bluuebunny/crossref_metadata_2025 huggingface dataset:
Second Paper: Failure-Survival Automatic Flight Control Systems for Aircraft with Particular Reference to a High Reliability Electrohydraulic Actuator
Authors: Ruggles R.
Published: October 2007

The author discusses some of the problems of failure-survival automatic flight control systems and suggests some basic ground rules as design criteria.

The advantages and disadvantages of some of the main types of system are discussed: duplex, triplex, triple component, duplicate-monitored and quadruplex systems being covered.

In particular, a quadruplex actuator is described which has been designed and developed mainly for automatic flight control system applications where a very high degrees of failure-survival capability is required.

A detailed failure analysis of the various systems is carried out and the importance of the electrical and hydraulic supply system configurations and failure rates is brought out.
Curing Instability in a Rotating Face Seal Control System: A Case History of the Application of Control Techniques in Mechanical Engineering
Authors: Tyler R. D. , Cooper B. J.
Published: October 2007

The paper is a case history of the solution of a control problem in mechanical engineering. The system concerned, namely a pneumatic control system which regulated the leakage to the atmosphere of carbon dioxide through a rotating face seal, had exhibited the familiar symptoms of drift and hunting and had defied ad hoc methods to cure it. The difficulties stemmed from the fact that the gain of the element being controlled could assume indefinitely large values, whilst in addition, the loop contained one highly non-linear element.

The solution of the problem did not require highly sophisticated techniques. In contrast, a combination of frequency-response testing and the application of quite elementary servo theory enabled the causes of the malfunctioning of the system to be pin-pointed and indicated the modifications required.

Details are presented of the four phases of the investigation which comprised the initial frequency-response testing of the malfunctioning system, the theoretical analysis, laboratory tests on a simulator model of the system and final proving tests on the modified system at site.
Friction and Wear of Unlubricated Steel Surfaces at Speeds up to 655 FT/S
Authors: Earles S. W. E. , Kadhim M. J.
Published: October 2007

The friction force between 1/8, 3/32 and 1/16 in diameter, and the wear of 3/32 in diameter, specimens of En 1A steel sliding on a disc of S62 steel are measured at speeds between 93 and 655 ft/s, the normal load on the specimen varying between 0.2 and 4.5 lbf.

The coefficient of friction is shown to be dependent on sliding speed, normal load and specimen diameter, and to be a function of N1/2 U, where N is the normal load and U is the sliding speed.

It is suggested that the coefficient of friction is dependent on the specimen contact surface condition which is dependent on the specimen surface temperature. There is evidence to suggest a gradual change in the mechanism of sliding with increasing magnitude of N1/2 U from, (i) metallic abrasion and tearing of an oxide layer, (ii) to skidding on and shallow ploughing of an oxide layer, (iii) to gliding over and shearing of a soft surface layer.

It appears that the coefficient of friction is independent of, whereas specimen wear is dependent on, the disc surface condition. At low loads the material transferred from the specimen tends to form a continuous oxide layer on the disc., while at high loads there is the formation and tearing of a thick oxide layer, presenting a more abrasive surface to the specimen with a relative increase in wear. Generally specimen wear per sliding distance increases with N and decreases with U.
Military Requirement and Employment of Engineering Equipment
Authors: Egan T. H. , Mackay E. M.
Published: October 2007

This paper is divided into two parts and covers two aspects important to the military engineer. The first part argues the case for military development of construction equipment. Its basis is the recent change of emphasis in military doctrine from the concept of general war in Europe towards that of limited war in more remote parts of the world. This makes air portability the most important but not the only parameter, and from this follows the paramount need for equipment of light weight, easy to break down to loads suitable for transport by helicopter, and as easily reassembled under field conditions. Military development is necessary because of these special requirements and in some cases because no commercial equivalents exist. The paper outlines the advantages and disadvantages of the ‘military special’ equipment, and Ministry of Defence (Army) policy regarding development of Engineering Construction equipment. It also suggests ways in which the commercial designer and manufacturer might help to make this policy effective without detriment to their product, and without attempting to design specifically for the military market, which is not an economic proposition anyway.

The second part of the paper is the actual experience of its author in airborne engineer operations in Borneo. It discusses the equipment used, methods of getting it into and away from relatively inaccessible sites, and offers advice on training, packaging of ‘on-equipment’ spares, and aids to breaking down and reassembling plant for airlifted operations.
The Behaviour of the Impact Damper
Authors: Sadek M. M.
Published: October 2007

In this investigation a theory is developed relating to the behaviour of the impact damper. The analysis is based on the assumptions that

(1) two un-equispaced impacts per cycle occur in the steady state, and (2) the impact force-time curve is of rectangular shape and of infinitesimal duration.

Fourier series are used to represent the impact cycle and the differential equation of motion is derived. This is solved using the dynamic equations of impact to determine the boundary conditions. Three equations are developed to determine the variation of impulse, phase angle and vibrational amplitude with the change of the damper parameters.

