bluuebunny/crossref_metadata_2025 huggingface dataset:
The Expansion of the Fisheries: New Applications of Mechanical Power in Man's Oldest Industry
Authors: Eddie G. C.
Published: October 2007

In the last 20 years, adoption of new vessel types and methods has helped to secure a three-fold increase in world catch. Studies of the performance of new designs, to ensure operational effectiveness at economic cost, have now led to further innovations. Intensified competition and scarcity of manpower necessitate a continuing programme of development. The object is to improve the availability and acceptability of a foodstuff to the consumer.
The Effect of Extraneous Factors on the Development of Test Methods
Authors: Hall M. A. W.
Published: October 2007

Comparative testing of cars for a quarterly consumer magazine poses a particular set of problems. The main ones are time and the designing of apparatus to produce objective comparisons between cars. A subsidiary, but important, problem is the need to produce information which is technically valid and yet readily interpretable by a non-technical public.

A test unit is described, and a typical test programme is outlined. Examples are given of the way in which particular problems have been overcome: in particular, the evolution of equipment for measuring acceleration, which has reduced the time necessary for testing by 75 per cent, is described. The development of comparative tests for handling is discussed, and the difficulty of defining a simple measurement of the noise inside a car is used as an example of the difficulty of producing objective measurements which correlate with subjective impressions.

It is concluded that, whilst rationalization of test methods is often both desirable and practicable, it is sometimes necessary for individual organizations to retain their own particular methods.
Design of Active Suspensions
Authors: Thompson A. G.
Published: October 2007

The synthesis method is employed for the design of servo-suspensions of the electro-hydraulic type. Two alternative arrangements are considered in which the hydraulic actuators and the body support springs are respectively in series and in parallel. The achieved designs for active suspensions of this type are superior to conventional systems both in ride quality and in overall stiffness to resist body load forces, but slightly less effective in regard to road-holding. If dynamic absorbers are used for the control of axle vibrations it is shown that considerably greater improvements in ride quality than hitherto possible may be obtained with the aid of an additional feedforward compensating signal flow path. The derivation of the necessary compensation circuits to achieve the specified overall system performances is demonstrated by examples. A simple method of banking control of the vehicle by inclined sensing accelerometers is suggested.
The Effect of the Method of Gas Admission on Performance of a Spark-Ignition Gas Engine
Authors: Mitchell G. P. , Whitehouse N. D.
Published: October 2007

This paper reports on the effect of position and timing of gas admission on the performance of a spark-ignition engine using methane. The investigation was aimed at exploring the effect of design limitations experienced with turbocharged medium-speed engines.

Performance was judged on the criteria of optimum specific fuel consumption combined with minimum cyclic dispersion.

Results were obtained at a fixed fuel consumption and mostly at fixed air/gas ratios and are not, therefore, necessarily directly applicable to commercial engines. For near stoichiometric air/gas ratios, optimum performance was obtained most easily by early and prolonged gas admission. Better thermal efficiency was obtained with weak mixtures, about 80 per cent of stoichiometric, and optimum gas admission was generally less obvious. Performance patterns did not vary consistently with gas admission timing; they improved or deteriorated with late gas admission, depending on the type of air inlet valve—presumably owing to air motion and gas/air mixing in the cylinder.

From the results obtained, it seems probable that cyclic dispersion was minimal when the mixture around the spark was at, or near, stoichiometric and was most easily achieved by perfect mixing when the overall mixture was near stoichiometric.
The Measurement of Air Velocity in a Motored Internal Combustion Engine Using a Hot-Wire Anemometer
Authors: Hassan H. , Dent J. C.
Published: October 2007

The application of the constant temperature hot-wire anemometer to the measurement of instantaneous gas velocity in the pre-chamber of a motored I.C. engine is shown to be possible. The correction of the anemometer output to allow for the operation of the wire at conditions greatly removed from those of a windtunnel calibration are discussed. The variation of gas velocity at a fixed point in the pre-chamber with variation of engine compression ratio and engine speed was studied.
The Effect of Heat Treatment and Decarburization on the Fretting Fatigue Behaviour of a 0·7 per Cent Carbon Steel
Authors: Waterhouse R. B. , Taylor D. E.
Published: October 2007

Fretting fatigue produces a smaller lowering of the fatigue strength of a 0·7 per cent C steel when the surface is decarburized than when the steel is cold-worked. The rapid rate of abrasion of the decarburized surface results in large amounts of oxide debris which prevents metal-to-metal contact. The cold-worked steel has a low fretting fatigue strength because of its greater susceptibility to high strain fatigue.
A New Unified Approach to Surface Metrology
Authors: Spragg R. C. , Whitehouse D. J.
Published: October 2007

