bluuebunny/crossref_metadata_2025 huggingface dataset:
Modern Methods of Water Treatment
Authors: Walter A. J. R.
Published: October 2007

Water is one of the most important raw materials used in industry. Its uses are multifarious, including the processing of other materials, steam and power generation, cooling condensers and water-jacketed machinery, and for drinking purposes.

It is often spoken of as “pure”, but in fact seldom is. Indeed, all natural water supplies contain impurities which often have a profound and far-reaching effect on the products being made and on the manufacturing costs.

This fact has become more and more realized as industry has progressed. The introduction of new processes for materials and more efficient power generation has in turn made essential the removal of even extremely small amounts of impurities from water that a few years ago would have been tolerated. For example, the increase in boiler pressures alone over the last twenty-five years has called for complete revision of the quality standard of boiler feed water.

Fortunately those responsible for research into, and practising the art of, water purification have kept a step ahead of these new requirements and most waters can now be treated in one way or another so as to render them suitable for practically any purpose.

Revolutionary discoveries have been made and applied in the field of water treatment. This paper describes the major advances, among them new crystallization and precipitation processes developed for lime-soda softening and particularly the entirely new chemical field discovered in hydrogen ion exchange materials and acid adsorption materials. The combined use of these two new discoveries has resulted in the development of equipment for the production of the equivalent of distilled water without heat or evaporation.
Low-Pressure Ash-Sluicing Systems, with Particular Reference to Power Station Practice
Authors: Carr T. H.
Published: October 2007

The purpose of the paper is to outline some of the salient features of the low-pressure recirculating water systems of ash handling, and to discuss some of the difficulties encountered with the pumps and the associated equipment employed. The author introduces his subject with a general consideration of the factors affecting the design of the ash plant, including its location in regard to the rest of the power station, the best type of plant to employ, and the general working conditions of the power station itself. This is followed by a description of the low-pressure systems for the water-sluicing of ashes and the methods of handling and disposing of the material. Space is also devoted to those features which require particular attention in order to secure the best results in operation. The physical characteristics of boiler ash are considered in some detail and typical ash and grit analyses and properties are given.

One of the most important problems arising in this field is the corrosion which takes place in ash handling plant. The author gives details of the loss of metal in such circumstances, and gives the results of carefully controlled tests. The chief desiderata in the design of troughs and pumps are also outlined, and the paper concludes with some useful information on the costs of operation and maintenance of ash-handling plants.
Expanded Tube Joints in Boiler Drums with Special Reference to the Battersea High-Pressure Boilers
Authors: Shannon W. B. , Pratt C. W. , Webb T. B. , Carlson W. B.
Published: October 2007

Particulars are given of the major pressure parts of two high-pressure boilers installed at Battersea Power Station, each comprising four alloy steel drums and their interconnecting mild steel tubing. Their design and working conditions are described, and a historical review is presented of their erection and of problems which arose whilst rendering the expanded tube joints leakproof. The gradual resolution of these problems is then traced through several stages. It was realized that the leakage was fundamentally due to the elastic strain which occurs in the tube holes of highly stressed drums, which, at Battersea, amounts to about twice that pertaining to mild steel drums. The holding power of the joint is thus relaxed to an abnormal extent, sufficient to permit leakage. The elastic deflexions, or total “spring” of the joint, resulting from the expanding operation, must therefore be correspondingly increased to accommodate the increased drum strain.

Various suggested methods of achieving this are reviewed. Insertion ferrules were selected as the most promising, and experimental development tests to investigate its possibilities are described. A full-scale rehearsal of the method carried out on one of the steam receivers is recorded, and this is followed by a description of the final ferruling and testing of both boilers. A number of general observations and conclusions are given, and the subject of leakage and its causes is discussed in some detail.

It is concluded that full advantage can be taken of the benefits which result from the use of high-tensile steel boiler drums, with mild steel tubes expanded into the drums. It is, however, essential that in the design stages the expected operating conditions of the expanded joints should be investigated on the lines suggested in this paper.

The adoption of high-tensile steel ferrules as a feature of original design is justified by the results obtained at Battersea.
Powder Metallurgy
Authors: Newson J. E.
Published: October 2007

