bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial Variation of Heat Transfer to Pistons and Liners of Some Medium Speed Diesel Engines
Authors: Seale W. J. , Taylor D. H. C. 
Published: October 2007

Heat transfer coefficients have been measured on the gas side of pistons and liners, the water side of liners, and the oil side of pistons. A significant radial variation in heat transfer across the piston crown has been found. The position of the maximum heat transfer coefficient appears to be coincident with the maximum air concentration, or the position the tips of the fuel sprays have reached at the time of ignition, and the radial variation of heat transfer is possibly related to the amount of fuel burnt at each radius. For four-stroke engines, equations are presented to describe this variation. Heat transfer coefficients at the exposed section of the liner have been found to be similar to the values at the outer edge of the piston. Heat transfer between piston undercrown and cooling oil has been measured for various types of cooling arrangement and, for jet cooling, an expression has been suggested for the heat transfer coefficient. Equations have also been derived to enable coefficients to be predicted for heat transfer from liner to cooling water.
The Use and Abuse of Materials in Ocean Engineering
Authors: Birchon D. 
Published: October 2007

Almost every kind of material and fabrication process now has to be used to meet the demands of ocean engineering, ranging as it does from hydrofoils to research submersibles, and from giant tankers to offshore drilling rigs. Some of the difficulties are obvious, for example when aircraft-like design procedures must be adopted for hovercraft to operate at sea; others, such as the vagaries of corrosion and the risks of brittle fracture, are more subtle. This paper briefly reviews the history of the use of materials in ocean engineering and touches upon their impact on contemporary affairs; some present material capabilities and weaknesses are discussed, and the new philosophy of structural validation and some of the supporting techniques being introduced into the Navy are outlined. Some case histories of the use and abuse of materials in ocean engineering are also described and the paper closes with a glance to the future and some suggested golden rules which may help designers to minimize the abuse of materials.
Comparative Dynamic Acceptance Tests for Machine Tools Applied to Horizontal Milling Machines
Authors: Sadek M. M. , Tobias S. A. 
Published: October 2007

The paper is concerned with the objective evaluation of performance improvements achieved in three successive stages of development of a horizontal milling machine. It is proposed that the dynamic quality of machine tools be measured by the coefficient of merit (c.o.m.) of the structure under consideration. This is a measure of the chatter resistance of the machine, being proportional to the maximum width of cut which is stable at all cutting speeds. The c.o.m. is obtained with the aid of vibration tests. It is derived from the ‘operative receptance’ of the system as inversely proportional to its maximum negative in-phase amplitude. After discussing the general basis of this type of acceptance test, the concepts are applied to the particular case of the evaluation of the relative performance of three successive stages of development of a horizontal milling machine. For this purpose the c.o.m. of the three machines are plotted as a function of the depth of cut, with the angle between the normal to the centre of the arc of contact and the representative cutting force as a parameter specifying tool design. These curves can be combined to show the relative improvement achieved in the second or third stages of development with respect to the former designs. The predicted performance of the three machines is verified, for one particular value of the depth of cut, by determining experimentally the stability charts of a milling process carried out on each of them. Some indirect confirmation of the validity of the proposed method for assessing machine tool performance is given by investigating its consistency.
Cumulative Damage in Push-Pull Fatigue of Fillet-Welded Mild Steel Plate Subjected to Narrow Band Random Loading
Authors: White D. J. , Lewszuk J. 
Published: October 2007

Push-pull fatigue tests have been made in constant amplitude loading and in narrow band random loading on fillet-welded cruciforms made from 3/8 in thick mild steel plate to B.S. 1501-151 Grade 28. The test frequency was 250 Hz, mean tensile stresses of 0, 5 and 10 tonf/in2were employed and tests were extended for endurances of up to 108cycles. Curves have been fitted to the S-N results using the relationship N( S — So)α= C and on the assumption that this may be extrapolated beyond 108cycles, curves showing the effect of mean stress are given for both constant amplitude loading and narrow band random loading for endurances up to 1012cycles. Suitable factors of safety should be applied to these stresses before use in design. For endurances beyond 107cycles, an increase in tensile mean stress from 0 to 10 tonf/in2reduced the fatigue strength by about 50 per cent in both constant amplitude loading and random loading. Reasonable agreement was found at all mean stresses between the experimental random loading S-N curves and those predicted using the constant amplitude results and the Palmgren-Miner cumulative damage hypothesis.
Fourth Paper: A New Design of Angular Contact Ball Race
Authors: Haines D. J. , Edmonds M. J. 
Published: October 2007

