bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Verification of a Digital Computer Simulation Method for Predicting Gas Turbine Dynamic Behaviour
Authors: Fawke A. J. , Saravanamuttoo H. I. H. , Holmes M.
Published: October 2007

A mathematical model which simulates the transient response of a twin-spool gas turbine engine on a general purpose digital computer is described together with test results verifying the simulation.
Fourth Paper: The Batchmatic 50: The Development of a Numerically Controlled Turning Machine
Authors: Austin E. R. , Conner C. I.
Published: October 2007

This paper describes the philosophy leading to the design and development of a numerically controlled turning machine, the Batchmatic 50, aimed specifically at the small batch production market. The machine has a maximum capacity of 2 in diameter bar, with a maximum turning length of 8 in. Particular attention is given in the paper to the reasons and thinking behind the design, and emphasis is given to consideration at the design stage of pre-set tooling and simple programming. The machine is seen as part of a manufacturing system, in which planning and organization play a vital part.
Fifth Paper: The Design of Machining Centres
Authors: Davies B. J. , Walker J. H.
Published: October 2007

Design features of a range of machining centres are described. A four-axis horizontal machining centre with a 1 1/2 m diameter table is described in detail. It is fitted with a 60-station tool changer and automatic pallet loading and uses hydrostatic slideway and spindle bearings. The elements of the machine are of modular design and other configurations and sizes of machine can be made from the same modules.
Governing: An Examination of a Torque Feedforward Loop
Authors: Blair J. R.
Published: October 2007

The inclusion of a load sensing loop in a governor is known to counteract the effects on engine speed of changes in the external load. To derive the maximum benefit from load sensing, it is necessary to possess a detailed mathematical representation of the individual elements within the governing loops.

In this paper, a method of identifying the dynamic behaviour of a small generating set is described. A governor is designed on the basis of this dynamic model, and results are presented of tests performed on the generating set controlled by the governor. The governing action is a combination of the feedforward of a load signal, and the feedback of a speed signal. Careful selection of the gain of the feedforward path results in improved governing with only proportional action in the feedback loop.

A simple criterion, derived from the mathematical model, predicts a range within which the feedforward gain should lie. The feedback loop is designed by standard control techniques.

The experimental results compare favourably with the theoretical predictions. In the tests on the rig, a steady-state droop of ±1 per cent was held over the full-load range. A 100 per cent step change in the load produced a transient overshoot of less than 1·5 per cent, and a settling time of 1·5 s.
Turbulent Flow Characteristics of an Impinging Jet
Authors: Russell P. J. , Hatton A. P.
Published: October 2007

Measurements of shear stress, turbulence energy and other parameters were made in the impingement region of a plane two-dimensional jet confined between parallel walls. Hot wire anemometer arrays were used to examine the turbulance levels in the three directions. The object of the experiments was to make comparisons with a prediction method previously proposed. Measurements were also made in the free jet and these agreed well with the many earlier results available. In the impingement zone where the turbulence levels are very high the order of agreement is encouraging despite the uncertainties present both in the theory and the experiment. In particular, the assumption of a constant turbulence length scale in such a complex flow is not confined by the measurements.
Systematic Approach to the Analysis of a Solenoid-Actuated Hydraulic Valve
Authors: Korn J. , Simpson K.
Published: October 2007

A spool-type, hydraulic, directional-control valve is considered. The valve has four ports; it is actuated by a solenoid, and its spool overlaps the ports. The valve is looked upon as a system consisting of electrical, mechanical and hydraulic sub-systems.

The sub-systems are represented as networks, which are then interconnected to form the network of the complete valve system. Hence a set of independent equations are derived which describe the dynamic behaviour of the valve between no flow and full flow states of the spool. The equations are simulated on an analogue computer to provide comparison with experimental results.
Some Factors Influencing Cylinder Head Gasket Problems and Design
Authors: Herrington M. G.
Published: October 2007

The environment under which a cylinder-head gasket has to function is reviewed and a typical cylinder head to cylinder block assembly is considered, outlining the temperature variations in the inlet and exhaust ports. Curves showing head-face to block-face movement for varying engine speeds and coolant temperatures are reviewed with power units running at accelerated gasket destruction test conditions. Comparisons are made between cast-iron block and aluminium head and cast-iron head and block for both petrol and diesel engines.
A Finite Element Method for the Calculation of Locus Paths in Dynamically Loaded Bearings
Authors: Shelly P. D. , Ettles C.
Published: October 2007

A method using finite elements for the solution of journal bearings is outlined. The special properties of an exponentially shaped element are used together with a satisfactory approximation for the axial pressure profile. This approach is one hundred times faster than a conventional finite difference solution of equivalent accuracy. The method can be applied to the solution of locus paths for journal bearings under external dynamic load or under whirl conditions.

