bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulse Converters—A Method of Improving the Performance of the Turbocharged Diesel Engine
Authors: Janota M. S. , Watson N.
Published: October 2007

Today, most turbocharged diesel engines operate on the pulse system. This is most effective on those engines whose exhaust manifolds can connect groups of three cylinders to a turbine entry without scavenging interference, e.g. three-, six-, nine- and twelve-cylinder engines. However, when only two cylinders can be connected to each turbine entry, e.g. four-, eight- and sixteen-cylinder engines, without interference, the system is usually less efficient. This is because the widely fluctuating, partial admission turbine conditions lower the average turbine efficiency. Recently, the pulse converter has been developed to improve the performance of such engines.

A detailed investigation into the operation and application of the pulse converter has been conducted. Test results from three completely different types of engines showed substantial improvements in performance. The dependence of the pulse converter on engine speed and load, the effect of area variations in the pulse converter and the timing of the interfering exhaust pressure waves have been studied. A comparison of theoretically predicted and measured transient pressures (from a model pulse converter fitted to a pulse generator) was made. The theoretical analysis is based on empirical steady-flow loss coefficients and forms a boundary condition for a method of characteristics analysis. Results are compared with those predicted by the simple constant-pressure theory.
Design of Pump Impellers for Optimum Cavitation Performance
Authors: Pearsall I. S.
Published: October 2007

Although there is much empirical information on the cavitation performance of centrifugal and other types of pumps, there is very little theoretical basis for their design. Certainly these empirical data have been used to suggest certain fundamental requirements that produce pumps of good performance, but there is no scientific way of assessing the influence of such variables as blade incidence, blade number or shape of blade or passageway.

A theory is presented for optimizing the geometric parameters to give the best cavitation performance or alternatively to assess the influences of working away from the design. From this, a theoretical method based on cascade data transformed into the radial plane is used for detail design for given cavitation inception conditions. Following on this, a new method has been developed for predicting cavitation performance breakdown, based on linearized potential flow theory.

Comparisons are made between these theoretical predictions and experimental data obtained both at NEL and those quoted in the literature. Agreement is on the whole very good.
Aim Investigation of the Axial Load Carrying Capacity of Cylindrical Roller Bearings
Authors: Taylor C. M.
Published: October 2007

Normally cylindrical roller bearings are employed to transmit purely radial loads. However, depending upon the configuration of lips or flanges on the rings, it is sometimes possible to carry an axial load. In certain applications, an axial load capability is essential. A significant feature in determining the performance of a cylindrical roller bearing under axial loading is the lubrication conditions existing between the lips and rolling elements. The paper describes a study of such conditions. The long-term aim of the work is to provide a basis for the design of cylindrical roller bearings to carry axial loads.
Effects of Suspension Design on the Attitudes of a Car during Braking and Acceleration
Authors: Ellis J. R.
Published: October 2007

Two degrees of freedom models of a car are employed to demonstrate the effects of the suspension derivative ∂ x/∂ z on the pitch and bounce attitudes during braking or accelerating. The work equation is employed to show that brake effort distribution between the axles has a significant effect on the attitudes when anti-dive suspension characteristics are utilized. The steady-state positions in both pitch and bounce are developed for linear systems of typical suspensions that may be either standard or coupled systems. Non-linear systems are considered using simulation techniques. A description of some simulation circuits is contained in an appendix.
Heat Transfer in the Furnaces of Shell Type Boilers
Authors: Gunn D. C.
Published: October 2007

Peak heat fluxes which occur near the oil burner can be predicted by a simple mathematical model to within 12 per cent and thus help to estimate peak metal temperatures. Although peaks of 150 000 Btu/ft2 h can occur in current practice, the metal of the furnace is not at risk provided the waterside is clean. Conversely, the risk is great when even a small amount of scale has built up.
The Influence of Ambient Temperature and Pressure on Compression-Ignition Engine Performance
Authors: Spence P. B. , Williams T. J.
Published: October 2007

The effect of changes in atmospheric pressure and temperature on the performance of a compression-ignition engine without a turbocharger has been investigated. In addition, variations in exhaust smoke and temperature, cylinder peak pressure, coolant heat flow, engine friction and air flow rate were observed. A method has been devised for the prediction of the brake power and fuel consumption of an engine at any pressure and temperature using information obtained at normal atmospheric conditions only. This method has been checked using the results of several investigators. A prediction method for calculating the maximum permissible power output is also suggested in relation to various rating criteria.
Turbocharging the 3 Litre V6 Ford Essex Engine
Authors: Fuchs E. R. R. , Parker K. G. , Lovell B. T. Pritchard
Published: October 2007

Power and torque improvements of 30 per cent and 26 per cent respectively have been produced by turbocharging. A compression ratio of 7·6:1 is employed and petrol of 97 octane number RM is adequate.