Current standards for the assessment of surface texture are based on some form of height index, such as peak-to-valley or arithmetic average ( Ra). Although useful, these parameters take little or no account of the openness or closeness of the texture. In this paper, an additional parameter, the average wavelength, is introduced which is wavelength conscious and intended to supplement the information given by the Ra index. The authors show how this new parameter can be derived from arithmetic average/average slope and highlight the problem of small wavelength filtering and the importance of fully defined bandpass measurement. The average wavelength index, when considered together with the Ra value for a given meter cut-off, is useful in the control of surface roughness and could also be useful in the measurement of waviness, straightness and errors of form. Finally, in surfaces where the asymmetry of the waveform is important, a third parameter derived from the peak and valley distribution is introduced. This is essentially a measure of the asymmetry of the profile about the mean line and, consequently, is a measure of the skew.
Mechanical Handling Aspects of the Tilbury Grain Terminal
Authors: Griffith J. B. , Addicott D. W. R.
Published: October 2007

The grain terminal for the Port of London Authority (P.L.A.) began commercial operation in April 1969. It is designed for discharge of ships up to about 45 000 ton dead weight (d.w.) at rates up to a maximum of 2000 ton/h. The installation provides two discharging machines of the marine tower type, 105 000 ton of silo storage capacity and an ability to handle from ships to silo, rail, road, coaster or to adjacent flour mills.

It also permits loading out to coaster or barge either by direct trans-shipment or from silo. Many alternative handling routes are provided and a very large degree of remote control has been incorporated. The majority of the routes are capable of handling up to 1000 ton/h over a single conveyor. The marine towers are unique in Europe and probably incorporate a greater degree of sophistication than exists in any similar equipment in the world.

This paper describes briefly the background leading to the construction of the terminal and the layout of the whole installation. Some of the more interesting points in the mechanical handling control system employed with particular reference to the marine towers, methods of routing, tripper control and dust suppression are described in detail. Comparisons are made between the installation at Tilbury and the installation at present under construction for the Mersey Docks and Harbour Company at Seaforth.
Possible Flow Regimes of Adiabatic One-Dimensional Compressible Fluid Flow with Friction in Convergent and Divergent Ducts
Authors: Shouman A. R. , Garcia C. E.
Published: October 2007

An analytical solution for the compressible one-dimensional flow in convergent and divergent ducts with friction is obtained. It is found that a non-dimensional parameter, N, can be formed using the friction factor, duct half-angle and the ratio of specific heats of the gas. Seven flow regimes are describable with the solution, based on certain bounds on the magnitude of N. The regimes are discussed and corollary data are presented graphically.
Heat Transfer in Compression-Ignition Engines: First Paper: Heat Transfer in a Quiescent Chamber Diesel Engine
Authors: Whitehouse N. D.
Published: October 2007

Instantaneous and mean values of heat transfer at various positions in the combustion chamber were obtained, by means of surface thermocouples, for different loads and speeds and compared with those obtained theoretically from synthesized cycle calculations. The results show that the usual model of homogeneity in the cylinder is inadequate for heat transfer calculations. Peak rates of heat transfer when in the vicinity of a fuel spray were comparatively little dependent upon load or speed. At the periphery of the combustion chamber the mean heat transfer rates were appreciably lower than to the cylinder head and piston and the rapid rise in instantaneous values occurred appreciably later. The results all suggest the need for a more realistic model based upon the geometry and penetration of the fuel sprays.
The Design of Alaskan North Slope Production Wells
Authors: Koch R. D.
Published: October 2007

In 1970, three senior members of BP's Exploration Department received the MacRobert award for their outstandingly successful Alaskan North Slope exploration, which led to BP's acquisition of the leases to over half of the great Prudhoe Bay oilfield, estimated to contain in excess of 1000m tons of recoverable high quality crude oil. Their determination of the distribution of the permafrost, permanently frozen ground, and the effect that permafrost had on seismic reflections, significantly contributed to their successes.

While a great deal of information on operating under Arctic conditions and providing livable working conditions for hundreds of men was available, nothing was known of the effects of producing hot oil from wells completed through up to 2000 feet of permafrost.

The paper traces the events leading to the discovery of oil on the North Slope and outlines some of the design problems which BP had to resolve to exploit this discovery.
A Study of the Hot Rolling of Thick Flat Slabs
Authors: Sparling L. G. M. , Willows R. A. L.
Published: October 2007

This investigation into the hot rolling of aluminium slabs which have a thickness approaching the roll radius is divided into two parts. First, experimental load and torque values are compared with ones calculated from proposed shear plane configurations with compatible hodographs (velocity vector diagrams). Secondly, experimental slip line fields (fields of maximum shear strain lines) and hodographs are determined from measured displacements of an orthogonal grid, scribed on the central vertical longitudinal plane of a slab which had been rolled into a cobble and slit along this plane, the whole slab then being incrementally re-rolled.
Unsteady Heat Transfer in a Motored I.C. Engine Cylinder
Authors: Hassan H.
Published: October 2007

After a brief review of the existing formulae for the unsteady heat transfer in I.C. engine cylinders, a new approach is described.