The predictor-corrector method used to march out a locus path is briefly outlined and several typical loci are presented as examples.
Developments in Naval Propulsion: The Engineer's Role
Authors: Norton E.
Published: October 2007

This lecture discusses the current trends in the design of naval propulsion machinery and makes reference to a number of recent requirements including standardization, configuration control, and identicality. Problems associated with the building of warships are discussed ranging through financial aspects, usage of skilled manpower, management systems, and engineering problems. The need for further progress in the development of propulsion machinery is emphasized. The central position of the administrative engineer in the development of warships is the principal theme of the lecture.
Condensation Phenomena in High Speed Flow of Steam—Experimental Apparatus
Authors: Campbell B. A. , Bakhtar F.
Published: October 2007

The paper describes a steam circuit for studies of nucleation and behaviour of wet steam. The test section is a duct of rectangular cross-section in which particular geometries are produced by fitting shaped profiles to its sides. To deliver steam to the test section, at required conditions, a turbine, cooler and superheater are included in the circuit.

The experimental results presented are concerned with the variations of Wilson point as a function of pressure. Comparisons are made with the results of a theoretical treatment already published (1)‡ and agreement is shown to be good.
Recent Developments in B.S. 806: Ferrous Pipes for and in Connection with Boilers
Authors: Popplewell P. L. , Hammill J.
Published: October 2007

The paper deals in general terms with certain aspects of B.S. 806 such as design pressure, design temperature and design stresses. These are discussed and those areas where the requirements of this standard differ from others are highlighted. There is also some discussion on the welding, inspection and testing requirements of the revised standard.

The bulk of the paper is concerned with an explanation of the sections of the standard dealing with branch design and with flexibility which have been extensively revised.

The paper does not claim to submit any new research work but indicates the way in which the results of such work can be incorporated into the requirements of a national standard.
Second Paper: Experiments on a Transpiration Cooled Combustion Chamber
Authors: Bayley F. J. , Cornforth J. W. , Turner A. B.
Published: October 2007

The first part of an experimental and theoretical investigation into the feasibility of transpiration cooled combustion chambers is discussed, as well as the design and testing of two Rolls-Royce ‘Dart’ porous flame tubes. The theory of heat transfer in porous materials is briefly described and correlations for heat transfer and pressure drop-mass flow are presented for selected samples of porous metal. Experimental results are presented in which the cooling efficiency of the original ‘Dart’ splash-cooled flame tube is compared with two porous replacements constructed from sintered woven wire porous metal compacts having different permeabilities. Tests were conducted at 1 and 4 atm pressure and some selected results are compared with theoretical predictions made with and without account being taken of the effect of coolant injection on the convective heat flux.

The high effectiveness of transpiration cooling is clearly demonstrated but it is also shown that the distribution of static pressure in the annulus formed between the flame tube and the casing, both longitudinally and circumferentially, plays a very important part in the design of a porous flame tube.
Forming and Shaping Operations for Iron and Steel
Authors: Ford Hugh
Published: October 2007

Although many years of research have gone into the present knowledge of the forming and shaping of metals, most of our capability of making components in ferrous materials goes back to the days of craft and skill. The major expenditure on fundamental studies in metal working has been effective only in refining existing processes rather than leading to new ways of manufacture.

A better understanding of the relationship of material properties to stress and deformation modes has had some influence on process developments. Much more is owed to developments in the size of plant units, economic, production engineering, marketing and managerial factors.

The more recent developments and trends in secondary manufacturing processes are reviewed.
Full Power Hydraulic Brake Actuation System for Motor Vehicles
Authors: Firth A. C. , Parsons D.
Published: October 2007

The vast majority of motor vehicles have had for some 30 years hydraulically actuated wheel brakes of the fixed displacement type. This paper describes the limitations of such a system and the justification for going to the more advanced full-power system that is at present offered on a limited number of vehicles. Once the decision to adopt a full-power system is taken, a considerable new potential is available to the vehicle designer. The basic philosophy and design parameters of a power system are described at length and detailed analysis is made of the several component unit designs.
Dynamic Chip Formation and its Significance to Machining Stability
Authors: Pearce D. F. , MacManus B. R.
Published: October 2007

The physical processes of dynamic chip formation were examined experimentally using direct photographic techniques; motion in the cutting zone was frozen by synchronizing an intense stroboscopic flash to particular positions in the waveform of the cutting force. Measurements obtained under conditions of controlled vibratory machining gave instantaneous values of the uncut chip thickness, tool-chip contact length, effective shear angle and cutting force. At a given amplitude of uncut chip thickness the peak-to-peak variation of contact length was seen to attenuate with increasing frequency, an effect which was shown to be significant in causing relatively high amplitude shear angle oscillations. Amplitude and phase measurements of the tangential component of the cutting force on wave removal were directly related to the deduced waveform of specific contact length, a process yielding considerable predictability.