An acceptable torque curve has been obtained by the use of a turbine outlet restrictor; the standard intake manifold is retained and the compressor delivers to the standard carburettor. A unique combination of vehicle performance and driveability has resulted and exhaust and intake noise is readily controlled.

Only minor engine component changes are necessary and mechanical reliability presents no problems. Specific fuel consumption is no higher than that of the normally-aspirated version of the engine, and emision of oxides of nitrogen is low.
Fatigue at High Temperature-Prediction and Interpretation
Authors: Coffin L. F.
Published: October 2007

This lecture reviews the significant developments in fatigue over the last twenty years as they pertain to the prediction of life in high-temperature service. Particular attention is given to the interpretation of fatigue test results for both low and high cycle fatigue at room and elevated temperatures. Emphasis is given to such effects as environment, frequency and strain rate, metallurgical factors, wave shape and thermal cycling, and some attempt is made to sort out their relative importance. Applicability of low cycle fatigue information to notch geometries is discussed. Lastly considered is the significance of these several factors to the current state of life prediction as well as to future directions for development of this important topic.
First Paper: An Investigation of the Transient Flows in Tunnel Complexes of the Type Proposed for the Channel Tunnel
Authors: Henson D. A. , Fox J. A.
Published: October 2007

The paper describes a practical method of calculating the aerodynamic effects of trains passing through interconnected tunnel systems so that these can be designed for acceptable pressure pulse levels, air velocities and train drag. The equations of unsteady compressible flow were developed into a form suitable for solving by the Method of Characteristics on a computer. Results obtained were compared with measurements taken on models and in real tunnels and some of the comparisons are shown and discussed.
A New Concept of Truck Transmission Design
Authors: Morrison W. M. M.
Published: October 2007

The object of this paper is to re-assess the existing principles used in the design of synchronized mechanical transmissions from the point of view of synchronizer duty. By a logical approach, when the main emphasis is given to synchronizer duty, a new transmission concept, known as the ‘M’ series, has been evolved, which brings with it some important advantages: saving of weight; faster synchronization, making for greater road safety; less space; lower manufacturing costs.

The theoretical study compares the expected performance with that of a conventional five-speed synchronized transmission under identical conditions. Laboratory and road tests have established the validity of the theoretical appraisal.
New Family of High-Ratio Reduction Gears with Multiple Drive Paths
Authors: White G.
Published: October 2007

A new family of high-efficiency, high-ratio reduction gears is described in which a counter-rotating epicyclic gear distributes power equally between two, three or four parallel drive paths. The mechanisms employ zero stiffness torque-balancing within and external to the epicyclic unit and work within a spectrum of operation bounded by designs having a fixed annulus or a fixed planet carrier.

A theory is developed to investigate the principal design problems associated with reduction ratios, bearing speed, centrifugal loading, bearing life and epicyclic efficiency. A primary application is to high-output torque transmission systems such as those used in helicopters.
Third Paper: Lubricant Development for the Wankel-Type Rotary Engine
Authors: Beavis D. A. , Towle A.
Published: October 2007

A review has been made of the factors which may influence the development of lubricants suitable for the Wankel-type engines.

The lubricant requirements of the Audi-NSU Ro80 engine are discussed in comparison with the performance level of lubricants currently in use with conventional reciprocating piston engines.

In Europe, high-speed pre-ignition has been one of the main causes for concern, but at the other end of the performance scale, cold wear of cast-iron apex seals under ‘stop and go’ driving conditions, created conflicting performance requirements for the lubricant under development.

A compromise lubricant formulation has given complete freedom from pre-ignition and a marked decrease in the ‘cold wear’ rates, whilst maintaining the other desirable properties necessary for satisfactory Wankel-engine performance.
Hydrogen as a Fuel for Vehicle Propulsion
Authors: Varde K. S. , Lucas G. G.
Published: October 2007

This feasibility study of hydrogen as a fuel for future vehicle propulsion considers fuel availability, economics and the storage system. The compatibility of a hydrogen-air engine with possible future requirements is assessed. The rate of formation of nitric oxide, based on the rate kinetics in a hydrogen-air mixture, indicates a higher nitric-oxide concentration in the exhaust gas of a hydrogen engine than in the exhaust gas of an equivalent petrol engine. Methods of reducing the emission levels and the design changes are discussed.
Second Paper: Predicting Nitric Oxide and Carbon Monoxide Concentrations in Spark-Ignition Engines
Authors: Daneshyar H. , Watfa M.
Published: October 2007

Kinetic models, incorporating elementary chemical reactions, are used to predict the concentrations of NO (nitric oxide) and CO (carbon monoxide) in spark-ignition engines during the expansion process. The kinetic equations are*** incorporated in a cycle synthesis computer programme, which can be used to calculate the thermodynamic state and the concentration of a number of species in the burnt gas.

