be vehicle speed and deceleration, frequency of gear change and ambient pressure. Of the ambient factors examined, only pressure had any significant independent effect. The associations derived from factor analyses point the way to realistic correction techniques for vehicle test data.

Regression models were constructed to fit the measured fuel consumption data to an expression derived to give fuel consumption as a function of engine, vehicle and environmental parameters. For purely urban, suburban and motorway travel and an overall journey based on a 50/40/10 per cent split of urban, suburban and motorway road types, 93.8, 92.4, 88.2 and 95 per cent of fuel consumption variance was explained by the respective regression models. Regression variables based on engine power correction factors for ambient temperature and humidity showed a degree of statistical significance in all models.
Hybrid Solid State Fluidic Technique in Engine Fuel Injection Systems
Authors: Huang Q , Jones B , Leighton N J
Published: February 2007

This paper describes a multi-point fuel injection system utilizing fiuidic devices as fuel injector stages for spark ignition engines. The novel fuel injector unit consists of no-moving-part fluidic devices controlled by a solenoid valve interface and unique air/fuel mixing nozzles for good fuel atomization.

The results of laboratory tests show that the fluidic device stage has a fast dynamic response and its on/off switching delay to the control flow signal is within 1 ms. A balanced fuel distribution at the four fluidic injector stages (for a four-cylinder engine) and well-atomized air/fuel mixture at the mixing nozzles were obtained from this injection system.

The engine tests show that this fuel injection system provides an extended lean limit of the air/fuel mixture, 7 per cent improvement in fuel economy and 10 per cent reduction in hydrocarbon (HC) emissions compared with a base-line carburetted fuelling system due to the improved fuel distribution and air/fuel mixing quality by the multi-point fluidic injection system.
Methanol as a Fuel for Spark Ignition Engines: A Review and Analysis
Authors: Kowalewicz A
Published: February 2007

A review and analysis of recent literature data on the use of methanol as an alternative fuel for internal combustion engines have been performed. The properties of methanol have been analysed from the point of view of its application to spark ignition (SI) and compression ignition (CI) engines. From this analysis it may be concluded that fewer modifications to the engine are expected when methanol is used in SI engines than in CI engines. Neat methanol is the most suitable, because all the positive properties of methanol as a fuel can be utilized. In the case of SI engines, only minor modifications of the fuel system and/or addition of ignition improver to the fuel are required. Use of methanol-gasoline blends of up to 15 per cent methanol (by volume) and diesel oil-methanol blends of up to 20 per cent methanol require only minor engine modifications. However, miscibility of methanol and conventional fuels is poor; in order to avoid fuel separation, mixtures of these fuels require fuel additives. Methanol engines burn cleaner and more efficiently, but have higher emissions of aldehydes, which increase with increasing mileage of the vehicle. In the presence of an oxidation catalyst unburned methanol can be converted to formaldehyde and simultaneously nitrous oxide to nitrogen dioxide. The advantage of engine fuelling with reformed methanol (CO + H2) is shown. The reasons for better efficiency, performance and less emissions (except of aldehydes) of methanol-fuelled SI engines in comparison with gasoline- and diesel oil-fuelled engines respectively have been analysed. Technical aspects of using methanol as an automotive fuel that have not yet been satisfactorily solved are pointed out. The feasibility of the widespread use of methanol as a transportation fuel for SI engines is discussed from technical, economic and ecological points of view. The need for further research and development work on problems related to methanol as a fuel for SI engines is also discussed.
Automated bumper assembly Using a Vision-Guided Robot
Authors: Davies J L , Gill K F
Published: February 2007

This paper follows the planning, design and operation of an automated assembly system incorporating vision. A full analysis of the performance characteristics of the system is undertaken, with a view to assessing the viability of using a vision-guided robot in a production environment. The results indicate that the assembly accuracy and repeatability are within acceptable limits and that with further development such a system could be used in a production plant.
The Role of the Engineer in the Future European Automotive Industry
Authors: McKnight J
Published: February 2007

After briefly reviewing the progress of the motor industry from its inception, the paper describes how the major markets have changed in response to various pressures in an effort to remain competitive. Suggestions are then made as to how engineers can prepare for the future in a changing market.
The Evolution of Bus Design—a European Perspective
Authors: McKnight J
Published: February 2007

For the 1992 SAE/IMechE exchange lecture, the Chairman of the Automobile Division of the Institution of Mechanical Engineers reviews the background to the major evolutions in bus design in Europe over the past decade or so. This includes a review of the bus and its environment, together with the effect of legislation. An overview of European bus operations is included, with comments on the climate of change within the industry in Great Britain. Trends in bus production levels in Europe are also examined.

