bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Experimental Study of Some of the Factors Affecting the Contact Conditions and the Slip between a Rolling Ball and Its Track
Authors: Hailing J. , Al-Qishtaini M. A. 
Published: October 2007

The problem of a rolling ball subjected to combined normal load and tangential tractions has been studied for a variety of operating conditions. It is shown that for dry steady state loading the resultant slip may be explained in terms of a microslip theory based on the differential elastic straining of the ball and the track. Such results necessitate a careful experimental technique in which the surfaces must be free from contamination and loose wear debris. It is also shown that the preceding arguments are not significantly affected by dynamically varying loads or by speed variations in the range 0-150 in/min. The slip behaviour is found to be markedly affected by the presence of a lubricant. The behaviour with load and speed now indicates a definite hydrodynamic effect, although the theoretical film thickness is considerably less than the surface roughness. These results agree well with the results of other investigations for similar conditions. Using these experimental results and theoretical considerations a tentative power law formulation for the slip under such conditions is proposed.
Chatter When Machining Aluminium Alloy: An Investigation Using a Structural Model
Authors: Johnson B. M. , Andrew C. 
Published: October 2007

This paper describes an experimental investigation of machine tool chatter, in which the machine tool structure was replaced by a model, two-degrees-of-freedom structure with adjustable and consistent vibration characteristics. Primarily non-regenerative chatter, and secondarily regenerative chatter, were investigated for orthogonal cutting of an aluminium alloy with both conventional and restricted-contact cutting tools. The results are presented in the form of stability charts; these show the limiting widths of cut which can be machined without chatter, for given sets of machining and structural conditions. For non-regenerative chatter, it was found that the limiting width of cut: increases with a decrease in the structure's cross-receptance between the directions normal and tangential to the cut surface; increases with a decrease in cutting speed, but in a manner depending on the structural characteristics; is substantially independent of the mean undeformed chip thickness; increases by at least 25 per cent if contact is restricted to a length approximately equal to the undeformed chip thickness. For regenerative chatter it was found that the limiting width of cut: was approximately one half of the limiting width for non-regenerative chatter, for the otherwise similar machining and structural conditions investigated; increases with a decrease in cutting speed; increases by at least 25 per cent if contact is restricted to a length approximately equal to the undeformed chip thickness. Theoretical predictions of non-regenerative chatter with a conventional tool, based on independent measurements of machining force oscillations during tool vibration, agree well with experimental results. For regenerative chatter with a conventional tool, the theory was based on the superposition of machining force oscillations arising from tool vibration and from removing a wavy surface. The predictions were in error at low cutting speeds, indicating that the force oscillations are not superposable at this condition.
An Experimental and Analytical Investigation of the Gas Exchange Process in a Multi-Cylinder Pressure-Charged Two-Stroke Engine
Authors: Benson R. S. , Galloway K. 
Published: October 2007

The results are given of a comprehensive investigation of the pressure and temperature diagrams in a multi-cylinder two-stroke engine during the gas-exchange process. A six-cylinder turbocharged two-stroke diesel engine was fully instrumented to record transient pressures in three cylinders, in the scavenge belt, and in a number of positions in a specially designed exhaust pipe. Transient-temperature records were taken in the exhaust pipe. Steady-flow tests were carried out on the inlet ports, the exhaust valves, and the exhaust pipe. The steady-flow data were then used in a computer programme (see references (9) (12)‡) to predict the pressure in the cylinder and the pressures and temperatures in the exhaust pipe. Discounting some measured cylinder-pressure records, which were suspect, the investigation showed good agreement between the predicted and measured pressures in the cylinders and exhaust pipe. The analysis of the temperature records showed there was evidence of mixing and longitudinal heat transfer in the exhaust pipe; however, the mean computed temperature in the exhaust pipe at the nozzle end agreed with the measured temperature. Comparison of the measured and computed mass flows at the nozzle end of the pipe using the theoretical diagrams gave good agreement. It was concluded that the computer programme was a satisfactory method for calculating the pressures in the cylinder and exhaust pipe during the gas-exchange process.
Design of Centrifugal Pumps with Computer Aid
Authors: Peck J. F. 
Published: October 2007