The term “powder metallurgy” covers the art of producing objects from metal powders, with or without the addition of non-metallic constituents. The powders may be pressed to a desired form in a suitable die and subsequently or simultaneously heated to produce a welded, alloyed, or coalesced mass. The material may then be suitable for immediate use or may be further worked by conventional methods, as, for example, by drawing down to fine wire. The chief advantages of this technique are that (1) it is possible to produce articles having unique properties unobtainable by other methods, e.g. controlled porosity; (2) it offers a method of producing parts in metals which cannot be melted commercially or only with considerable difficulty, and do not lend themselves to casting; (3) it is suitable for mixtures of metals and non-metals; (4) it can be used for metals which do not alloy; (5) it can be applied to metals of widely separated melting points or greatly different densities; (6) it offers a mass-production method of producing large quantities of parts identical in size and quality, perhaps of complex shape, without further operations; and is specially competitive where final machining constitutes a large proportion of the finishing costs by conventional methods. The limitations are: (1) restriction on the size of parts that can be produced on the presses available; (2) the restriction on the design of parts that lend themselves to pressing; (3) the fact that large quantities are required to justify the cost of dies and tools; (4) the cost of metal powders; and (5) the fact that the volume of the uncompressed powder is 2–3 times that of the finished piece.

Future developments appear to lie in the direction of hot pressing, extended use of the process as the preferred technique for small parts in iron and other metals, and in combinations which retain desirable characteristics of the component metals, e.g. high wear resistance coupled with high electrical conductivity, which powder metallurgy makes possible in a way unobtainable by other means.
Elementary Principles of Plant Organization and Maintenance for Civil Engineering Contractors
Authors: Parrack H. O.
Published: October 2007

The paper has been written as the result of evidence to the effect that the general standard of the application of plant to the requirements of the civil engineer in this country is in need of improvement.

After brief reference to the position of the mechanical engineer in civil engineering industry, sections are devoted to repair depots, site maintenance, stores, mechanical plant organization, and personnel. The methods advocated have been tried in practice during some years' experience with a considerable volume of widely differing classes of plant, employed on contract sites of various types and sizes.

No attempt is made to explain the actual work of operating and maintaining any particular type or make of machine—a matter which is related to the intention of the paper only to the extent by which the same principles of organization might apply.
Fluid Film Lubrication of Parallel Thrust Surfaces
Authors: Fogg A.
Published: October 2007

During the course of an investigation into the general characteristics of various types of thrust bearing, it has been shown that opposed parallel surfaces, under certain conditions of operation, have a load carrying capacity approaching that of tilting pad bearings of the Michell type and of the same bearing area. Considerable evidence has been obtained, such as the low friction losses, the dependence of coefficient of friction on viscosity, speed and load, and the apparent absence of metallic contact, which strongly indicates that these bearings operate under fluid film conditions. Their performance does not seem to depend on a rounded inlet edge, and the apparent establishment of fluid film conditions without the usually accepted requirement of convergence of the bearing surfaces is regarded as a new phenomenon in lubrication. A tentative theory on broad lines is suggested as an explanation of the behaviour.
Steam Flow in Nozzles: Velocity Coefficient at Low Steam Speeds
Authors: Giffen E. , Crang T. F.
Published: October 2007

A considerable amount of controversy was raised by one aspect of the results reported by the Steam Nozzles Research Committee of the Institution over the years 1923–30. This was concerned with the variation of the velocity coefficient of a steam nozzle at low steam speeds, the Committee's results showing a tendency to higher values of coefficient at very low speeds. The work described in the present paper was undertaken to provide additional experimental evidence on this point and, in order to be comparable with that of the Committee, was carried out on apparatus employing the same general principles, but embodying certain improvements in detail.

The impulse plate method was used in determining the steam velocity at the exit from the test nozzle. The apparatus was designed on a small scale for use with a small self-contained steam generating unit, and particular care was accordingly given to accuracy in all the necessary measurements. The design eliminated frictional effects in the determination of the force on the impulse plate, and tests could be carried out with wet steam as well as superheated.

Two series of tests were made, one with steam superheated after expansion and the other with expansion into the supersaturated region. The exit velocity varied from about 500 to 1,200 ft. per sec., the final pressure being nominally atmospheric in all cases. The results showed that the velocity coefficient decreased continuously from the maximum to the minimum steam velocity, and that the values of the coefficient were substantially the same for the two series at corresponding speeds. This result is not in agreement with the Steam Nozzles Research Committee's work, but confirms the conclusions of other investigators in this field.
The Disk Spring or Belleville Washer
Authors: Ashworth Graham
Published: October 2007

The conical disk spring, often known after the original patentee as the Belleville Washer, has considerable potentialities for cushioning purposes, but its use in this country has been restricted owing to the lack of published information regarding the load-deflexion and stress-deflexion relations obtaining.

