bluuebunny/crossref_metadata_2025 huggingface dataset:
Loads Borne on Elastic Supports
Authors: Lamb E. H.
Published: October 2007

There are many instances in engineering practice of loads carried upon a number of supports which possess some degree of elasticity and where, owing to the number of the supports, the proportion of the load carried by each cannot be determined by the principles of statics alone but depends in a large measure on the elastic properties of the supports. Problems of this indeterminate type are of common occurrence in the theory of structures and the present paper describes an exact method specially suitable for application to such problems as occur in connexion with the wheel loading of railway rolling stock and locomotives, motor vehicles, etc., and in particular is directed to the question of the adjustment of the springs necessary to produce a desired distribution of the loads upon them. It is shown in this latter case that if the initial loading on the springs, i.e. before adjustment is known by direct measurement, the equations which give the amounts of the adjustments to be made in terms of the desired increments of load take a conveniently simple form, and the adjustments can be calculated and made once for all without any necessity for trial and error methods. A few simple examples are worked out in the paper and an Appendix contains a short account of an extension of Castigliano's second theorem from which the equations in the paper may be derived, and an example showing the application of the method to the adjustment of the wheel loading of a locomotive.
Drawing Office Practice in Relation to Interchangeable Components
Authors: Gladman C A.
Published: October 2007

The paper describes some features of the work of a special Service Committee set up by the Admiralty, for the purpose of standardizing drawing office practice in certain of their design departments.

Basic principles are established for the guidance of designers and draughtsmen when preparing drawings for interchangeable components, and logical methods of approaching solutions to dimensional problems and of stating these on drawings are discussed. Particular attention has been paid to such problems as the best method of analysing, and dimensioning and applying tolerances to interchangeable components which involve tapered, concentric, or positional features such as holes and studs.

Stress is laid upon the need for foreseeing, and avoiding as far as possible in the design stage, any special difficulties which may arise in practice in the construction of manufacturing equipment or of practical gauges for controlling the dimensions of components.

It is understood that the British Standards Institution have in contemplation the preparation of a handbook dealing with the subject of the dimensioning of production drawings and of indicating the tolerances on them. Such a handbook, when completed, not only would be of great use to industry at large, but wouldal so form a valuable textbook for courses of instruction to engineering students in technical colleges and universities. It is hoped that this paper may be the means of stimulating thought on this aspect of interchangeable manufacture and that it will provoke discussion which may lead to the development of a uniform system suitable for use both by Service Departments and by industry in general.
Controlling Pipe Line Surges by Means of Air Vessels
Authors: Blair J. S.
Published: October 2007

Tests have been carried out on the surge pressures in a suction and pumping main whose total length is some two and a half miles, there being air vessels on both sides of the centrifugal pump house. Surging in the delivery main was being aggravated by the presence of a non-return valve and after this had been removed and the surge reduced, it was possible to establish a relationship between the volume of air in the air vessel and the frequency and amplitude of the surge. It was then found that the surge could be considerably diminished and more rapidly damped out by what is believed to be a novel method, namely, the introduction of damping, which is effected by constricting the opening between the air vessel and the main.
Protective Air Vessels for Rising Pipe Lines
Authors: Binnie A. M.
Published: October 2007

A long rising pipe line should be protected against the damage due to shock (or “water hammer”) which might ensue if the pumps suddenly failed. The most satisfactory method is to fit an air vessel on the delivery side of the pumps. The connexion between the air vessel and the pipe line should be constricted so that the oscillations of the water-level in the air vessel are damped.

An approximate method is described in the paper for calculating the maximum expansion and pressure of the air, and its predictions are shown to be in satisfactory accord with experiment. The onset of water hammer, observed when damping was carried too far, was found to occur at velocities somewhat greater than theory suggests.
Design, Construction, and Use of Some Inspection Gauges
Authors: Leedham L. H.
Published: October 2007

The paper begins with a reference to the necessity of regarding inspection as part of the manufacturing programme. The provision of equipment for this purpose is just as important as the use of jigs and fixtures, and in all cases where “set-ups” would have to be made for inspection purposes, the provision of specially designed gauging fixtures is advised.

Some fundamental principles of such equipment are next discussed, the weak features in some and the advantages of adopting the good points of others being stressed. The use of the crossed-strip mounting, developed at the National Physical Laboratory, for indicating-arms is discussed, and the use of dial and signal indicators receives attention.

Descriptions are then given of varied applications to gauging apparatus for different components, each of which presents a problem in inspection. The possibility of utilizing the component itself, in such a way as to make it amplify variations in the feature being inspected, also receives some consideration. The multiple gauging of mass-produced components, using an ingenious indicator unit, concludes the descriptions of the practical applications.