The design of centrifugal pumps involves a large number of interdependent variables, so that there are several possible alternative designs for the same duty. One of the most difficult design problems is to predict the impeller ‘head slip’, i.e. the difference between the theoretical head for an infinite number of impeller vanes H th ∞ as derived by Euler, and the theoretical head deduced from the net horsepower given to the fluid passing through the impeller after deducting external losses H thn. In a previous experimental paper (1)† the author showed that the head slip was related to the mean blade loading and this has been applied in the present paper. He also suggested that the mean blade loading was an important factor in cavitation problems, having an advantage over the Thoma cavitation constant, as it allows for variations in the number of impeller vanes. For preliminary design of the main dimensions the author has plotted a number of dimensionless parameters to a base of specific speed and derived mathematical equations for them which can be fed into a computer for rapid solution. The suggested computer programmes are in Fortran IV language and in four sections: (1) Internal hydraulic losses, related to Reynolds number and relative roughness of the flow passages, external losses, efficiencies, and horsepower. (2) Impeller outlet dimensions, with allowance for head slip based on the mean blade loading. (3) Impeller inlet, eye diameter, inlet angles, etc. (4) Estimation of the direction and magnitude of the absolute velocity leaving the impeller, and determination of the throat areas of volute casing or diffuser vanes. Also estimation of required net positive suction head (n.p.s.h.), again based on the mean blade loading. These programmes have been check tested on the International Computers and Tabulators (I.C.T.) 1905 computer at Loughborough University of Technology and give results which agree with the test results within 1 or 2 per cent over a wide range, except for very small pumps. To illustrate the method worked examples of impeller and diffuser are given in the Appendices, and corresponding results of a number of other alternative designs for the same duty are shown in a table. The main advantage of the computer aid is that it permits a wide range of design constants to be investigated in a very short time, so that the optimum design can be selected more readily. Consequently the skill and experience of the designer are still required, as the optimum design is a compromise between high efficiency with low running power costs, and low production costs to secure an order against severe international competition.
Refuse as a Fuel: First Paper: Municipal Refuse as a Fuel
Authors: Watson R. H. , Burnett J. M. 
Published: October 2007

Quantitative and qualitative information on domestic refuse as a fuel is given; attention is drawn to its heterogeneous nature and variability in properties both short term and long term. Modern equipment for incineration is referred to and particular reference is made to the associated aspects of flue gas attemperation and chimney emissions. Potential usage of the heat produced by incineration in boiler or other heat exchanging plant is discussed in terms of functional considerations and economics; in Appendix 1 a more detailed study of the economics of generation of electricity is made. It is concluded that there is no prima facie case for heat recuperation of all incinerators and in the present circumstances each case must be examined on its merits.
The Fatigue Strength of Large Single-Pinned and Double-Pinned Connections Made from Alloy Steel FV520B
Authors: White D. J. 
Published: October 2007

Fatigue tests have been conducted on single-pinned and double-pinned lugs made from alloy steel FV520B and loaded by means of 2 in diameter pins. The effects of pin fit for both clearance and interference and of various treatments were investigated. The treatments included side relieving the lug hole, bushing the bore, applying the Sulfinuz process to the lug or overstraining the lug bore. Two conditions of mean stress were investigated, namely, pulsating or repeated tension and 15 tons/in2 mean tension. Basing comparison on the fatigue strength at 30 × 106 cycles, the untreated lugs with close fit pins showed the lowest strength of all. Both clearance and interference fits were beneficial and by appropriate choice, the fatigue strength could be at least doubled and in some cases trebled. Lugs which had side relief, had been bushed, Sulfinuz treated or which had overstrained bores also gave worthwhile increases in fatigue strength and the strength ratios were generally in excess of 2. An increase in mean stress significantly reduced fatigue strength for all lugs tested, except for those with close fit or clearance fit pins. Comparing the present results with those obtained on lugs one-quarter the size, a considerable size effect is evident for some conditions, large lugs being weaker than small lugs.
A Theoretical and Experimental Study of a Liquid-Lubricated Hydrostatic Journal Bearing
Authors: Betts C. , Roberts W. H. 
Published: October 2007