The circular conical disk of constant thickness, with a concentric hole and under central loading, is analysed in theory and design. Part I deals with theoretical aspects of the single disk, shows that a range of load-deflexion curves can be obtained (the shape of the curve depending on the ratio of the free camber to the thickness of the disk) and develops the relation between the distribution of internal stress and the ratio of the outside diameter of the disk to the inside diameter (showing that for economic utilization of space and material this ratio should not be more than two). Part II deals with the design of nests of disk springs, with particular reference to the use of these nests for buffering duties outside those for which helical springs can be easily employed. A figure for the maximum permissible calculated stress is suggested and a set of simple formulae which facilitate rapid design is developed from a consideration of the storage of energy under deflexion.
The Deflexion of a Thick Plain Ring under a Uniformly Distributed Couple
Authors: Johnson A. E.
Published: October 2007

Several theoretical methods of estimating the deflexion of a thick plain ring under a uniformly distributed couple have been published, both in this country and in the U.S.A. Probably the best-known of these theories is that of Dr. R. W. Bailey.† In all cases the treatment has not been rigid from a mathematical point of view, the axial or shear forces in the ring notably being neglected, and the load being assumed concentrated on particular loading circles whereas in fact it is distributed over an appreciable area.

The present paper attempts to treat the problem in a more rigid manner, with due consideration of the effect of load distribution.

Expressions for the axial and radial deflexions, and the axial, shear, radial, and circumferential stresses in the ring are developed, and values of these functions are obtained for a wide range of ring dimensions, and are compared with the values of similar quantities obtained by the use of the theory of Dr. R. W. Bailey.
Considerations Affecting the Improvements in the Thermal Efficiencies of Non-Reheating Plants at High Steam Pressures
Authors: Finniecome J. R.
Published: October 2007

This contribution is supplementary to the paper presented by Mr. K. Baumann entitled “Improvements in Thermal Efficiencies with High Steam Pressures and Temperatures in Non-Reheating Plant” (see p. 125).†

It reviews the basic assumptions made in that paper. Particular attention is drawn to the condition line, to the corrections in the turbine efficiency due to higher pressures and temperatures relative to the basic conditions of 600 lb. per sq. in. gauge and 800 deg. F., and to the assessment of the decrease in the heat consumption due to feed heating. The method applied is demonstrated in detail by a typical calculation of a feed heating heat balance. Consideration is also given to the optimum decrease in heat consumption due to feed heating and also to the economic feed temperature for various operating factors.

The factors affecting the improvement in thermal efficiency for the economic feed temperature and the power of the station auxiliaries for river and cooling tower conditions, at various pressures and temperatures at the stop valve, are presented by a series of graphs. The use of these graphs is clarified by a summary of comparative data on the improvement in thermal efficiency relative to 600 lb. per sq. in. gauge and 800 deg. F.

The final results of the improvement in thermal efficiency for the economic feed temperature relative to 600 lb. per sq. in. gauge and for temperatures from 800 deg. F. to 950 deg. F. with five stage feed heating are indicated by a group of graphs for a range in pressure of 600 to 1,800 lb. per sq. in. gauge for a vacuum of 29 inches of mercury, both excluding and including power station auxiliaries. Finally, a graph indicates the percentage difference in the heat consumption per inch of mercury between 28 inches and 29 inches for temperatures from 800 to 950 deg. F. The results are summarized in seventeen figures and in two comprehensive tables.
An Analysis of the Lubrication between the Piston Rings and Cylinder Wall of a Running Engine
Authors: Courtney-Pratt J. S. , Tudor G. K.
Published: October 2007

A method has been developed for the study of the lubrication in the cylinder of an engine under actual running conditions by an analysis of the electrical conductance between a piston ring and the cylinder wall. One of the compression rings was electrically insulated from the piston and a current passed from this ring to the cylinder wall: the potential drop between the moving surfaces was calibrated in terms of the resistance. With good conditions of lubrication, the electrical resistance is high, while low resistance values indicate breakdown of the lubricant film and consequent abrasive wear of the surfaces. A study of this resistance variation was made by means of a cathode ray oscillograph with the time base synchronized with the stroke of the engine.

Results indicate that, with the oils used, the surfaces of the piston ring and the cylinder wall are not separated by a continuous oil film throughout the entire cycle. Intermittent breakdown of the oil film occurs to a varying degree under all circumstances, even using oils much heavier than are common in automobile practice. Also, in general, the resistance is lower; that is, more metallic contact occurs in the regions of top and bottom dead centres than during the remainder of the cycle. The method confirms the improvement in lubrication expected with increase of engine speed, or with increase of viscosity. The effects of gas pressure behind the rings are shown to be small, at least with the low brake mean effective pressure in the particular engine studied. A marked deterioration in the quality of the lubrication accompanies any increase in the temperature of the oil film on the cylinder wall—greater deterioration than can be accounted for simply by the decrease of viscosity due to the temperature rise.