It is shown that the existing empirical heat transfer data of forced convective case for the flat plates or pipes can be used to predict the heat transfer. Experimental results obtained on a motored engine are presented which include the measurement of gas velocity, temperature, pressure and metal surface temperature to obtain the convective unsteady heat transfer through the engine cycle. The experimental results are compared with the empirical data on a flat plate and it is concluded that the agreement is within 20 per cent.
The Starved Lubrication of Cylinders in Line Contact
Authors: Wolveridge P. E. , Baglin K. P. , Archard J. F.
Published: October 2007

A semi-analytical solution is presented showing the effect of variations in the position of the inlet boundary of the lubricant film upon the load capacity of cylinders in line contact. Firstly, isoviscous conditions and undeformed surfaces are assumed; by the use of appropriate non-dimensional parameters, the results of the theory can be exhibited as a single function applicable to all possible experimental conditions. This can then be transformed to deduce a similar unique expression showing the proportional reduction in the minimum film thickness for variations in the position of the inlet boundary, all other conditions being maintained constant. A similar analytical solution is presented showing the effect of the position of the inlet boundary upon the film thickness under heavy loads. This assumes full elastohydrodynamic conditions and is based upon an analysis similar to the familiar theoretical treatment of Grubin.

Comparisons show that published computer solutions of these problems, for specific sets of conditions, are in good agreement with the more general analytical solutions presented here.
The Development of the Porsche Type 917 Car
Authors: Mezger Hans
Published: October 2007

For approximately twenty years Porsche has participated in motor racing. The development of Porsche production cars takes advantage of a major part of the experience accumulated during these performance-oriented activities.

This paper deals with the development of the Porsche 917 racing car which is powered by an air-cooled 12-cylinder engine producing about 630 DIN hp. The application of lightweight materials like titanium, aluminium, magnesium, fibreglass, etc. is also described.

The Porsche 917 racing car which obtained its Fédération Internationale de l'Automobile homologation by a series of 25 in April 1969 has now become the most successful car in motor racing throughout the world. In 1970 the 917 car was the overall winner at the 24 hours race at Le Mans.
Gas Turbimes for High-Specific-Output Industrial Heat-Transfer Equipment
Authors: Kellett E.
Published: October 2007

The incompatibility of the dual role of air as a combustion and heat-transfer fluid is apparent in the unbalance of convective heat transfer in a water boiler. Pressurized combustion has, since the middle of the nineteenth century, been postulated as a means of increasing the gas-side convective heat transfer to more nearly correspond with the water-side rate.

Gas turbines, in the form of turbine-driven supercharged boilers, have been made, but without significant commercial success, in Europe and America.

Modern gas turbines are employed in total-energy systems but because of the premium value of their shaft power output, additional heat exchangers must have the minimum pressure loss and therefore conventional heat-transfer criteria apply.

Small turbine-driven superchargers are now mass produced for automotive diesel engines and particularly with the availability of natural gas the feasibility of pressurized combustion by their use justifies re-appraisal. Although these turbochargers have little value as gas-turbine power units the margin of turbine output over compressor power absorption can be employed to improve heat-exchanger convective heat-transfer rates significantly.

The provision of a second compressor in the rotor system enables a stoichiometric air and gaseous fuel charge to be induced into a simple pre-mixed combustor thus preserving the low-cost aspect of the turbocharger and providing improved control and safety in a very durable gas-turbine device. The addition of a simple after-burner allows total combustion at relatively low excess air rates.

The arguments leading to the foregoing design are presented and some of the more important product developments are described. Examination of the wider application potential of such low-cost turbomachinery indicates prospects for their employment in diverse uses particularly where high heat-transfer rates are desirable.
Variable Valve-Timing Unit Suitable for Internal Combustion Engines
Authors: Roe G. E.
Published: October 2007

As the specific power output of I.C. engines is increased, the range of engine speed over which useful torque is available is reduced. This ‘power band’ can be widened by having automatically varying valve timing, with the timing being a function of engine speed and/or load. A prototype cyclic phasing unit has been tested which successfully varies the timing of a poppet valve with opening, closing points, and the form of valve lift curve being readily varied independently. The unit is simple mechanically, but ideally one unit is needed for each valve, so principal application is likely to be on engines with a small number of cylinders. In addition to flattening the torque curve, such a unit is likely to give improved fuel consumption and lower exhaust emissions, particularly hydrocarbons.
Impact Behaviour of Small Scale Model Motor Coaches
Authors: Lowe W. T. , Al-Hassani S. T. S. , Johnson W.
Published: October 2007

Simplified small scale model motor coaches were designed and tested under both static and dynamic loading and attempts are made to relate the results to a full scale collision.