In studying the examples, a mental comparison should be made with the problem which each case would present to the inspector, in the absence of the special equipment.
The Isothermal Flow of Gases through Beds of Granular Materials
Authors: Rose H. E.
Published: October 2007

In this paper it is shown that the equation of flow of liquids through beds of granular material, developed in a previous research, may be used as a basis for calculation of the rate of flow of gases through granular beds under isothermal conditions of expansion.

The equation covering the isothermal flow of gases through a granular bed is developed from an expression evolved by Unwin for the motion of a gas in a pipe, by the substitution of the equation for the flow of a liquid through a bed in place of the equation of flow of a liquid through a pipe.

The equation is verified by several experimental determinations and is shown to be in accordance with the experimental results of a number of different workers.

Examination of the equation developed shows that for beds of extremely open packing the pressure drop to maintain an assigned rate of flow is not a linear function of the depth of bed but for beds of the normal densities of packing the deviation from linearity is negligible.
A Comparison of Some Carbon Steels on the Basis of Various Creep Limits
Authors: Johnson A. E. , Tapsell H. J.
Published: October 2007

The present report has been prepared with a view to determining whether any relationship exists between the results of the various short-time and long-time creep tests, which will permit the use of short-time tests, not merely as a means of separating good from bad steels, but also as the basis of design stresses intended to give satisfactory performance of the steel over working periods of considerable duration.

Indications are given of some of the difficulties and limitations concerned in the use of short-time creep results in the case of carbon steels, and suggestions are made for some rational basis for steps which might be taken to offset these difficulties and limitations in applying the results of short-time tests to estimation of design stresses.
The Generation and Utilization of Steam in the Heavy Industries
Authors: Hider G. E.
Published: October 2007

The author has for many years considered that it should be possible to design a diagram for the graphical analysis of problems arising in the transmission of heat in boilers.

It became clear that such a diagram, comparable with the ideal indicator diagram or the temperature-entropy chart, could easily be designed if reliable and explicit data relative to transmission of heat by radiation were available.

The position seemed to be this: the simple efficiency formula ( T1 — T2)/ T1 could be used if the correct temperature T1 could be determined, assuming also that the variation in the specific heat of the gases at widely varying temperatures was relatively unimportant. This T1 temperature is not, of course, the temperature measured over the furnace bed, but the temperature which would be observed if the coal were burned in a highly refractory chamber instead of being subject to more or less rapid cooling by the adjacent heating surfaces of a boiler. Thus this so-called theoretical temperature may be calculated for any given coal and CO2 content, provided the latter is not influenced by air leaks.

The temperature of rejection T2 is, of course, easy to ascertain with accuracy.

The author expresses the hope that such a diagram may be of some value to lecturers, and examples of its use are given. Arising from the design of the diagram, the author proposes a method of investigating the heat transmission by radiation and convection through the plates of Lancashire boilers: other matters of importance to the heavy industries were dealt with in detail in the original paper, and the salient features are discussed in this abridgement.
Boiler Installations on the Continent, and Future Problems
Authors: Bock J. H.
Published: October 2007

On account of the diverse fuel situation on the Continent, boiler development since the 1914–18 war has been very different from that of Great Britain. The paper shows how combustion appliances such as travelling-grate stokers, grates for inferior coal, for lignites, and for pulverized fuel combustion, have been designed.

It became necessary for boiler installations to be designed for higher pressures and, over a comparatively short period, extensive experiments were carried out which led to various new designs in boilers, superheaters, economizers, air heaters, etc.

A possible line of future development is covered by reference to a scheme put into operation in 1930 by the West Moravian Electricity Works, Ltd., and the author concludes that two types of power station, i.e. the low pressure pit-head station for the burning of inferior fuel, and the high-pressure power station with district heating in towns, using fuels of low ash and water content, would form the ideal combination for the future.
An Experiment in the Use of a Standard Limit System
Authors: Loxham John
Published: October 2007

The limit system recommended by the British Standards Institution (B.S.I.) was issued first in 1906 and again in 1924, under the title of British Standard Specification No. 164, “Limits and Fits for Engineering”. The engineering industry of this country, it is contended, has found it impracticable to use the tables contained in these publications, and it would appear desirable to ascertain the reason for this striking neglect of so important a publication. There are numerous instances where certain limits have been taken from these publications, but the author is not aware of a single instance where the B.S.I, system is the only system used, and it is claimed that it supplies all the reasonable requirements of a designing draughtsman engaged on ordinary commercial engineering work. This state of affairs cannot be considered as satisfactory and the present paper is put forward in the hope that it will form the basis of a discussion, the findings of which will assist the appropriate committee in making suitable revisions to this British Standard publication.