Finally, the results demonstrate the applicability of this method of analysis to problems of cylinder lubrication and abrasive wear, its chief value being the rapidity with which results may be obtained as compared with conventional wear tests.
An Improved Method of Measuring Piston Ring Wall Thrust
Authors: Pugh B.
Published: October 2007

An important factor in the selection of piston rings is the thrust the ring is capable of exerting on the cylinder wall. A common inspection method of selecting rings consists of wrapping a band around the ring and determining the tangential force required to close the ring gap to the required working value. This method giving as it does a result which is of the nature of an average is unsuitable for the comparison of rings having wall thrust patterns of different form. The piece of apparatus described was designed originally for comparing the wall thrust patterns of new and used rings and has also been used to study the effect of variation of ring “toe-out” and ovality. This work has indicated that there is a definite limit to increasing the toe-out and ovality with a view to stiffening the ring at the horns and beyond this limit increase of toe-out and ovality is accompanied by rapid and progressive break-up of the wall thrust pattern.
The Development of the La Mont Boiler in Great Britain
Authors: Plummer G. A.
Published: October 2007

The La Mont system of controlled forced-circulation was promoted in America in 1926, and developed in Europe by German interests from 1929.

This development commenced with water walls added to existing natural-circulation boilers and proceeded to complete steam generators employing the La Mont principle. British engineers became interested, and in 1936 the La Mont boiler was introduced for manufacture in this country. Several visits of investigation were made to the Continent, which indicated that whilst much valuable experience was already available from the 150 or so installations then existing, a considerable amount of work would be required to adapt the La Mont boiler to British requirements. It was also realized that experience with larger units at higher pressures show the necessity for modifications in detailed design. The paper describes several difficulties encountered in the development of this type of boiler and how they have been overcome.
Operating Experience with La Mont Boilers, with Special Reference to Feed Water Problems
Authors: Begg G. A. J. , Hebblethwaite W. M. , Cooke G.
Published: October 2007

The paper describes the chief troubles encountered in operating high-pressure La Mont forced circulation boilers with a difficult feed water consisting of 80 per cent chemically treated make-up. Attention is drawn to the thermodynamic and financial advantages gained by the use of the higher pressure system.

The reasons for the choice of the La Mont boiler are given and also a summary of information obtained on the Continent in 1939 relating to feed water treatment with La Mont boilers working under nearly similar conditions of pressure and feed water. The initial feed water treatment and after-conditioning, together with details of the feed water treatment plant for the boilers actually installed, are described. The early troubles with feed water treatment and their effect on the availability of the boiler are dealt with in detail and the precautions found to be necessary to avoid accumulation of sludge in the headers and the formation of “Analcite” scale in the generating tubes are also described. Information is given of the troubles with secondary combustion as a result of insufficient turbulence in the combustion chamber and the fouling of the air heaters and the remedies employed. The general design of the boiler and power plant and of all auxiliary plant are described, and the reduction in power costs achieved, in spite of war time increases in the cost of coal and labour, are enumerated.
High-Pressure Gear Pumps
Authors: Beacham T. E.
Published: October 2007

Gear pumps have been used in very large numbers for the various hydraulic services of war aircraft.

For the higher pressures the main problems have been in connexion with the load on the journal bearings, with wear, and with the reduction in volumetric efficiency caused by internal leakage.

The journal loads are affected by the number of teeth and by the ratio of width to diameter of the gears. With high pressures it is difficult to accommodate standard ball or roller races on account of their diameter: designs are illustrated using a combination of standard races and special needle roller bearings.

Small amounts of wear cause comparatively large reductions in volumetric efficiency. Major causes of wear are rubbing on the gear end faces and solid matter in suspension in the liquid and methods of dealing with these are discussed.

The percentage slip due to internal leakage varies inversely as the factor (r.p.m. × viscosity). At low speeds and with low-viscosity liquids, internal leakage often limits the pressure at which the pump can be used. Multistage pumps reduce the leakage and have been used extensively for undercarriage operation. Internal leakage becomes relatively less as the size of the pump is increased and the paper gives a graph, showing the relationship between the limit of pressure at which 80 per cent volumetric efficiency is possible, the capacity and rotational speed of the pump, and the viscosity of the liquid.

Aircraft pumps generally use gears with involute teeth: ports in the end covers of the casing are used to prevent excessive pressure in the liquid trapped between the teeth. Low- and high-leakage conditions call for difficult arrangements of ports, and this involves differing displacements and variations in flow velocity.
Large-Capacity High-Pressure Pumping Plant
Authors: Roberts F. H.
Published: October 2007