Two theoretical approaches for the modelling of a motor vehicle collision are discussed and generally developed using dimensionless analysis and a technique of relating the actual vehicle and models to tubular structures.
Shakedown of Pressure Vessels with Ellipsoidal Heads
Authors: Fox J. D. , Kraus H. , Penny R. K.
Published: October 2007

The shakedown of cylindrical pressure vessels with arbitrary heads is described in general by means of Leckie's adaptation of Melan's shakedown theorem. The procedure is mated with an elastic shell analysis programme, which is then used to calculate shakedown pressures for vessels with ellipsoidal heads that have aspect ratios of 3, 2 1/2, 2, 1 1/2, 1, and a variety of thickness ratios. Comparisons with the design pressures obtained by the methods of the A.S.M.E. Boiler and Pressure Vessel Code are also made.
A Study into the Use of Pseudo Random Binary Sequence Pressure Disturbances to Measure Sonic Velocity in a Two-Phase Flow System
Authors: Gill K. F. , Reed E. W.
Published: October 2007

A literature survey into gas-solids flow has revealed that most of the existing work is of a theoretical nature. Of fundamental importance to this theoretical work is the concept of sonic velocity. Presented here is a novel method that enables this parameter to be measured experimentally. The technique used is to inject small amplitude pseudo random binary sequence pressure disturbances into a two-phase flow system and compute a cross-correlation function between two measuring locations within the flow system. The time shift of the peak value of this function gives a direct measure of the sonic velocity existing between these two locations. The experimental results demonstrate that by using a pseudo random pressure disturbance on-line evaluation of sonic velocity becomes feasible.
Numerically Controlled Machines
Authors: Chadbund J. E. , Parker M. N.
Published: October 2007

The paper describes the preparation of machine control tapes using a computer programme package, and the B.S.R.A. (British Ship Research Association) part-programming processor system. The comprehensive nature of the system, the development of a modular basis and the modification of the general engineering 2CL to provide a shipbuilding version are described.

N.C. (Numerical Control) machines in use in shipbuilding include automatic draughting machines, several varieties of N.C. flame-cutting machines and their associated computer programmes, and a N.C. frame bending machine.

The advantages of Numerical Control are listed and the importance of considering the system as a whole is emphasized.
Hydraulic and Thermal Hydraulic Instability in Condensate Feed Systems for Large Thermal Power Stations
Authors: Dartnell Lawrence
Published: October 2007

Hydraulic shocks and instabilities occurring in condensate feed systems associated with large steam turbine generating plants have been investigated and found to be diverse in origin and character.

In service instabilities are attributed, inter alia, to powerful interstage cavitation in centrifugal condensate pumps, to the penetration of unstable zones of pump suction water level, to swiftly stroking valves, to inventory shifts and the placing of pressurized systems in communication with voided systems. Shock is attributed to pumping into evacuated systems.

Sustained heat transfer in steam-water and water-water heat exchangers has caused system over-pressurization during off-service conditions. Some difficulties encountered during operations are described and discussed. Recommendations are made for the elimination or minimization of trouble in existing systems and for the avoidance of trouble in future systems.
The Prediction of the Optimum Performance of Ejectors
Authors: Kentfield J. A. C. , Barnes R. W.
Published: October 2007

A simple, incompressible flow, ejector model was formulated and analysed. It was found that the results obtained analytically agreed closely with those of an experimentally conducted optimization carried out by other workers. The model was also used to compare the relative merits of constant static pressure versus constant area mixing: it was shown that the latter was superior to the former when nozzle, mixing tube and diffuser friction losses were taken into account. The work also indicated that the efficiency of an ejector tends to increase as the secondary-to-primary stream density ratio decreases.
An Assessment of Diesel Engine Poppet Valves
Authors: Bertodo R. , Sivakumaran S.
Published: October 2007

The paper reviews an assessment of the factors affecting the reliability and durability of poppet valves of highly rated medium speed diesels burning standard or residual oils.

Detailed analysis demonstrated that an undercut (tuliped) profile is preferable. Optimum dimensional proportions are derived. The valve behaviour under operating conditions was such as to suggest that it plays a passive part in the phenomenon of ‘valve sinkage’. The adoption of ‘differentially angled seats’ appears to have little meaning in practice. Cylinder head deflection was a governing feature of seat ‘guttering’.