The work reported in the second and third papers revealed that under high speed operating conditions significant slide occurs at the contact points. The full extent of the present limitations became apparent in 1967 and led in that year to the new race design. In this design the balls contact the outer track at two points simultaneously instead of the conventional one point. An approximate analysis of race behaviour is presented which indicates that when the new bearing is driven from the inner track the ball motion is controlled at this track over most of the operating range. This fact and the retention of the inner, and the major outer contact positions, at points close to their static positions result in improvements in performance of up to 30 per cent at high speeds.
Plane Strain Compression of Anisotropic Sheet Metal
Authors: Taghvaipour M. , Mellor P. B. 
Published: October 2007

The plane strain compression of steel, aluminium, titanium and zinc sheet is investigated. Particular attention is paid to the lubrication of the dies and to methods of testing which eliminate creep. It is recommended that 0-001 in p.t.f.e. film is the most suitable form of lubrication, provided that the final thickness of the sheet is not less than 0025 in. To eliminate the possibility of creep in sheet materials, continuous testing in separate indentations is recommended. The experimental results are correlated with Hill's theory of plastic anisotropy. Agreement is good for steel and aluminium, and for most engineering purposes satisfactory for titanium. The correlation for zinc is poor.
Effect of Pins with Flats and Resin-Bonded Polytetrafluorethylene Coatings on the Fatigue Strength of Large Pinned Connections Made from Alloy Steel FV520B
Authors: White D. J. 
Published: October 2007

Results are presented of fatigue tests made on large lugs 4·25 in wide, loaded by means of a 2-in diameter pin. The effect on fatigue strength of a thin layer of resin-bonded p.t.f.e. stuck to the bore of the lug was studied and a systematic investigation was made of flats milled opposite to one another on the pin. The size of the flat is described by the angle (±θ) subtended by the flat at the pin centre and values from zero to +40° were covered. Two conditions of mean stress were investigated, namely, pulsating or repeated tension and 15 tonf/in2mean tension. Although resin-bonded p.t.f.e. coatings prolonged fatigue life, they did not offer a reliable means of improving fatigue strength. Pins with flats were found to be of great benefit and for ±40° flats, as compared with a round pin, the strength ratio in pulsating tension was 3·6 and, at 15 tonf/in2, mean tension was 2·9. The combination of mean stress and size of flat is of critical importance because the strength can be increased or decreased by the addition of flats to a round pin.
Effects of Tilt on the Performance of Hydrostatic Thrust Pads
Authors: Howarth R. B. 
Published: October 2007

The majority of hydrostatic thrust bearings are designed on the assumption that the bearing surfaces are parallel but, with the possibility of manufacturing and assembly errors and structural deformations, this condition is rarely, if ever, achieved in practice. With the increasing demands being made in modern machinery, more detailed design information is required. An experimental and theoretical investigation was carried out into the effects of tilt on the operation of circular hydrostatic thrust pads, the results of which show that, for static conditions, the characteristics of a tilted pad can be reliably predicted, assuming the lubricant to be isoviscous. With this information, a thrust pad can be designed to operate in any specified tilted configuration or can be incorporated in a rigorous structural design. In many applications, however, it may be difficult to specify the tilt and in such situations it is more useful for the designer to have some indication of how the operating conditions may be modified by tilt when the design is based on parallel surfaces. For a system which is supplied from a constant pressure source through a viscous external restrictor, the modified operating conditions can be predicted. The effect of tilt on the operating conditions depends on the pad geometry and design resistance ratio but significant changes may occur in mean pad clearance, required flow rate and static stiffness. Although this investigation was limited to static conditions, the results are still valid for sliding conditions where the hydrodynamic effects are small compared with the hydrostatic contribution. The general effects of tilt observed with circular pads are indicative of what may be expected with pads of other geometries.
Cracking in Cast Iron Diesel Engine Cylinder Heads
Authors: Smith L. W. L. , Angus H. T. , Lamb A. D. 
Published: October 2007

The nature and mechanism of cracking in cast iron diesel cylinder heads arising from the differential thermal strains which occur in service are reviewed. The results of experimental work with test apparatus simulating the conditions in a cylinder head are presented, illustrating the importance of controlling the boiling conditions of the water at the cooling face of the flame deck. It is concluded that cylinder head temperatures, and therefore the danger of cracking, can be successfully reduced by increasing the flow of cooling water over critical areas by some form of directed flow.
Investigation into the Consequences of the Failure of a Turbine-Generator at Hinkley Point ‘A’ Power Station
Authors: Gray J. L. 
Published: October 2007