The stability and accuracy of the programme is discussed and the validity of the results is confirmed by comparing the theoretical predictions with experimental results.
Incipient Lift-off in Preloaded Plane Externally-Pressurized Compliant Surface Bearings
Authors: Gupta P. K.
Published: October 2007

The coupled elasticity and hydrodynamic equations are solved for a plane externally-pressurized bearing consisting of an elastic layer bonded to a rigid substrate. Solutions for bearing load support, flow and minimum film thickness are presented for a wide range of bearing geometries and for both compressible and incompressible lubricants. For preloaded bearings, i.e. bearings with interference fits such that the compliant surface is initially indented by the mating surface, a criterion for incipient lift-off is postulated and formulae for calculating the lift-off pressure are derived.
New Look at the Slip in a Centrifugal Impeller
Authors: Yedidiah Sh.
Published: October 2007

Factual evidence is presented here which proves that the slip factor for a given impeller is not constant, but varies with the flow rate.

A schematic model is established that gives a possible explanation to the observed discrepancies between the existing theories and reality.
Measuring the Oscillating Flow from an Electro-Hydraulic Servo-Valve Using an Indirect Method
Authors: Burrows C. R. , Martin D. J.
Published: October 2007

Recently published work concerning the dynamic flow-rate through servo-valves is discussed. It is shown that there is some disagreement amongst workers concerning the effects that fluid inertia and valve discharge coefficients have on the dynamic performance of these devices.

The problem of measuring pulsating flow is discussed and the various commercially available transducers are shown to have shortcomings when used in conjunction with servo-valves. An alternative indirect dynamic flow measurement technique is described.

The technique is evaluated using an analogue model. It is concluded that the method is capable of determining the dynamic volumetric flow-rate. The difficulties involved in identifying the valve dynamics from these measurements are discussed.

The method is applied to determine the volumetric flow-rate in an experimental rig consisting of a servo-valve controlling a rectilinear motor used to position an inertial load.
Characteristics of Externally Pressurized Journal Bearings with Membrane-Type Variable-Flow Restrictors as Compensating Elements
Authors: Ms C. Cusano
Published: October 2007

The characteristics of externally pressurized journal bearings with four recesses and with membrane-type variable-flow restrictors as compensating elements are analytically investigated by using the bearing model of Raimondi and Boyd. The effects of the ratio of the recess pressure at zero eccentricity to the supply pressure (pressure ratio), the eccentricity ratio, the compliance of the membrane and the shaft rotation on the lubricant flow rate, the load capacity and the stiffness of these bearings are presented for a given aspect ratio and inter-recess*** land width-to-diameter ratio. For a non-rotating shaft, it is shown that when the bearing operates at zero eccentricity there is a pressure ratio that gives an optimum bearing stiffness. This pressure ratio is a function of the aspect ratio of the bearing only. Using this pressure ratio, data for the load capacity and stiffness of the bearing are presented for an eccentricity ratio that varies from 0 to 0·1. For these data, the membrane compliances used are those that would give an infinite bearing stiffness if the bearing were operating at zero eccentricity.
Cold Consolidation of Powder by Hydrostatic Extrusion
Authors: Hewitt R. L. , Wallace W. , Demalherbe M. C.
Published: October 2007

The isostatic compaction and hydrostatic extrusion of two atomized powders, namely Alcoa grade 1202 aluminium and Atomet 28 iron, are described and it is shown that the extrusion pressures for these powders may be 50-100 per cent greater than for an equivalent wrought material.

Results of mechanical testing and metallographic and fractographic examinations of the extruded aluminium compacts are presented which show that good bonding can be developed by hydrostatic extrusion at ratios of 6·25 and that the resultant strengths can be higher than that of wrought material of a similar composition. This strength improvement is attributed to the strain hardening undergone by the materials during compaction. An interpretation of the bonding mechanism is also given.

Although it has been shown that isostatic compaction and hydrostatic extrusion can be combined to produce well-bonded bar material from metal powder at room temperature, it is suggested that the method is limited by the very high pressures that would be required to produce materials of commercial interest.
Pitting of Gears and Discs
Authors: Onions R. A. , Archard J. F.
Published: October 2007

Pitting tests using 127 mm (5 in) centres distance gear rig under controlled conditions are described. These are compared with similar disc tests using the same materials and lubricants. Tests of both types confirm Dawson's conclusion that an important factor influencing pitting life is the ratio of surface roughness to the calculated lubricant film thickness. It has been shown that using a hunting tooth ratio, particularly when associated with a rough harder surface and a surface finish oriented normal to the motion, increases the likelihood of wear. Most importantly, the results show that using disc tests can greatly overestimate the pitting life of gears. These experiments and other evidence from the literature suggest that the most probable reason for these differences between gears and discs lies in dynamic gear loads.
Hydrodynamic Entrance-Region Flow of Pseudoplastic Fluids
Authors: Mashelkar R. A.
Published: October 2007