Measurements were made of the damping inherent in the cutting process; results obtained by applying the techniques of impulse response testing showed the sensitivity of this damping to both the amplitude and the frequency of the variation of the uncut chip thickness. Internal damping resulting from the process of chip formation is not uniquely positive or negative but may vary, depending upon the combination of these parameters.
High Temperature Stress-Strain Properties of a Low-Carbon Steel from Hot Machining Tests
Authors: Stevenson M. G. , Oxley P. L. B.
Published: October 2007

Machining tests are described in which the cutting speed is kept constant and the primary shear zone temperature varied through a wide range by preheating the workpiece. Variations of the constants σ1 and n of the assumed stress-strain equation σ = σ1 εn with temperature, for an estimated strain rate of 900/s, are obtained. These show a range of temperature in which dynamic strain ageing takes place. This is consistent with results of conventional machining tests on the same material in which dynamic strain ageing takes place in the secondary zone in a certain speed range.

Implications of the results for the machining process are discussed and explanations suggested for variation of force with speed in conventional machining and force with temperature in hot machining.
Block-Programme Fatigue Testing of Automobile Wheel Spindles
Authors: Tedford J. D. , Crossland B.
Published: October 2007

The paper reports the results of fatigue tests carried out on Ford Capri wheel spindle bodies. The first three programmes were aimed at investigating the effect of the sequence in which the loads were applied in a multilevel constant-frequency block programme. A further programme was carried out to investigate the effect on the fatigue life of removing the low-load cycles from the test sequence.

The first three programmes demonstrated that the sequence in which individual blocks were applied had no significant effect on the fatigue life. From the fourth programme it was concluded that the removal of stress levels equal to and less than 1·75 times the r.m.s. (root mean square) value of the normal load frequency distribution had no effect on the fatigue damage. If these stress levels are removed there is an 87 1/2 per cent reduction in testing time. The slopes of the life function curves for all four programmes were nearly identical, and gave a mean value of 6·9 which is in agreement with other workers. Lastly it was concluded that tests on small notched cantilever specimens led to very similar conclusions, and that such specimens could be used for proving and developing testing programmes.
Flank-Wear Model and Optimization of Machining Process and its Control in Turning
Authors: Koren Y. , Ben-Uri J.
Published: October 2007

Designing the optimal control for a machine tool necessitates a mathematical model of the cutting process. In the present paper, a flank-wear model was developed for a carbide tool used in steel turning. It yields the relation between the process parameters (cutting speed, feed and depth of cut) on the one hand, and the width of the wear land on the other.

In the second stage—the optimization proper—the problem consists of optimizing a non-linear system with the initial, and part of the final, conditions known, and the terminal time not given explicitly. Complexity was reduced by converting from time- to path-derivatives, and the problem was solved using the gradient method, yielding cost differences which are negligible compared with the conventional method.

To complete the picture, a motor control system was sought minimizing the error in obeying the speed change command on the one hand, and the path error during simultaneous operation of several feed spindles on the other.
Effect of Contact Geometry and Elastic Deformations on the Torque Characteristics of a Drum Brake
Authors: Millner N. , Parsons B.
Published: October 2007

Existing torque analyses of drum brakes, based on the assumption that the shoe and drum are rigid, fail to predict torques accurately, especially when the lining makes non-uniform contact with the drum. An analysis has been made therefore of a floating shoe brake in which the elastic deflections of the shoe and the drum have been included.

The analysis has been verified by measuring the torque developed by a standard two-leading shoe brake on an inertia dynamometer under different contact conditions. The agreement between the theoretical and observed torques was found to be better than ± 10 per cent even under extreme contact conditions and much better under more moderate conditions. Some consequences of the theory are discussed because of their practical importance.
Clutch Judder in Automobile Drivelines
Authors: Jarvis R. P. , Oldershaw R. M.
Published: October 2007

A review of experience and records from a car enables a realistic simulation to be developed on an analogue computer, demonstrating clutch judder in a driveline system. Possible causes of judder are discussed.
Stresses in Centrifugal Fan Impellers
Authors: Patton R. G.
Published: October 2007

The conventional, theoretical method for estimating impeller stresses combined with large factors of safety is unsatisfactory for the design of the high-pressure fans being demanded today.

For economic design, a more precise knowledge of the stresses involved in high-speed impellers is essential and this has been made possible by the considerable developments which have taken place over recent years in the field of strain measurement.