Resonance curves are obtained and the theory is examined experimentally. The regions of validity of the above assumptions are studied both theoretically and experimentally. Non-linearity in the behaviour of this damper is very clear, especially in the range of its optimum behaviour. Two design curves are developed which can be used to determine the damper parameters necessary for a certain amplitude reduction.
Experimental Stress Analysis of Rails
Authors: Babb A. S.
Published: October 2007

The paper describes the experimental stress analysis of a range of rail sections and a fishplated joint carried out by means of a loading frame which accommodated a short length of track, hydraulic jacks with load cells, and electrical resistance strain gauges.

The most detailed test was that of the B.S. 110A rail which after being tested ‘as rolled’ was successively re-tested at states representing six stages of head wear, simulated by planing the rail head. The stress ranges determined under various loading conditions were compared with those for a bullhead rail planed to represent its known safe limit of wear and gave a guide to the permissible head wear of the B.S. 110A rail from stress criteria. The B.R. 116 lb/yd thick web rail was tested for comparison with the B.S. 110A, and rails representing three weights of the new B.S. A series were compared with three of the older B.S. R series rails of the same weights. From the test results various general conclusions have been drawn. The relationships between rail weight, head wear and fillet stresses, and the effect of different fastenings are discussed.

A fishplated joint for 60 lb/yd rail was tested. The fillet, bolthole and bending stresses on the rail end, and the bending and bolthole stresses on the fishplates were determined. Although this is a light rail by modern main-line standards, the stress distributions and the conclusions drawn are believed to be typical of joints in heavier rail also.
Hydraulic Design of Syphons
Authors: Kelly A. G.
Published: October 2007

This paper puts forward anew theory on the operation of syphons. It proposes, and gives proof from test results, that the rising leg of a syphon can be greater than heretofore thought (i.e. it can be greater than atmospheric pressure expressed in feet of the fluid being used minus the friction loss). It also shows that the length of the down leg of a syphon has no limit. Test results are given using heated water in syphons; having residence time near the apex; using water supplied off pumps. Pressures and vacua throughout syphons are also tested.

It is shown that hydraulic gradient has no significance because the fluid stores energy in parts of some syphons; this matter is discussed in some detail. Other items discussed are friction factors to be used for syphons using water; noise in syphons; priming flows and parallel operation of syphons. It is shown that model tests for syphons have pitfalls. Lines for further investigation are indicated.
Thermometric Methods of Measuring the Rate of Mass Flow
Authors: El Agib A. A. R.
Published: October 2007

By measurement of the unit-mass and the unit-time rates of exchange of energy between a flowing fluid and a heating or actuating source, the rates of mass flow can be directly determined, provided that certain thermodynamic properties of the fluid are known.

Various methods of application of this principle are described and an account of proving tests is given. In these tests special techniques of precision thermometry were used. The results obtained were very promising and warrant further laboratory and field investigations.
Performance of P.T.F.E. Based Piston Rings in an Unlubricated Reciprocating Compressor
Authors: Hart R. R.
Published: October 2007

Published data on the wear of non-metals is usually based on tests using a sliding disc on a rotating drum, with atmospheric air surrounding the equipment. Although this type of test gives a fair indication of the relative merits of the materials, it is impossible to accurately estimate the wear of piston rings under working conditions. Tests have therefore been carried out on various filled polytetrafluorethylene (P.T.F.E.) materials in an un-lubricated reciprocating compressor. The materials were tested as piston rings with helium as the working gas. The gas was used in two conditions:

(1) ‘Wet’ where the moisture content was approximately 200 parts per million (p.p.m.) by volume. (2) ‘Dry’ where the moisture content was approximately 7 p.p.m.

The fillers used were carbon, glass fibre and molybdenum disulphide and it was found that the carbon filled materials had the lowest wear rate in the wet gas. Using the dry gas the glass fibre filled materials gave the lowest wear rates.

All the materials showed a tendency to local decomposition of the P.T.F.E. to carbon and fluorine and this is thought to be due to local hot spots formed by the relative movement of the ring in its groove.
Peat-Fired Boilers for Electricity Generation
Authors: Lang J. F. , Meyler J. J.
Published: October 2007

The Electricity Supply Board of Ireland has been using peat-fired boilers for electricity generation for over 15 years. Peat is produced in two forms—sod and milled. Sod peat is burned on chain-grate stokers in boilers of up to 20 MW capacity; milled peat is fired as pulverized fuel in boilers of up to 40 MW capacity. Total peat-fired plant is 407 MW.

