bluuebunny/crossref_metadata_2025 huggingface dataset:
Turbulent Flow and Heat Transfer in the Entrance Region of a Parallel Wall Passage
Authors: Byrne J. , Hatton A. P. , Marriott P. G.
Published: October 2007

Measurements of boundary layer development and heat transfer were made in the entrance region of a parallel passage and compared with a computer solution based on the law of the wall. Little difference was found between the heat transfer, both measured and predicted, with a developing flow and that predicted with a fully developed flow. The experiments also show that boundary layer parameters, such as momentum thickness, do not approach their fully developed values asymptotically.
Tribology Problems in Process Industries
Authors: Summers-Smith D.
Published: October 2007

It is considered that the majority of problems in the field of tribology that are currently responsible for operating difficulties and loss of production in the process industries arise through lack of application of existing experience or the results of research, rather than in limitations of fundamental understanding. This suggests a need for determining limits of commercial reliability based on experience. This paper attempts to define such limits, mainly as a stimulus to discussion, not only of the actual values themselves, but also how such values can be obtained, the limits refined and better guidance given to manufacturer and user alike.
First Paper: The Effect of Heat Treatment on the Ductility of Alloy Steel Wires in a Cold Heading Process
Authors: Thomason P. F.
Published: October 2007

Longitudinal grooves of various depths ranging from 0.001 in to 0.011 in were machined on the cylindrical surface of steel slugs prior to carrying out an automatic two-stage transfer heading operation. The longitudinal grooves were used to estimate the ‘critical groove depth’, which was defined as the depth of longitudinal groove that contained a ductile fracture crack just on the point of ‘opening out’ at the end of the heading process, thus giving a measure of the ductility of the wire.

A half-replicate of a two-level factorial experiment was carried out to assess the effects and interactions of annealing temperature, annealing time, cooling rate and ageing temperature on the ductility of four different types of 1/2 in diameter cold heading steel wire.

The results show that certain types of steel wires have optimum ductility in the ‘as-received’, cold-drawn, state. Other types of steel are shown to respond favourably to process annealing treatments, in which case annealing at 700°C for 1 hour followed by air cooling should give optimum ductility. It is shown that there is no general correlation between decreasing hardness and increasing ductility for steel wire.
Third Paper: A Theoretical Estimate of the Limits of Ductility in the Free Extrusion Process
Authors: Thomason P. F.
Published: October 2007

The paper presents a theoretical method of estimating the limits of ductile flow in metal forming operations. The method is applied in detail to the problems of ‘arrowhead’ and ‘fir-tree’ cracking in the free forward extrusion of a bar through conical dies.

An approximate method is introduced for integrating the equations of equilibrium along the axisymmetric slip lines in the plastic deformation zone. The results give estimates of the mean extrusion pressures and the bulge limits which compare well with experiments and thus suggest that the theoretical internal stresses will be close to the true internal stresses in free extrusion. The theoretical internal stresses are used, together with the theoretical strains to fracture from the instability theory of fracture, to predict the conditions of die and specimen geometry which lead to internal cracking. The theoretical fracture limits are found to be in close agreement with experimental results.
Experiences of the Italian State Railways with Diesel Shunting Locomotives Using Hydrostatic Transmissions
Authors: Camposano P. , Brandani V.
Published: October 2007

The Italian State Railways (F.S.) have in service 150 two-and three-axle diesel shunting locomotives equipped with hydrostatic transmission, powered at rates from 150 to 450 hp.

In these locomotives some operating characteristics give better performance than locomotives equipped with hydrodynamic transmissions, specifically: easy running reversibility; high flexibility factor which allows elimination of the slow-fast running gears and simplicity of installation.

Other theoretical advantages of hydrostatic transmission were found to be unimportant in practice, for example: initial loss of power due to the transmission increases remarkably with service and the braking action is limited by the overrunning of the diesel engine.

Disadvantages of the hydrostatic transmissions in service are: the ‘rigid’ connection between the engine and the axles and the absence of ‘coasting’; the maintenance costs of the transmission increase more than linearly with power ratio.

In conclusion, the experience of the F.S. with hydrostatic transmission units shows that this type of transmission can be competitive in the field of diesel power of less than 150 kW.
The Response of a High-Pressure Pneumatic Servomechanism to Step and Sinewave Inputs
Authors: Botting L. R. , Eynon G. T. , Foster K.
Published: October 2007

Linearized analysis is used to design the feedback networks of a high-pressure pneumatic servomechanism in order to meet a performance specification. The effect of torque motor dynamics is pointed out and then digital computation of the complete non-linear equations is used to predict the effect of the following important parameters: saturation, inertia load, stiction and coulomb friction, valve laps and leakage. Others considered briefly are: velocity feedback limiting, position error limiting, the use of a cascade lead network to improve the torque motor response and the effect of different inlet to exhaust port width ratios.