A review of material properties suggested that the often quoted Eichelberg quality factor is inadequate and an alternative parameter for assessing the suitability of materials is derived. All materials suitable for valve manufacture possess poor resistance to corrosion attack. A number of possible palliatives are examined.
A Numerical Solution for the Hydrodynamic Lubrication of Finite Porous Journal Bearings
Authors: Reason B. R. , Dyer D.
Published: October 2007

We present a numerical solution for the operating conditions of a hydrodynamic porous journal bearing. The numerical method allows for the possibility of variable porosity in the bearing matrix, but the solution has been achieved on the assumption of matrix homogeneity. The relation between the various bearing parameters have been shown for a variety of bearing geometries and permeabilities enabling the operating conditions for this type of bearing to be better appreciated. A comparison of the present solution with approximate solutions used by other authors has been made, which indicates the useful working range of the approximate solutions.
Natural Frequencies and Modeshapes of Systems of Generally Interconnected Shafts
Authors: Palmer N. S. , McCallion H.
Published: October 2007

This paper describes a method for the evaluation of natural frequencies and modeshapes of a general system of shafts linked by general interconnections. A detailed description is given of the particular case where a connection is made by two meshing spur gears; transverse displacement of gear centres as well as torsional displacement being taken into account. The method which has been developed can be applied to any type of connection in which a linear relation exists between the displacements.

A gearbox rig is described which has been designed and constructed for experimental testing of the spur gear interconnection. The measured natural frequencies of the rig and its casing separately are given and evaluated in terms of the predicted values. Satisfactory identification is obtained for the lower frequency modes.
Carry-Under Performance of Drums in High Pressure Circulation Boilers
Authors: Gardner G. C. , Crow I. G. , Neller P. H.
Published: October 2007

The results of several experimental programmes defining the various mechanisms of importance in determining the carry-under of steam in boiler drums are described. One programme examined the performance of cyclones and the natural separation of steam in the water pool in a full-size section of drum by employing Freon 12 liquid and vapour as the working fluids. Another programme studied the drawdown of the main liquid-vapour interface into the downcomers in a fifth-scale cold water model and theoretically described the critical conditions. Also discussed is a programme concerning heat transfer by the subcooled feed.
Random Load Fatigue Damage Accumulation in Mild Steel
Authors: Fisher B. C. , Sherratt F.
Published: October 2007

Using high-sensitivity eddy-current crack detection, quantitative division of fatigue life into two stages has been achieved for a variety of random and constant amplitude loading conditions. The divisions adopted were:

Stage A, microcrack initiation and propagation, and Stage B, macrocrack propagation.

The results of specimen sectioning and optical microscope work show that this behaviour is physically compatible with the observations of Forsyth (1)‡.

It is established under random loading that for a given specimen configuration, the proportion of time spent in stage A behaviour for a given fatigue life remains unaltered for changes in the waveform irregularity factor. This statement applies to two series of tests for loading waveforms of unaltered fundamental p.s.d. (power spectral density) shapes and Gaussian amplitude probability density distributions. It is suggested that the signal maximum peak/r.m.s. ratio is a significant factor in determining the proportion of life spent in crack initiation.

Cumulative damage predictions are made using Miner's hypothesis on a basis of positive peak stresses to failure for stage A and stage B lives, and overall fatigue life. The results confirm that Miner seriously underestimates the damage contribution at low stresses on fatigue life as a whole, and also for the crack initiation phase of life.
Effect of Pre-Injection Fuel Temperature upon Diesel Engine Ignition Delay and Soot Emission
Authors: Tempk-Pediani R. W.
Published: October 2007

The effect of pre-injection fuel temperature upon the ignition delay and soot emission has been investigated on an i.d.i. engine running on diesel oil. Effects of evaporation in the engine cycle, at both subcritical and supercritical pressures, are discussed and attention focused on the probable attainment of the critical temperature by liquid droplets in certain ambient conditions. Stress is laid on the future need concurrently to optimize the injection equipment and the level of air swirl to realize the potential of fuel preheating.
The Selection of Lubricating Oils for Industrial Plant: The User's Point of View
Authors: Summers-Smith D.
Published: October 2007

It is shown that a small number of oil viscosity grades should satisfy the lubrication requirements of most industrial plants. Problems with lubricating oil additives are discussed and it is concluded that such materials should only be used where proven essential.
The Supercavitating Pump
Authors: Pearsall I. S.
Published: October 2007

Cavitation in conventional pumps can cause loss of efficiency and erosion damage. For these reasons speeds and suction pressure are limited to avoid these effects. There are, however, applications where, for technical or economic reasons, these limitations are not acceptable. For these, the supercavitating pump has been developed. Basically it comprises an axial-type impeller with cavities forming over the suction side of the blade and collapsing downstream where they cause no damage. For duties requiring higher pressures, it can be staged in front of a conventional centrifugal pump.