The pumping unit described was governed in design by its long and arduous duty, and is not of a general competitive type. On account of the high pressure the design incorporated three-throw reciprocating pumps; and because of local power conditions electrically driven pumps were chosen, in preference to steam-hydraulic intensifiers that have hitherto held the field in heavy forging plant. Detailed information regarding the mechanical features of the pump, such as cranks, rams, pumps, and valves, is given with special notes on tests of materials, efficiency, flywheel speed regulation, and flexible couplings. A complete cross-section of the pump is given, together with a photograph of the pump completely equipped. A diagram of the control gears indicates the simplicity of operation which is reflected in the performance data made availabe with regard to power and maintenance. Details of the forging work carried out under different sizes of presses having the same control are also included. In an addendum some outstanding particulars are given of pumps applied to plate-bending presses, involving the use of torque converters to obtain fully controlled pressures.
Control and Planning of Maintenance with an Incentive Bonus Scheme
Authors: Talbot R. , Satow G. F.
Published: October 2007

The paper describes the successful application at Royal Filling Factories of time study principles and techniques to the difficult problem of the control of the maintenance of production machinery.

A considerable proportion of the work was analysed and reduced to a routine. Maintenance in this category could then be planned beforehand and the performance of the work controlled against predetermined schedules. The labour required was then found by a specialized form of time study and the paper gives a brief account of time study in general. Two methods are described: “work content” method, in which the labour is built up operation by operation, and “rating” method, in which the labour is found by an assessment of present efficiency. Finally, a standard team is determined, taking into account the varying degrees of skill required and the limited amount of time actually available for maintenance.

An incentive to improved maintenance was devised and made the basis of a bonus scheme. This, together with the necessary records, both for the bonus and for the maintenance control, is fully described.

The scheme, which has also been extended to the engineering shops in a modified form, has resulted in an increase in the quantity and quality of maintenance and in a reduction in the labour force.
The Development of Locomotive Power at Speed
Authors: Diamond E. L.
Published: October 2007

The power developed per unit of cylinder volume of locomotives in the speed range from 250 to 400 r.p.m. has in recent years been doubled. Forty years ago it was often the case that the diminution of the mean effective pressure with increase of speed, rather than the evaporative capacity of the boiler, limited the power of the engine. The most advanced designs maintain the mean pressure at a high percentage of the calculated value to the highest speeds, and the effect of valve events and clearance volume on the calculated mean pressure thus becomes of practical importance, especially as designers are endeavouring to use considerably higher steam pressures in single-expansion cylinders.

The first part of this paper sets out the effect of these factors over a wide range of steam pressures in the form of basic data graphs of mean pressure, relative efficiency, and steam consumption. It is shown that without the decrease of clearance volume and increase of expansion ratio which compound expansion affords, the improved thermal efficiency which higher steam pressure offers cannot be fully realized above about 250 lb. per sq. in. boiler pressure, though greater power can be obtained.

The second part of the paper is devoted to an examination of the actual deviation of mean pressure with speed for a wide range of locomotives, including some of the most recent designs, and the reasons for the radical improvement are indicated. In 1905 the late Professor Dalby suggested a simple proportional relationship between mean pressure and speed. Such a relationship does not hold for modern locomotives, and at the end of the paper a simple exponential law is proposed with a single coefficient characteristic of the locomotive. This law may be used to estimate the power of a future design at any speed, or as a criterion for assessing the performance of an existing locomotive in respect of power developed, which is generally of more importance to railway companies than thermal efficiency.
The Use of Vibration as a Means of Industrial Drive
Authors: Thornton C. A. M.
Published: October 2007

The application of vibration as a means of industrial drive has been considerably developed in the last twenty years. Starting from the obvious application of screening, it has been extended to conveying, heat interchanging, consolidation of material in packages to reduce shipping space, keeping material “fluid” in hoppers and chutes, hammering, etc. The paper discusses that part of the subject involved in the production and control of the vibration by mechanical or electrical means under all conditions of load. Formulae are developed for calculation of spring strength and for the calculation of the spring dimensions, and for the avoidance of spring fatigue. The various methods of electrical excitation are compared, and the relative advantages and disadvantages are discussed. The desirable instrument equipment is described, including the remote indication of vibration amplitude. A method is outlined by which it is claimed that vibration can be maintained constant at all loads and at any desired frequency. The testing of vibrating drives at the manufacturer's works and on site is discussed.

In an Appendix to the paper the problem of transverse vibrations in long vibrating conveyors is treated mathematically, and a formula is developed for the natural frequency of transverse vibration of a conveyor of any uniform section and of any length.
Efficiency and Cavitation of Fluid Machines
Authors: Anderson H. H.
Published: October 2007

In order to predict the performance of a fluid machine from scale-model tests, correction formulae are required. Professor Lewis F. Moody's formula is used for water turbine efficiencies but does not appear to be accepted for pumps; Pfleiderer† states that it is not practicable to use Reynolds number; and Wislicenus‡ does not give a formula for scale correction but states that efficiency increases slowly with size and speed. For cavitation, the only general formula is Thoma's parameter§ from which is developed suction specific speed. Wislicenus, Watson, and Karassik‖ rely entirely on suction specific speed and state that the influence of Reynolds number can be neglected.