The equations are non-dimensionalized, a load factor α being first defined which is the equivalent of a parameter found to be useful in hydraulic servo design. A saturation ratio is later defined which includes α, and quantifies the ratio of electrical pneumatic gain.

The major part of the results are for step inputs, but the generally poor shape of the response to sinusoidal inputs is examined in some detail. Experiments were conducted to check the validity of the equations, and it is shown that high loop gains can be achieved with adequate stability. It is also shown that the sinewave response can be improved by the correct design of the shaping networks and by a suitable choice of α.
Design and Commissioning of the Boilers for the Oldbury Nuclear Power Station
Authors: Whitehouse P. R.
Published: October 2007

This paper describes design features, pre-commissioning tests and commissioning experience on the boiler plant of the 600 MW(e) Oldbury nuclear power station.
A General Theory of Composite Gear Trains
Authors: Sanger D. J. , White G.
Published: October 2007

Some basic gear arrangements which use a minimum number of gears are noted; the gear pairs in these composite gear trains are seen to be interdependent.

A general and widely applicable method of gear train analysis is developed. Expressions and index numbers are deduced which define optimum designs and the gear sizes for optimum or other design points. The analysis is extended to include gears external to the composite gear sections, so providing a unified theory which covers all known and feasible minimum-gear arrangements based on three shafts. An example of application is included.
First Paper: An Investigation into the Steady-State Characteristics of Plain Slideways
Authors: Bell R. , Burdekin M.
Published: October 2007

This paper describes steady-state friction tests on a scraped-cup ground combination of cast iron surfaces. The experimental conditions were representative of the operating conditions on a machine tool feed drive employing plain slideways.

The range of the relative sliding velocity investigated was 0 → 1 in s-1, and the influence of lubricant viscosity of both polar and non-polar additive lubricants is shown. An investigation into the effect of oil grooves is also reported.

Data obtained from squeeze film measurements enabled the characteristics, normal to the sliding plane, to be specified. These characteristics, together with measurements of the separation of the surfaces, enabled the steady-state friction characteristics to be predicted over the range of mixed and hydrodynamic lubrication covered by the tests. This work formed a basis for the investigation into the mechanism of the friction characteristics under dynamic conditions.
Second Paper: An Investigation into the Mechanism of the Frictional Damping of Machine Tool Slideways
Authors: Bell R. , Burdekin M.
Published: October 2007

The damping action of a plain slideway is considerably influenced by a number of parameters and is difficult to assess. It has been necessary, therefore, to obtain experimental data from adequately scaled experiments. The major emphasis is placed on the influence of polar additive lubricants as they offer considerable advantages in stabilizing feed drives at low feed speeds. This paper describes an investigation into the mechanism of the interaction between vibration in the direction of motion and the vibration normal to the plane of the slideway interface. Steady-state characteristics do not give an adequate guide to the damping action of a machine tool slideway. All the work discussed in this paper is restricted to vibration amplitudes that do not cause the instantaneous velocity of the feed drive to be reversed.
First Paper: Performance Characteristics of Petro-Forge MK I and MK II Machines
Authors: Chan L. T. , Tobias S. A.
Published: October 2007

Petro-Forge is the name given to a high energy-rate forming machine actuated by the combustion of hydrocarbon fuel and air mixtures. The feasibility of this kind of device, which has been demonstrated with a prototype machine, was discussed in a previous publication (1). Based on the experience gained, several models have been developed. This paper describes the design, development and control aspects of the Mk I and Mk II machines. In particular, the procedure for devising the optimum control programme and experimental work aiming at the determination of the performance characteristics will be discussed, leading to the experimental and analytical determination of a calibration chart which relates energy output with performance parameters and stroke. The specific performances of the two machines are also compared.
The Italian Heavy Mechanical Engineering Industry
Authors: Gamucci Pier Giovanni
Published: October 2007

This paper is divided into two parts. The first deals with the Italian heavy mechanical engineering industry in general. It contains a brief history of the industry from the nineteenth century to the present day and then considers three important factors at present affecting the industry: technological progress; the growth of labour-training facilities as the number of men employed increases; the increase in size of companies.

