bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymmetrically Ring Reinforced Circular Hole in a Uniformly End-Loaded Flat Plate with Reference to Pressure Vessel Design
Authors: Hicks Raymond
Published: October 2007

General expressions are obtained for the stress distribution in an infinite flat plate end- loaded by equal principal stresses and containing a circular hole reinforced by a compact ring. The ring reinforcement being placed on one side of the plate only so that the other side of the plate remains flush.

It is shown that the effect of an asymmetrically placed reinforcement is to induce in the plate and reinforcement bending stresses which are not negligible compared with the externally applied direct stress. Furthermore, from particular examples considered, it is found that reinforcements having practical dimensions can give rise to stress concentrations in the same order of magnitude as those in a similarly loaded plate containing an unreinforced hole.

Thus, a reinforcement designed to satisfy B.S. 1500:1949 has a small compensating effect compared with a symmetrically placed reinforcement having the same cross-sectional area.

For practical purposes, data have been obtained which enable the designer to determine quickly the stress distributions associated with reinforcements and plates having a reasonably representative range of dimensions.
Experimental Study of Some Variables of the Tube-Expanding Process
Authors: Culver L. E. , Ford Hugh
Published: October 2007

This paper deals with certain aspects of the tube-expanding process, which have been investigated using the test rig previously developed as part of a research sponsored by the British Shipbuilding Research Association.

The factors investigated are (1) retubing, (2) the starting position of the roller cage within the tube, and (3) the initial clearance between tube and seat. A few tests are also reported on the relaxation of the joint with time.

In the retubing tests, further tubes were expanded into seat plates used in previous tests, from which the original tube had been removed. The main conclusion was that seat pressures can approach the theoretical maximum in retubing, and that if an extra pass is made to take advantage of the work-hardened seat, a stronger joint than in a first expanding results.

To study the effect of the starting position of the rollers within the joint, four complete tests were made. The results show conclusively that a much stronger joint is obtained with less work, if the rollers start with their front ends almost at the back of the joint.

Tests to study the effect of the initial clearance between tube and seat showed that clearance is not a major factor in joint strength.
The Behaviour of Narrow-Faced, Bolted, Flanged Joints under the Influence of Internal Pressure
Authors: Donald M. B. , Salomon J. M.
Published: October 2007

A narrow-faced, bolted, flanged joint is a highly complicated stress-system. When internal pressure is applied, the stress-system changes. In order to establish, quantitatively, what these changes are, a series of experiments were carried out on a pair of -in. nominal bore screw-on hubbed flanges.

The apparatus was assembled as shown in Donald and Salomon (1, Fig. 1)† An accurate measure of bolt stress and, hence, the stress on the gasket was obtained by attaching a total of four electric resistance strain-gauges to two ‘measuring’ bolts. As the nuts were all tightened carefully by means of a torsion wrench, an average of the readings of the four gauges gave the average bolt stress of the eight bolts.

Care was taken that the gauges were cemented to diametrically opposite sides of the bolts and that two of the gauges were pointing toward the centre of the flange while the other two were pointing in the opposite direction. From the readings of the two pairs of strain-gauges, it was possible to calculate the extent of bending of the bolts during application of internal pressure and, hence, the rotation of the flange-rings due to pressure. The results of the experiments indicated:

(1) (a) There is a linear relationship between bolt load and internal pressure. (b) The slope of the line giving this relationship depends on the elastic properties and the dimensions of the components of the joint. (c) This slope can be predicted mathematically. (d) This slope can, in the case of pseudo-elastic gasket materials such as compressed asbestos composition, be positive, negative, or zero; the slope in any particular joint depending only on the initial load on the gasket. (2) (a) The rotation of the flange rings due to pressure increases as the slope of the bolt load versus internal pressure line changes from negative to positive. (b) The rotation, as calculated from strain-gauge measurements agrees fairly well with that calculated by use of the theory of Wesstrom and Bergh. (3) The circumferential strain in the flange and pipe assembly is at a maximum in the pipe at the back of the hub. This result is in agreement with that reported by several other investigators and is not discussed in this paper.
Flow Pattern in Diesel Nozzle Spray Holes
Authors: Bergwerk W.
Published: October 2007

The paper presents a study of the flow in spray holes of 0.2 to 2.5 mm diameter and shows how the changes in cavitation pattern affect the appearance of the jet. The influence of the cavitation number, Reynolds number, the upstream edge sharpness, and the length/diameter ratio is investigated.

A cavity first formed near the upstream corner, but soon caused the jet to leave the wall altogether so that only the upstream corner had any effect on the flow. Under noncavitating conditions the emerging jet had a ruffled appearance, but under conditions when the jet had left the wall, it emerged smooth and glass-like. The glass-like stage could only be obtained with very accurately made spray holes, and any disturbance upstream, such as occurs in actual Diesel nozzles, caused the jet to appear ruffled at all times.