The complete development of the supercavitating pump, the theoretical optimization of the geometric parameters to get good or best performance and the theoretical design method based on potential flow cascade data are described. Experimental results are given for a series of impellers of different size, speed, stagger angle and blade shape. Comparison of the experimental results with the design method gives good agreement on the whole. Data are also given on the effects of secondary losses, tip clearance losses, blade thickness and blade rake. Some of the applications and uses of such pumps in the process industry, as boiler feed and aircraft fuel pumps and for water jet propulsion, are discussed.
Ultra-High-Speed Machining: A Review and an Analysis of Cutting Forces
Authors: Arndt G.
Published: October 2007

As part of the search for a new cutting mechanism, a few largely empirical investigations into ultra-high-speed machining (velocity greater than 500 ft/s) have been performed in the past. A comprehensive review of this and other work related to machining at very high cutting speeds is presented and the physical factors predominating in UHSM are discussed. As a consequence of this a new theory of cutting forces at ultra-high speeds is presented, based on inertia and temperature effects, adiabatic shear, and strain-rate dependent yield stress. This theory shows that workpiece properties greatly influence force behaviour, the latter determining the feasibility of machining at ultra-high speeds.
Developments in Computer Control Systems for Machine Tools
Authors: Wightman E. J.
Published: October 2007

This lecture sets out to review developments in numerical-control machine-tool technology with particular reference to the application of general-purpose digital computers to the control of individual machine tools or groups of machine tools, to meet the requirements of the end user.

The subject matter embraces very broad-based technology, ranging from factors which directly contribute to machine utilization to the application of advanced digital-control techniques which directly contribute to the versatility of modern numerical-control machine tools. Thus, the lecture begins with a review of worldwide growth in numerical-control machine business and a discussion on the technological evolution of numerical-control systems with particular reference to the fast growing utilization of mini-computers. The subject is illustrated by a practical case history in the United Kingdom based on a computer control system developed by the author's firm for turning, milling, and boring machines.

The lecture concludes with a review of operational benefits to be derived from the application of modern numerical-control machines to production processes and makes predictions concerning future developments in the application of general-purpose digital computers.
Design and Evaluation of Flight Control Systems
Authors: Gill F. R.
Published: October 2007

Studies at the Royal Aircraft Establishment are aimed at the in-flight demonstration of improved control systems and policies in a fighter-attack and/or a transport aircraft. The systems being flight evaluated at the present time employ conventional linear-control policies, the design being based on a parameter-optimization technique. Two important modes are discussed briefly in the paper: a pitch-rate manoeuvre-demand system for the fighter-attack aircraft and an ILS glide path and flare system for the transport aircraft.

The design studies of these and other modes have yielded quantitative data on conflicts between different performance requirements which cannot be avoided when linear-control policies are used. Studies are being made therefore to replace linear control by variable-gain policies in selected parts of the control system in order to reduce the extent of these conflicts. The reasons for and principles of the variable-gain control policies are outlined in the paper; in addition certain system improvements are discussed (e.g. trim problems) which result from the application of these non-linear control policies.
Pressure Transients in an Axial Piston Hydraulic Pump
Authors: Helgestad B. O. , Foster K. , Bannister F. K.
Published: October 2007

A method is given for calculating pressure transients in an axial piston hydraulic pump. Some theoretical predictions are given of the effect of port timing and the effect of introducing restricting grooves at the ends of the kidney ports in the valve plate and suggestions are made of the effects of these parameters on noise emission; comparative measurements of noise are then quoted that support the general arguments. A parallel shot is recommended as the best compromise for the restrictor groove geometry to give good results over the widest range of operating conditions, including reverse rotation. Finally, mention is made of the use of a relief valve in the port plate for noise reduction.
First Paper: Measurement of the Oil-Film Thickness between the Piston Rings and Liner of a Small Diesel Engine
Authors: Hamilton G. M. , Moore S. L.
Published: October 2007

A capacity gauge has been designed for operating in the conditions of a working engine. The method of using it for determining the oil-film thickness and piston-ring profile is described. Oil-film thicknesses in the range 0·4-2·5 μm between the piston rings and the cylinder liner have been observed. Their variation with speed, load and temperature has been measured and it is concluded that their behaviour is essentially hydrodynamic.
First Paper: Rotary Engines: Operation, Pre-Ignition and Wear
Authors: Brandone B. , Jeu Jh. Du
Published: October 2007

This paper shows firstly how the choice of base stock reduces apex-seal wear. Results emphasize the influence of volatility, and particularly of the quantity and viscosity of the residue after heating.

The second part (section 3) concerns pre-ignition. Testing was difficult, but a connection was found between the ash content of the oil and severity of pre-ignition. Testing of anti-wear formulations for pre-ignition was found to be necessary.

The third part (section 4) is devoted to engine smoothness, which must not be confused with pre-ignition. Spark plugs and mixture strengths are the most important factors, fuel probably having only a secondary effect.
Predicting Changes in Operating Variables for Hydrostatic Thrust Pads Subjected to Tilt and Dynamic Action
Authors: Newton M. J. , Howarth R. B.
Published: October 2007

Hydrostatic thrust bearings are frequently designed for static operation with parallel surfaces although, in practice, they are required to operate under dynamic conditions and probably in a tilted state. Introducing tilt and dynamic action may result in the operating variables being quite different from those predicted for parallel static conditions.