The second part deals in some detail with the following sectors of the industry: power-generating machines; thermal power-generating equipment for industrial applications; machine tools; pumps and compressors; lifting and handling equipment. In all these sectors significant progress has been made.
Topical Problems with Rolling Stock on the Italian State Railways
Authors: Ricco N.
Published: October 2007

This paper describes the requirements of a modern railway transport system and shows how they may be met under the headings: motive power: braking; comfort; safety. Motive power: for really high speeds a locomotive is not suitable. The alternatives are discussed. Braking: friction braking alone is not enough at really high speeds. Rheostatic or regenerative braking must also be used. Comfort: the physical and psychological factors involved are discussed in some detail and the O.R.E. and Sperling methods of estimating comfort are mentioned. It is shown that attention to both track and vehicle is necessary for comfort at high speed. Methods of suspension used in France, U.S.A., Germany, Great Britain, and Italy are compared. Safety: improvements in signalling and electronic control are essential. The paper concludes with a description of new trains now coming into use or being designed for the Italian State Railways.
Technological Forecasting
Authors: Armytage W. H. G.
Published: October 2007

In this lecture, the author of Yesterday's Tomorrows looks at the roots and present efflorescence of technological forecasting and offers a few observations on its relevances rather than its excesses. He sees it as part of the rising anticipatory temper of modern society. This temper is reflected in most fields of social policy where forecasts, such as those on numbers in universities, for example, need reinforcement from sophisticated estimates as to the ways in which society might develop. This itself has a technological core and it is with this that the lecture is concerned.
Developments in High-Speed Marine Craft
Authors: Silverleaf A.
Published: October 2007

Ways of travelling fast and comfortably over water have interested inventors and designers for many years. Recently, impressive and significant developments have led to three relatively unconventional types of highspeed marine craft large enough to serve practical commercial or naval purposes, while some conventional large ships now also have high service speeds.

The development of hovercraft, hydrofoil ships and high-speed displacement or planing craft is reviewed in the first section of the lecture, and criteria for assessing the performance of these different types in calm water and in typical service conditions are examined and compared.

The purposes for which high-speed marine craft are needed are discussed; these can be divided into passenger and cargo services on short sea ferry routes, container and similar cargo services on longer open water and ocean routes, and special tasks for which high speed, sometimes linked to amphibious capability, can significantly increase effectiveness.

Finally, the likely role of high-speed craft in future marine transport and other systems is considered.
The Development of an Electronically Controlled Petrol Injection System
Authors: Croft B. H.
Published: October 2007

The requirements of the modern automotive petrol engine in relation to higher specific power outputs while retaining good driveability and satisfying the impending exhaust emission control regulations, motivated an investigation into the potential of petrol injection.

Consideration of the control requirements and accuracy necessary led, at an early stage, to the selection of electronic control on the basis of control capability, long term reliability, relatively low cost and the potential for future development.

The fuel system was designed round the electronic control, manifold injection being used instead of direct injection on the basis of simplicity, lower cost and greater installation flexibility.

The original system concept has changed only in detail, development effort being applied to the refinement of the system components to achieve a high standard of performance and the facility to apply the system with minimal modification to a wide range of engine types.

The system is described in some detail and typical examples of the system performance on vehicles are presented.
Disc Brake Pad Wear Evaluation
Authors: Moore M. W. , Watton B.
Published: October 2007

An instrument is described that provides an economical means by which normal motoring on public highways can be used to obtain reliable and relevant brake lining wear rate assessments, thus eliminating the need for the conventional artificial, repetitive, test.

The development and final form of the instrument is detailed and its employment to monitor the brake usage, to provide a means of obviating abnormalities and to detect changes in the wear rate of material, is explained. Formulae are derived showing how the wear accumulated during any journey may be related to the mean brake temperature and the distance travelled and graphs are used to demonstrate how the range of application of the instrument accommodates driver changes.
Designing Warships for a Cost-Effective Life
Authors: Raper R. G.
Published: October 2007

In the past the effectiveness of a ship was measured in terms of her weapon performance, speed and cruising range. Today more attention is paid to availability, in terms of the percentage of her total life for which the ship and all her systems are ready for operations.

The lecture outlines the design of modern warships from the basic concept, its justification in terms of cost-effectiveness, the system of modelling costs to indicate the effect on the overall cost of adding or subtracting a weapons system, the development of the design and specification to a point at which the contract can be placed, and the reduction of upkeep costs and crew numbers.

Machinery and equipment are being standardized for different classes of ships and the intervals between docking and refit periods will eventually be doubled. Health monitoring of machinery is being investigated as a means of reducing maintenance and increasing reliability. The effect of considering life costs as a percentage of the total spent on procurement, upkeep, modernization, etc, is discussed and the additional work now required during the design process to detail the whole of the upkeep task is outlined. Research and development on materials and corrosion problems are affected by the new thinking.
Onload Cleaning of Steam Turbine Blading
Authors: Keogh F. G.
Published: October 2007

The paper describes how, by programmed reduction of steam pressures and temperatures, the saturation point in the blade system of a steam turbine may be moved towards the inlet end, thus progressively washing off soluble blade deposits.

The condition of steam wetness, produced in the blades, results from the heat drop and it is pointed out that having the machine on load is an essential part of the process. The effects of pressure and temperature variations on turbine expansion and vibrations are also considered.

The effect of varying pressure on the boiler brings to light the important fact that this is the more sensitive element in the unit and the drum conditions will limit the process rate.