The discharge coefficient was found to vary with Reynolds number and cavitation number and a contour map covering Reynolds number of 1000 to 20 000 and cavitation number of 0·2 to 100 is presented.
Mechanics of Secondary Water-Hammer Waves
Authors: Gayed Y. K. , Kamel M. Y. M.
Published: October 2007

While tests were being carried out on the motion which follows sudden closure of a valve at the beginning of a pipe, certain irregularities of the ensuing wave trains were noticed. Such irregularities were brought out all the more clearly because a sensitive electronic recorder was used. The special experimental arrangement prevented the appearance of these irregularities, henceforth called secondary waves, during the first surge, which helped considerably the theoretical exposition. However, they were later superimposed on both the negative and positive surges. The reasons, which are not entirely different in both instances, are the main subject of discussion in this paper.
Optimum Design of Thin Circular Plates on an Elastic Foundation
Authors: Galletly G. D.
Published: October 2007

An analysis is given of a thin, constant-thickness, circular plate subjected to uniform lateral pressure. The plate is assumed to rest on an elastic foundation and to be elastically restrained at the edges against rotation and vertical deflection. The equations for the magnitude and location of the maximum stress in the plate were programmed for an electronic computer and curves obtained for both these quantities for various values of two dimensionless parameters. These curves are presented in the paper and it is shown how the optimum design of a constant-thickness circular plate can be quickly effected with their aid.

One interesting result of the analysis is that it is possible to design plates in which the maximum stress is between 25 and 50 per cent smaller than that in similar plates with simply supported ends. This possibility does not appear to have been appreciated before and its utilization has obvious economic advantages. Another result of interest is that the value of the dimensionless elastic rotational restraint parameter giving minimum thickness is almost a constant for most cases occurring in practice.

A brief discussion is also included of the application of the curves obtained for homogeneous plates to the design of perforated tube-plates.
Free-Convection Heat Transfer in the Inclined Open Thermosyphon
Authors: Martin B. W.
Published: October 2007

This paper describes a fundamental experimental investigation of heat transfer by free convection in a static heated tube, sealed at its lower end, and arranged so that the inclination of the tube to the vertical can be varied. Heated fluid adjacent to the tube wall forms an annulus which is discharged from the open end into a suitably cooled large reservoir, while a central core of cool fluid is continuously drawn into the tube by way of replacement. The case of the vertical tube under both laminar and turbulent flow conditions has been previously studied (Martin (1)†) and the present work continues the investigation of the system.

Inclination of the tube sets up a secondary acceleration normal to its principal axis. The pressure gradients which are thereby induced should assist the circulation of fluid from the cold to the hot stream, thus reducing the thickness of the annulus and increasing the area of the core. The increased effectiveness of the system might then be expected to improve the heat-transfer rate. This is found to be true in laminar flow (of the boundary layer type) except for small tilting angles. The weak secondary pressure gradients which then occur are believed to be responsible for mingling of the fluid particles on the common boundary, and this reduces the heat transfer. The same general trends are apparent even when there is some degree of turbulence in the system.

The stable turbulent regime is not of the boundary-layer type, because of the tendency for the cool entering fluid also to become turbulent, but what is called fully mixed flow, where the two turbulent streams mix. This causes reduced circulation and heat transfer. Under these conditions sufficient tilting of the tube eventually brings about the elimination of the mixing effect and a more efficient transfer of fluid particles between the two streams. The greatly increased heat transfer appears to be consistent with a stable turbulent boundarylayer flow regime, which, if attained, would improve the effectiveness of the open thermosyphon as a cooling device for both nuclear reactors and gas-turbine rotor blades.
The Influence of Elastic Deformation upon the Motion of a Ball Rolling between Two Surfaces
Authors: Johnson K. L.
Published: October 2007

When a ball rolls between two surfaces, in general, a tangential contact force and a relative angular velocity of spin are present at each point of contact. Both these actions give rise to tangential frictional tractions transmitted across the contact surface which are shown to result in a velocity of creep of the ball in a direction perpendicular to the nominal rolling path.

The magnitude of the creep velocity depends critically upon the magnitudes of the tangential force and the velocity of spin. If these actions are small there is negligible slip between the contacting surfaces and the creep motion is predominantly a function of the elastic properties of the materials. At larger spin velocities slip extends over a greater proportion of the contact area and the creep is influenced by the frictional properties of the surfaces.

Creep measurements have been made over a wide range of conditions of rolling. The results are reduced to non-dimensional form, in terms of two parameters expressing the effect of tangential forces and spin respectively.