The further investigation was extensive and is continuing but the present account is limited to what throws light on the Hinkley Point ‘A’ incident and its immediate consequences. There were three main areas of investigation: (1) laboratory and on-site exploration of conditions for stress corrosion cracking of relevant steels; (2) a survey of all relevant rotors to explore the effects of applying a purely fracture mechanics approach in ignorance of the mechanism causing the initial crack or defect; (3) an examination of rotors withdrawn from machines of similar mechanical design and of properties deemed to be in the highest risk category. Interim conclusions have been drawn. They suggest that in certain non-reheat turbines it is possible to generate high chemical concentrations in regions of high stress and thus to promote stress corrosion cracking. The rate of propagation of such cracks is sufficient to produce critical stress intensities in discs of low fracture toughness in a region of high stress concentration.
The Dynamic Characteristics of a Hydrostatic Transmission System
Authors: Bowns D. E. , Worton-Griffiths J. 
Published: October 2007

The dynamic performance of a hydrostatic transmission with a variable delivery pump used for speed control is predicted using a simple mathematical model. The analysis is then extended to take into account the transmission slip and torque losses, and the prime mover droop by employing signal flow techniques. The results were compared with those from an extensive test programme employing electro-hydraulic test techniques carried out on a typical hydrostatic drive. The signal flow analysis improved the prediction of the transmission dynamic performance, but it was found that errors of up to 40 per cent were occurring, as many of the loads employed could not be accurately represented by simple mathematical models. A vector approach was adopted, using measured load loci that provided a correlation of within 4 per cent of the experimentally measured response, by using a value of oil bulk modulus midway between the isothermal and isentropic tangent values. Mean return line pressure, restricted boost system and flexible pipeline effects were investigated.
Film Recession in Hydrostatic Thrust Bearings
Authors: Newton M. J. , Howarth R. B. 
Published: October 2007

In general, hydrostatic thrust bearings are designed to operate with parallel bearing surfaces and it is assumed that the lubricant film completely fills the bearing clearance. In practice, bearings almost inevitably operate in a tilted condition and this modifies the behaviour of the bearing. In addition, when the surface approaching the bearing under sliding conditions is free of lubricant, recession of the film boundary can occur which further modifies the bearing characteristics. An experimental and theoretical investigation has been undertaken into the behaviour of tilted and parallel hydrostatic thrust pads operating under ‘dry’ sliding conditions. It has been shown that recession of the lubricant film can occur under quite modest operating conditions and that this results in a substantial modification of the bearing characteristics whether the bearing is parallel or tilted. Another feature of film recession revealed by the investigation is that it eliminates the occurrence of cavitation in the film. Boundary recession greatly complicates prediction of the bearing characteristics, but it is shown that this can be carried out successfully giving predicted characteristics that are in reasonable agreement with the experimental data.
Prediction of Flow and Heat Transfer in Ducts of Square Cross-Section
Authors: Launder B. E. , Ying W. M. 
Published: October 2007

Numerical predictions are presented of the hydrodynamic and heat transfer characteristics of fully developed turbulent flow in square-sectioned ducts. The turbo stresses in the plane of the cross-section, whose gradients cause the well-known secondary motion, are approximated by gradients in the axial mean velocity. Predicted results are in close agreement with available experimental data of primary and secondary velocities as well as the shear stress and heat flux variations around the perimeter.
A Review of the Operational Behaviour and Design of Direct Contact Feed Water Heating Plants for Large Thermal Power Stations
Authors: Dartnell Lawrence 
Published: October 2007

Condensate heated by direct exposure to bled steam in pressure vessels gravitates through heaters in cascade and is transferred by pumps to the next cascade or to the deaerator-storage tank. Direct contact heaters are proved to be thermally effective but the systems in which they are incorporated are shown by operational experience, by review and by analysis to need careful and detailed design for trouble-free operation. Operational experiences are described together with predicted modes of behaviour of the cascades when subjected to extreme conditions of operation and to fault conditions.
A Contribution to the Study of Analogies of Power Transmissions in Machines
Authors: Schlösser W. M. J. 
Published: October 2007

In this lecture an analogy is described by means of which transmissions can be analysed and compared. Two important design parameters are the force density Δ and the effective volume V*, which can be used to analyse stationary and moving methods of transmission. With this analogy a tool is given to the designer to compare transmissions with regard to performance, controllability, size and weight, intensity of loading, dynamic properties. A beginning has been made with formulating a relation between the intensity of loading and wear phenomena (II). With this work we hope to have contributed to a sounder basis for the study and development of power transmissions and their use in machines. As mechanical, electrical, pneumatic, and hydraulic power transmissions can be compared by means of this analogy, the selection of transmissions can be made on a sounder basis.
Turbocharging of Small Engines
Authors: Goodlet I. W. 
Published: October 2007

During the last 20 years, progressively smaller diesel engines have been turbocharged, so that units of 50-60 hp are produced today. Spark-ignition engines remain normally aspirated for most applications, although this picture may change. Progress followed the adoption of radial flow turbines using lost-wax cast rotors. Other developments included:raising component efficiencies; dealing with bearing and seal design problems, and with vane vibration; and in devising manufacturing methods for quantities approaching 3000 weekly, in mixed and rapidly changing batch sizes. Various control systems are available to match the turbocharger to the demands of variable speed engines.
An Advanced High-Speed Dynamometer for Testing Aircraft Tyres, Wheels and Brakes
Authors: Roberts J. B. 
Published: October 2007