The paper shows how a genuine attempt was made to use the B.S.I, system for every problem of design and manufacture for which standard limits seemed desirable, and how the system was modified only when it was found impracticable to use it in its original form.
The Development of Ultra High-Pressure Hydraulic Systems
Authors: Parker S. M.
Published: October 2007

Most engineers seek to reduce weight and bulk by the use of higher specific loading of their material. The hydraulic engineer is no exception to this; but his choice of working pressure determines to an unusually large extent the detail construction of most parts of the system.

The purpose of this paper is to examine briefly the reasons which lie behind this choice of pressure, with particular reference to the possibility of using a higher working pressure than is in common use at present for the lighter forms of equipment in aircraft, automobile, and industrial design.

Within the scope of this paper it will only be possible to examine the essentials of the problem, and to suggest likely solutions, with the knowledge that time and experience will probably provide other and better answers.
An Alternative Form of Pressure Vessel of Novel Laminar Construction
Authors: Birchall H. , Lake G. F.
Published: October 2007

Although Class 1 welded vessels have been used to an increasing extent for what might be termed moderate-pressure purposes, most of the vessels required for chemical reactions at really high pressures have up to the present been of forged construction—at any rate in this country. There are certain drawbacks and limitations associated with the forging method of construction, and attempts have therefore been made to develop an alternative type of pressure vessel. One such attempt is that of the “multi-layer” vessel developed in the United States by the A. O. Smith Corporation. This consists of a central welded tube on which successive layers of relatively thin plate are wrapped and welded. The present paper describes a vessel of novel laminar design, the main advantages of which are that the vessel can be built up from plate, which is relatively cheap and available from many sources of supply, and the actual construction and assembly does not call for equipment other than that likely to be found in a good engineering construction shop. Furthermore, the present proposed method of construction will allow the manufacture of vessels far larger than can be produced as single forgings, where the limit in regard to ingot size has already been reached. Two of these laminar vessels have been constructed and have given satisfactory service at 350 atmos. pressure for some years. The paper describes the design, construction and testing of these vessels and makes observations on the cost aspect and the future possibilities.
Design of Centrifugal Spray Nozzles for Outputs Up to 1,800 Gallons Per Hour
Authors: Doble S. M.
Published: October 2007

Work previously carried out on spray nozzle design† provided data from which spray nozzles of defined characteristics could be constructed having an output range of from 4 to 200 gal. per hour. This proved inadequate for several plant installations, so work has now been completed extending the range up to 1,800 gal. per hour with spray cone angles up to 150 deg.

Section I deals with the design of the nozzle and the calibration results at various working pressures; section II gives the methods used for determining the volume distribution in the spray cone, the spray cone angle and the particle size distribution with some typical results; and in section III, nomograms relating the critical dimensions of the spray nozzle with output, pressure, and spray cone angle are given, with details of the use of these nomograms.

As a result of the previous work and this present work, it is possible to give the exact dimensions necessary for a nozzle to deliver any quantity of water from 4 to 1,800 gal. per hour in the pressure range of 20 to 100 lb. per sq. in. Further, by the correct selection of the number, shape, and size of the channels in the distributing washers and the exit orifice diameter, a spray cone angle of any value up to 150 deg. can be obtained.
Journal Bearing Lubrication and Design
Authors: Thomson A. S. T.
Published: October 2007

The paper summarizes the results of an experimental investigation on the effects of variation in bearing width and radial clearance on the operating conditions of centrally loaded clearance journal bearings, the bearing arc being kept constant at 120 deg. The investigation, which was carried out prior to 1940, is complementary to an earlier paper by the author in which the effects of variations in bearing width and arc of embrace were investigated. The experimental results are compared with theoretical values modified by the relevant leakage coefficients. The measure of agreement obtained indicates that theoretical values so modified may be used with confidence in design.

A short series of experiments is described; in these, high-point contact at starting and stopping is eliminated by supplying oil to a groove in the loaded side of the bearing at a pressure sufficiently great to overcome the applied load. The effect of a groove on the loaded side of the brass under various conditions of lubrication is investigated.
Modern Cutting Tools and Machine Tool Design
Authors: Eatough C.
Published: October 2007

The object of tool research is to reduce the cost of production. The paper describes how the cost of production is determined to a great extent by the rate of feed; and high cutting speeds have been developed in order to give high rates of feed.