The hydrodynamic entrance-region flow of pseudoplastic liquids is studied by solving both the differential and integral equations of the boundary-layer flow simultaneously by extending the procedure of Fargie and Martin. The results are strictly applicable in the high Reynolds number region only. Simple closed-form expressions for the velocity distribution, pressure distribution and loss coefficients in the entrance section result, which are presented in a form suitable for engineering design. Comparing the predictions of this work with the literature data shows agreement which is comparable to or sometimes even better than the more complicated analyses available in the literature.
Market-Oriented Product Planning
Authors: Karlsson T. G. T.
Published: October 2007

This paper describes how the market research and analysis organization of the Truck Division of the author's company, AB Volvo, provides information as a basis for product policy decisions.
The All-British High-Powered Marine Diesel Engine
Authors: Butler J. F.
Published: October 2007

Over the past quarter of a century, British-designed marine propulsion diesel engines have more than doubled their power output per cylinder. During the same period weight per kilowatt, and engine length per kilowatt, have both been reduced by nearly 75 per cent, specific fuel consumption has been reduced, and reliability has improved.

This progress has been achieved by detail design improvements to even out stresses in components and to reduce temperature differences between hot and cold surfaces, combined with the application of the results of advanced computer methods to air flow, fuel distribution, and separation of rubbing surfaces by oil films.

At the present stage of development the marine diesel engine is in many ways more advanced than the small automotive engine and can also compete in economic power production with prime movers at the opposite end of the scale such as super-large high-pressure steam turbines.
Experimental and Theoretical Investigations into Chimney Emissions
Authors: Moore D. J.
Published: October 2007

The simple ‘conical’ model of plume dispersion from an elevated source of effective height H (m) which indicates that the maximum ground-level concentration Cm (units m-3) is proportional to Q (rate of emission, units s-1) (σZ/ày)/ U (wind speed, ms-1) X H2 assumes that the vertical (σz) and cross-wind (σ y) spreads of plume material are similar functions of distance downwind

For time average values of Cm of duration about 1 h, the length scale of the turbulence responsible for the cross-wind spread is, in general, much greater than that responsible for the vertical spread. This length *** l is restricted either by the depth h of the boundary layer or the height above the ground. In this case (σz /σy) in the expression for Cm must be replaced by (Some representative vertical turbulent velocity * l)/(Some representative cross-wind turbulent velocity X H) ’***

In conditions of strong thermal convection and light winds the turbulent vertical velocities are effectively independent of the wind speed and so the form of the first expression for Cm will change both with wind speed, atmospheric stability and the height of the plume in relation to the top of the boundary layer.

Simple boundary-layer models for ‘convective’ and ‘windy’ conditions are shown to lead to equations for predicting Cm which are similar to those previously shown by the author to give a good representation of the ground-level concentrations in all categories of wind speed and stability observed on 2500 separate occasions in the Tilbury-Northfleet plume rise and dispersion experiment.

The application of these expressions to other locations and sizes of plant is discussed.
Combustion, Knock and Emission Characteristics of a Natural Gas Fuelled Spark Ignition Engine with Particular Reference to Low Intake Temperature Conditions
Authors: Karim G. A. , Ali I. A.
Published: October 2007

For various fuel-air mixtures and different compression ratios, the intake temperature was varied over the entire range of ***200°F (366K) down to − 100°F (200K) when employing a single cylinder spark ignited research engine fuelled with natural gas. Performance data such as knock and ignition limits the nature and extent of exhaust emission and chamber pressure cyclic variation were obtained. Means were then suggested for the interpretation of the above mentioned data in terms of engine operation on liquefied natural gas. The experimental work confirmed in general the attractive features of the use of natural gas as a fuel in a spark ignition engine operated under extremely cold intake temperature conditions and that emissions of pollutants were not significantly increased.
Some Experiences of Fuel Dilution of Lubricating Oils in Small Diesel Engines
Authors: Thornber J. C. P.
Published: October 2007

Fuel dilution of lubricating oils in small diesel engines is normally attributed to fuel leaking past seals, pumping elements or feed pump diaphragms. Some authorities advise that dilution greater than 10 to 15 per cent is inadvisable; others advocate an oil change if the viscosity is more than an S.A.E. grade.

Another possible cause of dilution depends on fuel properties, nozzle design and aspects of air-How into a cylinder. The fuel introduced in this way plays some part in the combustion process and influences engine smoke levels. The dilution so caused is speed and temperature dependant.