The result of washing is to present the turbine and boiler in the optimum condition for maintenance. The saving in cooling time is considerable, barring time on a 60 MW turbine is reduced by 50 h and the boiler may be cooled and emptied of water overnight.
A Review of Liquid Cooling of High-Temperature Gas-Turbine Rotor Blades
Authors: Bayley F. J. , Martin B. W.
Published: October 2007

This paper reviews post-war progress in evaluating the heat transfer performance of the single-phase and evaporative systems proposed for liquid-cooling gas turbine rotor blades. Laboratory investigations of the heat transfer processes are considered in detail, particular attention being given to the open and closed thermosyphon systems of cooling. Where relevant investigations of experimental turbines have been reported these are considered also but it is in this area—the practical application of liquid cooling—that the principal gaps in knowledge lie.
Extrapolation of Creep Strain and Rupture Properties of 1/2 per Cent Cr, 1/2 per Cent Mo, 1/4 per Cent V Pipe Steel
Authors: Cummings W. M. , King R. H.
Published: October 2007

Both 1 per cent total plastic strain data and rupture data of up to 21 000 h duration are presented for 1/2 per cent Cr, 1/2 per cent Mo, 1/4 per cent V pipe steel. Four parametric methods commonly used for extrapolation purposes are assessed for their accuracy of prediction within the time covered by the present experimental data. The Manson-Haferd parameter, which emerged as the most satisfactory of the four, is used as the basis for the long-time estimates of material properties.

Based on the full 1 per cent strain and rupture data, 10 000, 30 000 and 100 000 h predictions are compared with the current British Steelmakers' Creep Committee recommendations.

The tendency of both the Larson-Miller and Orr-Sherby-Dorn parameters to provide optimistic estimates at longer times is again demonstrated, and while the Manson Generalized parameter fits the data excellently within the experimental range, it is shown that care is required in selecting values of parametric constants if instability is to be avoided.

To meet the increasing need for long-time creep strain data, each individual creep curve is represented by a creep strain/time relationship.
Wind Effects on Structures
Authors: Scruton C.
Published: October 2007

After several spectacular collapses caused by wind, there has been increased interest in the accurate prediction of the wind loading to which buildings and structures are subjected. The reliability of these design wind loads depends to a very large extent on the accurate prediction of the most severe wind conditions to be experienced for many years into the future, and on the accuracy of the wind force and pressure coefficients applicable to the structure. Many factors influence these coefficients and hitherto many of these factors have not been reproduced in measurements on models in wind tunnels, so much of the existing data is of uncertain reliability.

For many structures it is sufficient to regard the wind as causing static loadings and for this purpose to use time-averaged wind forces. However, the advent of modern design and fabrication of structures has rendered them more prone to respond to the dynamic action of wind. Increasing attention is therefore being given to the time-dependency of the wind forces resulting either from the fluctuations of speed caused by the turbulence of natural wind, or from some form of aerodynamic instability arising from the interaction of the structure with the airstream. The calculation of the dynamic response to turbulent winds involves the application of statistical theories to calculate the maximum amplitude of the response (stress or displacement) and the frequency of its occurrence, coupled with the concept of an acceptable degree of risk that the structure will not fulfil its functional requirements during its lifetime.
Third Paper: The Behaviour of Lubricated Steel Balls under Close-Conformity Aero-Engine Mainshaft Ball Race Conditions
Authors: Haines D. J.
Published: October 2007

The behaviour of individual ball to track contact areas is studied in close conformity oil lubricated conditions. Although primarily concerned with aero-engine operating conditions the results are expressed in dimension-less forms which permit use over a wide field of ball race geometries.

An arbitrary boundary is established, based upon electrical conductance through the oil film, between running conditions which produce minimal wear damage and conditions which are probably unacceptable from this point of view. The major purpose of the paper is to focus attention on this criterion and to relate ball to track kinematic situations to it.
Design of Large Diesels for Operational Reliability
Authors: Bertodo R.
Published: October 2007

This paper considers the conventional approach to the design of large diesel engines, based, as it generally is, on experimental validation by limited engine and/or rig running. It is concluded that to ensure the attainment of a specific degree of reliability the extent of testing required would be economically prohibitive. Consequently, the amount of testing undertaken is largely irrelevant and the failure rates to be expected in service are a matter for intuitive judgement and good fortune.

An attempt is made to establish more realistic design criteria for engines manufactured in small batches and designed to remain operational for long periods of time (15-20 years, typically) with infrequent major overhauls (say, every 20 000 h). It is shown that for structural integrity this may be achieved if the criterion [Formula: see text] is met, where [Formula: see text] is the mean strength derived from ideal specimens, [Formula: see text] is the mean load obtained from a consideration of the engine manufacturing and operational tolerances, f is a factor taking into consideration deterministic errors in [Formula: see text] and [Formula: see text], and r is a statistical risk factor characteristic of the component and application. Typical values for f and r are derived for a medium speed diesel and the detailed application to a typical critical engine component described.