The changes in machine design which have been brought about by the introduction of carbide tools are discussed, and also the limitations of the tools are mentioned. One of the limitations is the necessity for cutting at high speeds, and this has brought to light many machine design problems in view of the necessity of providing not only for high speeds but for wide speed ranges, as carbide tools cannot be used at present for low-speed tools such as threading dies.

Tool life is largely determined by cratering and the rate of crater growth is dealt with at varying speeds and feeds.

Reasons are given for the effectiveness of the grooved type of turning tool which encourages the formation of corkscrew type chips.
Plastic Stress-Strain Relations
Authors: Shepherd W. M.
Published: October 2007

The author derives stress-strain relations which are applicable to problems in which the elastic and plastic strains are of comparable magnitude. Two alternative criteria are used, one based on the Mises-Hencky function and the other on the maximum shear stress. Shear stress-shear strain curves are deduced from tensile stress-strain curves and the result is in one case compared with experiment. The problem of a thin tube strained in tension beyond the onset of plasticity and then subjected to an increasing torque is considered, and the tensile and shear strains due to the torque are found. A result relating to the energy lost in plastic straining is obtained.
Researches into the Deformation of Metals by Cold Rolling
Authors: Ford Hugh
Published: October 2007

A large number of experiments have been carried out on an experimental cold rolling mill installed at Sheffield University by the Steel Industry, and this paper summarizes the results obtained. The experimental technique is described, and details are given of the mechanical tests made on the strip materials used.

In connexion with various theories of rolling, the yield stress characteristic of the strip is required. Two methods of determining the yield stress—one depending on a tensile test, the other on a compression test—are put forward. The principal theories of rolling are examined in relation to the experimental results. Using the theory of Orowan as criterion, it is found that the theories of von-Karman and Ekelund yield satisfactory accuracy for practical calculation of the roll force over the normal range of cold rolling conditions. These theories do not allow the torque to be directly calculated, but it is shown that the “lever arm” method can be modified to allow for roll flattening, and can then be used, in combination with the simple methods for roll force, to determine the torque.

It was considered that a method of calculation was required, simpler than Orowan's exact method, yet applicable when rolling with strip tension. A new theory was evolved which fulfils these requirements, and is examined in relation to the experimental results. The method allows of further simplification, so that calculation is reduced to a minimum, most of the information being obtained from graphs, with very little loss of accuracy. It is shown that there is an approximate relationship between the roll force and the corresponding energy of deformation. This relationship is used in the “energy method” for rapid calculation of rolling schedules.
The Part-Load Performance of Various Gas-Turbine Engine Schemes
Authors: Mallinson D. H. , Lewis W. G. E.
Published: October 2007

The literature on the gas turbine already contains much information concerning the performance of the “constant-pressure” cycle both in its simple form and in its more complicated forms involving intercooled compression, reheated expansion, and heat exchange. Such information enables the design performance of a particular engine to be estimated, but there appears to be very little published work to help the designer to foretell what changes in performance are to be expected when particular engines operate at non-design conditions. What work there is seems to have been restricted to very simple engines, and is often further limited by the assumption of unalterable component performance characteristics.

In this lecture we attempt to include in a general comparison of part-load performance characteristics not only the simpler designs but also some of the more complex turbine engines which will be needed for land and marine applications. At the same time, by considering, in appropriate cases, the influence of changes in the assumed component performance features on the part-load operation of an engine, a broadening of the basis of comparison is made possible. As a result of the work we shall describe we feel that, although as yet so little of the possible field of investigation has been surveyed, it is nevertheless possible to indicate the main guiding principles by which the comparative part-load performance of different gas turbine schemes may be assessed.
The Development of Variable Specific Heat Charts and Graphs, and their Application to Internal Combustion Motor Problems
Authors: Walker W. J. , Rogers C.
Published: October 2007

The paper describes the development of a method of investigation, both analytical and graphical, into problems relating to internal combustion motor design and performance.

The authors have provided a chart, together with auxiliary graphs, by means of which theoretical indicator diagrams may be constructed for any internal combustion engine cycle under conditions of variable specific heat. It may also be used for studying any indicator diagram obtained under test conditions.

The main feature of the chart is the provision of means to enable it to be used for any hypothetical or initial conditions encountered in practice. It has been so generalized as to enable it to be used, not only for the examination and construction of indicator diagrams involving expansion down to atmospheric pressure or to the initial compression volume, but to any degree.

The auxiliary graphs provide a means whereby the thermal efficiency, mean effective pressure, and other essential quantities may more easily and readily be calculated than has previously been possible.