The paper describes tests to establish the basic characteristics, the mechanism at work and modifications to minimize this cause of oil dilution. Some tests are included to show that some fractions of fuel that is diluting lubricating oil can evaporate during engine operation; heavier fractions, however, are more likely to persist.
Simulation Model for a Crankcase-Compression Two-Stroke Spark-Ignition Engine Including Intake and Exhaust Systems
Authors: Benson R. S. , Baruah P. C. , Whelan B.
Published: October 2007

A model is presented to simulate the power cycle and gas exchange process in a crankcase-compression two-stroke spark-ignition engine which includes intake and exhaust systems. Chemical equilibrium and a two-zone combustion model with a spherical flame front are assumed for the power cycle and generalized non-steady gas dynamic expressions, including variable composition, variable specific heats, friction and heat transfer, are assumed for the gas exchange process in the intake and exhaust systems. For the scavenge process in the cylinder, a thermal mixing model is used to calculate the pressure changes. Experiments with a small high-speed engine showed that the model gave good predictions of the pressure changes during the gas exchange process and the air flow rate. The power predictions followed the experimental trend, but the quantitative results were not so good as the air flow predictions. Despite the limitations of the power predictions, the method offers the designer a tool for improving the performance of the crankcase-compression engine.
Air Entrainment into Bounded Axisymmetric Sprays
Authors: McQuaid J.
Published: October 2007

The entrainment of air into a conical spray centred on the axis of a short tube is investigated. Dimensional analysis successfully correlates the experimental results of both the present and previous investigations for the case of an unrestricted system. The case where the spray operates against a back pressure, such as might be represented by a length of ducting connected to the outlet, is also considered. Morton's analysis of entrainment into the wake of an isolated body is adapted and some agreement is obtained with experimental results for small flight distance of the drops.
Measuring the Pressure Distribution along the Surfaces of the Blades in a Francis Turbine Runner
Authors: Opelt B. , Khalifa A. H.
Published: October 2007

Measurements were made of the static pressure distribution along the surfaces of the blades of a Francis turbine runner operating near its optimum efficiency and at the extremes of unit speeds where incidences stretched from + 80° to −54°. The paper describes equipment and experimental procedure aimed at accuracy and compares the results against theoretical predictions furnished by computer programmes available at GEC Power Engineering Ltd. The correlation between curves was good in the optimum efficiency region and it was concluded that the mathematical model was a valuable aid to design and development and, subject to some restrictions, could reduce the need for scale models.
Investigations on the Pumping Effect of Rotating Discs
Authors: Barske U. M.
Published: October 2007

The mathematical and experimental work described in this paper were carried out in the pump laboratory of the Rocket Propulsion Establishment (RPE) Westcott in 1955. In 1956 test runs took place with a ‘disc pump’ the impeller of which was described in the author's paper (l)t (Figs 19, 20 and 21)†

The information in the present paper was not made widely available by the RPE, at that time. Since the author's view the treatment used differs widely from that described in later publications (see References in Appendix 3); the results can be readily applied to practical design work.
Injuries to Car Occupants — Theoretical Considerations
Authors: Grime G.
Published: October 2007

A method is described for calculating the percentages of fatal, serious, slight and uninjured occupants in collisions; the first calculations being made for drivers in head-on collisions. The starting points are (1) a diagram giving the probabilities of the four injury levels versus velocity change of the vehicle, and (2) a distribution diagram of the percentages of head-on collisions within successive equal intervals of relative velocity at impact. Calculations of these percentages were made for ratios of the masses of the two vehicles of 1.0 to 9.0, and satisfactory agreement was found with results derived from the national accident statistics. The relevance of the theory to the assessment of the value of safety measures and the determination of human tolerance to impact is discussed.
Studies in a Simulated Job Shop
Authors: Eilon Samuel , Chowdhury I. G.
Published: October 2007

The effectiveness of various scheduling or loading rules in a job shop has been widely studied through simulation, where a given shop can be subjected to alternative patterns of arrivals and processing. This study is particularly concerned with the case when arrivals are in batches, either of regular size or where the batch size is Poisson distributed, and when the batches arrive at regular time intervals, and certain empirical relationships between three loading rules are investigated. Two types of operational flexibility are examined, the first where more than one machine may perform a given operation and the second where changes in the sequence of operations are allowed, and the effect of such flexibilities on the expected job waiting time is determined. Finally, the effect of different procedures for determining due-dates for arriving jobs is investigated.
Development of Corrugations on Surfaces in Rolling Contact
Authors: Johnson K. L. , Gray G. G.
Published: October 2007

The self-generation of corrugations on metal surfaces in rolling contact has been studied experimentally in a rolling contact disc machine and theoretically using a computer simulation. The system vibrates in the ‘contact resonance’ mode excited by surface irregularities. If the damping is low and the load high, the vibration may be severe enough to cause plastic indentation of the surface in one revolution which then amplifies the vibration in the next revolution. A stability map has been produced which indicates the ranges of load, damping and surface roughness for which corrugations would be expected to develop.
Effect of Gas-Side Physical-Property Variations on the Heat Transfer to a Bank of Tubes in Cross-Flow
Authors: Preece R. J. , Lis J. , Hitchcock J. A.
Published: October 2007

The paper describes a study of the effect of variations in the physical properties of a gas caused by large gas-to-wall temperature differences on the convective heat transfer to plain tubes in cross-flow.

