bluuebunny/crossref_metadata_2025 huggingface dataset:
Third Paper: Comparison of the Behaviour of Different Sheet Materials Formed by the Underwater Spark Discharge Method
Authors: Duncan J. L. , Johnson W.
Published: October 2007

The effect of certain electrical parameters on the forming of flat circular aluminium sheet specimens clamped at their periphery and formed by means of the underwater spark discharge process as described in a previous paper (40) is extended to cover a number of different materials. Experimental observations on the effect of stand-off distance and material thickness on deformation and deflection are included and the speed of movement during the deflection of specimens of different materials is compared. The variation with polar deflection of strain at a particular radius is presented and the nature of the discharge current is also discussed.
Fifth Paper: A Comparison of the Energy Required for Slow Speed and Dynamic Blanking Using an Improved Linear Motor
Authors: Johnson W. , Slater R. A. C.
Published: October 2007

The manner in which the overall energy efficiency of a small linear induction motor, previously used by the authors for impact extrusion, has been increased is described. The improved motor has been used to perform the impact blanking of 1 in and 2 in dia. circular blanks of aluminium, brass, copper, and mild steel in various thicknesses of strip. The energy required to blank when the piercing tool is initially moving at between 9 and 36 ft/s was found to be less than 50 per cent greater than that required for an identical slow-speed operation.
Sixth Paper: Explosive Welding and Cladding: An Introductory Survey and Preliminary Results
Authors: Bahrain A. S. , Grassland B.
Published: October 2007

This paper reviews the published literature on the explosive welding of metals and the related subject of pressure welding. The mechanism of explosive welding is closely associated with that of shaped charges with metal linings, so a brief résumé of the theory of such charges is given. It is also noted that fluid waves are sometimes generated at the weld interface in explosively welded joints, and the mechanism of their generation is discussed.

Experiments are reported on the explosive cladding of mild steel with stainless steel, 70/30 brass, and high-conductivity copper. These have been aimed at establishing the effect of impact angle, weight of charge, and the thickness of the flyer plate on the form of the weld achieved. The mechanical strength of the welded joints has been investigated by shear, tension, and bend tests, and the variation of hardness across the weld interface has also been examined. Results of these various tests are presented and discussed.

It is concluded that explosively cladded material has some advantages over conventionally pressure cladded material. In particular it is probable that the strength of the welded interface is much stronger. With large charges and small angles of impact it is possible for the parent plate to suffer from shock damage which can be clearly seen under a microscope, but it is not known if this is harmful to the mechanical properties. Hardness is increased each side of the interface but a reduced value is measured close to the interface.
A Generalized Analysis of Regenerative Feedheating Trains
Authors: Weir C. D.
Published: October 2007

The basic feature of the paper is the development of the exact characteristic equation for a feedheating train composed of a number of cascaded heater groups in which each heater is taken to be of a rather general type. With the aid of this equation a systematic computational procedure may be devised which permits the variation of the train performance resulting from changes in the heater characteristics to be exactly and easily determined. A differential method, suitable for most practical analyses, and based on a series expansion of the characteristic equation, is also presented in some detail. The relation of the content of the paper to the ultimate objective of estimating variations in cycle heat rate resulting from changes in feedheating train performance is discussed in Appendix III.

Appendix II contains an example of a complete feedheating calculation and compares the results of exact analyses of variations with those obtained by the differential method.
Transmission of Power by Sinusoidal Wave Motion through Hydraulic Oil in a Uniform Pipe
Authors: Foster K. , Parker G. A.
Published: October 2007

An analysis is made of the viscous power losses in a liquid-filled pipe under oscillatory compressible flow conditions, particular attention being paid to Shell Tellus 27 oil in a 7/8 in diameter pipe, 80 ft long.

Using an effective friction coefficient to take into account oscillating flow, the efficiency and the power-carrying capacity of the pipe are calculated for four discrete values of resistive output load. It is shown that if the load is not equal to the characteristic impedance of the pipe, then the efficiency is reduced and the power capacity depends upon the frequency of operation of the pipeline. A mismatched load should be resistive with the pipe preferably tuned to the quarter wavelength frequency supplied from a constant pressure generator. Relative power output increases under these conditions are achieved at the expense of efficiency and increased pipe pressure.