The resistance to rolling has been measured and is shown to control the axis about which the ball rolls. The detailed mechanism of the rolling process is discussed.
Application of Pneumatic Equipment to the Centralized Control of Compressors
Authors: Martin E. N. , Wilkinson T. W.
Published: October 2007

Centralized control of a compression plant, in which the speeds of a number of large compressors are remotely controlled by pneumatic means, has been in full operation since 1955.

In this paper are discussed the principal design features leading to the choice of pneumatic equipment, the application of which is illustrated by detailed descriptions of typical machine installations. Descriptions of the control-room layout and the means adopted for ensuring reliability of the compressed air supply are also included.
Present-Day Feed-Water Treatment for High-Pressure Boilers
Authors: Hamer P.
Published: October 2007

The paper is concerned with industrial boiler plant generating steam for power and process at pressures of 1000–2000 lb/in2 and having a high make-up of treated feed water. The capital and running costs of the water treatment plant and process are therefore much more important than in power station boilers where make-up is small. A few figures are given to illustrate this point and a plea is made that water treatment should be studied carefully at an early stage in any project for new boilers.

The quality of feed and boiler waters now in use, or recommended, is shown in two tables and it is clear that above about 1500 lb/in2 the trend is toward ‘pure’ feed water, though this may not be essential.

The next section discusses the control of steam purity to prevent corrosion and deposits, by elimination of carbon dioxide and oxygen, addition of volatile amines, control of the concentration of salts and silica in the boiler water, and the possibility of steam washing.

A short description is given of the circumstances which, it is believed, have caused numerous cases of corrosion in high-pressure boilers, and countermeasures are suggested. These comprise strict deaeration of the feed water, addition of alkalis to the boiler feed water, to prevent corrosion in the pre-boiler equipment and in the boiler, and the avoidance of hot spots or sluggish flow by boiler design and operation.

The paper concludes with a reference to the prevention of corrosion in boilers which are standing during erection or normal operation, and to acid cleaning.
Design and Construction of Power Station Feed Heaters
Authors: Bigg J. V.
Published: October 2007

The paper presents a survey of a number of aspects of the design and construction of feed heaters for present-day steam-turbine cycles.

Many papers have been published in recent years which cover a variety of the detail factors which can enter into the design of a feed heater (for example, the design of tube plates). No attempt has been made to add to such information. The aim of the paper is to present the overall picture and to confine detail description to those items where existing literature is scanty or where the author feels that information of interest can be presented.

Firstly, a methed is discussed whereby the optimum economic size of the individual feed heater can be investigated. This is followed by consideration of the thermal design of the heater nest, and of the pattern of temperature difference introduced by the advent of heaters containing desuperheating and drain-cooling sections. Several methods are shown by which such sections may be arranged in a feed-heater nest.

The remainder of the paper deals with particular aspects of detail construction. The choice of tube materials and their safe working stresses is discussed. The problem of the production of a satisfactory roller expanded tube to tube-plate joint is examined in some detail, together with methods for the consistent production of this joint. An account is given of development work on means for evaluating the soundness of expanded joints by both non-destructive methods and by tube pull-out tests.

A description is given of the investigational work which has taken place and has led to the introduction of welded tube to tube-plate joints with both ferrous and non-ferrous tubes.

Information is presented regarding the amount of torque necessary to achieve desired loadings in heavy bolted constructions and the problem of achieving uniform bolt loading is discussed.

A method of investigation is described which enables the resilience of compressed asbestos jointing to be examined when subjected to a cycle of loading, including heating which simulates working conditions as closely as possible.

The main problems occurring in the design of tube plates and heater headers are examined in a brief discussion.
The Strength of Rails with Particular Reference to Rail Joints
Authors: Wise S. , Lindsay D. , Duncan I. G. T.
Published: October 2007

This three-part paper describes recent work on rails carried out by the Research Department of British Railways.

Part I details the rail sections considered, theoretical considerations of longitudinal bending strength and an analysis of failures in service.

Part II describes a site investigation which was made into the dynamic stresses experienced by rail joints under traffic. Stresses in both flat bottom (F.B.) and bull head (B.H.) rail joints have been measured with both normal and abnormal conditions of sleeper packing. Electrical resistance strain gauges were used at the calculated positions of maximum stress in each fishbolt hole, and at other positions in the joint.

The work initially covered the effects of steam locomotives and steam hauled stock, but was later extended to a second site so that electric locomotives and multiple unit electric stock could be similarly covered.

The investigation brought out the marked influence of speed, wheel diameter and axle load on the magnitude of the stresses induced; and in view of the prospective increase in speeds, and the employment of diesel electric and electric locomotives with heavy axle loads on smaller wheels than as is usual currently, importance attaches to these results and their implications on the life expectancy of rail steel under fatigue loading.