The experiments were carried out in air at bulk air-to-wall temperature differences ranging from 109 K to 397 K with two levels of tube-wall temperature, 40°C or 120°C. The bulk Reynolds number ranged from 104 to 2.65 times 104.

It was found that the variation in physical properties could be accommodated by evaluating all of these properties in the dimensionless groups of the conventional type of correlation at the air bulk temperature.
Particle Tribology
Authors: Scott D.
Published: October 2007

Progress in wear prevention can be made only when a better understanding of the mechanisms by which wear occurs and of the controlling factors has been achieved. Much of the research on wear has been directed towards the study of surfaces in relative motion and the changes brought about by their interaction and the lubricant or environment present. Little attention has been paid to the particles generated by the interaction of surfaces in relative motion and thus valuable information has been neglected. Each particle present in a lubricant carries with it the history of the conditions under which it was formed, and thus careful examination of particles can yield specific information concerning the condition of the moving surfaces from which they were produced. Techniques of particle examination are reviewed and the various theories of wear are considered in the light of information obtained by the examination of lubricant contaminant particles. The development of a powerful new technique of machinery condition monitoring by particle tribology to allow a prognostic approach to failure prevention and the safe switch from expensive periodic maintenance to failure prevention maintenance is outlined with examples from the work of NEL. The role of particle tribo-analysis in the development of machinery to ensure a maintenance and failure free life of sufficient duration to adequately cover capital expenditure is discussed.
An Investigation into the Use of a Cone-Jet Sensor for Clearance and Eccentricity Measurement in Turbomachinery
Authors: Hall L. C. , Jones B. E.
Published: October 2007

SYNOPSIS The paper describes experiments which demonstrate the feasibility of using a fluidic cone-jet sensor supplied with air and producing a pressure output to measure mean clearance, eccentricity and rotor speed inside a steam turbine. Mean clearance can be indicated on a bourdon tube pressure gauge whilst eccentricity can be measured using a piezo-electric pressure transducer and phase sensitive detection. Variation in mean clearance from 2mm to 4mm and eccentricity up to 0.37 mm have been shown to provide linear outputs within ± 5% of full scale. There is no significant fall-off in eccentricity signal up to a turbine rotor speed of 6000 rev/min.
Measurement of Coarse Water Distribution in the L.P. Cylinders of Operating Steam Turbines
Authors: Williams G. J. , Lord M. J.
Published: October 2007

SYNOPSIS The development of a ‘catchpot’ probe to measure coarse water flows (formed by deposition and re-entrainment, or agglomeration, of fog droplets) in the low pressure stages of a steam turbine is described. Theoretical considerations and laboratory calibration showed acceptable performance and accuracy limits.

Results taken in three operating turbines at measuring stations situated downstream of the unshrouded penultimate and last row rotors are presented. These results show a peak in the radial distribution of the coarse water flow coinciding with the steam tip leakage region. The measured yaw angles of the coarse water flow agreed with the respective steam yaw angles except near the outer casing. The results are interpreted to give a simple model for the coarse water flows downstream of an unshrouded rotor and its implications for turbine design are discussed.
A Cost Minimization Approach to the Design of Fluid Power Circuits
Authors: Burrows C. R. , Jones N. B. , Shields R.J.
Published: October 2007

A technique is described for selecting the operating: pressure and pipe sizes in fluid power circuits. The method is based upon the formulation and minimization of a cost function which quantifies the capital and running costs of the circuit. (The running costs are broadly defined in order to include the cost penalty due to the weight of the system, as well as the cost of lost power.)

The limitation imposed upon design by the commercial availability of only a limited range of stock sizes of pipe is taken into account to ensure that the design is realizable from stock components.

An example is given which compares the results of a design based upon the cost criterion with a design arising from the use of empirical flow velocities to select pipe sizes.
Some Problems in Diesel Engine Research with Special Reference to Computer Control and Data Acquisition
Authors: Marzouk M. , Watson N.
Published: October 2007

SYNOPSIS A versatile computer-based testing and data acquisition facility developed to improve the speed and accuracy of engine research work is described. The role of computer-aided technology is illustrated through the discussion of two quite separate problems.

Fuel burning rates (heat release diagrams) are the most basic measurement of combustion, yet highly sophisticated equipment and techniques are required to obtain accurate rate diagrams. The problem is illustrated through the derivation of heat release data by analysis of averaged and smoothed cylinder pressure diagrams from naturally aspirated and turbocharged diesel engines. Techniques developed for transducer mounting, choice of sampling interval, data-logging, processing, smoothing, etc. are presented.