The use of mechanical pumps for circulating high-temperature liquid-sodium coolant in nuclear-powered fast reactors emphasizes the problem of designing suitable bearings. This paper presents a semi-empirical theory which describes the (static) performance of a hydrostatic jet journal bearing for such applications where the flow through the bearing is predominantly turbulent. The theory covers both viscous and turbulent regimes of flow. In the presentation non-dimensional groups are plotted to facilitate direct application of the theory to specific design problems. Experiments using paraffin and water as the working fluid are described; Reynolds numbers of approximately 1700 and 7000 respectively were achieved—compared with Re in excess of 20 000 likely to be encountered in practice. The design and performance of an 8 in diameter bearing for a 6000 gal/min mechanical sodium pump prototype are briefly described.
Dynamic Characteristics of an Oil Hydraulic Constant Speed Drive
Authors: Healey A. J. , Stringer J. D. 
Published: October 2007

Experimental and analytical studies are made of an oil hydraulic system which uses a pressure compensated flow control valve for speed regulation. The study concerns dynamic response with special reference to the effects on the system of the sudden application of a retarding force to the mass it is moving. Equations of a typical ‘meter-out’ type of system are first developed and solved. The consequent predictions are then compared with experimental results from an apparatus which simulated a machine tool application. The advantages of incorporating a restrictor in the inlet (supply) line are then examined both experimentally and analytically using an analogue computer. The results show that the mathematical models give satisfactory predictions of the maximum changes of velocity and pressure occurring during the transients. The restrictor reduced the magnitudes of these transient changes and also eliminated ‘stick-slip’ oscillations at low speed. It is concluded that the methods of analysis outlined in this paper could be used to advantage in the design of practical systems.
Design Methods for Model-Reference Adaptive Systems
Authors: Phillipson P. H. 
Published: October 2007

The ‘M.I.T. rule’ and two Lyapunov synthesis methods of design are critically reviewed. The latter are the input modification scheme of Grayson and Parks' method for the determination of parameter-adjusting feedback loops. For large inputs such methods are unsatisfactory: this is demonstrated by root locus plots for the step response of a second-order system with adaptive gain. A Lyapunov synthesis procedure is proposed which is a composite solution. The feedback loops of Parks are employed but an input modification signal is superimposed. This can be conveniently chosen from existing signals to add a fourth order negative definite term to V, thus promoting a greater degree of stability for large inputs. Results from an analogue computer study are included. The method is general in application.
Geometry and Leakage Aspects of Involute Rotors for the Roots Blower
Authors: Ritchie J. B. , Patterson J. 
Published: October 2007

For maximum operating efficiency of Roots type blowers, the leakage of compressed air through clearance must be reduced to a minimum. At the same time it is desirable to keep the design as compact as possible. The following analysis endeavours to show, for involute rotors, the effect of the geometrical design variables, pressure angle, rotor tip radius, and base circle radius, on leakage and compactness. Firstly limits of permissible values of the geometrical design variables, to allow correct mating between rotors, are established. Within these limits, relative blower compactness and carry-over of compressed air back to the inlet tract is obtained for the ideal blower with no clearance between relative rotating parts. The analysis and results are expressed in dimensionless form independent of blower size, and results are compared with cycloid rotors. Leakage through blower clearances, in terms of the geometrical design variables, is then determined for a range of pressure ratios, and the dependence on blower size is examined. It is concluded that optimum design values cannot be obtained. A compromise solution between minimum total leakage and maximum compactness is necessary, depending on the operating requirements for a particular Roots blower.
Ocean Engineering
Authors: Bishop R. E. D. 
Published: October 2007