Unlike tyres, wheels and brakes for commercial vehicles which can be tested on the road as a major part of their development programme, such equipment for aircraft must be qualified to full service conditions in the laboratory before being fitted to an aircraft. This paper covers the specification background, design features and construction of a large, high-speed dynamometer on which the development and qualification of aircraft tyres, wheels and brakes are carried out. Particular attention is given to several fundamental advances in design including the electrical stimulation of brake inertia, computer control and monitoring of the main systems and the real-time recording of tyre forces in three planes. The paper covers a combination of the mechanical, electrical and instrumentation engineering content of the facility.
The Training Needs of the Profession for the Next Decade
Authors: Shaw F. 
Published: October 2007

The main theme of this Address is the training of professional engineers, although it is apparent that training cannot be completely divorced from education. Primary education is dealt with briefly, but sufficiently to indicate its importance. A proposal is made for a system of mentor and tutorial guidance extending from the sixth form through the industrial student stage, and through University to Corporate Membership of C.E.I. and into management. At each stage of development the responsibilities of the various participants are clearly outlined, and proposals are made for training and educational programmes. These are broad enough to be applicable to almost any discipline, and should be tailored to suit the individual requirements of any organization. The Address is concerned with the methods which should be adopted for manager development, not only for the graduate but right through, as a continuing process, for all grades of management.
Experimental Evaluation of a Streamline-Curvature Method for Flared Subsonic Cascades and for Transonic Cascades
Authors: Bindon J. P. , Day I. J. 
Published: October 2007

The accuracy of the streamline-curvature method has hitherto not been evaluated for curved-axis convergent-divergent flow as found in transonic turbine cascades and for flow in cascades with flow divergence or flare. To provide the data for evaluation, two simple single-channel rectangular-section wind tunnels were built to simulate the flow between turbine blades. The supersonic channel was successfully and economically powered by a large steam ejector. In transonic and supersonic flow, an examination of the sonic and M = 1·1 lines was used as a basis for evaluating the predictions. The correlation was found to be good near the convex surface, but showed a deterioration towards the concave surface. Both test and prediction revealed the unexpected fact that the sonic line contour is not smooth, but wavy. The correlation at the M = 1·1 line was positionally the same as the sonic line, but the experimental contour was considerably more wavy. The accuracy deteriorated further into the supersonic region. The discrepancies in the transonic region are thought to be caused by a very slow rate of change of area, which produces a complex boundary layer interaction in the throat region, affecting both the location of the throat and the area ratios in that zone. The prediction method was shown to be extremely accurate for flared-cascade flow even up to the very exacting situation of a 40 per cent blade height increase, the only error being that due to boundary layers in the apparatus that effect the velocity distribution over the latter half of the suction surface in a highly staggered cascade.
Air Motion in a Four-Stroke Direct Injection Diesel Engine
Authors: Dent J. C. , Derham J. A. 
Published: October 2007

This paper presents the results of a study of the air motion in a motored four-stroke direct injection diesel engine using hot-wire anemometry. The effects of engine speed, valve masking and supercharging on mean air swirl have been studied. A theoretical analysis is developed for the mean air swirl which in general shows good agreement with the experiments reported here and with the measurements of other workers on similarly sized engines. The problem of ‘squish’ has been investigated and it is shown to be the radial component of the spiralling swirl flow entering the combustion chamber. Reasonable agreement has been found between measurement of the radial flow component at the edge of the combustion bowl and a theoretical analysis that considers the bulk radial flow of air to the combustion bowl during the last 30°-40° b.t.d.c. of the compression period.
Slip Factor of a Centrifugal Compressor and Its Variation with Flow Rate
Authors: Whitfield A. 
Published: October 2007

To predict the complete performance map of turbocharger centrifugal compressors, it has been found essential to include a procedure for estimating the slip factor at off-design flow rates. The many correlations available for the slip factor only concern themselves with design-point operation and consequently only provide a single value for the slip factor. The approach presented here attempts, within the confines of a one-dimensional procedure, to recognize the changing flow pattern at the impeller discharge in order to predict the variation of slip factor with flow rate. The procedure is based upon the well-established jet-wake flow model of Dean and the overall slip factor calculated from the jet slip factor. Experimental and theoretical slip factors are presented for three impellers with 34, 30 and 12 radial blades, respectively. The complete performance map of the 12-bladed turbocharger compressor and the effect of using a constant and varying slip factor on the predicted performance are presented.