The economic implications of design on the basis of failure rate, rather than arbitrarily chosen safety factors, are discussed in terms of design economy and better understanding of the factors likely to influence service reliability.
A Laboratory Pneumatic Tyre Testing Rig
Authors: Phillips B. D. A.
Published: October 2007

The author describes a tyre testing rig which has recently been designed and constructed at the Lanchester Polytechnic, Coventry. The rig measures the six force and moment components acting in the contact patch of a tyre rolling slowly on a flat continuous surface for a wide range of slip angles, camber angles, tyre pressures and wheel loads.

Either driving or braking torques can be applied to the wheel axle and both the slip angle and the lateral displacement of the wheel can be varied sinusoidally or instantaneously in order to investigate the frequency responses and step responses of tyres.
The Contact of Two Nominally Flat Rough Surfaces
Authors: Greenwood J. A. , Tripp J. H.
Published: October 2007

Most models of surface contact consider the surface roughness to be on one of the contacting surfaces only. The authors give a general theory of contact between two rough plane surfaces. They show that the important results of the previous models are unaffected: in particular, the load and the area of contact remain almost proportional, independently of the detailed mechanical and geometrical properties of the asperities. Further, a single-rough-surface model can always be found which will predict the same laws as a given two-rough-surface model, although the required model may be unrealistic. It does not seem possible to deduce the asperity shape or deformation mode from the load-compliance curve.
The Influence of Surface Roughness on the Capacitive Measurement of Film Thickness in Elastohydrodynamic Contacts
Authors: ten Napel W. E. , Bosma R.
Published: October 2007

Measurements of oil film thickness according to the capacitive method as carried out on a disc machine with discs having a surface roughness of 10 μin c.l.a. showed marked deviations from the theoretical values predicted by Dowson and Higginson (1)†, especially in the region of small film thickness, i.e. smaller than 0–6 μm (23·6 [μin).

In this paper the authors show that surface roughness is the cause of this discrepancy.
Transient Torque of Steam Turbines in Power Systems
Authors: Sheard G. , Evans F. J.
Published: October 2007

Techniques for the calculation of the transient torque of a steam turbine following step and ramp type displacements of throttle valves are developed. The objective is an improvement in steam turbine representation for digital and other studies of electric power systems under disturbed conditions, including transient stability.

The turbine model used as a building block for the transient theory is a length of pipe, representing loop pipe or reheat boiler, followed by a multi-stage turbine. The theory of unsteady flow of compressible fluids is applied to the problem and this, together with throttle, nozzle and steam turbine equations, allows the transient torque to be calculated. A digital computer programme has been developed which could be used as a sub-routine in an overall transient stability programme.

The dominant transient feature is a transport lag and not an exponential time delay, as is commonly assumed. Moreover this transport lag, being associated with the local sonic velocity rather than the steam particle velocity, has a value about one-tenth of the usually assumed exponential time lag in mass-flow.

Methods are indicated for extending the transient response obtained for the above turbine model to multi-cylinder turbines.

The conclusion to be drawn is that, for any fast turbine control or transient condition (on a time-scale of seconds rather than tens of seconds), the conventional assumption of an exponential time constant will be substantially in error. Such fast disturbances will almost certainly have their origins on the power system side.

It is from the power system point of view that this paper is written.
Effect of Specimen Size and Preparation on the Fatigue Strength of a Plain Carbon Steel Tested in Rotating Bending and in Torsion
Authors: Kelly D. A. , Morrison J. L. M.
Published: October 2007

A survey of the literature indicates that, in the presence of a stress gradient, the fatigue strength of large components is generally less than the fatigue limit exhibited by small specimens of similar material. In some cases the ‘size effect’ reported is of alarming proportions. However, a closer examination of the literature and the results of some exploratory tests in rotating bending suggest that the effects observed may not be attributable simply to size but may also be dependent on the final stages of specimen preparation.

An extensive test programme carried out on notch-free 0·32 C steel specimens, ranging in minimum diameter from 0·05 to 05 in in torsion and from 0·05 to 1·6 in in bending, provides results showing four main features. As other workers have found, very small specimens have generally high fatigue limits and as-polished specimens have higher fatigue limits than as-heat-treated specimens. For specimens that were normalized, carefully machined and polished, then stress-relieved and finally lightly repolished, the fatigue strength shows a significant increase as the diameter decreases, the maximum increases being about 15 per cent in torsion and 20 per cent in bending. For specimens finally stress-relieved the size effect, over the ranges from 0·25 in diameter upwards, is negligible.
The Application of Finite Element Techniques to the Analysis of an Automobile Structure: First Paper: Static Analysis of an Automobile Chassis Frame
Authors: Ali R. , Hedges J. L. , Mills B.
Published: October 2007