This paper describes an experimental programme of stress analysis using brittle-lacquer and strain-gauge techniques, carried out on a range of centrifugal fan impellers. The actual stresses in the various components of these impellers are compared with those predicted by elementary theory.
Second Paper: The M.I.R.A. Cross-Wind Generator
Authors: Rose M. J.
Published: October 2007

The response of vehicles to the transient forces associated with gusting of the natural wind is assuming greater prominence. Total reliance upon natural gusts is unsatisfactory since these are unpredictable and unrepeatable. Major Continental manufacturers have for several years utilized gusts produced by multiple-fan installations, the power source being either electric motors or internal-combustion engines. The M.I.R.A. equipment is centred on a single Rolls-Royce Avon gas-turbine engine, the exhaust gases from which are directed across a roadway. Measurements have indicated that the gust profiles are similar to those encountered on motorways in respect of rise-time.
Third Paper: Wind Gusts Measured on High-Speed Roads
Authors: Smith N. P.
Published: October 2007

Cross-winds increase in importance as more motorways are built; measurements made with an instrumented car in windy conditions on motorways are described. It is demonstrated that wind patterns and the occurrence of most gusts are dependent on the topography and features, such as bridges and cuttings, adjacent to the road. The relative importance of the various gust-causing features is enumerated and typical gusts, measured near these features, are shown. The value of artificial cross-winds is discussed, with particular reference to the realism of the M.I.R.A. facility.
Sampling of High-Quality Wet Steam from Steam Mains Operating at 11·4 Bar Pressure
Authors: Ryley D. J. , Holmes M. J.
Published: October 2007

A venturi device was employed to strip and entrain liquid from the wall of a 3 in (7·5 cm) diameter steam main prior to isokinetic sampling. By injecting heated water into dry steam the wetness fraction was controlled between 1 and 5 per cent. Venturi convergence half-cone angles of 20, 30, 40 and 50° were employed and steam flow rates varied from 360–730 kg/h (800–1600 1b/h). Observations were made of the distribution through the test section of static pressure, recovered temperature and film thickness (for pressure 3·8 bar (55 1b/in2 absolute) only). Sampling across a diameter showed that under the most advantageous conditions the ratio, aggregate mass of entrained water: mass of injected water did not exceed 23 per cent. The optimum venturi half-cone angle lay between 40 and 50°. While capable of further development, the stripping-sampling principle seems unlikely to lead to significant improvements in wet steam sampling for quality.
Performance Characteristics of a Centrifugal Compressor with Air Injection
Authors: Ledger J. D. , Benson R. S. , Furukawa H.
Published: October 2007

The parameters which influence the performance characteristics of centrifugal compressors with air injection through nozzles at the rotor tip are developed using both dimensional analysis and a simple model. Experiments on a small centrifugal compressor show that the injection air pressure is the main influence on the overall performance such as excess torque, increased delivery pressure and increased delivery flow. With air injection the pressure-mass flow characteristics are displaced to the right with surge occurring at increased total mass flow rates and the overall pressure ratio across the compressor is increased for the same total mass flow.
Viscous Heating and Varying Viscosity Effects on Developing Laminar Flow in a Circular Pipe
Authors: Martin B. W.
Published: October 2007

An integral profile procedure is used to predict the effects of viscous heating and viscosity reduction on laminar flow development in a uniform pipe of circular cross-section under adiabatic conditions. The effects on fluid and pipe wall temperature, though small in the entrance region for conditions likely to be encountered in practice, become significant for viscous fluids in well-developed flow; the reduced pressure drops predicted relative to isothermal flow compare favourably with available measurements when allowance is made for the possibility of axial conduction therein.
Some Experiments on Packed-Bed Drying
Authors: Oliver D. R. , Clarke D. L.
Published: October 2007

Drying equipment is described in which streams of air of accurately-controlled temperature and humidity may be passed over the surface of a packed bed. The materials used in the beds are sieved spherical particles of copper, glass and polystyrene whilst the liquids are water, methanol and a series of organic solvents.

Experiments are described in which the effect of physical variables on drying rate is measured. Surface tension is shown to have a major effect on the shape of drying rate curves; under the experimental conditions water is the only liquid for which the rate of drying during the constant-rate period is equal to that from a free liquid surface. The equivalent period for liquids of lower surface tension corresponds to a distinctly lower drying rate. Possible reasons for this behaviour are discussed. An increase in liquid viscosity causes reduction in drying rate, but only when the rate of drying is itself high.

The effect of using solids of differing thermal conductivities is investigated. At high drying rates, increasing thermal conductivity produces increasing drying rate. Surprisingly a mixed bed (e.g. of copper and glass) often dries faster than beds of the constituent materials alone.

Split beds are also used (beds of which the halves are of different materials). For these beds it is possible to observe the growth of dry patches on the surface of the beds and the manner in which liquid appears to migrate across the interface between the particles of the two halves. The temperature distribution across the interface is shown to be abnormal in part of the drying cycle.

A conclusion which may be drawn from the work is that it is often an advantage, from the drying standpoint, to have particles that have either a wide range of thermal conductivities or a wide range of particle sizes.
Heat and Mass Transfer during Contact Drying in a Laundry Calender
Authors: MacLaren J. F. T. , Nicol A. A. , Wallace R.
Published: October 2007

Contact drying of fabric was studied using a two-roll steam-heated laundry calender. The effects on heat and mass transfer of steam temperature, fabric initial moisture content, fabric velocity, contact pressure and steam-side heat transfer coefficient were observed experimentally. Bed and roller surface temperature profiles were measured to assist in interpreting and subsequently analysing the drying process.