During transient conditions (e.g. sudden load chnages) a turbocharged diesel engine moves through operating regimes not normally encountered in steady state operation. Although empirical models have been used to prodict the transient response of these engines, only high-speed data-logging of many engine parameters during a transient will permit the development of more basic models. A fully instrumented turbocharged diesel engine has been run (under computer control) through a series of dynamic tests comprising load and speed demand changes, plus combinations of the two. The use of a computer controlled system allowed transients to be re-enacted with a very high order of accuracy following engine design changes. The high-speed data logging system enabled basic data, such as fuel burning rates, to be obtained for each cycle during the transient.
The Energy Involved in Producing Engineering Materials
Authors: Barnes Robert S.
Published: October 2007

Energy is needed to convert minerals into the basic materials which are used in the engineering industry and then to form them into end products. It is in the conversion that most of the energy is normally consumed, and increases in the costs of energy influence the relative costs of these materials. The energy needed to form the materials into the various end products is normally small in comparison and, even from an energy conservation point of view, it is more important to employ forming methods which use the minimum amount of material than to choose methods which inherently use less energy. The ability to recycle with low energy consumption the material which is discarded during the forming or shaping process is important and improved recycling could have considerable impact upon the overall energy consumption. Whereas the overall energy consumption is important, it is the cost of the raw materials themselves and the total cost of the process to the finished product (offset by any return on waste products) which determines the relative cost of each of the various engineering materials. The united Kingdom energy situation and its effect on the relative positions of these materials is discussed.
The Pad and Quad Resistors - Two New Methods of Fluid Flow Measurements
Authors: Morsi S. A.
Published: October 2007

This paper describes two methods of fluid flow measurements of the differential pressure type. The first method uses a new type of linear resistor in which the flow rate is linearly proportional to the pressure drop. This linear resistor, called a pad-resistor, may be used in a single configuration when the flow rate is limited to small values. For a flowmeter of high capacity and low resistance a multi-pad multi-stage configuration, where several pad-resistors are connected in parallel, has been adopted.

The second method uses a non-linear resistor called a quad-resistor. This type of resistor has a flow characteristic proportional to the fourth order of the pressure drop. By combining the quad-resistor with an orifice, the relationship between the pressure drop and the flow rate becomes approximately linear. The quad-resistor has been used in conjunction with a fluidic analogue amplifier to give a linearized output pressure proportional to the flow rate in a fluid duct.
Heat Transfer Problems in Nuclear Reactor Safety
Authors: Hall W. B.
Published: October 2007

Reactor safety assessment is a highly specialized topic which, in many of its aspects, depends heavily on a satisfactory understanding of a wide variety of heat transfer phenomena. It is the aim of the paper to air some of these problems outside the ranks of the reactor safety specialists. Typical liquid-cooled reactors, their operating characteristics, and some heat transfer aspects of their safety assessment are discussed: for example, transient boiling, quenching of hot surfaces and thermal explosions.
Combined Thermal Engine-Heat Pump Systems for Low-Temperature Heat Generation
Authors: Angelino G. , Ferrari P. , Giglioli G. , Macchi E.
Published: October 2007

SYNOPSIS A system is described for low-temperature heat generation for space heating envisaging the adoption of an organic fluid external combustion engine as the direct drive for a heat pump. Waste heat from the engine condenser contributes a substantial fraction of the overall heat output. Progress in experimental work to ascertain the suitability of organic fluids to operate at comparatively high temperature without appreciable decomposition or corrosive action on materials is reported. Results are given of a computation program predicting the performance of systems of various capacity. For the examples considered yearly fuel consumption was calculated to range between 41 and 48% of that of a conventional plant.
The Use of Velocity Gradient Factor as a Pressure Gradient Parameter
Authors: Brown A. , Martin B.W.
Published: October 2007

SYNOPSIS This paper traces the evolution of the velocity gradient factor as the most appropriate boundary-layer laminarisation criterion as a prelude to examination of its advantages over the original and modified Pohlhausen parameters for laminar boundary-layer situations involving positive and negative pressure gradients. The velocity gradient factor, which involves only directly-measurable quantities, appears a more sensitive indicator of changes in other parameters over a wide range of flow models, including the onset of transition in the presence of significant mainstream turbulence.
The Unsteady Boundary Layer in a Shock Tube
Authors: Deckker B. E. L. , Weekes M. E.
Published: October 2007

SYNOPSIS The unsteady boundary layer behind a moving shock wave in a rectangular duct 7.62 cm wide × 5.08 cm high has been studied using a high quality schlieren system. Growth of the boundary layer has been compared with the results of calculations for laminar and turbulent flows. The experimental results indicate that three dimensional effects are present which cause, in some cases, very early transition from laminar to turbulent flow. Agreement with theory is satisfactory only in the case of the weakest shock wave examined although the trends in growth rates generally conform to theoretical predictions.
Creep Fatigue Interactions in a 1 CrMo V Steel
Authors: Ellison E.G. , Paterson A.J.F.
Published: October 2007