Part III describes fatigue tests which have been made on B.H. and F.B. rails, both plain and when drilled with fishbolt holes. The susceptibility to cracks starting at bolt holes, due to shear stresses in the web, is compared for the two rail sections, and some consideration is given to various methods of increasing the resistance to cracking of this type. It is shown that ordinary atmospheric corrosion greatly reduces the fatigue strength of rails, and any proposed method of reducing bolt hole failures must therefore take this into account.
Power, Flow and Pressure Measurements in Pump Testing
Authors: Young Leslie , Nixon R. A.
Published: October 2007

The measuring methods available for obtaining pump performance are examined in the light of experience obtained at the National Engineering Laboratory (N.E.L.). Consideration is given both to experimental procedure and to the interpretation of results.

Since it has been found that pump performance can be markedly influenced by installation conditions, some typical effects are examined.
An Approximate Analysis Giving Design Data for Corrugated Pipes
Authors: Palmer P. J.
Published: October 2007

This paper gives an approximate method of analysis for corrugated pipes and ducts, of the type in which the corrugations have a constant radius of curvature. The method is applicable to corrugations of any included angle, provided that the radius of curvature of the corrugation is small compared with the radius of the pipe. The analysis is carried out using the principle of minimum strain energy, in which the smallest possible number of terms are employed.

The advantage of the method is that results giving extension, bending stress and circumferential stress can be evaluated for corrugations with different included angles, and simply presented in graphical form. These results are then readily available for design considerations covering corrugated pipes with internal pressure, axial load, and bending moment.

The approximate results are compared, where possible, with some results from more precise methods of analysis, and also with some experimental results, and the comparison shows the present method to be sufficiently accurate for design considerations.
Pipe Ranges for Water at High Pressures and High Temperatures with Special Reference to Boiler Feed Systems
Authors: Jacob K. B.
Published: October 2007

With the pressures now being used for central station boiler plant, the feed water pipelines may be excessively stiff and distortion of feed pump bodies is possible owing to the thermal expansion of the pipes when carrying feed water at temperatures up to 500°F. Everything must, therefore, be done to increase the flexibility of the feed pipelines by providing an arrangement which will reduce the pipe thrust and bending moment on the pump terminals, by reducing the pipe bore and increasing the velocity consistent with economic pressure drop, and by reducing the pipe wall thickness to the limit imposed by the safe working stress for the available materials.
Leak Tests on Calder-Type Reactors
Authors: Smith J. K. , Cheetham J.
Published: October 2007

The operation of the first reactors at Calder Hall revealed a significant leakage of carbon dioxide coolant. Tests have been carried out on subsequent reactors to establish the leakage rate and to trace and minimize this loss of coolant gas. This paper deals with the tests carried out on Calder reactors 3 and 4 and Chapelcross reactors 1 and 2. The authors outline the various methods used to determine the rate and to locate the origin of gas leaks.

A number of conclusions have been reached on design aspects and several suggestions are made for improving gas tightness of future plants of a similar construction.
Plane Strain Theories of Drawing
Authors: Green A. P.
Published: October 2007

A review is given of existing theories of drawing under conditions of plane strain†, and these theories are extended in certain respects.

Comparison between accurate and approximate theories in which work hardening is neglected, shows that one of the approximate theories is reasonably accurate in predicting the distribution of pressure on the die, and the effect of friction on the drawing load.

A new approximate method is proposed to allow simultaneously for work hardening, friction, and redundant work, in calculating die pressures and drawing loads. Redundant work is allowed for by suitably modifying the stress-strain curve of the metal. Formulae are derived for drawing through a wedge-shape die, using analytical approximations for the stress-strain curve. Similar formulae have not yet been found for dies with a cylindrical profile.

The possible errors involved in calculating a mean coefficient of friction from the measurement of forces acting on each half of a wedge-shape die are analysed.
Design of Modern Boiler Feed Pumps
Authors:   Hydraulic Plant and Machinery Group, Anderson H. H.
Published: October 2007

Feed pumps for large steam power stations must accept severe thermal shocks in order to protect the boiler from such shocks, since boiler failure would be catastrophic.

The treatment of feed water to give minimum corrosion of the boiler may result in a liquid which is quite erosive at the flow speeds associated with a high-pressure pump.

In this paper the research into transient thermal phenomena is described, and it is shown how modern feed pumps for steam power units up to the largest powers visualized are designed to give symmetry of construction, of flow and of stresses in order to withstand rapid temperature changes without distortion of alignment.

Modern steam and gas turbines similarly aim at symmetry about the shaft axis.