Considered in the bus design evolution are: the changing nature of vehicle configurations with a movement towards low floor one-step entry products, changes in engine design to achieve diesel exhaust emission standards and innovations in transmission design yielding benefits in fuel economy and improved foundation brake life. Views are expressed on future design needs, including alternative fuels and vehicle electrics. The progress towards a European bus is reviewed.
The Influence of Automotive Diesel Back End Volatility and New Fuel Additive Technology on Regulated Emissions
Authors: Bertoli C , Del Giacomo N , Caprotti R , Smith A K
Published: February 2007

Public concern over diesel emissions and air quality has provided the focus for testing the effects of changes to diesel fuel back end volatility using test fuels obtained by closely following real refinery practice and new fuel additive technology.

On a typical European city bus engine, the increase in 95 per cent distillation temperature has no overall effects on regulated emissions; conversely, particulate emissions can be controlled by new fuel additive technology.
Finite Element Analysis of Synchronous Belt Tooth Failure
Authors: Dalgarno K W , Day A J , Childs T H C
Published: February 2007

This paper describes a finite element analysis of a synchronous belt tooth under operational loads and conditions with the objective of obtaining a greater understanding of belt failure by tooth root cracking through an examination of the strains within the facing fabric in the belt. The analysis used the ABAQUS finite element program, and was based on a two-dimensional finite element model incorporating a hyperelastic material model for the elastomer compound. Contact between the belt tooth face and the pulley groove was modelled using surface interface elements which allowed only compression and shear forces at the contact surfaces. It is concluded that the critical strains in the facing fabric of the belt, and therefore the belt life, are largely determined by the tangential loading condition on the belt teeth.
A Review of Internal Combustion Engine Losses Part 2: Studies for Global Evaluations
Authors: Ciulli E
Published: February 2007

The global evaluation of losses is important in providing information about the behaviour of an engine. This may be used, for instance, in design and development of new models, where one with inherently the lowest friction may be chosen with a consequent potential gain in fuel economy.

This paper reviews studies on the determination of total engine losses. Experimental works are reported from which, sometimes with theoretical support, empirical formulae are obtained that allow an extension of the results to engines similar to those investigated. Besides formulae in which losses are expressed as an equivalent pressure averaged in the complete cycle, more detailed formulae for the determination of instantaneous loss torques are reported, which are also useful in obtaining a better evaluation of the engine speed trend in fault diagnosis. All formulae can be used in computer programs for the numerical simulation of engine performance, a use that can reduce the time needed for experimental work.
Effect of Reduction of Payload on Stability During Tipping of Granular Materials
Authors: Fessler H , Hyde T H , Sun W
Published: February 2007

Experiments have been carried out with an open-ended box representing the body of a tipping truck during emptying of dry sand while standing on sideways-sloping ground. The mass that had flowed out and the shape of the remaining sand were measured after tilting the box to different inclinations.

After measuring the angle of repose of the sand and making simplifying assumptions, the shape of the remaining payload could be defined using coordinate geometry. Excellent agreement between calculated and measured values allowed the method of calculation to be used confidently to determine the roll-over couples at different sideways slopes and tipping angles when emptying granular materials with different repose angles.

The reductions of the roll-over couples due to allowing for the material that has flowed out are shown to be significant. A simple relationship between maximum roll-over couple, sideways slope and repose angle is established.
The Design and Development of the LotusSport Pursuit Bicycle
Authors: Hill R D
Published: February 2007

Aerodynamic drag constitutes over 96 per cent of the overall resistance to motion for a typical rider and bicycle combination. Although the rider of a typical track pursuit bicycle constitutes approximately two-thirds of the overall aerodynamic drag, the bicycle itself still contributes one-third. Any reduction in the drag generated by the bicycle can therefore have a significant effect on the maximum attainable speed for a given power input, and thus the time to cover a given race distance. At the same time it is important to optimize the riding position so as to minimize both the rider drag and any interference effects between the rider and bicycle.