Only the sea can meet a greatly increased demand for protein, for minerals, for fresh water or for power generation. Any of these requirements alone would ensure that man's interest in the oceans must quicken. In fact we have all of these needs and more besides, so that the case for closer study of the sea is overwhelming. This lecture is in two parts. The first points out the need for teaching and research in ocean engineering and describes briefly a scheme that has been set up in an attempt to meet a part of the country's needs. The second examines some of the wider problems of British industrial involvement in marine technology. The obstacles to progress are substantial and some suggestions are offered on how they might be overcome.
The Performance of Steelworks Equipment in Service
Authors: Lake R. A. 
Published: October 2007

The processes of an integrated steelworks are coking, sintering, smelting, refining and re-heating for rolling. Most of the machinery is conventional or specialized mechanical handling equipment and rolling is a special form of such mechanical handling. Such equipment is an assembly of basic mechanisms such as shafts, bearings, couplings, gears, brakes and hydraulic actuators. The paper gives experiences in service of these mechanisms and deals more generally with the E.O.T. cranes which play a large part in the handling of steel from one process to the next. These experiences are drawn from the Spencer Steelworks which went into production in 1962.
Performance of Inward Radial Flow Turbines under Non-Steady Flow Conditions
Authors: Wallace F. J. , Adgey J. M. , Blair G. P. 
Published: October 2007

The paper describes theoretical and experimental work on pulse operation of inward radial flow turbines, together with certain essential steady flow data. Power measurement was by means of a specially developed high speed dynamometer, capable of speeds up to 10 000 rev/min, which is described in some detail. Steady flow tests confirmed the expected trends of mass flow and torque as functions of turbine speed and overall pressure ratio, and in addition proved the reliability, consistency and accuracy of the dynamometer. The unsteady flow analysis of Appendix 1 which is unique in incorporating a very full description of rotor geometry as well as of the complex nozzle-rotor interspace conditions, was applied to two particular experimental cases and gives good agreement with respect to pressure variation in the pipe system, turbine volute and at nozzle exit, but rather less satisfactory agreement with respect to power. Further theoretical work is summarized at the end of the paper.
Availability of Power Stations and Their Equipment
Authors: Shannon W. B. , Campbell W. W. , Carstairs R. , Dollin F. , Frankel A. , Hirst A. W. C. , Sherry A. 
Published: October 2007

Comprehensive and self-consistent data relating to plant availability and outage rates are essential for the assessment of plant performance, thereby enabling standby requirements to be estimated, plant extensions planned and the performance of different types of plant compared. The present paper deals with the essential requirements that must be met to ensure the comparability and adequacy of the statistical data. Five main points are emphasized in the paper: the assessment of plant performance is best given by outage rates, stated in terms of time; three classes of outage are described; namely forced, deferable and planned. Shortfall is considered separately; since the practical consequences of the three kinds of outage will in general be very different, and since one may affect another the record must always include the three outage rates shown as separate items; to permit the assessment and comparison of statistics from different sources the record should also include an output factor—(total output of item during period/rated capacity x total hours in period), a service factor—(total hours of item in service during period/total hours in period) and the number of starts during the period under review; statistics from plants of very dissimilar properties and design and with widely different operating regimes should be compared cautiously.
Optical Elastohydrodynamics
Authors: Foord C. A. , Wedeven L. D. , Westlake F. J. , Cameron A. 
Published: October 2007