Agreement between theory and experiment for the load conditions considered is good.
Second Paper: The Application of an Analogue Computer to a Problem of Pantograph and Overhead Line Dynamics
Authors: Morris R. B.
Published: October 2007

Conditions of instability are known to occur in railway overhead current collecting systems during the passage of trains at high speeds. They are manifested as oscillations in the vertical plane of such amplitude as to prevent continuous mechanical contact of the static equipment and the moving collector, thereby causing undesirable interruptions in the supply of electric traction current. An introduction and a brief historical survey precede a short study of the methods of theoretical analysis. It is shown that the completely theoretical approach breaks down because of its complexity, and that simulation by means of an electronic analogue is a way of overcoming the complications. The analogues of the overhead equipment and the collector are treated in detail, as is the task of combining the two under the criteria for their interaction. The simulation is still under development but it is possible to give evidence of the method's potential success. A comprehensive list of references gives details of the world-wide sources of present information from full-scale railway systems.
Third Paper: Calculating the Behaviour of an Overhead Catenary System for Railway Electrification
Authors: Andrews H. I.
Published: October 2007

An exploratory investigation into the vertical displacement of catenary contact systems under load, a problem usually regarded as mathematically intractable, has been carried out using relaxation methods. Solutions for typical simple, stitched, and compound catenary systems under static loading are presented and compared. Solutions for the simple catenary system under conditions of dynamic loading are also given for train speeds of 30, 60, and 90 mile/h, and, by treating the problem without including the effect of friction, as yet unknown, it is shown that this factor alone prevents severe oscillation of the system above about 62 mile/h. The method of calculation adopted is intended to serve as a basis for the more rapid solution of such problems by electronic computer.
Series Analysis of a Closed-Loop System Containing a Loaded Hydraulic Relay
Authors: Cook A. E. , Heaps H. S.
Published: October 2007

Analysis is made of a closed-loop system that contains a hydraulic relay. It is shown that the ramp response of a system with an error signal, velocity feed-forward, and velocity feedback, may be expressed as a rapidly convergent infinite series whose terms may each be determined as the response of a linear system in the presence of a forcing function. Inclusion of a small number of terms in the series is sufficient to provide excellent prediction of the error signal. Similar analysis and results are presented for the system subject to a Coulomb load.
Further Experiments with Forged Nozzles in Pressure Vessels
Authors: Kitching R. , Olsen B. E.
Published: October 2007

The investigation was a continuation of previous work involving the measurement of strains in the vicinity of forged rings of the type used to connect cylindrical ducts to large spherical shells. On two such rings of different shape strains were measured for the following loading conditions: internal hydraulic pressure in the vessel; axial loads applied to the nozzles; bending moments applied to the nozzles. Results for these two designs of ring, and two designs previously reported, have been compared.

An approximate method of assessing elastic stresses (in such rings) due to the effect of axial loads and bending moments has been found reasonably reliable as a design method.

A method previously found to give reliable predictions for the effect of internal pressure gave, for the two specimens considered here, lower estimates of maximum stress than the experimental maxima.
Progress in Naval Machinery during the Last Thirty Years
Authors: Hawkins R. S.
Published: October 2007

The problems and aims of Naval engineering have remained remarkably constant during the last 30 years, but requirements dictated by military developments have had an increasing effect not only upon machinery design, but also upon the design of the ship as a whole. The manner and conditions in which our ships must be operated have also changed considerably during this period, calling for additional equipment to make living conditions more tolerable. These changes have required not only the solution of complex design and development problems, but also the development of high standards of manufacture and installation, and the development of efficient organizations for maintenance and spare gear. It is safe to say that the demands made on Naval machinery will become even more exacting, and we can never afford to relax our efforts in striving for perfection in the engineering of our machinery designs.
Ex Opera Et Industria
Authors: Allen H. Norman G.
Published: October 2007

An urgent plea for unity of purpose in engineering thought and action in a rapidly changing world is the underlying theme of this Address. An historical example forms the basis of the reflections and questions posed on the subject.
Studies in Pressure Drop with Lateral Mass Extraction: First Paper: Pressure Gradients for Air Flowing along Porous Tubes with Uniform Extraction at the Walls
Authors: Wallis G. B.
Published: October 2007

Experiments are described in which the pressure drop and pressure gradient were measured for air flowing through porous tubes with uniform extraction at the walls. A simple correlation is derived and is shown to be approximately consistent with the theoretical work of Silver (1)†. The results may be of particular interest to designers of condenser equipment in which pressure changes are important.
Low-Endurance Fatigue Strength of Thick-Walled Cylinders: Development of a Testing Machine and Preliminary Results
Authors: Austin B. A. , Crossland B.
Published: October 2007

Owing to the nature of the stress system in a thick-walled cylinder it is possible to produce fatigue failures in such components after a relatively few repetitions of internal pressure, while still maintaining dimensional stability. This is particularly true for cylinders in which stress raisers are present, a situation of considerable practical importance.