Production methods for sod and milled peat are outlined. The paper describes the combustion technique adopted for these two fuel forms and the special maintenance and operational difficulties experienced over the years. The influence of peat characteristics on boiler design and the salient differences compared with coal and oil-fired boilers are explained. Details are given of performance and cost figures compared with coal and oil-fired plants.
Experimental Study of Water Flow in Full-Size Test Rig for Water-Cooled Turbo-Generator Rotor
Authors: Csillag I. K.
Published: October 2007

The demand for electric power has doubled in the last decade. The most economical way to meet this demand is by building large-output generating units. The study of the major factors which determine the output of such generators shows that the only effective way to increase the output is by improving the cooling of their windings. For that reason design has progressed from air-cooling to indirect hydrogen-cooling, then to direct hydrogen-cooling. Now the trend is towards direct water-cooling where the water is in direct contact with the copper windings. The introduction of water into the stator winding was established in 1956 (1)† and was in fact directly responsible for the present increase in unit rating.

The introduction of water to a rotating winding presents difficult problems in both design and manufacture. The test rig dealt with in this paper was built to study some of these problems and to carry out experimental investigations on a full size model of the special hydraulic features for a water-cooled turbo-generator rotor. The investigations were concentrated around the following five different problems which are dealt with in detail: (1) increase in pressure drop due to rotation; (2) free-rotating seal (inlet seal) (2); (3) vacuum-breaking device (water outlet) (3); (4) loss-distribution in the rotor; (5) measurement of the rotor vibrations in various operating conditions.
Second Paper: Cooling Equipment for Internal Combustion Engines
Authors: Montgomerie G. A. , Forbes M. K.
Published: October 2007

The several positions in engine fluid systems in which cooling equipment is commonly used are examined and the fluid pressures and temperatures to which the heat exchangers are subjected outlined. General considerations affecting the designs from the points of view of performance (heat transfer and power loss) and environment (chemical and mechanical) are examined and amongst other points it is shown that the best ratio of cooling surfaces in a secondary surface heat exchanger is

If ρ = 1 this reduces to r = √ R which is very different from the usual recommendation that r and R should be equal.

The second part of the paper is descriptive, and deals with the mechanical design of heat exchangers used for cooling engines in various applications: marine engines; stationary engines; locomotive and railcar engines; agricultural machinery; road vehicles; and aircraft.
Second Paper: Analysis of Spin/Roll Conditions and the Frictional-Energy Dissipation in Angular-Contact Thrust Ball Bearings
Authors: Hailing J.
Published: October 2007

In current analyses of the contact conditions in angular-contact ball bearings it is assumed that sliding occurs in all regions where tangential surface tractions are operative. Other work in similar rolling-contact situations has, however, demonstrated that some of this slip requirement may be accommodated by the elastic surface deformations. This type of analysis leads to areas of sliding and sticking coexisting within the contact areas. These concepts are here applied to angular-contact thrust ball bearings and lead to some interesting deviations from the results obtained using the complete slip analysis. In particular, these concepts of microslip enable the determination of the spin/roll ratio at each race contact. Detailed calculations for conical ball thrust bearings illustrate the main discrepancy of the full slip analysis in over-estimating the frictional-energy losses, such discrepancies being most marked with decreasing contact angle, increasing pitch/ball radii, and increasing coefficient of sliding friction.
Investigation of the Discharge-Voltage Method of Measuring the Thickness of Oil Films Formed in a Disc Machine under Conditions of Elastohydrodynamic Lubrication
Authors: Dyson A.
Published: October 2007

It is reported in the literature that the ‘discharge-voltage’ method offers a simple means of measuring the thickness of oil films between moving metal surfaces. To confirm this report it is necessary to compare discharge-voltage measurements with film thickness measured by an alternative method. So far as the author is aware no such comparison of measured film thicknesses in elastohydrodynamic lubrication conditions has been published.

Under these conditions, a suitable alternative way of estimating the thicknesses of oil films between moving metal surfaces is to measure the electrical capacity between them. This method has been applied to a disc machine and a short programme of work undertaken to compare film thickness estimated in this way with the results of discharge-voltage determinations.

It was found that there was some relation between discharge voltage and film thickness but that, in general, this relation was non-linear and depended on the slide/roll ratio and on the temperature. It is therefore concluded that the discharge voltage does not measure the thickness of oil films in the simple way suggested; there were some indications that it may be possible to use it to measure relatively thick films, of the order of 40 μin (1 μm) or thicker, at high slide/roll ratios.
Hydrodynamic Model for Cold Strip Rolling
Authors: Bedi D. S. , Hillier M. J.
Published: October 2007

The theory of rolling is modified to allow calculation of a hydrodynamic film thickness and viscous friction coefficient using Reynolds equation for the lubricant. Calculations are made for the case where the fluid film covers the arc of contact. The film thickness is assumed uniform and is determined by the principle of minimum rate of entropy production. It is shown that the apparent coefficient of friction varies significantly over the arc of contact. At small reductions the roll load tends to decrease with speed of rolling, while at high reductions the load tends to increase. The point of maximum roll pressure does not coincide with the neutral plane; and under certain rolling conditions there may be no maximum in the pressure over the arc of contact.
Influence of Rotor Metal on Bearing Failures Generally Classified as the Machining Type
Authors: Karpe S. A.
Published: October 2007

An unusual and often severe type of journal and thrust bearing failure has been encountered in both marine and land-based turbine installations. These failures have occurred with steel rotors running against high-tin babbitt metal. From the outward appearance of damage, these failures have been called ‘machining’ or ‘wire-wool’ failures.