The finite element technique has been used for the static analysis of a chassis structure. A computer program was developed to predict static deflections under bending and torsion loads. The program is quite general, but its use has been restricted to structures consisting of beam elements only. The effects of shear deflections and tapered beams and manufacturing tolerances of cross sections are also considered. Predictions of static deflections are compared with experimental results.
Second Paper: Stress Analysis of an Automobile Chassis Frame
Authors: Hedges J. L. , Norville C. C. , Gurdogan O.
Published: October 2007

The finite element technique has been used for the stress analysis of a chassis structure. A computer program was developed to predict stress levels under bending and torsion loads. The program is quite general but its use has been restricted to structures consisting of beam elements only. Coarse and refined idealizations of the structure are analysed and the effect of manufacturing tolerances of cross-sections. Predictions of stresses are compared with experimental results.
Third Paper: Dynamic Analysis of an Automobile Chassis Frame
Authors: Ali R. , Hedges J. L. , Mills B.
Published: October 2007

The finite element technique has been used for the prediction of natural frequencies and mode shapes of a chassis structure. The program developed in Paper 1 was extended by adding an inertia matrix. The effects of shear and tapered beams were also considered and predictions of frequencies and mode shapes are compared with experimental results.
Analogue Investigation of the Inertia-Coupled Free-Piston Engine
Authors: Moore A.
Published: October 2007

An engine is described in which a free piston is located inside a cylinder assembly which is also allowed freedom of movement in the axial direction. Power is taken from the unit by coupling the pistons of a hydrostatic pump directly to the cylinder assembly.

The equations of motion for the device are presented in non-dimensional form, and solved with the aid of an analogue computer. Results are presented for an engine of practical dimensions and the inherent ability of the system to torque multiply is confirmed. Estimates of the overall mechanical efficiency are included.
Kinematics of Compound Differential Mechanisms
Authors: Molian S.
Published: October 2007

Rules for the type-synthesis of compound differential mechanisms are derived from the equation relating the angular velocities of the three shafts of a single differential. Compounds incorporating up to three differentials are synthesized and listed, but the method can be used for compounds of any order. The theory is illustrated by applications to bifurcated-power transmissions and to change-speed gearboxes of the Wilson type. It is shown that there are three distinct types of two-speed box and fourteen distinct types of three-speed box.
The Design and Performance of High-Pressure Injectors as Gas Jet Boosters
Authors: Hoggarth M. L.
Published: October 2007

Injectors have a large potential application as jet boosters in gas distribution networks by using the gas from high-pressure supplies to boost the pressure of gas from low-pressure holders to that required by the distribution system.

A theoretical study of the design and performance of injectors for this purpose is described. A one-dimensional theory which takes friction into account is proposed for predicting the performance of injectors with driving pressure ratios up to 14:1. Optimization of the theoretical equations is carried out so that the most suitable dimensions can be chosen for any specified performance. Alternatively, the best operating conditions for a given geometry may be predicted.

Experimental results compared well with predictions from the proposed theory particularly in the region close to the optimum working point. Where deviations did occur these are explained by the excessive recirculation of the driving gas at the inlet to the mixing throat, when operated away from the optimum working point at low injection ratios and high pressure lifts. By moving the driving nozzle closer to the inlet of the throat and dispensing with the inlet cone, marked improvements in performance could be obtained at these off-optimum operating conditions.
The Enhancement of Turbulent Diffusion in a Parallel-Wall Duct
Authors: Betts C. , Hatton A. P.
Published: October 2007

Experiments were carried out on the diffusion of nitr ous oxide from a line source in a turbulent flow in a parallel-wall duct over a range of Reynolds number 104to 105. Eddy diffusivity was derived from the concentration profiles in th e lateral direction, with and without obstructions of various shapes in the centre of the duct. Without obstructions the velocity profiles and friction factors agreed well with previous measurements and, for the central portion where the turbulence appears homogeneous, the turbulent Schmidt number was found to be 0·64. Turbulence enhancement caused by obstructions was mainly dependent on the blockage ratio and the shape of the trailing edge.
City Planning and Engineering: Energy, Communications, and the Environment
Authors: Borg Neville
Published: October 2007

In the U.K. at the present time, city planning and engineering arise almost entirely from the need for redevelopment and renewal. The increasing rate of energy consumption, manifested in various forms of human activity, continually intensifies the use of land and of highways and other means of communication. Some of the power derived from energy consumption is devoted to the production of static structures, some of it to demolition and rebuilding in order to provide highways, some of it in movement and in industrial and commercial production, and an increasing part of it in maintenance. The modern paradox arises from an increasing mass of structures and technical complexity and a shorter economic life.
Knock Limits and Performance of Some Gaseous Fuels in a Supercharged Spark-Ignition Engine
Authors: Annand W. J. D. , Sulaiman S. J.
Published: October 2007

Observations of knock limits, in terms of ignition time for borderline knock, are presented for methane and propane at a range of supercharge conditions up to 9 ***lbf/in2boost, in a spark-ignition engine of 105 mm bore running at speeds of 600 and 920 rev/min, with compression ratios of 7·7/1 and 9·5/1. Associated measurements of output and economy are given. Less extensive observations on a butane fuel, and on methane-propane and propane-butane mixtures, are also included.