To illustrate the method of using the charts and graphs, examples have been worked out for the dual combustion cycle, the Diesel cycle and the constant volume cycle.
The Application of Free Jets to the Mixing of Fluids in Bulk
Authors: Fossett H. , Prosser L. E.
Published: October 2007

A laboratory investigation with scale models was made to determine the performance figures of free jets for mixing fluids in large circular tanks, primarily for the war-time purpose of utilizing existing underground storage tanks for blending aviation petrol. The investigation showed that a simple jet directed across a diameter of the tank caused complete mixing in a time approximately equal to 8 D2/√ QU seconds, where D was the tank diameter, Q the volumetric rate of flow through the nozzle, and U the velocity at the nozzle—all expressed in self-consistent units—provided the time taken to inject the second fluid was less than half the total time. The model tests also showed the necessity of using a sufficiently large vertical component of the jet velocity to avoid stratification when mixing fluids of different densities, and quantitative values depending on a modified type of Froude number have been determined. The tests predicted that mixing by simple jets would occur in a time much shorter than is usually taken by conventional mixing devices, and this has been confirmed in full-scale practice in a number of cases varying from relatively small lubricating-oil tanks to four million gallon petroleum tanks. Possible applications to other mixing problems, such as the sterilization of swimming baths, are briefly discussed.
The Design and Operation of the Parsons Experimental Gas Turbine
Authors: Bowden A. T. , Jefferson J. L.
Published: October 2007

The paper describes the principal design features of the Parsons 500 h.p. experimental industrial gas turbine, and records the operating results obtained in running the plant since December 1945.

A section is devoted to some of the preliminary investigations on the compressor, combustion, and heat exchanger components, undertaken prior to the building of the unit.

Some of the early work on the axial-flow compressor is, it is considered, of particular interest.

One of the most important questions remaining to be answered in gas-turbine operation, is the quality of the oil fuel which can be regularly and reliably burned. Details are included in the paper of operating results using a residual oil fuel. Considerable trouble was experienced as a result of the building up of deposits in the turbine blading; these deposits are analysed and compared with the parent oil-fuel analysis, and photographs of spindle and cylinder blading show the nature of the build-up.
Further Researches in Fluid Flow through Beds of Granular Material
Authors: Rose H. E. , Rizk A. M. A.
Published: October 2007

In this paper the results of previous researches are extended and equations developed by means of which the resistance to fluid flow offered by a bed of spherical or non-spherical material may be computed with reasonable accuracy.

The equations cover a range of porosity of the bed from 30 per cent to 90 per cent and practically the whole of the technically important range of Reynolds number, while particle shapes ranging from spheres to hollow cylinders, shell insulators and wire nails are covered. A new curve for wall-effect, depending upon Reynolds number, is also included.

It is believed that the present work is of more general application than any which has previously been suggested.
The Dynamic Principles of Machine Foundations and Ground
Authors: Crockett J. H. A. , Hammond R. E. R.
Published: October 2007

Recent research on soil dynamics and machine foundations has revealed that there are correct design principles for vibrating foundations which can be used without dependence on empirical methods.

The most important discovery has been that any ground can oscillate at its own particular natural frequency, and machines and ground quite often vibrate in resonance. Stress waves, some with similar properties to light and sound waves, are of considerable and often of paramount importance, for their interaction can lead to structural failure.

The authors have considered only steadily running machines and have merely indicated the mathematics, the designer being advised to consult the proper engineering text-books for a fuller account. They hope that the problem has not been over-simplified and that their conclusions may form a sound basis for future design practice.
Preliminary Report of Developments in Interrupted Surface Finishes
Authors: Martz L. S.
Published: October 2007

Expanding interest and investigation in the development of interrupted surface finishes indicates the current trend renascent as the result of experience during the 1939–45 war with various types of mechanical equipment. It is here attempted only to highlight the results of service use and laboratory tests in three generic types: mechanically, chemically, and electrolytically generated surface finishes and their combinations.

Because of the innumerable variables involved by the wide range of functional use, only the most general conclusions are drawn to prompt further study and investigation of this promising development, and to emphasize the desirability of avoiding controversial interpretations and attempted correlations until more data are available.
The Ideal Performance of Petrol Engines
Authors: Leah A. S.
Published: October 2007

A method of calculating the ideal thermal efficiencies of petrol engines is described which may be of value when thermodynamic charts for the particular fuels and mixture strengths under consideration are not available. Results of such calculations are given for engines running on octane, benzene, and ethyl-alcohol at compression ratios between 4/1 and 9/1 and at various mixture strengths.