Theoretical analyses of hydrostatic thrust bearings usually present the performance characteristics in a non-dimensional form. These describe the quasi-static operating conditions, but they do not give a direct indication of changes in individual operating variables because the parameters are interrelated.

This paper utilizes the non-dimensional parameters in a small perturbation analysis that allows the changes in individual operating variables to be evaluated directly. The analysis gives results that are in reasonable agreement with those observed during experimental tests, both for small and large variations in operating parameters.
Experiments on the Accuracy of Holders Used in Gas Meter Calibration—Effects of Evaporation
Authors: Smith A. J. Ward , Martini J. D.
Published: October 2007

Tests have been conducted on a 0·057 m3 (2 ft3) holder taken out of normal service and specially instrumented. The effects of water sealant temperature changes and evaporation on the volumetric readings of the holder have been measured. From these results, the mass transfer coefficient k, which is a measure of the rate of evaporation, has been evaluated.

It is concluded that well-maintained holders, whether used for pressure or vacuum testing, give rise to insignificant errors in volume measurement under normal test conditions, such as those specified in B.S. 4161, in a room with reasonable temperature control. Only when a holder is used to measure low flow rates do evaporative effects give rise to substantial errors.
Die Variator Mandrel Forces Encountered in Blow Moulding Parison Control Systems—Computer-Aided Design
Authors: Parnaby J. , Worth R. A.
Published: October 2007

In designing control systems for parison shape in the blow moulding process it is necessary to take into account the forces that act upon the movable mandrel inside the convergent annular die.

These forces can be considered as consisting of two parts; firstly, a steady-state force acting along the axis of the mandrel whilst it is stationary and, secondly, an axial force Pertubation that arises as a consequence of controlled movements of the mandrel during the parison shape control process.

The present paper deals only with steady-state axial forces and its aim is to assist the design engineer by showing him how to calculate mandrel forces and die pressure drops, using a digital computer, for dies having a form composed of a series of tapered and parallel annular flow passages.

By careful design, under certain circumstances, an almost force-free arrangement can be obtained, so minimizing the power and strength requirements of the mandrel drive control system.

The theoretical analyses used assume that the polymer being processed is described by a power-law equation relating shear stress and shear rate. This is typical of polymers such as high-density and low-density polyethylene.
Fluid-Actuated Temperature Sensor
Authors: Morsi S. A.
Published: October 2007

A new temperature sensor has been designed and tested, in which a change in ambient temperature changes its flow resistance. It may be constructed to give either a positive or negative change of resistance for an increase of temperature and may be capable of fluid shut-off. This paper gives the operating characteristics for three different configurations operating with air, which illustrate the high-pressure gain possible with this type of temperature sensor. Such a device may operate directly in the process pneumatic control pressure range without amplification.
Cumulative Damage in Fatigue under Multiaxial Stress Conditions
Authors: Mcdiarmid D. L.
Published: October 2007

Previous investigations into cumulative damage fatigue under uniaxial stress are discussed in conjunction with the parameters relevant to the present experimental investigation. The results of two-level block programme tests on 2L65 aluminium alloy at four values of constant principal stress ratio and at several combinations of two different principal stress ratios are presented and discussed with reference to cumulative damage criteria developed for the case of uniaxial fatigue stress.
Steady and Non-Steady Flow in a Simple Carburettor
Authors: Benson R. S. , Baruah P. C. , Sierens R.
Published: October 2007

A study is made of steady and non-steady flow through a carburettor. A model is presented in which the carburettor is represented by an adiabatic pressure loss at a discontinuity in the intake system of an engine. It is shown that this simple model gives excellent predictions of the pressure-time development in the intake system except at small throttle openings where there is some error in the peak amplitude. Mass flow and trapped mass predictions are excellent.
The Rolls-Royce Rb 211 Turbofan Engine
Authors: Eltis E. M. , Wilde G. L.
Published: October 2007

The lecture gives a technical account of the Rolls-Royce RB 211 42 000 lb thrust turbofan engine now powering the Lockheed TriStar passenger transport.

This engine was the result of extensive preliminary design studies begun in 1960 to evolve a turbofan successor to the Conway bypass engine. The aim was to provide Rolls-Royce with a propulsion system that would give the United Kingdom the opportunity to share in the most important section of the air-transport market during the last quarter of this century. Low fuel consumption, low noise and low maintenance costs were the principal objectives. These studies led to the RB 211 three-shaft design which was specified for the Lockheed L1011 ordered in 1968 by a number of the larger U.S. airlines.

An idea of the large scale of the RB 211 project is given and some of the development problems and lessons are discussed. There is a brief outline of the supporting component, rig and high-temperature turbine development and a summary of the engine's performance is given which includes thrust, specific fuel consumption and noise, all of which have met or beaten the design targets.