The present paper covers in some detail the design and development of apparatus capable of repeatedly applying to cylinders internal pressures of up to 40 tonf/in2. Results are presented for such tests on plain bored cylinders of two diameter ratios, 1.4 and 1.8, and on cylinders in which radial holes have been drilled, the latter having a diameter ratio of 2.25. The investigation has been confined to a 2 1/2 per cent nickel-chromium-molybdenum steel, with an ultimate tensile strength in the region of 58 tonf/in2; the results are intended to supplement the long life data obtained for this material by other investigators.
Characteristics of a Two-Stroke Opposed-Piston Compression-Ignition Engine Operating at High Boost
Authors: Wallace F. J. , Wright E. J.
Published: October 2007

The paper describes an experimental investigation arising out of theoretical work by one of the authors (1)†, of the thermodynamic performance of a production opposed-piston compression-ignition engine under conditions of very high boost. By operating the engine with substantial internal cooling in the form of excess scavenge air, b.m.e.p.'s of the order of 230 lbf/in2-at a boost pressure ratio of 3/1 were achieved without imposing excessive thermal or mechanical loading on the engine, and at very high brake thermal efficiencies, exceeding 40 per cent in several instances.

The primary independent operating variables were: boost pressure ratio, trapped air/fuel ratio, scavenge ratio, engine speed and simulated compressor efficiency.

Very satisfactory agreement with predicted performance figures was obtained and, in addition, a promising correlation of aggregate heat transfer from the engine cylinders with the above operating variables has been devised.

The investigation is to be regarded as preliminary to a differential compound engine project, based on theoretical performance predictions by one of the authors (2), in which the engine is merely part of a power unit comprising, in addition, compressors, turbines and differential gearing.
High Speed Impact Extrusion of Metals
Authors: Cole B. N. , Davies R. , Austin E. R. , Bakhtar F.
Published: October 2007

The paper describes an investigation of high speed or ‘high energy-rate’ extrusion of cold metal billets. Preliminary trials were carried out with a small pilot machine which, with low explosive drive, could supply up to 430 ft lb per blow at a striking velocity of 132 ft/s. Main trials were subsequently completed using two ‘full-scale’ machines, one explosively driven and the other driven by compressed air, designed to be complementary to each other in such a way that a wide range of energies and striking velocities could be achieved, up to 10 000 ft lb and over 300 ft/s. The metals used were aluminium, copper and mild steel, all in the annealed state. In the main the experience gained was satisfactory and encouraging, and while it was concluded that impact velocities of the order of 50–100 ft/s are feasible, it appeared that the disadvantages of much higher velocities would outweigh the advantages.
A Reassessment of Metering Orifices for Low Reynolds Numbers
Authors: Kastner L. J. , McVeigh J. C.
Published: October 2007

In view of the importance of accurate measurement of flow rate at low Reynolds numbers, there have been numerous attempts to develop metering devices having constant discharge coefficients in the range of pipe Reynolds numbers between about 3000 and 200 and even below this latter value, and some of these attempts have achieved a reasonable degrees of success. Nevertheless, some confusion exists regarding the dimensions and range of utility of certain designs which have been recommended and further information is necessary in order that the situation may be clarified.

The aims of the present investigation, which is believed to be wider in scope than any published in this field in recent years, were to review and correlate existing knowledge and to make an experimental study of the properties of various types of orifice in the low range of Reynolds numbers. Arising from this it was hoped that a design might be evolved which not only had a satisfactorily constant discharge coefficient throughout the range but was also simple to manufacture and reproduce, even for small orifice diameters of the order of 0.5 in or less, and it is believed that some success in attaining this aim was achieved.

The first section of the paper contains a review of previous investigations classified into three main groups. In the second part of the paper, experiments with various types of orifice plate are described and it is shown that a properly proportioned single-bevelled orifice has as good a performance in the low Reynolds number range as that of any of the more complicated shapes.
Fatigue of Thick Cylinders: Further Practical Information
Authors: Parry J. S. C.
Published: October 2007

Work on the fatigue strength of thick cylinders subjected to repeated internal pressure described in earlier papers has been continued. Topics investigated include size effect, the effect of radial and tangential cross-bores, the improvement obtainable by autofrettaging such cylinders and the effect of the surface finish of the bores of the cylinders. The additional materials tested include 13 per cent chromium steel (En 56), 18 per cent nickel-cobalt-molybdenum maraging steel, 1 per cent chromium ball race steel, fully hardened (En 31), beryllium copper and tungsten carbide. Not all these materials could be obtained in a size large enough to make the previously used 1 in bore cylinders and a new head for the fatigue machine was designed to accommodate a variety of cylinder sizes and industrial high pressure components.
Dynamics Analysis of a Nuclear Boiler
Authors: M'Pherson P. K. , Collins G. B. , Guppy C. B. , Sumner A.
Published: October 2007

A dynamics analysis of a nuclear boiler based on a steam-generating, pressure-tube, heavy-water-moderated design is presented. In effect the plant is very similar to a La Mont recirculating cycle. A detailed mathematical model to represent plant dynamics (linearized, full power) is discussed with special reference to the boiling channel, steam drum, and recirculating loop. A simplified model is derived for analogue computer studies. Dynamic performance is discussed in terms of: (1) boiler only (no reactivity feedbacks): influence of pressure feedbacks, steam drum design, subcooling, recirculating delay; (2) complete plant (including reactor): as above but including influence of void coefficient.