The potential magnitude and known consequences of this type of failure on large machinery units has led to the undertaking of an extensive research programme. The objective of the programme is to determine the causes, mechanisms, and means of eliminating or reducing the risk of such failures. This paper discusses the results obtained from a bench-scale apparatus, run under defined conditions, in which service-type failures can be reproduced. Main emphasis in this paper is on the influence of steel rotor metals on failure susceptibility. Also treated is the influence on failure susceptibility of chlorine-containing, load-carrying additives in the oil environment. The failure mechanism strongly implies that rotor steels can be developed which are less susceptible to this type of failure.
Investigation of Diesel Engine and Turbocharger Interaction
Authors: Kellett E. , Betteridge J. F. , Mistovski M.
Published: October 2007

The authors are concerned with the proper provisioning of turbochargers and fuel-injection equipment for diesel engines, particularly in the automotive class. Medium-speed engines are run at high mean effective pressures and there is a tendency towards similar outputs in automotive engines. Because of transmission demands these outputs will be required over a wide speed range and the relation of engine air and fuel requirements is examined.

The simple turbocharger is not ideally suited to wide range matching and the extent of the compromise inherent in fixed geometry compressors and turbines is discussed.

In order to survey engine, turbocharger, and fuel-system interactions tests are reported where turbocharger limitations are avoided by the use of two units in series. Engine operating limits were selected on the basis of safe engine factors and the output assessed with respect to the principal variables of turbocharger pressure ratio and engine compression ratio. The resulting compromise between high cylinder pressures and smoke control tended towards a traction-type torque curve with a higher-than-conventional fall-off in torque with speed.

A suggestion was verified that smoke occurred at higher air/fuel ratios as the charge density increased. Nevertheless accepted methods of heat-release prediction from rate of injection characteristics were not affected by variation in charge density.
Ejector Compression of Natural Gas for Small Turbines
Authors: Walker G.
Published: October 2007

Natural-gas-fuelled total-energy systems for supplying the utility demands of residential and commercial buildings typically require 500 s.h.p. for the machinery drives. Although gas turbines are competitive prime movers in this size range, difficulties arise from the need to compress the natural gas fuel to the pressure of the turbine combustion chamber.

In this study the use of non-condensing single-and two-stage steam-jet ejectors was analysed for gas compression to a pressure of 150 lb/in2. Steam-supply conditions from 5000 to 1000 lb/in2 and 800 to 1200°F were considered; methane was supplied at 15 lb/in2 and 60°F.

The specific steam consumption (lb steam per lb gas) of a two-stage ejector was found to be much better than that of a single-stage ejector. The minimum specific steam consumption (6 lb steam per lb gas) occurred at the extreme steam conditions considered in the study.

The steam-methane mixture this produced was not flammable when mixed in any proportion with air. Of several methods considered to reduce the steam content of the mixture delivered by the ejector, only one, post-ejector cooling and condensate removal, was suitable for analysis. Cooling-water flow rates in excess of 14 lb water per lb gas were necessary to produce potentially flammable mixtures.

Estimates were made of the major effects on turbine engine performance arising from the use of a steam ejector for gas compression. A comparison was drawn for two idealized cycles and for two others in which realistic values of component efficiencies were included. In each series the gas was compressed by conventional means in one cycle and by means of a steam-jet ejector in the other.

The steam injected with the methane in the turbine combustion chamber caused an appreciable decrease in the cycle temperatures and significant improvement in both the turbine output and thermal efficiency. When the additional heat input necessary to generate the steam for the ejector was included, the overall thermal efficiency of the steam-ejector cycle was less than that of the conventional cycle.
Use of the Least Squares Line and Plane in the Measurement of Straightness and Flatness
Authors: Scarr A. J.
Published: October 2007

The paper deals with tabular methods for calculating the least squares line and the least squares plane with respect to which errors in straightness and flatness may be defined.
First Paper: A General Approach to Hydraulic Lock
Authors: Dransfield P. , Bruce D. M. , Wadsworth M.
Published: October 2007

The present state of knowledge on the hydraulic lock phenomena of oil hydraulic control system components is reviewed briefly. A general one-dimensional solution of the Reynolds equation which governs hydraulic lock is presented. The solution embraces the particular solutions of past workers, and allows ready solution for piston-cylinder configurations for which a one-dimensional solution is adequate.