Illustrations are given of how erosion is avoided and performance improved by mathematical control of the acceleration within the pump and by the use of superior materials.
Inquiry into Amphibious Screw Traction
Authors:   Applied Mechanics Group, Cole B. N.
Published: October 2007

The paper describes an inquiry into the potentialities of the Archimedean screw as a device for amphibious travel and traction. The proposal is that a hulled machine should be supported by two such screws aligned beneath the port and starboard sides; the screws being oppositely handed and contra-rotating, so as to propel the machine either aground or afloat. A major attraction of the scheme lies in the positive action to be expected of the screws when working in difficult grounds of a loose granular, or semi-fluid, nature. The scheme is obviously unsuited to hard and paved surfaces, however, and is not proposed for these conditions. Comparisons are drawn between this and existing types of amphibious machine, with particular regard to the development of useful tractive effort. Theoretical examination of the rotor properties, for both aground and afloat conditions of duty, is supported by model-scale experimental work; and design recommendations are made. Favourable conclusions are reached; though it is necessary to add that the work has been in the nature of a pilot investigation only, and that full-scale tests would be necessary to reach a final verdict.
Performance of Some Plain Bearing Materials under Boundary Conditions at Low Temperatures
Authors:   Lubrication and Wear Group, Hargreaves R. , Tantam D. H.
Published: October 2007

This paper describes results of wear tests made on journal bearings for use at liquid oxygen and liquid nitrogen temperatures, i.e. at −183°C and −196°C, also the design of large bearings in use at these temperatures.

The problem of operating plain bearings at low temperatures, particularly in immersed conditions in liquid oxygen or liquid nitrogen, is one of using materials with suitable mechanical properties at these temperatures together with chemical and physical requirements associated with successful dry-bearing combinations in these two conditions of differing reactivity.

It is desirable for apparatus to be interchangeably used for handling liquid oxygen and liquid nitrogen and bearing combinations which can be used for this are described.
Performance of Grain Augers
Authors: Roberts A. W. , Willis A. H.
Published: October 2007

With the growing increase in the bulk handling of grain, the grain-auger type elevator is now being widely used. While some theoretical analyses of the grain auger have been made and performance data for particular size augers have been obtained, little information is available for general design purposes. This work, which is based on an experimental approach, is aimed at producing such information. The investigation has been carried out using a small scale model auger which allowed a comprehensive range of tests to be conducted on a more manageable basis

In the first part of the investigation, a study is made of the auger performance characteristics with the aim of determining the conditions for most efficient operation. An examination is made of output and volumetric efficiency in relation to speed, angle of elevation and choke length (the length of exposed screw projecting from the lower end of the casing). The effect of casing clearance on auger output is also partially examined. In addition, the variation of auger horsepower and overall efficiency with speed and angle of elevation is observed

In the second part of the investigation, equations are developed and design charts given which enable the performance of augers to be predicted. The equations and charts are based on the application of dimensional analysis and dynamic similarity and apply to augers of the same geometrical proportions as those of the model. The data apply mainly to granular materials of similar shape and properties to wheat. A comparison is made between the predicted performance with the actual performance of a 6-in. auger, good agreement being obtained

The investigation shows that many combinations of auger size, speed and angle of elevation may be adopted for a particular conveying application and general recommendations are given regarding the choice of these variables for efficient operation
Method of Predicting Some Aspects of Performance of a Diesel Engine Using a Digital Computer
Authors:   Internal Combustion Engines Group, Whitehouse N. D. , Stotter A. , Goudie G. O. , Prentice B. W.
Published: October 2007

While the design of diesel engines is necessarily based upon some estimate of the pressure and temperature conditions expected in the cylinder and in the air and exhaust manifolds, such estimates have usually been very approximate. The suitability of the design has to be proved, or improved, during a considerable programme of rigorous development

As engines become more highly rated the value of more accurate early estimates of engine performance, as a guide to the designer, becomes more obvious. The paper describes a method of calculating this information by digital computer based on a fundamental approach to the processes involved. It is demonstrated that the cylinder pressures and temperatures, exhaust gas temperatures, fuel consumption, air flow, heat losses, piston and wall temperatures and engine output so calculated, correlate very well with experimental results

Using this technique, different combinations of engine variables can be ‘tested’ by computation to reduce the range of engine tests necessary to develop the optimum design, and allow the designer and the development engineer to concentrate their practical experience and technical ‘know-how’ on the formidable problems of mechanical development and combustion improvement
A Standard Contaminant for Oil Filter Testing
Authors:   Lubrication and Wear Group, Weare A. T.
Published: October 2007

The paper describes the work carried out in the preparation of a ‘natural’ contaminant of a definite and reproducible composition for use in tests on oil filters. The arbitrary limits set in the specification of the contaminant are based on various factors from data on used oil filters and previous knowledge gained in the examination of used engine oils