It is suggested that both the total head loss—given by (1 – η) where η denotes the efficiency—and suction side loss (cavitation) may be treated similarly and analysed according to the Reynolds number. Examples of centrifugal pump efficiencies and cavitation characteristics are analysed, and the resulting curves are found to have the same shape as corresponding portions of the original Reynolds curve for pipe friction. The losses in a fluid machine are thus represented by the friction loss of a certain length of pipe. Extrapolation for sizes and speeds beyond the known field of tests can then be made by analogy with the pipe friction curve.

From the foregoing considerations, the author suggests that the Moody formula for the losses: (1– η)∝ 1/ D0·25 H0·1—where D and H refer to diameter and head respectively—should be replaced by (1 – η)∝ ( D✓ H)– x where x varies between 0·2 and 00·3, according to Reynolds number. A similar relation is derived for cavitation.
The Application of Cyclone Theories to Centrifugal Spray Nozzles
Authors: Doble S. M. , Halton E. M.
Published: October 2007

The problem of designing centrifugal spray nozzles has been attacked by applying well-established cyclone formulae; these provide a theoretical explanation for empirical relationships (which have been obtained previously‡) between nozzle output, spray cone angle, and pressure drop.

The nozzle is designed by first selecting suitable values of the following quantities:—

[Formula: see text]

Both the above quantities should be greater than 1 in order that the subsequent prediction of design data may be as accurate as possible. Apart from this limitation, the values assigned to those quantities are largely arbitrary in that they are not dependent upon the final spray characteristics required, but, as they affect the dimensions of the nozzle, the original selection may have to be adjusted after preliminary calculations if the estimated nozzle shape is in any way unsuitable. They may also have to be adjusted if they result in the calculated value of the quantity t/RE, i.e. (orifice film thickness)/(exit radius), being much greater than 00·5, as this will involve loss of accuracy in applying the theoretical equations. Having finally selected suitable values of Φ and Ri/ Re, the dimensions of the nozzle can be calculated by substituting the required values of the spray characteristics in the various formulae.
An Investigation of the Airbox Method of Measuring the Air Consumption of Internal Combustion Engines
Authors: Kastner L. J.
Published: October 2007

The mass of air taken in per unit time by an internal combustion engine is a quantity of considerable importance in any analysis of engine performance, and a convenient means of measuring this quantity will often be required by the research worker or development engineer. Where reciprocating engines are concerned, the problem of measurement is not easy, since the flow is of a pulsating nature, for which “constant flow” types of measuring apparatus will, in general, be unreliable. A few suitable methods for measuring pulsating flows have, however, been devised, and what is generally known as the “airbox method”—consisting of the use of a measuring orifice in conjunction with a smoothing capacity—has often been employed, mainly because of its simplicity and the ease with which the necessary apparatus can be constructed.

The work of Watson and Schofield (Proc. I.Mech.E., 1912, p. 517) has been of great value to users of the airbox method, but, though it has to some extent been supplemented by later investigations, several important questions still remain unanswered. The experiments described in the present paper represent an attempt to furnish additional information, in particular as regards the amplitude of the pressure fluctuations occurring in boxes of inadequate size and the errors in measurement produced thereby, a simple theory being given to account for these latter. The various factors governing the design of a reliable airbox meter are discussed, and it is shown that they can be related to the value of a dimensionless criterion which may be determined for any given engine.
Progress in Turbine Gear Manufacture in Recent Years
Authors: Sykes A.
Published: October 2007

The problem of producing accurately cut gears for high-speed work has received a great deal of attention, which commenced with the work done by Sir Charles Parsons introducing geared turbines for marine purposes. During the 1914–18 war, a considerable impetus was given to the production of geared turbines, which resulted in an abnormal rate of development. Soon after the war there was an outbreak of gear failures—particularly in double-reduction gears for merchant ships—and investigation showed that the most important requirement was improved accuracy in gear cutting.

Between 1920 and 1940 the search for accuracy continued, but there was a backward tendency in demand. An important incentive to improvement during the recent war came from Admiralty requirements for lighter and quieter running gears, and the subject was referred to the British Standards Institution.

After the outbreak of war with Japan, marked progress was made in America, both in quantity and quality of production, and there was a regular interchange of information between British and American naval authorities.

The hobbing machine still remains the accepted means of cutting high-speed gears, but there has been considerable difference of opinion as to whether creep or non-creep machines were to be preferred. A particular feature of improvement in non-creep machines has been the use of master index wheels having a much finer pitch than was at one time thought suitable, and this, combined with greater accuracy in construction, has led to a decided improvement in gear cutting.