The two most important results are: (1) the strong dependence of plant behaviour/stability on the degrees of float allowed to pressure; (2) the possibility of designing an inherently stable and self-regulating plant with a small positive void coefficient.

Finally, conclusions are drawn on the complete dynamic analysis under the heads: (1) optimal plant design; (2) control system design; (3) development of analytical/computing methods; (4) research into two-phase physics.
Flow Theory and Performance of Tangential Fans
Authors: Ilberg H. , Sadeh W. Z.
Published: October 2007

The investigation reported here deals with the conditions of flow through a tangential fan. In order to gain a better understanding of the flow an experimental apparatus for testing the fan was designed. Detailed measurements of velocity and pressure through the impeller interior were carried out. The results indicate that a combined vortex is the main component of the flow, namely, a forced vortex, surrounded by a potential vortex (free vortex). The centre of the combined vortex lies inside the impeller and its location does not change with impeller speed.

A suitable theoretical model of the flow was developed and acceptable correlation was found between it and the measured flow field. It was found that the flow regime through the impeller interior could be controlled and that the location of the combined vortex centre and its strength would be regulated by the shape and location of a diffuser baffle.

A secondary flow perpendicular to the main flow, hitherto not mentioned, was found and an explanation of this phenomenon is offered.

Test results show that the fan efficiency increases with increasing impeller speed in the test range. Previous available works on the subject are reviewed.
Wire-Wool Type Bearing Failures: The Formation of the Wire Wool
Authors: Dawson P. H. , Fidler F.
Published: October 2007

The examination of a number of laboratory induced ‘wire wool’ type bearing failures and service failures has led to the conclusion that the steel slivers forming the wire wool, which are responsible for the often self-propagating nature of these failures, are produced by a process of spinning of the journal surface.
Metering of Steam-Water Two-Phase Flow by Sharp-Edged Orifices
Authors: James Russell
Published: October 2007

This paper describes work conducted on the passage of steam-water mixtures through standard sharp-edged orifices for the prediction of flow conditions.

When the stagnation enthalpy or alternatively the dryness fraction at the orifice is known, it is shown that the mass flow rate can be approximately determined.

For the case where a steam-water mixture passes through a pipeline to the atmosphere or to a low-pressure receiver so that critical flow occurs at the outlet, both the mass flow rate and the stagnation enthalpy may be approximately evaluated using an orifice meter in series with a pressure tapping located at the point of critical flow. In this case, a trial-and-error method is necessary.

The experimental results were within a range of dryness fractions from 1 per cent to 56 per cent, orifice pressures from 75 to 275 lb/in2 abs., differentials from 15 to 780 mmHg under water and flow rates from 54 700 to 508 000 lb/h. Orifices of 5.591 and 6.615 in diameter were installed in 7.9-in diameter pipes which were equipped with radius ( D and D/2) taps.

The method employs a correlation between the homogeneous dryness fraction x, and a corrected dryness fraction x m necessary for evaluating the two-phase density used in the conventional single-phase meter equation.
Experience with Value Analysis as a Working Tool
Authors: Davies H.
Published: October 2007

Value analysis programmes in connection with the large scale production of two packaged liquid rocket engines are described. At the time of writing, costs in the order of $6.73 million had been removed from the total contract price of $70 million.

The fundamentals of the technique, organizational and motivational approaches and working examples are analysed and the implications reviewed. Value analysis is seen to exhibit no undesirable effects on fringe areas such as quality and reliability. It is concluded that a well structured value analysis programme is a most desirable management tool in carrying out the discipline of cost reduction.
An Experimental Investigation of the Non-Steady Flow Characteristics of a Centrifugal Compressor
Authors: Benson R. S. , Whitfield A.
Published: October 2007

The results are given of an experimental investigation of the flow characteristics of a centrifugal compressor under non-steady flow conditions. The compressor delivered air against a rotary valve with a tee branch located in the pipe system between the compressor and the rotary valve. By varying the areas of a nozzle located at the branch end and orifices in the rotary valve a range of flow conditions could be explored. The tests showed that the surge point was displaced to a point of greater mass flow (thus reducing the flow range of the compressor); the magnitude of the displacement depended on the frequency and amplitude of the pressure pulses. Except for small fluctuations in pressure the overall compressor efficiency was reduced for all the test conditions. The flow characteristic of the compressor, as represented by the pressure-mass flow curves, were displaced under all conditions of pulsating flow, the greatest deviation from steady flow characteristics occurring with largest fluctuations in rotary valve area and at low frequencies.
A Slip-Line Field Solution for Machining with Discontinuous Chips
Authors: Ho W. S. , Brewer R. C.
Published: October 2007

The importance of establishing a realistic model of the title problem is stressed, and this is achieved by studying the process experimentally using ciné photography. Development of the discontinuous chip was traced carefully during the whole cycle of its formation and disposal, particular attention being paid to the extent and history of the plastic zone, and subsequent fracture and crack propagation.