From the relationships between thermal efficiency, specific fuel consumption, volumetric efficiency, mixture strength, and indicated mean effective pressure, new charts based upon the familiar “consumption loop” diagram are developed. These charts yield information not generally obtained from the consumption loop diagrams, and the volumetric efficiency of the engine may be determined. The ideal consumption loops based upon a standard volumetric efficiency are included on the charts, and these values are readily corrected to the actual engine conditions by a simple construction. This enables a direct comparison between actual and ideal engine performance to be made, from which the relative merits of engines running under widely diverse conditions can be determined.
A Generalized Analysis of the Regenerative Steam Cycle for a Finite Number of Heaters
Authors: Haywood R. W.
Published: October 2007

The paper establishes a theoretical basis for approximate relationships which have been found to apply to feed heating calculations for a wide range of operating conditions. The designer, looking for short-cut methods in the calculation of multistage feed heating problems, will not find sufficient accuracy in the approximations to satisfy his more precise requirements. Other papers† have already catered for such requirements, but it is hoped that the present paper will give the designer and student a more complete understanding of the problem.

The determination of the optimum range of feed heating, and the improvement in heat consumption due to feed heating at the optimum condition, for a system employing n feed water heaters is investigated in the paper. A simple approximate relation is derived for these two quantities by expressing them non-dimensionally in terms of the respective quantities for a system employing an infinite number of heaters. The optimum distribution of heating amongst the heaters in the system is also determined analytically.
Some Developments in Instrumentation for Air-Flow Analysis
Authors: Todd K. W.
Published: October 2007

Evolution of research into flow conditions in confined spaces, such as model ducts or blade cascades under high subsonic or transonic air velocities, has necessitated the development of specialized forms of instrumentation for both optical and physical analysis. In this paper some of these special instruments are described, and an example of their application to a compressor-cascade examination in a high-speed wind tunnel is included.
Application of the Method of Characteristics to the Transient Flow of Gases
Authors: Kestin J. , Glass J. S.
Published: October 2007

Although problems relating to non-uniform flow of a compressible fluid have been tackled by a number of workers, investigations have generally been limited to the study of one-dimensional non-viscous adiabatic flow. This type of flow, however, is associated with so many problems encountered by mechanical engineers that an easy and reliable method of solution is extremely important.

The method of characteristics described in this paper provides a comparatively simple method of solving such problems by a graphical process. It consists essentially in the simultaneous construction of two corresponding diagrams:—

(a) The state diagram showing the changes in the state of the fluid produced by spreading disturbances. (b) The position diagram depicting the spreading of the disturbances.

The graphical construction of these diagrams is based upon certain special mathematical properties of the equations which describe the motion and enable boundary conditions corresponding to any particular problem to be readily taken into account.

Applications include the phenomena occurring in internal combustion engine exhaust and intake pipes, in particular, those relating to the Kadenacy system of scavenging. It is also applicable to the type of flow encountered during the emptying of cylinders, in pulsating ram jet engines and, in general, in any engine making use of the intermittent flow of gases. The phenomena occurring in long indicator passages during tests on high-speed engines also come within its scope.
An Experimental Investigation of Plastic Stress—Strain Relations
Authors: Morrison J. L. M. , Shepherd W. M.
Published: October 2007

The paper describes tests carried out on a steel and on an aluminium alloy, with the object of discriminating between and assessing the merits of the “incremental” and “total” plastic strain theories in the region where the elastic and plastic strains are of comparable magnitude. The tests appear to establish that for these two materials the “total” type of theory is incorrect, and in some instances may lead to large errors; for the types of stress applied, the experimental results give strong support to the “incremental” type of theory, and indicate that a particular variant of this theory (which uses the Mises-Hencky function as the criterion of plastic flow) gives results of satisfactory accuracy.
Gas Cooling and Humidification: Design of Packed Towers from Small-Scale Tests
Authors: Carey W. F. , Williamson G. J.
Published: October 2007

On plants in which gases are processed, the gases are often brought into direct contact with water—usually in packed towers. The purpose may be to cool a hot gas, to increase the humidity of a gas, or, in the well-known special case of water-cooling towers, to cool water by contact with atmospheric air. These processes involve simultaneous transfers of sensible heat and water vapour, and existing methods of analysis are complex and laborious, except for the cooling of water, for which Merkel's total-heat method has long been available.