Static and cyclic creep tests have been carried out on a 1 Cr Mo V steel at 565 °C. In addition, the effects of prior high strain fatigue on subsequent creep behaviour has been studied. A well defined ductile/brittle transition was noted which was unaffected by the type of load controlled cycle. The material softened under cyclic plastic strain and no experimental evidence was obtained which indicated that fatigue and creep damage interacted in a load controlled test to give rise to unexpectedly short lives. The conclusion derived is that “softened creep” data should be used in predictions of deformation and rupture behaviour, and that the use of virgin creep data can give rise to substantial errors.
Part 3: Predictions of Deformation and Life under Fatigue/Creep Conditions
Authors: Paterson A. J. F. , Ellison E. G.
Published: October 2007

Predictions of the behaviour of a 1 Cr Mo V steel at 565 °C under cyclic strain plus dwell conditions have been carried out. The strain hardening mechanical equation of state appears to be useful under virgin material conditions but the presence of cyclic softening can cause major errors. Reasonable success was obtained in predicting “softened creep” curves from the virgin creep data and the cyclic stress strain curve. Both strain and time are important in life prediction and a method is proposed which combines the strain range partitioning approach and a modified form of cumulative damage method. Predictions under various combinations of tensile and compressive dwell have been presented.
Component Interactions and their Influence on the Pressure Losses in Internal Flow Systems
Authors: Smith A. I. Ward
Published: October 2007

SYNOPSIS The pressure losses arising from the flow through internal flow systems are usually estimated by subdividing the system into elementary components, assigning a loss to each component, and then summing these individual contributions. This approach can lead to appreciable errors when the components are sufficiently close to one another for interactions to occur. As a contribution to the discussion of this complicated subject, this paper is concerned with the steady, turbulent flow through combinations of bends and diffusers.

Under some circumstances the combined losses of the interacting components are greater than the sum of the individual losses in interference free flow. In other circumstances the reverse is the case. However, as this paper demonstrates, in all cases it is possible to produce sound physical reasons for the variations and, as a consequence, it is possible to generalise the results to interactions involving other components in combination. The paper concludes with a list of broad design principles which have wide application to systems in which interaction effects are important.
The Application of Mechanism Theory to a Textile Machinery Innovation
Authors: Wray G. R.
Published: October 2007

The design of mechanisms for use in practical machinery applications is often of a trial-and-error nature based on traditional practice. Much emphasis has been given to the theory of mechanisms in recent years but this has yet to find wide practical application.

This paper is a case study of how a basic idea, conceived by University-based inventors and intended to improve a slow method of making a textile pile fabric, became a reality in the form of a completely new type of high-speed textile machine for making an improved textile product, all within a time scale of four years.

It also shows how recent University researches are further advancing its potential from both the machinery manufacturing and textile technology aspects.

Step-by-step from the early experimental stages, it illustrates how the challenges of developing the novel mechanisms required for this unconventional machine and process were met by combining practical experience of traditional machinery design with theoretical investigations based on the new techniques of mechanism analysis and synthesis.
Measurement and Prediction of Turbulence and Heat Transfer in the Entrance Region of a Pipe
Authors: Walklate P. , Heikal M. R. F. , Hatton A. P.
Published: October 2007

SYNOPSIS Measurements of turbulence kinetic energy, Reynolds stress, velocity profiles and heat transfer were made in the flow development region of a pipe. Predictions were made using a turbulent energy-dissipation rate two equation turbulence model with different assumed values of the inlet turbulence levels. Good agreement between predictions and measurements was obtained throughout the entrance region.
Structural Analysis of Ladder Frames under Torsion
Authors: Megson T. H. G. , Alade G. A.
Published: October 2007

SYNOPSIS The determination of the torsional stiffness of a ladder frame is investigated and a comparison made between the assumptions of infinite and finite bending stiffness of the members.

A method is proposed for the estimation of the torsion constants of the members of a ladder frame and is shown to give good agreement with measured values. Stress distributions in the cross-members of a ladder frame are also determined.

Finally charts are presented to enable the torsional stiffness and stress distributions to be calculated for ladder frames comprised of channel and I-Section members.
The Rheological Properties of Solid Rail Contaminants and their Effect on Wheel/Rail Adhesion
Authors: Beagley T. M.
Published: October 2007

SYNOPSIS Railwaymen commonly associate low adhesion with slightly wet rails. It is shown that solid railhead debris can cause extremely low values of wheel/rail adhesion when mixed with water or other fluids. The rheological properties of common track contaminants are examined in terms of yield stress and viscosity, concentrating on mixtures of iron oxide and water. The viscosity of these mixtures is found to increase exponentially with increasing solid content. Hydrodynamic equations are then developed to assess whether the train wheel could be lubricated by a limited quantity of viscous lubricant (i.e. railhead contamination). It is concluded that there are two explanations for low adhesion caused by debris. Solid contamination can be both sufficiently strong and pliable enough to support a wheel, yet have a low shear strength. When sufficient viscous contamination is present, however, a train wheel can be hydrodynamically lubricated with the resulting coefficient of adhesion being low.