It was interesting to observe that for the material considered, namely low carbon steel, the surfaces of the crack and chip were all sensibly straight, and cutting of the next chip began before separation of the one under consideration. It is suggested that discontinuous chip machining could perhaps be used as a method of evaluating strain rate dependencies in fracture mechanics in the same way that continuous chip machining offers possibilities for deriving stress-strain curves at high rates of strain.
Threshold Problems in Electro-Hydraulic Servomotors
Authors: Carrington J. E. , Martin H. R.
Published: October 2007

Apart from development testing and a few extreme conditions, a servo system spends most of its life dealing with small movements. These may be so small as to fall into the region of threshold conditions, where non-linearities become of the same order as command signals. In this paper an attempt is made to bring together some of the known facts associated with this region and the techniques used for improvement. It is hoped that this will stimulate further discussion in this interesting and rewarding topic.
Mechanical Engineering Aspects of Concrete Reactor Pressure Vessels for Oldbury Nuclear Power Station
Authors: Lakin R. W.
Published: October 2007

The use of prestrcssed concrete vessels to contain a nuclear reactor is not in itself novel, as the French in their G2 and G5 vessels at Marcoule had pioneered this form of construction, but the Oldbury vessels contained the first reactors of the integral type in which the core, boilers and gas circuit are contained within the same vessel. This type of reactor had been under consideration for some time by the author's company, and during the early part of 1960 a study had been completed which showed that this design was both feasible and economically attractive. The design formed the basis for the Oldbury Power Station, construction of which started in 1962.
The Measurement of Film Thickness in Thrust Bearings and the Deflected Shape of ‘Parallel’ Surface Thrust Pads
Authors: Hemingway E. W.
Published: October 2007

A transducer has been developed to sense the variation of oil-film thickness in a thrust bearing by sweeping across the working face of the pads and ‘viewing’ them from the rotor. This device was used to compare the deflection of a circular pad with theory, and some degrees of correlation was found. The pads tested formed wedge-shaped films by elastic flexure and successfully carried considerable loads. A tentative explanation is provided for their means of starting to operate successfully.
Fracture Behaviour of Two Creep-Resistant Materials Subjected to Cyclic Loading at Elevated Temperature
Authors: Tilly G. P.
Published: October 2007

An alloy steel and a nickel-chromium alloy are shown to exhibit similar fatigue behaviour over a wide range of temperatures. Endurances tended to be time-dependent at elevated temperatures, and repeated-tension cycles were found to be more damaging than push-pull but less damaging than static-tension (creep). The behaviour was reversed at room temperature where failures tended to be cycle-dependent (number of cycles to failure independent of applied frequency) and creep loading was least damaging.

Rupture data for repeated-tension tests at approximately 10 c/min were analysed by a creep technique. For a wide range of temperature, the expressions fitted the experimental points encouragingly closely and the technique appears to be a useful method of describing this type of data. Tests at room temperature having more than 104 cycles to failure were premature with respect to the analysed family of curves and this was attributed to failure occurring by a predominantly cycle-dependent mechanism. Fractures at higher stresses exhibited a ductile appearance attributed to a different fracture mechanism.

Time-dependent behaviour was enhanced by increase in the peak tensile stress, tensile mean stress, and temperature, or by decrease in cyclic frequency.
Two Papers on Engine Cooling First Paper: The Cooling of Diesel Engines by Water under Pressure
Authors: Gratzmuller J. , Davies S. J.
Published: October 2007

Water cooling in diesel engines is studied, with particular reference to the application of these engines in locomotives of high power. In this context, problems relating to weight, volume and radiator design become progressively more difficult to solve with the tendency towards increased unit powers.

In the solution considered the water in the cooling system is put under a high static pressure, which makes it possible to raise the water temperatures above the usual levels. Resulting from this, the formation of steam bubbles is reduced or eliminated, ‘cavitation corrosion’ is reduced considerably, and cavitation in the water pump is prevented. Water consumption is markedly reduced. Standard equipment for locomotives is described.

Cooling the supercharge air and the lubricating oil at relatively low temperatures is compatible with cooling the engine at a high temperature if two cooling circuits are used, with their radiators placed in series in the cooling air current.

The case of cooling engines of high supercharge is examined; in these, the heat taken from the admission air and from the lubricating oil exceeds that taken from the engine.