The preparation of the contaminant from the raw material is described in detail, and reference is made to a method of testing filters which is used to make sure that the standard contaminant affects a filter in a consistent manner. Detailed methods of chemical analysis for inorganic constituents and particle size measurement are given in the appendixes to the paper
Laboratory Assessment of Diesel Fuel Filters
Authors:   Lubrication and Wear Group, Onion G. , Rothwell A. J.
Published: October 2007

The choking of fuel filters in most services is caused by soft organic trace constituents of the fuel, and is independent of the extraneous contaminants over the range of concentrations normally encountered in service

It is possible for a filter which is reasonably efficient initially to deteriorate in service to such an extent that most of the damaging contaminants applied pass through the filter. Such a filter, when tested with hard particles only, can show a continuously improving efficiency due to the filtering action of the bed of retained particles. The choking life, as determined by the quantity of hard particles it retains before reaching a chosen limiting resistance, is a measure of the effective filtering area and the volume available for retained contaminants rather than of the life which would actually be experienced in service. It is therefore important in testing fuel filters that the service choking process should be reproduced

A combined choking and particle transmission test is described which gives information on the service life to be expected and on the particle transmission of the filter at any stage during that life. The methods of preparation and specification of the powders and choking medium used in this test are also described
An Analysis of Alternative Policies for the Issue of Commodities from Stores
Authors:   Industrial Administration and Engineering Production Group, Eilon S.
Published: October 2007

When the useful life of a commodity in the field (the field life) is affected by the time which the commodity spends in store prior to issue (the store age), it is possible to show that there is an optimum sequence for issuing a given number of items of this commodity from the store, when it is desirable to maximize their total useful life in the field. Two common issuing policies are FIFO (first in first out) and LIFO (last in first out) and it is shown that one of these policies becomes optimal, depending on the characteristics of the field life function, i.e. on the relationship between the useful life of a commodity in the field and its store age prior to issue. Attention is drawn to the risk of obsolescence, when items in the store cease to be useful owing to excessive storage periods, and the effect of this factor on the above two policies for issuing items from store is discussed. The cost of implementing these policies and problems relating to acquisition or replenishment of commodities for a stock-pile of two units are considered and the conditions under which each policy becomes less costly to apply are stated
Dependence of Joint Strength on the Degree of Expanding in the Tube Expanding Process
Authors:   Applied Mechanics Group, Culver L. E. , Ford H.
Published: October 2007

The experiments, which were sponsored by the British Shipbuilding Research Association, were designed to study how the strength of an expanded joint depends on the degree of expanding with normal propulsive type expanders. Fourteen tests were made, varying the back extrusion from 0.029 in. to 0.093 in. on a 2 in. O.D. × 11/2 in. bore tube in 1 1/4 in. long seat

There is an optimum degree of expanding for maximum joint strength measured either by the push-out load or mean seat pressure. The position of the maximum in the curve of push-out load is dependent upon surface finish. Within the inevitable variation present in industrial machining finishes the presence of a peak will be masked. Moreover, the peak occurs at a degree of expanding well beyond the values recommended by previous workers for the same size of joint. Bearing in mind the added difficulties of controlling the process in the field, these recommended figures are open to question

Mean seat pressures as high as 5 ton/in2 are easily reached at the optimum degree of expanding

In view of the large variations in joint strength that can occur even with carefully controlled expandings, reproducibility tests were carried out. It is shown that, where exceptional care is taken to control all the conditions of the test, good consistency in the characteristics of identically expanded joints is possible
Oil Whirl of Flexible Rotors
Authors:   Lubrication and Wear Group, Parszewski Z. , Cameron A.
Published: October 2007

The equations for a flexible rotor in journal bearings are set up and solved, extending the method previously used by Hummel and Cameron. It is shown that if w is the natural elastic frequency of the rotor, A the resonant oil frequency for an infinitely stiff but otherwise identical rotor, then the combined frequency s is given by l/ s2 = 1/Λ2 + 1/ w2. This resonant frequency will usually occur when it equals 1/2 the shaft rotational frequency

The frequency calculated by the method given here is applied to a number of cases of large turbines and alternators and found to give quite satisfactory results
Half-Speed Whirl and Load Capacity of Hydrodynamic Gas Journal Bearings
Authors:   Lubrication and Wear Group, Whitley S. , Bowhill A. J. , McEwan Miss P.
Published: October 2007

A phenomenological theory of the half-speed whirl of gas bearings is developed; it predicts the existence of four modes of whirl which depend variously on the mass and transverse inertia of the bearing and on the mass and transverse inertia of the shaft. All four modes of whirl have been distinguished experimentally, and related to each other theoretically. From these measurements, it is shown that the half-speed whirl properties of a plain bearing can be considerably improved by cutting an axial slot in the bearing. Further improvement, if required, can be effected by introducing an ovality into the bearing or cutting circumferential grooves in it. The introduction of these anti-whirl devices, however, reduces the load capacity, although measurements have shown the effect is not serious except for the circumferentially grooved bearing
Stresses in Branched Pipes under Internal Pressure
Authors:   Applied Mechanics Group, Fessler H. , Lewin B. H.
Published: October 2007