A general method for making full solutions of the Reynolds equation is presented, requiring the use of a digital computer for particular solutions. Pressure distribution, the lateral force on the piston which produces hydraulic lock, and the location of the lateral force can be obtained. The commonly occurring case of a single-land piston lying tilted in its bore is examined in detail.

The limit of accuracy of a one-dimensional solution is clearly shown by illustrating the discrepancies between the one-dimensional and two-dimensional solutions for several configurations.
Active Isolation Systems Using a Nozzle-Flapper Valve
Authors: Soliman J. I. , Tajer-Ardabili D.
Published: October 2007

Conventional isolation systems are not, even when a large amount of damping is present, capable of attenuating the amplitudes of transmitted vibration at frequencies below resonance. Thus, the low natural frequency of the isolation system is essential for effective isolation of vibration. However, this requirement increases the transmissibility of the isolation system at very low frequencies due to changes in the mass of the supported body or in the exciting forces. In many instances this cannot be tolerated. In this paper it is shown that when active isolators with nozzle-flapper valve and pneumatic springs are used, not only the transmissibility at very low frequencies is reduced to 10 per cent but also the absolute displacement transmissibility is kept below 30 per cent throughout the frequency range, even at resonance.
A Study of Nozzles in Pressure Vessels under Pressure Fatigue Loading
Authors: Spence J. , Carlson W. B.
Published: October 2007

Nozzles in cylindrical vessels have been of special interest to designers for some time and have offered a field of activity for many research workers. This paper presents some static and fatigue tests on five designs of full size pressure vessel nozzles manufactured in two materials. Supporting and other published work is reviewed showing that on the basis of the same maximum stress mild steel vessels give the same fatigue life as low alloy vessels. When compared on the basis of current codes it is shown that mild steel vessels may have five to ten times the fatigue life of low alloy vessels unless special precautions are taken.
Metallurgical Aspects of Bearing Failures Involving 3 per Cent Cr-Mo Steel Journals
Authors: Burns K. W.
Published: October 2007

Phase transformations in carbon and nickel steel journals have been shown to form a protective hard surface layer, preventing failure, when rubbed against a steel pin simulating swarf in a bearing. Under similar conditions transformations in a 3 per cent Cr-Mo steel did not occur allowing metal transfer, carburization, and eventual failure of the journal. Failures could be prevented by the selection of certain oils.
Temperatures at Lubricated Rolling/Sliding Contacts
Authors: Manton S. M. , O'Donoghue J. P. , Cameron A.
Published: October 2007

A numerical method for the prediction of oil-film and metal surface temperatures is given for the case of lubricated rolling contacts with sliding. Near-Hertzian conditions occurring in gears, discs and cams are considered and the temperature distributions, viscosity variations, and the heat partition values are calculated for a range of operating conditions. An asymmetry in the heat generation across the oil film is indicated and the effect of compression on the temperatures reached and the heat partition is also investigated.
The Pattern of Batch Manufacture and Its Influence on Machine Tool Design
Authors: Williamson D. T. N.
Published: October 2007

The majority of today's machine tools were developed in the first half of the 19th century. They have been improved; but not radically altered. For 150 years batch manufacture of engineering components has been carried out in factories using these machine tools as originally intended. Big factories have had more machine tools and more people but always the same basic organization, or lack of it. Because the organization has not changed, increased size has destroyed communication, and is destroying skill. A different type of organization could use the same men and equipment with great benefits if it were oriented towards the current problems.

Numerical control is capable of revolutionizing batch manufacture but it has not done so, because these new machine tools have been incorporated into the old organizational structure. By lifting numerical control out of its present context and designing round it a completely new organization, order-of-magnitude improvements are possible. The first attempt to do this, and its performance, are described, together with a glimpse into the future showing the even greater improvements which will be possible when manufacture is integrated with design.
The Engineer in Society
Authors: Vickers Antony
Published: October 2007

The paper is in three parts. The first concerns the social and economic implications of technological progress with particular reference to electric power generation, the iron and steel industry and transportation.

The second part relates to the fundamental principles of money as a means of payment and a measure of value; also explains the controlling factors which regulate the purchasing power of money.

In the third part the author suggests what might be achieved if, by more modern economic policies, redundant resources were to be transformed into national assets and increased gross national product.
Medium Speed Diesel Engine Noise
Authors: Bertodo R. , Worsfold J. H.
Published: October 2007

The paper briefly reviews past work on diesel engine noise with particular reference to medium speed engines. A survey carried out on a large number of British and European turbocharged and water-cooled dieseis having bores in the range 2 3/4 in to 33 in (∼ 70 mm to 840 mm) clearly indicated at least two main sources. A qualitative analysis of the problem suggested these to be due to combustion and piston transverse motion in the liner clearance space. None of the engines examined had an International Standards Organization rating lower than Noise Rating 85.