Merkel's approximate solution offers the engineer a simple method of working out, for any operating conditions, the amount of heat transferred and the “driving force” available for transferring it. The present paper generalizes the total-heat method and, with a permissible sacrifice in accuracy, preserves the essential simplicity of the water-cooling treatment for gas-cooling and humidification processes. To complete the design of a packed tower, a knowledge is required of the characteristics of the packing. Information obtained in small towers is given for a number of packings, and a worked example shows how to apply the method of treatment, and the packing data presented, to the design of a large plant tower.
The Effect of Macro-Roughness on the Performance of Parallel Thrust Bearings
Authors: Salama M. E.
Published: October 2007

This work was initiated to investigate the effect of surface macro-roughness on the performance of the parallel-faces thrust bearing and, at the same time, to find a rational explanation of its behaviour. The problem is treated both theoretically and experimentally and the main result arrived at indicates that macro-roughness is a prime factor in the behaviour of the bearing, as it provides passages which both feed the surfaces with the lubricant and allow the formation of hydrodynamic films so that the performance corresponds closer to that for film lubrication.

Further work on micro-roughness is proceeding.
The Gas Turbine in Perspective
Authors: Constant Hayne
Published: October 2007

A survey is made of the progress that has been achieved in Britain over the last decade in improving the performance of gas-turbine components. The effect of these improvements on the performance of jet-propulsion engines is then shown.

An attempt is also made to foresee the probable future trend of progress and to assess the nature of the important problems which have still to be overcome before the gas turbine can be more generally applied.
Some Fluid Dynamic Research Techniques
Authors: Carter A. D. S. , Andrews S. J. , Shaw H.
Published: October 2007

One of the main features characterizing gas-turbine technology has been the aerodynamic approach adopted towards such items as the axial compressor and turbine, the ducting components, and so forth. This has necessitated a lot of research into many basic fluid dynamic problems which had hitherto received little or no attention. Equipment has had to be constructed and special techniques developed or adapted to meet the new requirements. This lecture gives an account of such work, with particular reference to the methods adopted at the National Gas Turbine Establishment (N.G.T.E.).

In the first part of the lecture the simple cascade tunnel has been described. Its design involves many features encountered in work of this nature, and touches on many basic principles. Following this, some special forms of cascade tunnel are described. For example, heat-transfer tunnels, an icing tunnel, and annular tunnels are considered as departures from the conventional. Following a few notes on ducting research, the final section deals with general instrumentation techniques. The measurement of air pressures and direction is considered, together with the measurement of gas and wall or blade-surface temperatures. Some mention is made of boundary layer investigation and high-speed flow visualization. An apparatus for determining the potential flow past blades is also described. All these have been selected as examples representing techniques which have contributed in some way to our knowledge, and hence to the development of the gas turbine.
Analytical Investigation of Certain Types of Machine Frames Cut from Steel Plate, and Experimental Verification of Some of the Results by Photo-elasticity
Authors: Sag N.
Published: October 2007

Closed machine frames consisting of constant-section uprights and variable-section top and bottom bridges, as illustrated in Fig. 24 and loaded as indicated., are often fabricated from steel plate. They are used in the construction of punch and press frames and are subjected to dynamic loading. The design of such frames involves the solution of a statically indeterminate problem. The expression for the indeterminate moment involves the numerical solution by tables† of improper integrals such as

The object of this paper is to find dimensionless solutions of such frames and investigate the influence of the x = hmax/ h0 ratio on the static and energy load capacity of these frames. Some results of the theoretical investigations are verified by photo-elastic analysis.
Naval Gearing—War Experience and Present Development
Authors: Joughin J. H.
Published: October 2007

While the reduction gearing fitted in turbine-driven naval ships generally gave reliable service in the 1939–45 war, there were some costly exceptions. Turbine blade failures resulting from vibration, “scuffing” on trials (fortunately cured by hand dressing), and breaking of teeth at the roots, causing extensive damage requiring replacement of the gear-set, were experienced.

Examination of these failures revealed shortcomings in manufacture and design, which have now been largely remedied, and it has been possible to establish standards of manufacture necessary to ensure reliability, and to make economic use of available techniques and materials.

The use of harder steels hobbed and shaved in a heat-treated condition, or steels, case-hardened and then ground, or, in the very large sizes, air-hardened and ground, now presents no technical obstacle. Gears of alternative designs—hobbed and shaved, or case-hardened and ground—are being made for service at sea. They will be subjected to the same load conditions.

Other gears of identical design will be subjected to “back-to-back” tests on shore to investigate their further possibilities.

The modifications to pinion helices to compensate for deflexion under load and to safeguard against misalignment, the methods by which they are being applied to these test gears, and the opportunity they provide for making effective use of the full length of pinions, are all examined.
Fundamental Dynamics of Reaction-Powered Space Vehicles
Authors: Thompson L. N.
Published: October 2007

This paper is an attempt to place in correct perspective the current considerable speculation regarding the problem of interplanetary travel.