From an examination of computed temperature-pressure histories in the unburned portion of the mixture, it is found that the knock limited ignition advance on the propane fuel at chemically-correct mixture can be closely predicted over the full range of operating conditions covered, by the attainment of a certain critical value of a simple parameter.
Transpiration Cooled Turbines
Authors: Bayley F. J. , Turner A. B.
Published: October 2007

This paper lists the steps in the development chain of air cooling for gas turbine components, and represents transpiration cooling as the ultimate method. The three modes of heat transfer involved in transpiration cooling, gas side heat transfer, coolant side heat transfer and interstitial heat transfer, are discussed separately. Finally, consideration is given to the practical problems of transpiration cooling in advanced gas turbines.
Gas Turbines with Heat Exchanger and Water Injection in the Compressed Air
Authors: Gašparović N , Hellemans J. G.
Published: October 2007

Water injection into the compressed air between the compressor and the heat exchanger of a gas turbine plant represents only one of various possible methods of introducing water into a gas turbine cycle. With this process, it is advantageous to inject just sufficient water to produce saturation of the compressed air with water vapour.

Assuming that the same size of heat exchanger is used, the following changes are introduced as compared with a gas turbine cycle without water injection. The efficiency is increased to an extent equivalent to raising the temperature at the turbine inlet by 100 degC. The gain in specific work is still greater. It attains values which can only be achieved with about 140 degC higher temperature at the turbine inlet.

With a normal size of heat exchanger, the water consumption is about 6–8 per cent of the mass flow of air. This rate of consumption is not high enough to introduce any detrimental side effects in the cycle. Special water treatment is not necessary.

The performance of existing designs or installations without a heat exchanger can be improved by adding a heat exchanger and water injection without necessitating any change in pressure ratio.
Engineering Aspects of Tyre Testing
Authors: Turley J. A.
Published: October 2007

The engineering performance expected of tyres is analysed in the context of the machines they fit—saloon cars, racing cars, lorries, earthmoving equipment, aircraft, motor cycles and pedal cycles.

As the performance of vehicles depends on the reaction of their tyres to speed, braking, driving and steering forces, ways of measuring these forces and their effects using sophisticated tyre testing machinery are essential to both tyre and vehicle manufacturers. The tyre testing facilities at Fort Dunlop are described with specific reference to the circulating power machine. This machine enables the study of the effects of both high speed and driving and braking torques on tyres. One of the effects of large torques applied to tyres is the cracking and ‘chunking’ of the tread rubber and evaluation of this is described.

Various measurement techniques are employed and associated calibration methods have been developed which are applicable to many types of test machines.
Some Calculations to Assess the Effect of Spin on the Tractive Capacity of Rolling Contact Drives
Authors: Poon S. Y.
Published: October 2007

The tractive capacity of rolling with superimposed spinning motion in elastohydrodynamic lubrication is analysed on the basis of a simplification, that the contact area can be divided into strips in the direction of rolling and that the total traction carried by the contact can be obtained from the sum of these strips.

For the contact conditions considered here, the slide (or creep) occurs in the rolling direction. It is shown that the traction versus slide relationship for this situation can be constructed from the basic traction data of the lubricant provided by a two-disc machine.

The results can be used to assess the performance of a rolling contact drive design. The analysis also highlights the essential ***rheological properties of a good transmission fluid.
Predictive Validity of Examinations in an Undergraduate Course in Mechanical Engineering
Authors: Piatt R. R.
Published: October 2007

The results obtained by students on an honours degree course in examinations taken at the end of each year of the course are investigated to estimate their value as predictors of performance in comparable examinations taken in the following year of the course. The significance of the predictive value of examination results with reference to their use as occupational qualifications is discussed. It is suggested that the validity of qualifying examinations would be enhanced by a shift of emphasis from assessment of knowledge and techniques of the subjects of study towards assessment of those abilities and factors of personality of the candidates which contribute highly to success in the appropriate occupation.
A Study of the Performance of a Non-Linear Resonant Vibratory Conveyor
Authors: Leckie G. G. , Barr A. D. S.
Published: October 2007

The paper considers the performance of a resonant vibratory conveyor which incorporates a relatively stiff buffer spring in addition to the normal linear spring constraint. This form of non-linear spring characteristic has the advantage over its linear counterpart of being less critical in its requirement for accurate tuning and in providing less performance variation with load. Vibratory conveying with purely horizontal table motion is also possible with such a form of non-linear conveyor, and this could be of application in the transportation of particulate media having a wide range of particle size, in situations where segregation of the particles is undesirable.