The experimental results were correlated using dimensionless parameters derived from a dimensional analysis of a drying equation. An empirical expression was obtained that related the final moisture content of the fabric to the initial moisture content and the other pertinent physical variables.
Experimental Studies on the Design of Thermometer Pockets for Steam Mains
Authors: Roughton J. E.
Published: October 2007

The theory of thermometer pocket errors previously developed by the author has been tested by experiment using steam flows under steady-state conditions. When an appreciable temperature difference exists between steam and pipe wall, whatever the reason, errors arise from the temperature gradient in the steam and the loss of heat by conduction and radiation from the pocket. The results confirmed that the net error is a linear proportion of the steam/pipe wall temperature difference and can be substantial if the pocket is not of a suitable length. The effect of plating the pockets with rhodium was not as expected since the accompanying reduction in radiation error was offset by a larger increase in conduction error. In all other cases, the measured conduction plus radiation errors were in good agreement with the theory, while the effects of the steam temperature profile were also broadly as predicted. The basic theoretical approach was satisfactorily confirmed and the accuracy shown to be better than 5 per cent of the steam/pipe wall temperature difference.
Trial by Organization and Ordeal: An Engineer's Search for Quality
Authors: Alden J. H.
Published: October 2007

This paper covers two subjects of great interest to the writer: the organization of a design and development team and the operation of a controlled and audited test programme; the ultimate aim being quality and reliability of the product.

The design and development team headed by the Chief Product Engineer should have four major ‘components’ reporting to him: the Project Manager, the Chief Designer, the Test Engineer, and the Tooling Control Manager. Their individual functions are discussed in the paper.

Life testing of various components and the building of sufficient prototypes to prove the practicability of the product can all be achieved ‘on the premises’ by means of various rigs as described, but the real evidence of the success of the product can only be achieved by many thousands of miles of actual running on the most expensive test requirement of all, a modern well equipped proving ground, the many necessities of which are discussed.
Matching of High Output Diesel Engines with Associated Turbomachinery: First Paper: A General Approach to the Computer Solution of Single- and Two-Stage Turbocharged Diesel Engine Matching
Authors: Wallace F. J. , Cave P. R.
Published: October 2007

The first paper describes the general approach adopted in the solution of steady-state matching of single-stage turbocharged engines with fixed and variable geometry turbines and two-stage turbocharged engines developed from general principles first reported in (1). Individual components are represented either by systems of equations or by multi-dimensional numerical arrays embodied in separate subroutines which are called from a main-linking programme containing the overall matching equations. Appropriate iterative procedures from initially assumed values of boost and turbocharger speed (for single- or two-stage arrangements) are briefly described.

The programmes have been run both in batch processing and interactive mode, and in the latter form have been found particularly valuable as teaching aids.
Second Paper: Differential Compound Engine
Authors: Wallace F. J.
Published: October 2007

The second paper assesses the overall performance characteristics of the differential compound engine (d.c.e.) first reported in (21), designed to constitute an integrated engine-transmission system providing high unit output, combined with outstanding torque characteristics for traction applications.

Experimental results, for both equilibrium conditions and transient response are presented for the original two-stroke c.i. version of the laboratory unit, incorporating the Rootes TS 3 opposed piston engine. Theoretical predictions both for this version, and the later four-stroke version, using the Perkins 6·354 engine, based on the generalized computer approach of the first paper, are also presented.

The unit is then critically compared with existing or prospective traction prime movers using the following criteria.

(1) Fuel economy.

(2) Torque characteristics.

(3) Noise and emission.

(4) Unit specific weight and bulk.

Finally, a projected automotive unit of approximately 2 hp shaft output is described with illustrations to show the potential of the d.c.e. as an alternative engine-transmission system for heavy trucks and off-highway vehicles.
Maintenance Policy for Sugar Refinery Centrifuges
Authors: Jardine A. K. S. , Kirkham A. C. J.
Published: October 2007

The results of a study to determine the optimal policy (defined as that which minimizes downtime) for the maintenance of continuous process centrifuge machines used in a sugar refinery are reported.

It was identified that the machines could ‘fail’ as a result of any one of 34 reasons, 16 being mechanical faults and 18 electrical. Sufficient data were available to enable the six faults that caused most of the unscheduled downtime to be analysed quantitatively and an optimal maintenance policy to be identified.