In Part 1 an extended series of pictures are given showing the shape of a point elastohydrodynamic contact. Extremely good fringe visibility is obtained by taking account of the reflectivity of the semi-reflecting chromium layer on the glass plate and the reflectivity of the steel balls. The shape of the contact is quite different from the Hertzian shape frequently assumed. Figures are given for pure rolling, pure sliding and skewed contact giving a slide/roll ratio of 016. Careful collimation permits the 30th fringe order to be observed. In Part 2 detailed design considerations needed to give sharp single and multiple beam interference pictures are studied. Subjects considered are the qualities of the rolling pair, the degree of collimation and the design of collimators. The choice of reflecting layer and light sources is discussed. Methods of estimating phase change on reflection are described. A technique making possible film thicknesses down to 100 Å (0.4 μin) is given.
Problems Arising from the Water Cooling of Engine Components
Authors: French C. C. J. 
Published: October 2007

The local heat flows through the walls of components which form the boundary of the combustion chamber of internal combustion engines operating at high engine ratings exceed those found in most engineering equipment. Despite this the coolant-side face is normally in the ‘as cast’ condition, sometimes with core sand adhering to or embedded in the surface and a rust film, which is almost always present in the case of ferrous components. It is also common for additives such as glycol, soluble oils and/or corrosion inhibitors to be added to the coolant. This paper describes the techniques employed in, and gives the results of, an extensive series of tests into the effect of such surfaces and additives on heat transfer and then goes on to describe the use of the resulting data to predict the operating temperatures of diesel engine components in service. The paper also describes the design techniques that have been evolved to permit satisfactory engine operation under highly rated conditions.
The Rotary Forging Concept and Initial Work with an Experimental Machine
Authors: Slater R. A. C. , Barooah N. K. , Appleton E. , Johnson W. 
Published: October 2007

The rotary forging process is based on a recognition of the fact that the axial force required to effect a desired deformation during, for example, an upsetting operation may be reduced if the plastically deforming zone is confined throughout to a small region beneath the upper platen. The top portion of the workpiece is then rotated through this plastic zone thus resulting in a progressive deformation. An experimental rotary forging machine has been designed and constructed which incorporates a lower platen capable of axial movement only, whilst the upper conical platen is capable of rotation about the central axis of the machine and also about its own inclined axis. The principal design features of the experimental machine are described and the results of some preliminary experiments using the machine are presented. Operation of the experimental machine has demonstrated the feasibility of the process. The effect of the axial force on the rotary forging of cylindrical specimens having a height/diameter ( H/D) ratio of unity and for a fractional reduction of 0.5 is discussed. Pure lead at ambient temperature was used, as a model material, to simulate the rotary forging of steels in the approximate temperature range of 700-1400°C. A comparison is made between the axial force required to rotary forge and conventionally upset identical pure lead cylinders. It is shown that the optimum axial force required for slow rotary forging is a small fraction of that required for the conventional slow upsetting of circular cylinders having H/D ratios of less than unity.
First Paper: The Effect of Heat Treatment on the Ductility of Alloy Steel Wires in a Cold Heading Process
Authors: Thomason P. F. 
Published: October 2007

Longitudinal grooves of various depths ranging from 0.001 in to 0.011 in were machined on the cylindrical surface of steel slugs prior to carrying out an automatic two-stage transfer heading operation. The longitudinal grooves were used to estimate the ‘critical groove depth’, which was defined as the depth of longitudinal groove that contained a ductile fracture crack just on the point of ‘opening out’ at the end of the heading process, thus giving a measure of the ductility of the wire. A half-replicate of a two-level factorial experiment was carried out to assess the effects and interactions of annealing temperature, annealing time, cooling rate and ageing temperature on the ductility of four different types of 1/2 in diameter cold heading steel wire. The results show that certain types of steel wires have optimum ductility in the ‘as-received’, cold-drawn, state. Other types of steel are shown to respond favourably to process annealing treatments, in which case annealing at 700°C for 1 hour followed by air cooling should give optimum ductility. It is shown that there is no general correlation between decreasing hardness and increasing ductility for steel wire.