Future designs of heating and cooling systems for engines with very high supercharge are proposed.
Dynamic Behaviour of Plain Slideways
Authors: Bell R. , Burdekin M.
Published: October 2007

The friction characteristics resulting from the motion of one surface over another form a very important facet of the behaviour of many physical systems. This statement is particularly valid when considering the behaviour of machine tool slideways. Most slideway elements consist of two plain surfaces whose friction characteristic is modified by the addition of a lubricant. In many cases the complete slideway consists of many mating surfaces and the choice of slideway material, slideway machining and lubricant is often influenced by the long term problem of wear. The aim of this paper is to present results of experiments on a test rig designed to be representative of machine tool slideway conditions; the experiments were wholly concerned with the behaviour of the bearing under dynamic conditions. The major emphasis is on results obtained with a polar additive lubricant which appears to exclude the possibility of ‘stick-slip’ oscillations. A parallel series of tests are reported where a normal hydraulic oil was used as lubricant. The use of this second lubricant allowed some study of the ‘stick-slip’ process. The dynamic friction characteristics, cyclic friction characteristics and damping capacity of several slideway surface combinations have been obtained and are discussed in the context of earlier work in the field and the role of slideways in machine tool behaviour.
First Paper: Effect of Under-Lip Temperature on the Lubrication of Rotary Shaft Garter Spring Seals
Authors: Lines D. J. , Lawrie J. M. , O'Donoghue J. P.
Published: October 2007

Although rotary shaft garter spring seals are widely used throughout industry, very little is known about the sealing mechanism of the lip-shaft interface. It is now generally accepted that some sort of fluid film separates the lip and the shaft. Previous workers have also postulated a relationship between the coefficient of friction and a non-dimensional hydrodynamic parameter, as in standard lubrication theory. This present paper clarifies this relationship, and shows that seals can also operate over the mixed friction, as well as the full film lubrication region. The results were obtained by accurate knowledge of the operating temperature under the sealing lip. Two types of surface thermocouple were developed to do this and these are described in full.
Third Paper: Elastohydrodynamic Lubrication of O-Ring Seals
Authors: Hooke C. J. , Lines D. J. , O'Donoghue J. P.
Published: October 2007

The paper presents a theoretical solution to the ideal problem of an O-ring seal constructed of an isotropic elastic material moving at a constant axial velocity along a cylinder. By means of a standard solution for the elastic distortion of a circular section, and the inverse hydrodynamic theory proposed by Dowson and Higginson, compatible solutions for the hydrodynamic pressure and film shape between the seal and cylinder walls are obtained. It is shown that with a typical seal section taken from British Standard, with standard groove dimensions and ‘nip’, the sealing pressure, which is defined as the difference between the maximum pressure under the seal contact and the sealed pressure, remains independent of the sealed pressure. The net leakage past the seal, which is the difference between the fluid flow across the seal when it is ‘pumping’ against the pressure and that when the seal is ‘motoring’ or moving with the pressure, is shown to increase with sealed pressure.

The results are presented in non-dimensional form to generalize their application.
Second Paper: The Practical Applications of Theoretical Studies to the Tilting Pad Gas Bearing
Authors: Corniglion J.
Published: October 2007

In order to exploit the well-known advantages of gas bearings, it is necessary to be able to optimize each individual design. The non-linearity of the basic Reynolds equation makes this difficult. The application of numerical methods is tedious and expensive. Analytical solution can be obtained by making certain basic assumptions and linearizing the equation. An interesting way to linearize the Reynolds equation is the ph solution found by Ausman on his work on plain journal bearings. An extension of this method has been done by Pitts, for tilting pad bearings.

The aim of this paper is to compare the analytical solution with the experimental results, and so ascertain the validity of the hypothesis. During the experiments the influence on the shape and thickness of the gas film of the parameters (load, speed, bearing size, clearance and pivot location) has been studied. It is shown how a choice of pad may be made to fulfil a certain requirement.
Passive Temperature Control System for An Aerospace Instrument
Authors: Walker G. , Wolf Ludwig
Published: October 2007

In aerospace instruments, the problem of temperature control can become severe because convettive cooling cannot be used; heat must be transferred by radiative means alone. Systems are exposed to a rigorous thermal environment and there are strict limitations on the power, weight and volumes available. A surprisingly high degree of temperature control can be accomplished, however, by the use of a passive system of spectrally selective surfaces.

In this paper, one approach to the design of passive temperature control systems is discussed by detailed reference to an instrument intended for use on the lunar surface.
Effect of Offset Tolerance on Motion Characteristics of Reciprocating Cam-Followers
Authors: Fenton R. G.
Published: October 2007

The actual follower offset of a cam mechanism is affected by the manufacturing tolerances, deflections and clearances, and it is generally different from the nominal offset for which the cam profile has been designed to actuate a prescribed follower motion. The change in follower offset results in changes of follower motion characteristics. The actual values of follower displacement, stroke, velocity, acceleration, and pressure angle are derived in this paper, and the relationships between actual and nominal values of follower motion characteristics in terms of the effective follower offset tolerance are established.
First Paper: Plant Aspects of Turbine Generator Foundations
Authors: Flint I. J.
Published: October 2007

The paper begins with a description of the various types of turbine generator foundations that have been installed and those that are intended for use in the near future.