The problem was analysed by constructing a mathematical model of the situation, identifying the failure distributions of the components of the centrifuge that caused the six faults using Weibull probability paper and then using these data to solve the model. The optimal policy was identified to be breakdown maintenance.
The Accountant—Overhead Burden or Service?
Authors: Fea W. W.
Published: October 2007

Both engineers and accountants working in industry are experts in measurement. The engineer expresses his quantitative data in physical units; the accountant evaluates quantitative measurements into financial terms. Planning the future and controlling the present are two principal functions of management. Accounting provides the common language of communication between the different levels of management planning and controlling all activities of the business.

Cash flow, accounting for inflation, investment timing are important areas for the exercise of accountants' specialized training and outlook.

The lecturer then outlines an actual comprehensive accounting information system operating in a large and successful engineering company. This illustrates his conclusion that while the engineer is the customer of the accountant providing information, they are partners in optimizing its use in running a business.
Condensation on the Surface of a Low-Pressure Steam Turbine Suction Blade
Authors: Ryley D. J. , Patel P. D.
Published: October 2007

A 2·54 cm length of low-pressure turbine suction blade mounted between perspex walls to form a test section was used to determine the distribution of static pressure and surface temperature when passing near-saturated live steam at realistic turbine conditions. The distribution of static pressure conformed closely to that applicable to one-dimensional isentropic expansion with γ = 1·326.

Working surface temperatures were taken for ‘steam-only’ flow with and without blade suction and for ‘steam-with-surface-water’ flow with and without suction. For dry flow with no suction, recovered values of temperature approximated to stagnation values, but with suction applied, a temperature reduction was promoted by the inward heat transfer due to the colder blade interior.

Liquid film thickness was measured by electrical conductivity probes and values obtained were compared with predictions from turbulent film flow theories. Condensation on the blade surface was measured by three experimental methods and the results compared with predictions from turbulent-film condensation theories. A correlating equation is proposed which enables prediction of condensation rates from the average values of the steam Mach number and Reynolds number over the blade, and the Prandtl number of the water.
A Study of Two-Dimensional Supersonic Air Ejector Systems
Authors: Benson R. S. , Eustace V. A.
Published: October 2007

The performance and flow field characteristics for two-dimensional ejector systems are determined theoretically for the condition when operation is independent of ambient pressure. The method considers the detailed inviscid interaction between the primary and secondary streams within the mixing tube and an estimate is made of the secondary flow entrained by the two-stream viscous mixing region.

The validity of the theory is tested by comparing the performance characteristics of an experimental ejector facility with theoretical predictions and by comparing the theoretical flow field, in terms of constant density contours, with infinite fringe interferograms.
Flow Distributions in Boiler Downcomer Cages
Authors: Crow I. G. , Donovan A. J.
Published: October 2007

The factors affecting the flow rate distribution in boiler downcomer cages are discussed and data on entry loss coefficients for downcomer offtakes presented. A rapidly converging computational technique has been devised for the calculation of the flow distributions in downcomer cages which has wider application in the field of pipe networks. The predictions of the network computations have been tested against plant data and found to be in good agreement.
Pipework Purging by Water Flushing
Authors: Cranfield R. R. , Lawrence J.
Published: October 2007

In power stations it has been the practice to purge newly erected steam pipework of debris by blowing through steam at a higher rate than in normal operation. The cost of providing sufficient steam from temporary boilers can be high in some cases. This paper presents the results of a study of water flushing as a method of removing debris from pipework. The minimum necessary water velocity for varying pipe sizes can be calculated, data are given for purge time and pipework configurations are examined.
A Theory for Fatigue Failure under Multiaxial Stress-Strain Conditions
Authors: Brown M. W. , Miller K. J.
Published: October 2007

A new theory for multiaxial fatigue is presented that is based on a physical interpretation of the mechanisms of fatigue crack growth. It may be represented graphically by contours of constant life, which are expressed mathematically by

where ε1, ε2 and ε3 are the principal strains, •ε1 ≥ ε2 ≥ ε3.

This equation underlines the importance of strain parameters in correlating fatigue data. It illustrates the effect of both the shear strain and the tensile strain normal to the plane of maximum shear.

The theory is compared with several classical and recent theories, which are briefly reviewed. It is shown that classical theories of fatigue failure cannot correlate experimental data, and may be dangerous if used for design purposes.
Design of High Speed Hydraulic Position Servomechanisms Using Optimization Techniques
Authors: Armstrong P. J. , McCloy D.
Published: October 2007

This paper collates and extends recent research on the design of hydraulic position servomechanisms using optimization techniques in place of conventional linear feedback methods. Different methods of control are proposed on the basis of a formal application of time optimal control theory followed by an analytical study of the time optimal controller. Optimum designs for the proposed controllers are then derived using a digital computer simulation and parameter optimization sub-routines. Finally, the performance of the proposed controllers is compared with the best performance that can be achieved using conventional proportional control.
The Influence of Temperature and Metal Pairs on the Scuffing of a Commercial Oil
Authors: Bailey M. W. , Cameron A.
Published: October 2007