The frozen stress photo-elastic technique was employed to determine the elastic stresses in T-shaped branched pipes. All branches had the same ratio of inner diameter to outer diameter as the main pipes and this ratio varied from 1/6 to 1/1 1/2. The ratio of branch diameter to main pipe diameter varied from 1/4 to 1. The peak stresses measured in 21 models of plain intersections showed no significant changes due to variation of branch diameter. External reinforcements in the form of collars, ‘Blair triforms’ and horseshoes were shown to be effective.

Internal chamfers and counter-bores also reduced the peak stresses in thick pipes.
Acceleration and the Critical Heat Flux in Pool Boiling Heat Transfer
Authors:   Thermodynamics and Fluid Mechanics Group, Ivey H. J.
Published: October 2007

Many theories predicting the critical (or burnout) heat flux in saturation pool boiling have been proposed during the past decade. Although most are able to correlate existing experimental data, it is evident that the theoretical models upon which they are based are widely different in concept. Moreover, owing to lack of experimental evidence it is not clear which, if any, are based upon the more correct models. Certain of the theories implicitly contain the acceleration due to gravity raised to a different power; by performing a relatively simple experiment it may be possible to accept or reject certain of the theories. An experiment of this type is described in the present paper. On the basis of the results of this experiment it is possible to reject several of the above theories.

The extent to which the acceleration of the boiling system is important as a parameter in determining the critical heat flux was ascertained experimentally. A simple centrifugal apparatus is described which was used for determining the critical heat flux in pool boiling to water at atmospheric pressure and accelerations in the range 1 < ( a/g) < 160. A two-variable non-linear correlation involving a logarithmic transformation was made upon the experimental results after allowing for the possible effect of pressure and potential sub-cooling by extrapolation to zero subcooling. The resulting equation is of the form:
Operating Characteristics of Compound Engine Schemes for Traction Purposes Based on Opposed Piston Two-Stroke Engines and Differential Gearing
Authors:   Internal Combustion Engines Group, Wallace F. J.
Published: October 2007

In an earlier paper (1)†, the performance characteristics of combinations of two-stroke compression ignition engines with compressors and turbines were analysed under the headings

(1) Turbosupercharged engines with mechanically driven scavenge blowers, (2) Gas generators, (3) Compound engines with fixed ratio geared connection between engine., compressor, turbine and output shaft.

The object of the present paper is to extend the method of analysis outlined in the previous paper to cover various compound engine arrangements with differential rather than fixed ratio gear connection between the members of the aggregate. It is shown that such units meet to a very high degree the specific requirements of the traction application, namely

(1) High unit power achieved by the use of high boost pressures, (2) Torque-speed characteristics approaching the ideal hyperbolic law, and permitting drastic simplification of the external transmission system, (3) Good part-load efficiency—superior to both the turbocharged and the gas generator engine—made possible by free power flow between the members of the aggregate, (4) High degree of engine-assisted braking, and (5) Good response to sudden changes in load demand.

Two arrangements, both meeting these requirements to a high degree, are considered. These units constitute a significant advance over existing traction prime movers.
The Design and Construction of Heat Exchangers for Gas-Cooled Nuclear Power Plant
Authors:   Steam Plant Group Nuclear Energy Group, Webb T. B. , Wootton W. R.
Published: October 2007

The scope of the paper is limited to the design and construction of heat exchangers of the type used in gas-cooled nuclear power plant for the purpose of raising steam. Among the earliest examples of such heat exchangers were the steam-raising units at Calder Hall and Chapelcross: the paper discusses their development and behaviour in operation. Subsequent improvements exemplified by the plant at Hinkley Point and Sizewell are described and reference is made to considerations affecting current designs. Although the design and construction of these nuclear heat exchangers represent little extrapolation beyond well-established principles and practice, certain peculiarities do require special attention. Amongst these is their radiation environment and necessity of placing ancillaries requiring routine attendance in appropriately shielded positions. Another requirement is a knowledge of the transient behaviour of the heat exchangers both in normal and in emergency operation. Yet another relates to virtual elimination of the possibility of leakage. The paper concludes with reference to future trends and designs of steam raising plant suitable for advanced conditions.
Achievement of Clean Conditions in Gas-Cooled Nuclear Reactors
Authors: Anderson E.
Published: October 2007

Precautions taken to ensure ‘clean’ conditions in the first civil nuclear power stations resulted in excessive costs and delays. These precautions are aimed at the elimination of materials which could poison the core, create a maintenance hazard, affect the fuel elements or increase the fire risk in the core.