Then follows a section detailing the requisite characteristics of machine foundations and the factors that must be considered in order to obtain satisfactory operation.

As the foundations support rotating machinery, the subject of vibration is discussed, including fundamental equations and their practical applications to the problem of calculating frequencies in the structures.

Among the many factors that have to be considered when selecting the type of foundation are the size of machine and the station arrangement. The various factors are presented with comments.

Important characteristics relating to the material properties and to the erection and behaviour of steel and concrete foundations are described.

The topic of alignment is considered, including methods of maintaining machine alignment relative to the foundation structure. The causes of foundation distortion and the resulting effect on the alignment of the machine are summarized and some reference is made to precompensation in anticipation of misalignment developing.
New Technique for Shear Zone Thickness Determination in Orthogonal Metal Cutting
Authors: Clack V. W. , Brewer R. C.
Published: October 2007

The extent of the transition zone separating the uncut metal and fully formed chip in orthogonal cutting is examined. Earlier work in this field consisted of studying the magnified grain arrangement in the uncut metal and the chip, the width of the transition zone being measured at selected points.

The new method attempts a more positive assessment of the extent of the transition zone by the use of micro-hardness explorations along a series of generators running parallel to the sides of the chip, and passing through the shear zone into the workpiece. The transition zone and adjacent metal are thus covered with a network of indentations pitched a few thousandths of an inch apart.

As the variation in the size of the indentations is a measure of the work-hardening of the metal, it follows that, once the average hardness values of the uncut metal and the fully formed chip have been established, the transition zone is, in principle, defined by the location of those hardness values which lie between the average hardness values accepted for (1) the uncut metal and (2) the fully formed chip.

In order to find the width of the zone through which a definite increase in hardness occurs, four different methods have been investigated and the results are included. One of the methods gave satisfactory results on all the samples tested.
Influence of Free Surface Environment on the Shear Zone in Metal Cutting
Authors: Barlow P. L.
Published: October 2007

It has previously been suggested that the reduction in cutting forces obtained by the presence of fluids such as CCl4 on the backface or free surface of the forming chip was due to diffusion of the fluid into the body of the chip in the region of the shear zone. In the present work, experiments with carbon tetrachloride tagged with carbon-14 and with carbon tetrachloride tagged with chlorine-36 were performed with the object of assessing the extent of diffusion of lubricants into the chip when present on the free surface only. The results obtained disprove former hypotheses and suggest that the reduced cutting force is due solely to chemical reaction at the surface of the chip.

Confirmation of the sensitivity of the surface of the deforming shear zone to change in surface condition was obtained by removing metal from this region by an electropolishing technique during slow speed cutting. By varying the electropolishing conditions increased or decreased cutting forces could be obtained. It is proposed that the result both of chemical reaction at the surface and of surface removal is to reduce the strain-hardening rate of the metal undergoing shear by reducing the surface barrier to the flow of dislocations out of the metal.

The association of the surface reaction of carbon tetrachloride with a change in the strain-hardening characteristics of the metal in the shear zone leads to a classification of the backface phenomenon as a Rehbinder effect and enables this effect to be more closely defined than was hitherto possible.

Evidence is also presented which indicates that the backface effect does not contribute to the reduction in cutting forces during rakeface lubrication and is therefore unimportant in practice where flood lubrication of the cutting region invariably occurs.
Influence of Engine Inertia Forces on Minimum Film Thickness in Con-Rod Big-End Bearings
Authors: Martin F. A. , Booker J. F.
Published: October 2007

In the design of dynamically loaded bearings, the journal eccentricity will vary in magnitude and direction throughout the loading cycle. One of the designer's interests is in the trends of maximum eccentricity ratio and the corresponding oil film thickness for various bearing and engine conditions. From experience with journal eccentricity predictions for big-end bearings it has been found that the eccentricity ratio in the bearing due to the peak firing load seldom exceeds that due to the inertia load alone (although this load is smaller). Therefore, as an approximation, it is thought justifiable to neglect the gas forces.

The maximum eccentricity ratio for numerous inertia load cycles was computed based on the numerical mobility method of solution (1)†; because of its simplicity and as only trends were required, the short bearing solution was used.

The results of this study applied to big-end bearings show how the reciprocating and rotating masses affect the maximum eccentricity ratio. Also the effect of the ratio of crank radius to con-rod length is investigated, as is the effect of change in bearing clearance.

A useful general-purpose graph is presented which will enable the designer to estimate comparative values of minimum oil film thickness over a practical range of bearing operating conditions. It is emphasized that the value of oil film thickness by itself may not be very helpful if used in absolute terms, as its correctness will depend on the assumptions made. The general results will, however, be useful if used as a comparator, and should give some guidance on how to improve the performance of connecting-rod big-end bearings.
Nominated Lecture: Performance and Operation of Spark-Ignited Gas Engines
Authors: Land Malcolm L.
Published: October 2007

The author discusses the application of spark-ignited gas engines to such services as gas transmission, gas gathering and chemical processing with integral angle engine-compressors as well as directly coupled units.