A modified type of 4-ball machine—a ball running on three asymmetrically placed pegs—allows the scuffing behaviour of a commercial extreme pressure lubricant to be investigated. Particular emphasis has been placed on the reactivity of the steels used as test specimens and their position relative to the contact. The constant failure temperature hypothesis is found to be obeyed only under certain well defined conditions. It is shown that the friction-temperature behaviour measured at slow speed can be correlated with scuffing results at high speed. Little evidence is found to support the minimum film thickness failure criterion.
The Contribution of Tribology to the Development and Operation of Railways
Authors: Barwell F. T.
Published: October 2007

The contribution of the railway pioneers to the development and practice of tribology is reviewed, and it is contended that the engineers who had learned their craft on the steam locomotive were well equipped to tackle the sometimes more exacting tribological requirements occasioned by railway modernization. Steam cylinder lubrication is instanced as an example of the importance of ‘off design’ considerations and of the contribution, either helpful or unhelpful, made by those responsible for the operation of equipment.

The numerous locations within a modern electrified railway wherein surfaces interact in relative motion are listed and discussed from the point of view of reduction in maintenance and enhancement of reliability. In particular, recent work on adhesion between wheel and rail is reviewed.
A Theory and Evaluation of Tool-Electrode Shape Degeneration in Electro-Discharge Machining
Authors: Crookall J. R. , Moncrieff A. J. R.
Published: October 2007

An analytical approach is presented which provides the basis of the numerical analysis method for computation of tool-electrode shape degeneration in electro-discharge machining (e.d.m.). Following earlier work, the concept of ‘relative duty’ of the electrodes is utilized, and is found to predict the type, and to a less satisfactory degree the extent, of degeneration.

Further experimental work confirms that the effect of local profile curvature on the local tool/work erosion ratio is greater than that suggested by the geometrical ‘relative duty’ concept. Subsequent incorporation of the empirical results of these tests into the numerical analysis brings the predicted shape degeneration behaviour into quite close agreement with experiment.

Computed electrode profiles showing degeneration at different periods of elapsed sparking time are presented, together with the experimentally observed cases for comparison.
Safer Braking Systems
Authors: Ingram B. , Oppenheimer P.
Published: October 2007

This paper examines some of the problems involved in engineering safer braking systems which will be appropriate for modern road vehicles and traffic conditions. 2AH.

Braking systems are becoming more complicated, mainly because of the influence of international regulations, but also to take account of technical improvements in performance, which can be achieved with advanced forms of control systems, including anti-locking brakes.

The need to ensure maximum safety is emphasized; despite the increasing complexity and despite a shortage of accident know-how, increased road safety must always remain the ultimate objective.
Possibilities in Pollution Control
Authors: Warner Frederick
Published: October 2007

Recent controversies on pollution and the use of resources are reviewed against the background of the U.N. Conference on the Human Environment. The predictions of disaster are not supported by the positive advances in controlling air and water pollution in the U.K. The particular cases of cleaner air and biological recovery in the Thames Estuary are described against the background of pollution legislation. Many improvements arise from technological advance and the use of mathematical models is opening the way to stricter audits of pollution. Real progress can be made by identifying priorities and combining official action with public participation.
Quadratic Performance Indices and Optimum Suspension Design
Authors: Thompson A. G.
Published: October 2007

This paper presents some results obtained from the computer simulation of a two-dimensional linear vehicle model with coupled bounce and pitch modes. The effects of variations in the ratio of front to rear spring stiffnesses and the inertia coupling ratio on various performance indices for ride quality and road holding were investigated. Two forms of input to the system were considered, ( a) isolated smooth bumps of varying length and ( b) continuous random type excitations. Allowance was made for the time delay between the inputs at the front and rear wheels due to the forward speed of the vehicle.
Experiments on Transpiration Cooling: First Paper: Discrete Hole Injection as a Means of Transpiration Cooling; an Experimental Study
Authors: le Brocq P. V. , Launder B. E. , Priddin C. H.
Published: October 2007

Mean velocity and injectant concentration profiles are presented for the boundary layer on a flat plate with air injection through rows of discrete holes. An 8/1 pitch/diameter ratio was used. Three hole arrangements were studied in detail. For holes perpendicular to the surface, both in-line and staggered configurations were examined, while, for holes angled 45° downstream, only staggered holes were used. Some results are also presented for Freon injection and it is shown that this higher density injectant always gives higher concentrations at the wall. Angled injection is also shown to give improved cooling effectiveness.
Some Aerodynamic Aspects of Safety in Road Vehicles: First Paper: Aerodynamic Lift Characteristics of Cars
Authors: Carr G. W.
Published: October 2007

The principal factors determining the aerodynamic lift of cars are identified from the results of an extensive series of wind-tunnel tests involving simple models of bluff and streamlined form and a variable-geometry saloon-car model.