The present paper reviews the subject in the light of the considerable experience of constructing and running reactors now available, and an attempt is made to assess the importance of the various precautions.
The Project Method of Teaching Creative Mechanical Engineering
Authors: Hayes S. V. , Tobias S. A.
Published: October 2007

An account is given of a scheme for teaching design-development engineering to undergraduates which has now been in operation since 1960 in the Department of Mechanical Engineering, the University of Birmingham.

The essential feature of this scheme is that selected groups of final year students are engaged on the design of research and/or teaching equipment currently required in the Department. These designs are detailed by second-year students and are subsequently manufactured by them during their vacation employment in industry. The manufactured designs are taken back by them to the University to be developed in the first term of their final year. Following this, the equipment is either fed into the teaching or research activities or re-designed to start on a new cycle. Thus, the students concerned get direct experience of the complete design-production-assembly-development sequence.

A description of the detailed working of the scheme, its organization and the experience gained in running it, is given. A number of completed designs are discussed. A detailed statement of the overall drawing-design teaching system is presented in Appendix I.
Job Evaluation
Authors: Norris A. Mc. C.
Published: October 2007

Job evaluation is a technique which seeks to provide a logical basis for the setting of comparative pay rates. The methods used originated in America over 35 years ago and most job evaluation plans are adaptations of the three original ones described in this paper. A new technique has been evolved in Britain recently which is very akin to job evaluation but far more sophisticated in its approach. As far as is known, this technique has only been tried in a limited way at one firm so that only a brief mention is made of it, despite its obvious interest.

Like a lot of other modern management techniques, job evaluation can do more harm than good unless human nature is taken into account. A man still wants to be regarded as a unique individual and so resents any attempt to fit him into a cold scientific pattern.

Success in job evaluation, therefore, depends largely on the personalities of those responsible and on the creation of mutual trust between management and men.
The Pendulum Mill—A New Method of Rolling Metals
Authors: Saxl K.
Published: October 2007

The Pendulum process is a new incremental rolling method for producing thin metal strip from thick plate. This is done in a single step, bypassing a sequence of conventional and often unproductive operations, such as process coiling, storing, annealing or cleaning. Rolling is carried out generally without preheating.

The forces in the reduction zone are largely controllable and comparatively hard alloys can be rolled without overloading the equipment.

The ingoing material is forced by feed rolls into a gap formed by converging paths of the work rolls which are moved backwards and forwards. The work rolls are freely rotatable, each being supported by two rows of backing rollers. The rolls are rotated solely by frictional contact with the strip and must remain loaded during the whole cycle. Deformation takes place during both strokes of the cycle. The limitations of the method are discussed and some results reported.
Nitrogen Oxides and Other Toxic Gases in Diesel Engine Exhausts
Authors: Middleditch H.
Published: October 2007

The mode of production of carbon monoxide and of oxides of nitrogen and those aspects of combustion which control the formation of these gases in a diesel engine are examined.

It is deduced that carbon monoxide production is principally a function of engine maintenance; on the other hand, there is an inherent characteristic for the production of oxides of nitrogen which can be ascribed to each engine design with the engine in standard trim.

The characteristic oxides of nitrogen production for various engine designs will be compared and those aspects of design and operation which control this characteristic will be considered.
Second Paper: A Simple Theory for Longitudinal Pressure Drop in the Presence of Lateral Condensation
Authors: Silver R. S. , Wallis G. B.
Published: October 2007

The use of the Reynolds flux to assess momentum transfer and pressure drop behaviour in condensation was a basic idea of a paper by Silver (1)†. In the present paper the same concepts are used with more consistent logic to develop a simpler and more satisfactory treatment. Experimental results of velocity profile measurements show that the assumptions made are permissible. The predictions from the improved theory are generally in accord with those previously given by Silver (1) and now confirmed by Wallis in the first of these two papers.
High-Reliability Servos: First Paper: Development of Redundancy Techniques for the Achievement of Highly Reliable Autocontrol for Nuclear Reactors
Authors: Lawrence L. A. J.
Published: October 2007

Plant autocontrol systems are subject to failure; those occurring in autocontrolled nuclear reactors may necessitate a trip, with attendant economic penalties.

Such failures may be avoided by designing autocontrollers which comprise a number of identical subsystems.

The practical significance is discussed of some of the requirements for achieving high autocontrol reliability, and it is shown how these requirements have been translated into detailed design of hardware for a research reactor in which autocontrol of neutron flux and period is required.

The underlying theme is that autocontrol of the plant can continue in spite of subsystem failure, but that careful vigilance must be exercised over the duration of the failure.

Various devices are discussed which help to increase the efficiency of a redundant autocontrol system. Daily proof tests and passive monitoring devices can ensure that no relaxation of vigilance is allowed.