Cross-wind conditions are also of vital importance to cyclists. For most conventional tubular framed bicycles any wind on a velodrome will result in significantly slower times due to the increased drag. For a properly designed monocoque aero bicycle, however, a cross-wind can mean faster times on a velodrome due to a ‘sail’ effect being generated.

The LotusSport monocoque pursuit cycle has been designed and developed to gain maximum benefit from aerodynamic drag reduction and sail effects. It was produced for, and used at, the 1992 Barcelona Olympic Games where it was ridden to the gold medal in the 4000 metre individual pursuit event.
Analysis of the Effect of Inlet Valve Disablement on Swirl, Combustion and Emissions in a Spark Ignition Engine
Authors: Stone C R , Carden T R , Podmore I
Published: February 2007

A four-valve spark ignition engine combustion system has been tested with normal valve operation and with each inlet valve disabled in turn. A steady flow air rig has been used to establish the flow, barrel swirl and axial swirl characteristics. The combustion performance has been evaluated at five operating points, to determine the effect of the increased swirl with inlet valve disablement. The tests showed that the combustion was faster, with a lower level of cycle-by-cycle variation in combustion; the peak cylinder pressures also rose slightly and occurred closer to top dead centre (TDC). A computer model has been used to investigate the effect of faster burn on the trade-off between engine output, efficiency and nitrogen oxide emissions. It is concluded that a faster burn, with an ignition timing retarded to give the baseline output, should lead to a reduction in nitrogen oxide emissions. This is confirmed by a modelling exercise, which also indicated that using exhaust gas recirculation (EGR) should lead to reductions in both the nitrogen oxide emissions and the part load fuel consumption.
Multi-Valve High-Speed Direct Injection Diesel Engines—the Design Challenge
Authors: Gilbert I P , Heath A R , Johnstone I D
Published: February 2007

The need to increase power, to improve fuel economy and to meet stringent exhaust emissions legislation with a high level of refinement has provided a challenge for the design of a compact high-speed direct injection (HSDI) diesel engine. This paper describes various aspects of cylinder head design with particular consideration of layout and number of valves, valve actuation, port selection strategy, fuel injection systems and cylinder head construction.
Analysis of Combustion in the Cetane-Rating Engine Using High-Speed Photography
Authors: Ladommatos N , Parsi M , McGrath N , Mayne S
Published: February 2007

Modifications have been made to the injection system of the engine used for cetane-rating diesel fuels. These involved the replacement of the standard pintle nozzle with a single-hole orifice-type nozzle. The aim of the modifications was to improve the combustion process and thereby increase the precision of the cetane-rating test. The modifications to the injection system have been assessed using heat release analysis, exhaust emission measurements and high-speed photography of the combustion flames.
Safety and Risk: Models and Reality
Authors: Wolfram J
Published: February 2007

This paper provides a summary of how engineering safety practices have been built up over many centuries by hard-won experience through trial and error. Because engineers design new structures there was no way of deciding whether a structure was safe so methods had to be devised to increase the factor of safety. Today models are used to test for safety and a Code of Practice has been established to set standards. Reliability theory and risk assessment are used to estimate failure rates and prescriptive and goal-setting regulations have been introduced to reduce the risk of accidents. The paper also discusses how the public perceive risk and how training can be given to reduce accidents and improve safety and reliability.
Transverse Vibration of Buried Pipelines Due to Internal Excitation at a Point
Authors: Köpke U G
Published: February 2007

This paper is concerned with the dynamic response of buried pipelines due to excitation located inside the pipe. This work is important for application to techniques that employ vibration to investigate pipeline support conditions using a vibrating pipe inspection device. It also has application to the detection of spanning in off-shore pipelines.