The influence is examined of basic parameters such as camber, incidence, thickness, ground clearance, and underbody roughness. An indication is also given of the extent to which the lift is modified by the squaring of individual edges, particularly the horizontal leading and trailing edges; and the effectiveness of devices fitted under the nose of a car to reduce lift is discussed.
Further Experiments on the Sealing Mechanism of a Synthetic Rubber Lip Type Seal Operating on a Rotating Shaft
Authors: Jagger E. T. , Wallace D.
Published: October 2007

The paper shows that a seal of the type referred to operates under hydrodynamic lubrication conditions with a liquid film thickness of obout 0·5 μm. Contact angles of oil against rubber and steel are measured, and it is also shown by experiments with capillaries how a meniscus may be turned inside out to resist pressure. The conclusion is that the liquid film is prevented from leaking by the surface tension of the liquid itself.
Fan Performance Testing Using Inlet Measuring Methods
Authors: Whitaker J.
Published: October 2007

To contend with installation variants the fan must be tested in a system that resembles its site installation. Four simplified system arrangements are covered with two inlet test methods—ducted inlet and free inlet—by adding ducts to the free discharge.

With free inlet tests a plenum chamber is attached to the fan inlet in order to obtain the required measurements; investigations to provide information concerning the optimum configuration of this test method are described. Determination of static pressure, selection of inlet devices for flow measurement; simulation of inlet and outlet ducts and the method of loading are also discussed.
Plane-Jet Flow over a Backward-Facing Step
Authors: Matthews L. , Whitelaw J. H.
Published: October 2007

Measurements of mean velocity, the three components of fluctuating velocity and Reynolds shear stress are reported for the turbulent flow downstream of a wall jet blowing over a backward-facing step. The results quantify the complexity of this asymmetric flow and demonstrate the extent to which the slot-lip and backward-facing step destroy the jet-like nature of the flow in the near-slot region. Surface flow visualization experiments demonstrate the influence of the slot flow on the reattachment distance.
Lunar Roving Vehicle: Spacecraft on Wheels
Authors: Cowart E. G.
Published: October 2007

The lunar roving vehicle was the first manned extra-terrestrial automotive vehicle, providing increased exploratory capability on Apollo missions during 1971 and 1972. Vehicle design and development information is presented.
Stress-Strain Characteristics of Various Steels over a Wide Range of Strain-Rates and Temperatures
Authors: Dean T. A. , Sturgess C. E. N.
Published: October 2007

Compression tests are described to determine the flow stresses of steel of specifications: En 1A, En 8, En 26, En 30B, En 58 and 6:5:2 and 18:4:1 high-speed steels, which are presented for use in the analysis of metal working operations. Testing temperatures of 600°C, 800°C, 1000°C and 1200°C were employed and using each of two high-speed hammers and a mechanical press, strain-rates ranging from approximately 12/s to 2500/s were obtained.
Thermal Loading of a Petrol Engine
Authors: French C. C. J. , Atkins K. A.
Published: October 2007

This paper reports the results of an investigation into the thermal loading of a modern 1·975 1, four-cylinder petrol engine operating at engine speeds of up to 100 rev/s.

The effects of engine speed and load, mixture strength, ignition advance, compression ratio, coolant temperature and pressure, antifreeze, detonation, olefin content of fuel, and a piston modification on the local heat fluxes and metal temperatures have been determined and the maximum levels established.

The methods of temperature measurement were fixed and traversing thermocouples for the cylinder head and liner, fixed thermocouples for the valve seats and spark plug, disappearing-filament optimal pyrometer and hardness recovery for the exhaust valve, differential thermocouples for the gross heat losses, and intermittent-contact fixed thermocouples for the piston.

The greatest heat fluxes occurred at the centre of the combustion chamber, in the valve bridge and exhaust-valve seat region, and decreased towards the outside of the combustion chamber and down the cylinder liner.

For the form of combustion chamber investigated the heat flux varied as the 0·6 power of the gross fuel consumption and the operating variables generally gave only second-order effects.

The piston temperature is fairly sensitive to ignition advance, compression ratio, and high-speed detonation.
Elastic Hysteresis and a Catastrophic Wear Mechanism for Polymers
Authors: Wannop G. L. , Archard J. R
Published: October 2007

It is now accepted that hysteresis loss in sub-surface regions plays a major role in rolling friction; however, its influence upon wear has received little consideration. Similarly, the temperatures generated by frictional heating have been analysed only in terms of those mechanisms of sliding friction that result in heat generation at the surface. It is shown that hysteresis loss can cause significant increases in the sub-surface temperatures of rolling bodies with catastrophic consequences for their wear and damage. This mechanism of failure may apply to a wide range of engineering situations including nylon cams, automobile and aircraft tyres and the fibre-filled supercalender rolls used in paper mills.