The author also treats such performance aspects of two-and four-stroke cycle spark-ignited gas engines as: fuel consumption, cyclic dispersion in combustion, accommodation of ambient temperature variation, load variation and altitude. There is an extended discussion of pulse and constant pressure turbocharger characteristics and their influence on engine performance. Important hardware considerations are given, such as design of valves and valve inserts, cylinder heads and pistons.
Power Generation and Transmission in Quebec
Authors: Abbott H. F.
Published: October 2007

The paper covers in outline the growth of power generation and transmission in Quebec from the start of the century, and points out the particular features of Quebec which lead to very large hydroelectric developments. It is mentioned that, up to the present, only one large thermal plant is installed, with two units of 150 MW in operation. It is also mentioned that the hydraulic heads developed do not exceed 875 ft so that turbines are of the Francis or propeller type, and that it is unlikely that the Pelton type will ever be required. Outline dimensions of some of the record-size dams and canals are given, for instance the Manicouagan buttressed multi-arch dam with a crest length of 4275 ft and a height of 703 ft, controlling a reservoir containing 115 000 000 acre ft; also the 15-mile long, 3300-ft wide, 27-ft deep Beauharnois canal from which 200 million cubic yards of clay were excavated. The contrast is shown between the well-known 120-kV transmission systems and the 735-kV transmission system which is the highest voltage and capacity system in use anywhere, and is capable of carrying 2000 MW per three-phase circuit.
Acoustic Isolation of Fans in Ducts
Authors: Roberts A. W. , Luxton R. E.
Published: October 2007

A method of reducing the sound power radiated downstream from axial flow fans is described and investigated. The normal parallel duct fan housing is replaced by a contoured arrangement. With one type of contour and the use of porous absorbent material the reduction in the downstream overall sound power level is 5 dB, that is, the total sound power is reduced by a factor of three. The attenuation is effective in this case over the full audio frequency range but is largest at frequencies above about 1000 c/s.

The total pressure losses in each of the several contoured fan housings investigated are practically identical with those in the usual parallel housing and the fan absorbs no significant additional power. Although commercially available duct noise reduction devices may give higher attenuations than those obtained by the contouring method they usually do so at the expense of quite high total pressure losses. For example, the fan used in this investigation gives a total pressure rise of about 1.4 in water gauge and one commercial type of duct noise attenuator, suitable for use with this fan, introduces a total pressure loss of 0.25 in water gauge.

Two basic types of fan housing are investigated. One housing has contoured sections upstream and downstream of the fan rotor and the other is a composite arrangement with the normal parallel duct intake and a contoured downstream section. The effect of the presence of absorber on the performance of these basic types is determined. The acoustic performance of each type of fan housing duct is compared by the use of an ‘in duct’ method of sound pressure measurement. It is stressed that the design of low noise fan/duct systems is economically feasible provided sufficient effort is exerted to find a satisfactory compromise between the required aerodynamic and acoustic performances.
Theories and Experiments on Tube Sinking through Conical Dies
Authors: Moore G. G. , Wallace J. F.
Published: October 2007

Earlier theories of tube sinking through conical dies have been considered and the factors important in the calculation of stresses and strains have been determined. Using these theories drawing stresses have been calculated for a particular stress-strain curve by assuming an exponential strain hardening characteristic. These drawing stresses are essentially ‘lower bounds’ but comparative ‘upper bounds’ have been obtained using velocity field techniques; Coulomb friction has been included. Thickness strains for a smooth die and a non-strain hardening material have been computed. Experimental data has been obtained using conical dies under normal industrial conditions and comparisons made with theory. In addition, the problems encountered in the inlet and exit of the die are discussed.

It is suggested that drawing stresses and thickness strains determined for conical dies can be applied to other die profiles when the die inlet semi-angle does not exceed 15°.
Second Paper: Lateral Helmholtz Resonator Silencer with Turbulence Absorption
Authors: Chen Y. N.
Published: October 2007

Lateral Helmholtz resonators are ineffective for fast flow because of the turbulence caused by the movement of the gas mass from the resonator neck into the main pipe flow. The absorption of this turbulence at its source is an effective method for keeping the resonator silencing ability at a high level. Experimental results on an acoustic filter formed by resonators for flow velocities up to 80 m/s, so treated, are compared with the theory. There is evidence of lateral resonance of the gas column in the exhaust pipe at high flow velocities, detected as an intense noise of a discrete frequency (1000 Hz). The excitation of this resonance was found to be due to the pseudo-acoustic wave caused by the neck jets in the resonator. The influence of the flow upon the natural frequency of the resonator is also discussed. The Reynolds number of the flow seems to play an essential role on this point.