A developed version of the RB 211, now being tested at over 50 000 lb thrust, is described, as well as the potential for further improvements in fuel consumption and for expected additional aircraft and industrial applications.
Induction Ramming a Motored High-Speed Four-Stroke Reciprocating Engine—Influence of Inlet Port Pressure Waves on Volumetric Efficiency
Authors: Prosser T. G.
Published: October 2007

This paper describes calculation methods and the results obtained from a computer programme written for studying induction ramming in high-speed reciprocating engines. The calculation uses the method of characteristics for analysing the pressure fluctuations in the intake pipe. The calculated airflow figures are compared with results obtained experimentally from a motored air-cooled four-stroke motorcycle engine. Comparison shows a good correspondence between theoretical and experimental results of both the quantity of air flow and the engine speeds at which airflow peaks and troughs occur. The results also clearly illustrate how flow through the valve is affected by pressure variations at the inlet port.
Engineering Creativity
Authors: Jones R. V.
Published: October 2007

The example of Boulton and Watt demonstrates the main factors in the creative process: recognition of a problem (thermal losses in the cylinder walls in a Newcomen engine), scientific knowledge (that steam would expand into an evacuated chamber), inspiration and understanding between inventor and administrator. These themes are traced through the more recent history of engineering in Britain, and the lecture discusses the importance of a favourable ambience and the interaction of individuals and organizations. In the education of engineers, institutions of higher education and post-market training arrangements both have parts to play; and although creativity cannot be taught to those who are devoid of it, and although some men will be highly creative irrespective of the way in which they have been educated, a suitable education will speed their progress to the front line of their activity—and it may tip the balance in the case of the much larger number who possess some innate creativity, but who may be discouraged from developing it by unimaginative training. The master/apprentice relation remains the most promising approach, and, more than anything else, a sense of purpose is needed on a national scale if creativity is to be encouraged.
Some Effects on Conical Diffuser Performance of Preceding Normal Shock Boundary-Layer Interaction
Authors: Livesey J. L. , Odukwe A. O.
Published: October 2007

Experimental results are presented for the variation of the static pressure rise coefficient Cp, the transformation efficiency η the total pressure loss coefficient CL and the outlet kinetic energy coefficient ɛ2 with the Mach number and the effective throat length for subsonic conical diffusers with total expansion angles of 5°, 12° and 20° and an overall area ratio of 10:1. The junction between the parallel entry pipe and the diffuser cone is sharp and the diffuser inlet conditions are evaluated from measurements on a plane 1°5 diameters upstream of the diffuser's sharp transition. The shock Mach number was varied from 1°05 to 1°25 whilst the diffuser inlet Reynolds number varied between 9°0 × 105 and 1°22 × 106. A comparison of the results with those of diffusers preceded by wholly subsonic flow in the entry pipe shows the beneficial effect of interaction, the most significant gains being with the lowest angle diffuser.
Influence of Spring-Back on the Characteristics of the Spiral Spring
Authors: Swift W. A. C.
Published: October 2007

In this paper, the method of manufacturing the spiral spring is examined to develop a theory for this type of spring giving a closer agreement with practical tests than does the conventional theory. The theory makes use of Gardiner's (1***)† equation for spring-back to develop the equation of the free spiral of the spring and then considers that, in operation, the process of winding up or running down can be considered as the difference between winding up from the free spiral to the run-down state and winding up from the free spiral to the wound-up state.

In the conventional theory for this type of spring, the active length is considered to be constant and equal to the strip length and the moment versus the rotation of the arbor plot (torque characteristic) is apparently always linear. In the theory presented below, the variation in active length is taken into account and non-linearities in the torque characteristic become evident. The theory assumes that the forming of the spring takes place under the action of pure bending without anticlastic curvature and the strip is assumed to behave as an ideal elastic-perfectly plastic material.
Synthesis of Complex Cam Mechanisms
Authors: Fawcett G. F. , Fawcett J. N.
Published: October 2007

General equations are developed describing the kinematic behaviour of two rigid bodies in contact. The case of planar motion is then considered in more detail and the equations are developed in a form which is useful in synthesizing cam mechanisms.

Examples of the application of the general equations to synthesizing the profiles of rolling contact cams and of cam profiles for use with flat and circular followers are given. Use of the general equations in cases where the follower has a complex profile is also described.
Rolling Characteristics of Small Size Pneumatic Tyres
Authors: Singh D. V. , Goel V. K. , Bhattacharya M.
Published: October 2007

The dynamic characteristics of single-track vehicles are predominantly governed by forces and moments of tyre-pavement interaction. No experimental data are available in the literature on the rolling characteristics of the small size pneumatic tyres used on scooters. In the present investigations, a flat-type tyre testing machine was developed at Roorkee (India) and the free rolling characteristics of Dunlop 3·50-8, Inchek 3·50-8 and Kicorma 3·50-8 and 3·50-10 have been experimentally determined. Effects of tread wear and rim size have also been investigated and reported.