Three different theoretical models are developed and investigated. The first model employs the theory of elasticity, the second is a finite element model and the third is a beam-on-elastic Pasternak foundation. Good agreement between these models is demonstrated. The beam-on-elastic Pasternak foundation model is successfully used to predict ‘signatures’ of the pipe-soil response that characterize soil support features, such as hard and soft supports.
Safety Offshore—Loss Prevention in a Pioneering Industry
Authors: Denton A A
Published: February 2007

The President recalls his early days in a coal mining community which kindled his interest in mechanical engineering, and tells of his subsequent introduction into the nascent offshore oil and gas industry in the early 1960s. His career has been closely linked to the development of devices to drill for and produce oil in harsh environments in all quarters of the globe. Many of the novel ideas that emanated from a pioneering industry were subjected to the author's evaluation and certification, and the more interesting of these are described, together with pointers for future offshore developments. The Piper Alpha accident in the North Sea resulted in the Cullen Inquiry, to which the author presented the evidence of the Institution. Subsequent to this he has examined operating procedures of many offshore organizations and submits his evaluation of the Cullen recommendation and the prospect for safer operations in the future. Finally the President looks at unification and related matters, and offers views on the way forward for the Institution.
Failure of GRP Pipe Bends Under Out-of-Plane Flexure with and Without Pressure
Authors: Kitching R , Myler P
Published: February 2007

Tests to failure have been carried out on six smooth pipe bends constructed by hand lay-up from polyester resin and glass in the form of chopped strand mat. The failure loads under out-of-plane bending only are compared with those where this type of loading is combined with internal pressure. The results are discussed in relation to the design procedure adopted in BS 7159: 1989.
Modelling of Tandem Rolling Mills Including Tensional Stress Propagation
Authors: Kong T , Yang D C H
Published: February 2007

This paper presents an analytical model for dynamic simulation of the tandem mills. The model is a comprehensive one which includes the consideration of elasticity and damping effect at the rolls, plastic deformation at the bite region, stress propagation tensional waves among stands, external scroll force at the back-up rolls and torsional vibration of the work roll. Simulation results show that chatter and other dynamic phenomena can successfully be predicted. It is believed that this model will be useful in the design and control of tandem mills.
Development of Crashworthiness for Railway Vehicle Structures
Authors: Scholes A , Lewis J H
Published: February 2007

British Rail Research has been progressing the development of crashworthiness in rail vehicles over a number of years. Initial work entailed the development of a structural design philosophy which advocated progressive and controlled energy absorption in accidents, the investigation of theoretical methods for analysing large plastic deformations and the static crush testing of vehicle ends. In parallel, a programme of work was set up within the International Union of Railways which resulted in an instrumented collision between vehicles whose cabs had been designed to absorb energy in a predictable way. The lessons gained from these developments are being applied to the investigation of particular accidents and to the production of improved specifications for future BR vehicles.
Servo Actuated Railway Pantograph for High-Speed Running with Constant Contact Force
Authors: Galeotti G , Galanti M , Magrini S , Toni P
Published: February 2007

High-speed running on the Italian railway has been recently developed. One of the main problems to be solved for good high-speed running is the current pick-up with a pantograph from an overhead contact line.

This problem can be solved by biasing, at very high values, the stiffness of the springs acting on pantograph arms. Unfortunately, in this way the pantographs developed up to now, based on previous experience, gave bad results due to excessive contact force (that is, after 2000 km it is necessary to change the worn contact shoe). A simple approach to easily and quickly solve this problem is the use of a servo actuated pantograph able to maintain the contact force at a given value. In this way the main problem to be solved is the right choice of the force actuator kind.

Starting from the existing pantograph the authors show how it should be possible to have an almost constant contact force using an optimized servo actuated pantograph.
High-Speed Current Collection
Authors: Gostling R , Scott G
Published: February 2007

A seminar on ‘High-speed current collection’ was organized by the Railway Division of the Institution of Mechanical Engineers in London on 24 September 1992
Track-Transmission System Dynamic Analysis
Authors: Lu G , Gill K F
Published: February 2007

An analytical investigation of the motor bearing failure of the BB series EMUs vehicle in the FEA Railway was carried out. A track-transmission model with 23 degrees of freedom was developed to enable both linear and nonlinear analysis to be undertaken. The effect of the disturbances from periodic track roughness (corrugation), rail misalignment (dipped rail joint) and motor torque ripple harmonics on drive line dynamic behaviour is thoroughly investigated. The theoretical results obtained, together with information from field and laboratory test, indicate that the 40 Hz resonance within the drive line, induced by inadequate quality track, might be the cause of the bearing failure experienced by the FEA Railway company. As a result of this study, a proposal is made which will ensure a major improvement in the vibrational environment of the transmission system during operation. It is believed that this study contributes toward a better understanding of track-transmission system dynamics.
The Application of Computational Fluid Dynamics to Railway Aerodynamics
Authors: Gaylard A P
Published: February 2007