The concept and importance of “escape velocity” is dealt with first, and then the elementary mass-ratio equations for the motion of a space vehicle under various conditions are derived.

Available energy sources are considered next, the operational parameter being jet velocity. It is indicated that the maximum jet velocity conceivably attainable with chemical fuels is of the order of 20,000 ft. per sec. Nuclear fuels are dealt with and it is shown that, while energy potentials are very high, the problem of practical utilization is formidable. A thermodynamic type of atomic rocket motor employing an inert reaction mass to absorb the fission energy is postulated, and it is demonstrated that the heat transfer and materials requirements present a problem of the first magnitude.

The influence of propellent density on the performance characteristics of both chemical and atomic rockets is discussed, and it is shown that propellents giving high jet velocities may not necessarily be the best to use.

Orders of magnitude for the mass ratios required for various interplanetary flights are established, and it is indicated that only an atomic drive will render them small enough to be attainable in practice.

It is concluded that, unless nuclear energy can be suitably harnessed, economical space-travel will not be feasible.
The Fundamental Geometry of Cutting Tools
Authors: Stabler G. V.
Published: October 2007

A full geometrical analysis of a cutting tool edge is made, in which an effective rake of universal application is defined in terms of the primary rake and the angle of obliquity of the edge. The fundamental angles are related in an easy manner to the traditional workshop terms, and may readily be applied to any cutting tool. A law of chip flow is given and its effects on the resulting chip shape are analysed. The effect of unit cube passing through the shear plane is also analysed and a method is given of finding the direction cosines of the axes of the ellipsoid of stress.

The flow law is used to find the directions ofthe cutting force between chip and tool and its various components. An examination of velocity and force diagrams for oblique cutting in Merchant's shear theory leads to a debatable result at variance with his fundamental machining equation.

Although predominantly theoretical, the paper has a practical background.
Water Hammer in a Pumping Main and its Prevention
Authors: Binnie A. M. , Thackrah D. G.
Published: October 2007

An earlier investigation has been continued on the protection of a rising water main against the consequences of a sudden interruption in the supply. In place of the air bottle previously tried, an automatic air-inlet valve was placed at the lower end of the pipe-line. Experiments on a laboratory scale showed that the cushion of air thus introduced brought the returning water column to rest without sound or shock. Theoretical calculations of maximum pressure and of air drawn in were verified. The lift of the pipe-line being small compared with its length, it was found that, over the range of velocity usually employed, the maximum pressure set up by the returning column diminished as the initial velocity of the interrupted supply was increased.

With no protective device in use, a series of violent impacts took place owing to the column striking and rebounding from the closed valve at the lower end of the pipe-line. An electronic gauge, having a very high natural frequency, was used to measure the magnitude and duration of the shock pressures. Its indications were generally in accord with an analysis based on the usual theory of pressure waves, but the maximum pressures actually recorded somewhat exceeded the theoretical estimates, owing to the existence of additional pressure fluctuations caused by reflections from bends, sockets, and other discontinuities in the pipe-line. The insertion of a spring-loaded relief valve only slightly reduced the shock pressures.
Design Stresses in Fillet Weld Connexions
Authors: Koenigsberger F.
Published: October 2007

Intuition and personal opinion, rather than theoretical investigation, have often been the main guides in the determination of design stresses for fillet weld connexions. Excessive safety at the expense of accuracy and economy have resulted in weld connexions which, although they did not fail under working conditions, were not always economical.

In the case of eccentrically loaded joints the stress ftorsion under a torque T has been determined by using the polar moment of inertia J of the weld throats: ftorsion = Tr/J, where r is the distance of the extreme fibre from the centroid of the weld throat. This method, though accurate enough for closed weld arrangements, resulted in uneconomical sizes for other arrangements. This paper suggests a means of determining the working loads of eccentrically loaded fillet welded joints by working out the stresses in the plastic state prevailing immediately before failure occurs. From this calculation the value of the failing load is obtained, which is divided by a certain load factor, the result being taken as the permissible load. If the results are represented in the form of graphs the time spent on calculation is considerably reduced. Practical experiments gave results which were in close agreement with the result of these calculations.

In the second part of the paper, the two differing opinions on the best arrangement of fillet weld connexions joining rolled angle sections to gusset plates are investigated, so far as their effect upon the strength of the assembly is concerned, and no difference is found with regard to the static strength of the assembly, while stress peaks at the end of the welds may indicate a weakness of one arrangement under fatigue loading conditions. Further research in this direction is suggested.