A comparison of theoretical trends with those obtained from the survey proved encouraging and application of the analytical findings to five specific engines having bores of 5 in, 8 in, 10 1/4 in, 12 1/2 in and 14 1/4 in (∼ 127 mm, 200 mm, 260 mm, 320 mm and 360 mm) yielded reasonable estimates of the overall noise, but poor approximations to the relevant frequency spectra. Much more work on the effects of crankcase attenuation would appear in order.

It is concluded that the wider acceptance of medium speed dieseis will not lead to increased noise problems provided appropriate action is taken at the design stage. Broad design recommendations are presented and the causes of variations of noise with time and of engine to engine scatter discussed. The marked improvements obtained on a 14 1/4 in (∼ 360 mm) bore engine are shown.
Pressure Fluctuations Due to Interaction between Blade Rows in Axial Flow Compressors
Authors: Parker R.
Published: October 2007

The paper presents the results of a theoretical and experimental investigation into the potential flow interaction effects between blade rows in an axial flow compressor stage. The investigation is concentrated on the inlet guide vane/rotor interaction and shows that the passing of the rotor blades behind the guide vanes produces large pressure fluctuations on the surfaces of the guide vanes.

The available method of computation is not yet adequate for prediction of absolute values of pressure amplitude but does provide a sound basis for comparison between alternative designs.
Development of Spanwise Velocity Profiles through Cascades and Axial-Flow Turbomachines
Authors: Swainston M. J. C.
Published: October 2007

The development of the spanwise velocity profile in the incompressible viscous flow through cascades is approached from a new point of view. This approach shows the way in which the cascade loading, the secondary losses, and the inlet-flow conditions interact to produce the downstream profile. The analysis leads to the establishment of a family relationship for experimentally occurring profiles. An empirical velocity-profile shape is determined which has the same properties as the experimental family, and this is used to demonstrate the way in which the mean secondary losses are distributed over the blade height. The profile development is studied in multi-stage machinery, and the formation of an equilibrium state after some few stages is shown.

Work-done and blockage factors are computed for 50 per cent reaction compressor stages.
Experimental and Analytical Studies of the Compression Ignition of Fuel-Oxidant Mixtures
Authors: Karim G. A. , Watson H. C.
Published: October 2007

The paper describes an approach for predicting the time variation of the state of a non-adiabatic reacting charge undergoing a change in density, such as that in a motored autoigniting engine or the ‘end gas’ of a spark ignition engine. To describe accurately the rates of chemical reactions involved and to account for the production of intermediate combustion products and their survival, detailed chemical kinetics involving chain reactions are employed.

To test the approach developed, hydrogen gas is employed as a fuel in the closely controlled environment of a specially developed compression apparatus which is closely akin to that of the piston engine, yet more amenable to control and analysis. Subject to the availability of reliable detailed kinetic data for the reactions involved very good agreement between theory and experiment can be achieved. The future implications and utilization of such an approach is discussed.
First Paper: Temperature Effects on Cavitation in a Centrifugal Pump: Theory and Experiment
Authors: Chivers T. C.
Published: October 2007

A theoretical model is proposed to explain the development of cavitation in a centrifugal pump. A basic assumption is that the pump always behaves as a head generating-volume flow device, hence the density of the cavitating fluid becomes important, and this is estimated assuming that cavitation is a bubble growth problem. Essentially the model applies to best efficiency flowrate and complete breakdown, and is semi-empirical since test data at ambient conditions are required. From these data predictions are made of the variation of breakdown and inception points with temperature and speed. Experimental results are then presented and these show excellent agreement with the predicted results over a wide range of temperature, and hence thermodynamic properties, at constant speed. However, the agreement between the predicted speed effect and the experimental results indicates that the scaling used could be in error.
An Experimental Investigation of the Flow in a Classical Venturimeter
Authors: Lindley D.
Published: October 2007

The flow through two classical 10 in diameter venturimeters of 0.5 area ratio is investigated to determine the nature of the flow mechanism within the meter and its variation with Reynolds number. Separation occurs at the throat entry, the size and position of the resulting bubble apparently remaining unchanged up to a throat Reynolds number of approximately 2.9 × 105, while beyond this point the separation bubble seems to disappear. An investigation of the wall region of the throat boundary layer shows it to be fully turbulent throughout the throat Reynolds number range tested from 4 × 104to 7.5 × 105. A comparison of experimental data obtained from both air and water tests on the two meters indicates that the flow mechanism is substantially the same for both fluids. The experimental evidence suggests that any postulation of laminar-turbulent transition of the wall region of the boundary layer is inapplicable to the analysis of flow through classical venturimeters in a pipe having similar geometry to the meters studied.
An Analysis of Impeller and Volute Losses in Centrifugal Fans
Authors: Myles D. J.
Published: October 2007

The measured losses from tests on five centrifugal fan impellers of different blade angle, running at constant speed in a given volute, are analysed. Impeller and volute losses, expressed as a fraction of the dynamic exit pressure relative to impeller and volute respectively, are correlated with a diffusion factor over a wide volume flow range. The results are applied to other impellers and volutes.