The growing application of computational fluid dynamics (CFD) to railway aerodynamics is described. After cautioning against overselling the capabilities of CFD codes, a review is presented of the more significant computational work undertaken in this field. Three recent applications of CFD are examined: (a) a high-speed rail vehicle in a cross-wind; (b) cross-flow impingement on a freight vehicle in the Channel Tunnel; (c) the temperature environment in a stationary passenger train. Comparative experimental data are offered for each of the above. An analysis of these applications is used to derive a promising strategy for the practical application of CFD.
Surge Recovery and Compressor Working Line Control using Compressor Exit Mach Number Measurement
Authors: Dadd G J , Porter M J
Published: February 2007

Closed-loop compressor working line controls that act preferentially to suppress surge events offer improvements in both engine performance and simplification of engine fuel systems. This paper outlines aspects of a control strategy, applied to a military turbofan engine, to support these objectives. Compressor exit Mach number feedback was used to maintain steady running lines or limit working points during transients. The control laws used for this are described and engine test results for both low-pressure and high-pressure compression systems are presented which demonstrate effective working point control together with rapid surge detection and recovery.
Hypersonic Propulsion-breaking the Thermal Barrier
Authors: Weidner J P
Published: February 2007

The challenges of hypersonic propulsion impose unique features on the hypersonic vehicle—from large volume requirements to contain cryogenic fuel to airframe-integrated propulsion required to process sufficient quantities of air. Additional challenges exist in the design of the propulsion module that must be capable of efficiently processing air at very high enthalpies, adding and mixing fuel at supersonic speeds and expanding the exhaust products to generate thrust greater than drag. The paper explores the unique challenges of the integrated hypersonic propulsion system, addresses propulsion cycle selection to cope with the severe thermal environment and reviews the direction of propulsion research at hypervelocity speeds.
V-22 Nacelle Conversion Actuator
Authors: White G
Published: February 2007

A design outline is given of the actuator that rotates the engine and rotor nacelles on the V-22 aircraft. The actuator comprises a two-stage telescopic ballscrew that is driven either hydraulically from one end or electrically from the other. Requirements for structural redundancy, least weight, operation after any single failure and performance at low temperatures are shown to influence the choice of actuator configuration and the design of assemblies.
A Comparison of the Corrosion Fatigue Properties of Plate Aluminium Alloys for Aerospace Applications
Authors: Kemp R M J , Wilson R N , Gregson P J
Published: February 2007

A corrosive environment such as salt water can severely degrade the fatigue properties of aluminium alloys used in aerospace applications. The corrosion fatigue crack growth rate properties of two conventional alloys, that is Al-Zn-Mg-Cu-Zr alloy (7010-T7651) and Al-Cu-Mg alloy (2024–T351) have been compared with the more recently developed Al-Li-Cu-Mg alloy (8090-T8771). Increased growth rates were observed in salt water compared to air for 7010 and 8090 but not for 2024. Comparing the three alloys, the 8090 alloy corrosion fatigue rates were similar to those of 2024 which were considerably less than those for 7010. The increase in crack growth in 8090 due to environment was associated with a decrease in the high level of crack closure observed for tests in air. The susceptibility of an alloy to corrosion fatigue can be summarized using a ‘corrosion fatigue resistance’ index, Rcf
Flight Simulation of Military Aircraft Systems
Authors: Perrin J E
Published: February 2007

Manned flight simulation plays a key role in the design and development of modern aircraft systems where pilot interaction is an important consideration. Examples of the systems simulated during an aircraft project include the flight control system, the head-up display, the weapons system and the warnings system. Flight simulation allows the pilot to assess the system operation at an early stage in the design process, and modifications can be quickly implemented so that optimum system operation can be finalized. At British Aerospace (Military Aircraft Division), Warton, three differently configured simulators are currently utilized in the evaluation of aircraft systems.