Experimental results for a conveyor model transporting a single mass are found to be in good agreement with the performance predicted by analogue and digital computer studies.
Stress-Strain Curves for Oxygen-Free High Conductivity Copper at Shear Strain Rates of up to 103s-1
Authors: Bitans K. , Whitton P. W.
Published: October 2007

Shear stress-shear strain curves for o.f.h.c. copper at room temperature have been obtained at constant shear strain rates in the range 1 to 103s-1, using thin walled tubular specimens in a flywheel type torsion testing machine. Results show that, for a given value of strain, the stress decreases when the rate of strain is increased. Moreover, the elastic portion of the stress-strain curve tends to disappear as the rate of strain is increased. It is postulated that these effects are due to the formation of adiabatic shear bands in the material when the given rate of strain is impressed rapidly enough. A special feature of the design of the testing machine used is the rapid application of the chosen strain rate.
The Effect of Dwell Time on Die Wear in High Speed Hot Forging
Authors: Ali S. M. J. , Rooks B. W. , Tobias S. A.
Published: October 2007

This paper describes an automatic high energy-rate forging system, consisting of a Petro-forge machine linked to an induction furnace with an automatic billet transfer mechanism. The system contains also automatic die lubrication, as well as pyrometric and other safety interlocks, permitting the feeding and forging of hot billets at a rate of one every 5 s. Hot upsetting tests carried out with this automatic forging system, aiming at the determination of the effect of dwell time on die wear, are discussed. Two series of experiments were carried out, with dwell times of 40 and 250 ms respectively. In the shorter dwell time tests, five different die materials were evaluated with the aim of establishing their relative wear resistance. It was found that the higher alloyed die steels offer improved performance over the conventional low alloy steels, ‘good value for money’ being obtained by WEX 779.

An analysis of the dwell time, performed by taking a high speed cine film of the whole forging operation, showed that it consisted of forging, bouncing and after-forging phases. In both the short and the long dwell time tests the forging phase and the bouncing phase were 4 and 30 ms, respectively. However, the after-forge phase was 6 ms for the short dwell time and 216 ms for the long dwell time experiments. During the after-forge phase, the dies, with the upset workpiece between them, are pressed together by a relatively small force and in view of this heat transfer is poor. Nevertheless, the increase of the dwell time has a very large effect on die wear, doubling the rate of wear in some cases, depending on the type of die material used.
Higher Technological Education: The Other Half
Authors: Osborne-Moss J.
Published: October 2007

Early in its life the Council of Engineering Institutions (C.E.I.) set the standard for the academic qualifications of future Chartered Engineers at the level of United Kingdom university degrees in engineering. At that time the Council for National Academic Awards (C.N.A.A.) had not long obtained its charter. In recent years the rapid growth of the numbers of undergraduates on C.N.A.A. courses, i.e. undergraduates outside the university system, has justified the allegation that many members of C.E.I, who believe university degrees provide the only route to a Chartered Engineer status are sadly unaware of the very large advanced further education system.

Polytechnics and colleges of technology wishing to establish C.N.A.A. degree courses have a number of hurdles to surmount: the Department of Education and Science, regional advisory councils and local education authorities are all concerned with the approval of courses. The seeking of support from industry for the industrial training part of a sandwich course, the approval of C.E.I. constituent institutions in respect of exemptions and so on are just a few of the additional obstacles to approval.

Last, but not least, the C.N.A.A. itself will vigorously examine the proposed degree scheme, following this up by a visit in which the college staff, resources, equipment, teaching, philosophies and general environment come under the microscope.
A Simple Technique for Calculating Shakedown Loads in Pressure Vessels
Authors: Macfarlane W. A. , Findlay G. E.
Published: October 2007

A fundamental examination has been made of the post-yield behaviour at discontinuities in pressure vessels with a view to determining shakedown loads. The results of this indicate that a simple graphical construction can be devised whereby such loads are easily determined with only a knowledge of the elastic stresses and a yield criterion; in particular, a ‘five line construction’ method is suggested which can be applied to a wide range of engineering stress problems.

The method is exemplified by a study of shakedown loads for both flush cylinder-sphere and cylinder-cylinder intersections under internal pressure, and the implications of the results in terms of current design philosophies are discussed.
Non-Newtonian Flow and Heat Transfer
Authors: Wilkinson W. L.
Published: October 2007

Various types of non-Newtonian behaviour are reviewed together with examples commonly encountered in industrial situations. The effect of such fluid properties on isothermal laminar flow in simple geometries is considered. Various problems in laminar heat transfer to non-Newtonian fluids are also discussed and the effects of temperature dependent rheological properties and viscous dissipation are considered. The relevance of these simple examples to more complex industrial problems is discussed.