The low volume flow range of operation is also considered.
Mechanization of Hand Tooling in Open Die Press Forging
Authors: Alexander J. M. , Dunn P. , Harding D. B. , Pearson D. S. , Tomlinson A.
Published: October 2007

This paper describes a design study of equipment for the handling of ancillary forging tools employed in open die press forging. From an examination of manual tooling practice in a press forge a specification for a mechanical handler is drawn up and a suitable design completed. This is costed and assessed in relation to the savings in manpower and time, and is found to be economically viable.
Isotopes in Radiotherapy: Medical and Engineering Considerations
Authors: Shapiro J. S. , O'Connor A. D.
Published: October 2007

In Part 1 by Mr J. Shapiro, the merits of the chosen combined shielding design are explained. The geometry of the radiation head is given including the source movement mechanism. The problem, basic principle and engineering embodiment of the radiation beam definition and control mechanism are discussed. The fundamental approach and engineering solutions of the radiation head alignment system are described. The remote control of the unit and the treatment sequence are briefly reviewed.

In Part 2 by Dr A. D. O'Connor, the radioactive isotopes suitable for use in large treatment units in radiotherapy are reviewed with special reference to cobalt 60. In comparison with X-ray generators of such quality, such units are more reliable. The features of design of a unit desirable for isotope teletherapy are set out. The methods of treatment planning and execution are described and the advantages obtained from the Servotec Canterbury unit enumerated.
An Experimental Investigation of the Influence of Speed and Scale on the Strain-Rate in a Zone of Intense Plastic Deformation
Authors: Stevenson M. G. , Oxley P. L. B.
Published: October 2007

Experiments are described in which an explosive quick-stop device and printed grids (0.002 in square) were used to measure the deformation (streamlines of flow) in the zone of intense shear in which the removed chip is formed in orthogonal machining. A method is given for calculating the strain-rate from the experimental streamlines and it is shown that both the maximum and mean values of the maximum shear strain-rate in this zone are directly proportional to speed (shear velocity) and inversely proportional to scale (depth of cut).
An Investigation into a Novel Bubble Casting Process for Forming Thin-Walled Aluminium Containers
Authors: Horrocks D. , Hawkyard J. B. , Johnson W.
Published: October 2007

A method for producing thin-walled containers direct from the molten state, by forming a bubble into a mould somewhat on the lines of glass-blowing, has obvious attractions in terms of manufacturing cost and versatility in the shapes and sizes that might be readily produced. The design of experimental equipment for exploring the feasibility of such a process is described, together with some preliminary experimental results. The work was undertaken following various articles (2) (3)† reporting a ‘bubble forming’ process under development in the U.S.A.; a patent specification followed (4) giving brief details. There appears to have been no significant commercial application reported so far and no additional technical information has been published.
Interferometric Determination of Elastohydrodynamic Lubrication Contact Pressures
Authors: Cope D. L. , Haines D. J.
Published: October 2007

A study has been made of the stress distribution in optical quality glass rolling elements operating under conditions of elastohydrodynamic lubrication, and the pressure distribution in the lubricant film has been inferred from interferometric measurements of the distribution of principal stress sum and principal stress difference on the boundary of the contact region. The absolute retardation method of stress analysis which permits these evaluations has been developed and extended to the measurement of steady-state dynamic stresses, for this purpose. The techniques in use are also amenable to use in the analysis of plasto-elastic elastohydrodynamic lubrication problems.
Identification of Mechanical Sources of Noise in a Diesel Engine: Sound Originating from Piston Slap
Authors: Fielding B. J. , Skorecki J.
Published: October 2007

The sound produced by the piston slap of a diesel engine is investigated by standard methods of sound and vibration analysis augmented by correlation of incidence of individual transient components. This latter technique makes use of information obtained from the tuned outputs of the noise signal, focusing attention on the incidence of single-frequency transients.

The contribution of piston slap to the overall noise emitted by an engine is studied analytically by examining equations for the transverse motion of the piston and experimentally by varying engine parameters such as piston-cylinder clearance, gudgeon-pin offset, and piston lubrication.

By considering the various distinct characteristics, an insight is gained into the mechanism of noise generation and radiation.
Determination of the Dynamic Characteristics of Machine Tool Structures
Authors: Chowdhury I. , Sadek M. M. , Tobias S. A.
Published: October 2007

The ‘operative harmonic response locus’ of a machine tool structure, which is required for the prediction of machining stability, must be determined by vibration tests carried out under conditions which simulate closely those arising during cutting. This requires that such tests be performed while the tool or the workpiece spindle is rotating, the vibrations being excited by a small harmonic force superimposed on a large constant pre-load.