Problems associated with the cutting of accurate turbine gears are the production of accurate lead screws and profile-ground hobs for finishing teeth. The process of crossed axis shaving is a relatively new development which has resulted in a higher grade of finish and has been responsible for reducing certain types of error.

Reference is made to experiments with carbide-tipped hobs and an indication is given of the use of materials having higher tensile strength and greater hardness as possible future developments.
The Life of Carbide-Tipped Turning Tools
Authors: Bisacre F. F. P. , Bisacre G. H.
Published: October 2007

The paper is a contribution towards a rational quantitative theory of the tool-life problem.

In the first part of the paper, the authors discuss an adiabatic theory of high-speed metal cutting, with no coolant. In machining medium-carbon steel with dry tungsten-carbide, cutting takes place under two widely different physical conditions, depending on the speed of cutting. Plastic deformation of the metal takes place as the chip crosses the tool face, and a higher temperature is developed most intensely at or near the surface of the cutting in contact with the tool face. Consequently the temperatures generated are higher—perhaps much higher—in the lower layers of the chip than elsewhere.

If the speed of cutting is high, there is not sufficient time for effective diffusion of heat to take place into the colder parts of the cutting; the heat in fact stays where it is generated. The conditions are adiabatic. On the other hand, when cutting is slow enough, there is time for complete diffusion of heat to take place, whereby the temperature becomes uniform through the thickness of the chip. This is the isothermal case.

It is found that these extremes occur when Reynolds thermal number (speed × thickness of chip ÷ thermal diffusivity) is large or small, respectively.

In the second part of the paper, a series of experiments made by M. F. Judkins and W. E. Uecker in 1933 on tool life is examined, and a rule is given that embodies the results of these tests with unexpected accuracy.

In the third and last part of the paper, a study is made of those properties of the metal cut and of the tool that affect the life of the tool. The method of dimensional analysis is applied to deduce a general form for the life-law. Judkins and Uecker's experimental result conforms to this law within the limits of the tests. But further experiment alone can confirm the general form—in its wider application.
The Development of an Axial Flow Gas Turbine for Jet Propulsion
Authors: Smith D. M.
Published: October 2007

The paper reviews the technical development of the F2 jet propulsion engine, an axial flow gas turbine designed and manufactured by the Metropolitan-Vickers Electrical Company, Limited, under contract from the Ministry of Aircraft Production.

An account is given of the preliminary work in 1938–9, in collaboration with the Royal Aircraft Establishment, on gas turbines for aircraft propulsion. The development of a simple jet engine of the axial flow type was started in July 1940. The first engine ran on bench test in December 1941. The first flights took place in June 1943 on a flying testbed, and in November 1943 on a jet-propelled aircraft. The evolution of engines of this type, leading up to the current F2/4 jet propulsion engine, is described.

Each main component of the engine—the axial flow compressor, the annular combustion chamber and the high temperature turbine—necessitated extensive development work in fields previously unexplored; the methods used in the development of these and other components are explained.

The F2 engine was the first British jet propulsion engine of axial flow type, and it is also unique amongst British engines in the straight-through design and annular combustion chamber that gives an exceptionally low frontal area.
Practical Aspects of Cascade Wind Tunnel Research
Authors: Todd K. W.
Published: October 2007

This paper deals mainly with the development of a high-speed wind tunnel for the testing of turbine or compressor blade cascades under two-dimensional air flow at velocities up to that of sound. It includes a brief résumé of the early history of the technique, and goes on to enumerate the variables which must be brought under the operator's control. Reference is made to methods of presentation of results, including the use of optical systems for demonstration of shock phenomena. Finally, the control system evolved for operating the high-speed tunnel is described, and some notes are added on the protection of the operators from fatigue induced by monotony and noise.
A Contribution to the Solution of the Gas Turbine Problem
Authors: Lysholm A. J. R.
Published: October 2007

This paper, which is an attempt to summarize the author's work on the gas turbine, is to a great extent based upon his own ideas and inventions†. An attempt has been made to follow the trend of thought from, for the most part, unpublished test data, as well as diagrams and layouts. However, it has not been possible to give a complete story within the scope of this paper, and many interesting details have had to be left out. This paper covers the period 1929–45, and the latest developments in the marine, locomotive, and aeroplane field are not included.
The Air Cycle Heat Pump
Authors: Thomas T. F.
Published: October 2007

The air cycle heat pump, using air both as working medium and as heat carrier, and suggested by Lord Kelvin nearly 100 years ago, has advantages as a means of combined heating and ventilating, on account of its simplicity and the recovery of ventilation heat losses.