It is not possible to satisfy these conditions with vibrators working on electro-dynamic or electro-hydraulic principles and so an electro-magnetic vibrator was designed and developed to meet the above requirements (2). This excitor can be used with all types of machine tools, but in the present investigation its application is restricted to lathe and horizontal milling machines.

The effects of the rotational speed of the lathe spindle and milling machine spindle, of the exciting force amplitude and of the pre-load magnitude and direction on the response data, are investigated. It is found that the lathe structure behaves in a linear fashion whereas the behaviour of the milling machine is non-linear.
Hydraulic Lock Forces on Tapered Pistons
Authors: Hessey M. F. , Martin B. P. , Brighton D. K.
Published: October 2007

When a piston subject to an axial pressure drop has to be moved periodically along a bore sticking often occurs owing to hydraulic locking between the piston and the bore. The locking is caused by the hydrostatic pressures acting along the annulus between the two surfaces.

The hydraulic instability may be reduced by using a piston tapered to give a converging film shape in the direction of flow, and this paper considers a large number of tapered configurations. The hydraulic pressures are calculated by a solution of Reynolds' two-dimensional equation using a digital computer, and the resultant force and its line of action are obtained. From these results empirical equations for the locking force and its line of action are derived which are valid for a wide range of conditions. The values predicted by the equations agree well with experimental and theoretical results given in the literature.
A Comparison of the Performance of Three Model Axial Flow Turbines Tested under Both Steady and Pulse Flow Conditions
Authors: Daneshyar H. , Edwards K. J. , Horlock J. H. , Janota M. S. , Pearson R. D. , Shaw R.
Published: October 2007

Three turbines, covering a range of reaction of +20 per cent to − 10 per cent at their blade roots, have been tested under both steady and ‘pulse flow’ conditions in order to assess their degree of suitability for turbo-charger application.

The results have been analysed in a way which enables efficiencies to be plotted against a mean non-dimensional blade speed irrespective of the level of pulsation. This method of presentation enables the results to be used directly for design purposes and in matching calculations. Thus the efficiency penalty due to pulse flow, the effect of pulse flow on the choice of turbine size, and the preferred degree of reaction under pulse flow may be assessed.

For the present tests the range of variation in gas speed under pulsing conditions is thought to compare in severity with that produced when a single turbocharger is connected to three cylinders of a large two-stroke marine engine. For this case the design having the highest degree of reaction is shown to give an efficiency four percentage points higher than either of the other designs. It also has a clear advantage under steady flow. The intermediate design, having zero root reaction, corresponds to the type of turbine conventionally used in turbo-chargers and is shown to be the one most sensitive to losses in efficiency resulting from pulsation. It appears therefore that substantial improvements could be made in turbines for future turbocharger designs by increasing the reaction.

Further testing of these turbines under modified pulse conditions, with significant windage period, is advocated. The advantage of the high reaction design must be demonstrated for such conditions before a change of design reaction could be regarded as fully justifiable.
Piston Ring Scuffing—A Broad Survey of Problems and Practice
Authors: Neale M. J.
Published: October 2007

Piston ring and cylinder scuffing is frequently experienced at the development stage on most engines. The mechanism is not really understood because of the large number of interacting factors. Since, however, internal combustion engines are made in a wide range of sizes it is possible to view them as a range of scale models and, by studying these on a broad basis, seek general performance patterns. The author describes an investigation of this kind and brings out a relationship between scuffing problems and engine performance, oil consumption and wear rate. He also briefly reviews the present understanding of piston ring operation and gives design guidance and suggests lines of investigation. This process of analysing the performance of a range of existing devices appears to be a technique which can provide useful guidance on design, market planning and forecasting.
Systems of Engineering Organization
Authors: Wearne S. H.
Published: October 2007

The author has studied systems for the division of work and co-ordination of projects in large engineering design and development departments in a variety of industries, comparing systems in use with theories of organization. These studies indicate that the systems of organization appropriate to engineering departments primarily depend upon the programme of projects in design rather than the technical content of the work. It is also shown that the responsibility for a project can pass down from level to level in an organization as risk is reduced by proceeding with a project.
A Solution Using the Superposition Technique for Externally Pressurized Multi-Recess Journal Bearings Including Hydrodynamic Effects
Authors: O'Donoghue J. P. , Hooke C. J. , Rowe W. B.
Published: October 2007

The paper presents details of a computer solution to the problem of a rotating multi-recess externally pressurized bearing. It is shown that the bearing number Nη/ P8(cD/D)2correlates the results and permits the superposition of hydrodynamic and hydrostatic results for a given geometry. This significantly reduces the computer time necessary for a complete survey of results since only one solution for each of the Laplace equations and the Reynolds equation is required at any eccentricity. The problem of the control circuit is solved separately and is negligible in computer time taken in comparison with the main subroutines of the programme for finding the hydrodynamic and hydrostatic coefficients.