The paper briefly examines the theoretical possibilities of the air cycle for space heating and air drying. While the ideal air cycle is highly efficient with perfect machines, the inefficiency of actual machines and the temperature difference and air pressure drop across the heat exchanger reduce the performance considerably; but the power consumption for the net heat load is appreciably less than that for direct electric heating, whilst ventilation—for which electric heating is less suited—is provided in addition. Thus for certain applications such as hospitals, hotels, and restaurants where the number of air changes is greater, the air cycle heat pump might have economic advantages. The need for the improvement of heat exchangers is indicated, and the possibility of replacing separate compression and expansion machines by a “pressure exchanger” is discussed.
The Measurement of the Temperature of Sliding Surfaces, with Particular Reference to Railway Brake Blocks
Authors: Parker R. C. , Marshall P. R.
Published: October 2007

A pyrometer, which covers the temperature range 200 to 900 deg. C. (390 to 1,650 deg. F.) with a response time of 10−3 seconds, has been developed for studying the temperature of stationary and moving surfaces.

The values of the emissivities of bright and oxidized steel surfaces, determined by this method, agreed with other published work.

The pyrometer has been used to determine the temperature of the surface of a railway tyre, during brake applications under various conditions, just as it emerged from beneath the brake block. Evidence is adduced to prove that the temperatures measured are not very different from those actually under the block. It is shown that the possible change in emissivity of the tyre steel is insufficient to invalidate the results.

The variation and extent of the area of contact between brake block and tyre were investigated simultaneously with the temperature measurement. It was shown that high tyre surface temperatures (over 800 deg. C.; 1,470 deg. F.) are an inevitable result of “strip braking”. The preferred formation of heat spots between the spokes of the wheel, and the unequal growth of heat spots across and along the tread due to tyre distortion, were examined.

An attempt to eliminate strip braking by reducing the length of the standard brake block to three-quarters, one-half, and one-quarter of its original length was made. It was found that reducing the brake block to one-quarter of its original length completely inhibited heat spot formation, reduced by a factor of 2 the standard deviation of the stopping times under standard conditions, and reduced the maximum temperature attained during brake application from over 800 deg. C. (1,470 deg. F.) to under 400 deg. C. (750 deg. F.). The deleterious formation of martensite was thus eliminated. It was found that the wear of the half-length brake blocks, expressed on a thickness basis, was not twice but maybe equal to that of a full-length block. Since the cost of a brake block is somewhat proportional to its size it follows that a shorter block may be more economical than a full-length block. It is concluded that the optimum size of a railway brake block must be determined separately for each material and set of operating conditions.
Basic Physical Properties Relied upon in the Frozen Stress Technique
Authors: Fisher W. A. P.
Published: October 2007

The “Stress Freezing” method is a useful means of solving problems of three-dimensional stress by photo-elasticity.

The method makes use of the fact that some thermo-setting resins having photo-elastic properties possess considerable residual thermo-plasticity. When softened by heat they obey Hooke's law, though the Young's modulus is, of course, very much reduced. At a given temperature, the birefringence, as well as the strain, has been shown to be proportional to the stress.

Both strain and birefringence persist after cooling and unloading, and even after slicing the model. This behaviour is illustrated by means of a simplified concept.

In the U.S.A., Glyptal resin is used (Bakelite B.T. 61 893), but this material cannot be had in thicknesses greater than 1 inch. Glass-clear phenol-formaldehyde resin (Catalin 800), which gives a higher stress-optical coefficient, can be had in larger sizes.

The properties of both materials are compared, and troubles such as “rind effect” are discussed.

Some experimental results obtained with Catalin 800 are given by way of illustration. The suitability of this material has been under investigation for some time at the Royal Aircraft Establishment, Farnborough, and careful tests have shown that, when suitably cured, Catalin 800 can give reliable results, but that “rind effect” is still a serious drawback.
Erosion Due to Incipient Cavitation
Authors: Bottomley W. T.
Published: October 2007

Van Iterson's experiments show that cavitation erosion is produced by the collapse of minute air bubbles in water in a state of air supersaturation. This is contrary to the usual conception that cavitation erosion is due to the collapse of vapour bubbles. The author gives results of experiments which indicate that the bubbles which form and collapse at the stage of incipient cavitation in aerated water are air bubbles in a supersaturated state. The experiments also show that vapour bubbles which collapse in de-aerated water are in thermal equilibrium. It is shown that the collapse of bubbles in thermal equilibrium cannot cause erosion because the vapour pressure inside and the hydrostatic pressure surrounding the bubbles are balanced during collapse. The energy producing cavitation erosion is the free surface energy liberated by the collapse of the air bubbles. The final collapse velocity is the velocity of sound in water and the magnitude of the blow produced is of the order of 120 tons per sq. in. or more.

The effect of these views on the interpretation of the model tests in cavitation tunnels and on the cavitation number is discussed.