bluuebunny/crossref_metadata_2025_split huggingface dataset:
Paper 2: Education in Lubrication and Wear and Its Conceptual Integration into Machine Design
Authors: Blok H. 
Published: June 2010

The paper points out why the rationalization of education in lubrication and wear, through its conceptual integration in machine design, is indispensable for the future development of machinery and, therefore, for that of national economies. The paper is mainly devoted to outlining a philosophy of approach in education, based on broad unifying principles and concepts that are tangible to those having to apply them, i.e. the designers of machinery. By means of this philosophy one may achieve the conceptual integration of education in lubrication and wear into machine design. The philosophy also meets the demand for organizing the bewildering store of present-day knowledge on lubrication and wear, both of a fundamental and an empirical nature. The ensuing classification of the various states of lubrication and the types of mechanical wear rests mainly on the distinction between ‘conformal’ and ‘counterformal’ rubbing surfaces. This distinction runs broadly parallel to, amongst other things, the nature of contact, the potentialities for achieving full fluid-film lubrication, and the flash temperatures obtaining. The unifying principle most typical of the field of lubrication and wear is that of contact inhibition, which reflects itself in the design principle of the protective layer. Much importance is attached also to principles that are not specific to lubrication and wear, but are generally applicable to the design of machinery. Such principles are exemplified by that of the optimal grouping of functions to be fulfilled and by the even more universal principle of the so-called ‘comparison of scales’. Last but not least, the present philosophy of unified approach may well lend itself, at least in essence, to rationalizing education in the much wider field of mechanical engineering in general.
Paper 14: Rolling Contact Failure Control through Lubrication
Authors: Tallian T. E. 
Published: June 2010

Lubrication in rolling contacts serves primarily to control failure and must be engineered for that purpose. Four classes of failure are defined in rolling contact mechanisms: wear (mild wear and smearing, involving metal transfer); plastic flow (cold or due to overheating); fatigue (spalling and surface distress); and bulk failure modes occurring away from the contact areas. Generalized ‘stress fields’ leading to rolling contact failure are defined as mechanical, thermal and (possibly) chemical ‘stresses’. The severity parameters of these stress fields are developed and illustrated by typical relationships based on Hertzian assumptions and are progressively refined through the stepwise inclusion of tractive surface forces, plasticity, elastohydrodynamics, and of effects of surface micro-topography (boundary lubrication) and material inhomogeneities. Effects of lubrication on these severity parameters are identified. Experimental and theoretical findings on the detailed failure mechanism are used to derive failure criteria, including lubrication effects, for each failure mode. Methods are presented on this basis for the control of failures.
Paper 15: Cams and Friction Drives
Authors: Naylor H. 
Published: June 2010

The mechanism of lubrication of cam-follower systems and of rolling contact friction drives is essentially elastohydrodynamic. Existing knowledge of the design criteria to be satisfied by and the major forms of failure—fatigue pitting and scuffing—encountered in these mechanisms is discussed in the light of elastohydrodynamic theory. Examples of the successful application of the theory are reviewed. The role of development testing in rigs and in full-scale equipment is considered and the conclusions reached from such testing briefly summarized. The coefficient of friction in the contact is an important factor in the operation of rolling contact friction drives and its variation with operating conditions is complex. Knowledge of the frictional behaviour of elastohydrodynamic contacts is not complete; the present position is reviewed.
Paper 16: Solid Friction and Boundary Lubrication
Authors: Tabor D. 
Published: June 2010

During the last decade considerable progress has been made in our understanding of the contact between solid surfaces. Earlier work emphasized the plastic deformation and more recent work the elastic deformation of the surface asperities. However, when sliding occurs combined normal and tangential stresses in the contact zone greatly enhance the plastic régime. Broadly speaking, recent work supports the earlier view that friction is attributable to adhesion at the points of real contact and to the ploughing or tearing of one surface by asperities on the other. In high vacuum the surface films normally present can be removed either by heating or by repeated rubbing. As a result the adhesion, friction and wear can rise to very high values. However, even under very clean conditions some metallic pairs appear to show relatively weak adhesion. With non-metals similar processes occur but with brittle solids they are complicated by surface and sub-surface cracking. Here crystal orientation can be very important. With polymeric solids, where strength properties are rate and temperature dependent, marked variations in friction with speed and temperature are often observed. The more rigid the polymer the smaller the effect. In the field as a whole little work has been carried out on the interaction between the adhesion and the ploughing mechanisms. In the field of lubrication it is now apparent that a considerable amount of what was formerly termed boundary lubrication was probably elastohydrodynamic. However, recent studies show that elastohydrodynamic films can operate under more severe conditions if small quantities of surfactants are added. These do not affect the viscous properties of the lubricant but form protective surface films of molecular dimensions. During the last decade little work has been carried out on the formation, structure and strength properties of these boundary films. It remains an area of great importance.
Paper 18: Physical Properties of Fluid Lubricants: Rheological and Viscoelastic Behaviour
Authors: Lamb J. 
Published: June 2010

In order to predict the behaviour of lubricating fluids which are to be operated under elastohydrodynamic conditions, the designer requires to know the rheological properties of the lubricant at the pressure, temperature, and rate of shear encountered in practice. A review is given of the available evidence aimed at establishing a formal connection between the rate of shear behaviour and that observed under alternating shear stress. It is shown that the viscoelastic properties of liquids in oscillatory shear can be successfully predicted on the basis of a new phenomenological model and that complete results are available from oscillatory experiments. Possible correlation of these results with rate of shear behaviour is suggested.
Paper 32: Lubrication and Wear Problems in the Textile Industry
Authors: Catling H. , Pratt G. C. , Wilson W. H. 
Published: June 2010

Each stage of production in the textile industry presents its own bearing and friction problems. In addition there is contamination by oil or grease from bearings and gears of the fibres, yarn, or fabric being processed. Dust and fly penetrating every part of a machine clogs gears and bearings and makes effective lubrication very difficult. Sealed rolling contact bearings, self-lubricating plastics or porous metal, and unlubricated bearings based on plastics have found acceptance because of their ability to run cleanly without attention for long periods, but solutions to bearing problems must be cheap as well as effective because a single machine may have thousands of bearings. Difficult bearing conditions which have been resolved after much research and development work are found in the high-speed spinning spindle rotating unbalanced at 12 000 rev/min or more, and the ring and traveller where steel runs on steel at high pressure and velocity. Existing conventional textile processes have reached such a level of development that further major advances are likely to require completely new techniques but there is still much that engineers can do to increase the reliability, efficiency and smooth operation of conventional machines which will remain in the majority for many years to come. Lubrication plays a vital part in achieving optimum performance.
Paper 34: Lubrication in a Marine Environment
Authors: King H. F. , Glassman N. 
Published: June 2010

The lubrication of machinery in a marine environment is not without challenges for researchers, designers and operators. These challenges stem in navy ships from the presence of salt water and salt-bearing air in contact with machinery already designed to the outside limits of high output and light weight. Thus, to users of machinery in a marine environment, the mastery over sea water is directly related to machinery reliability, maintainability and capability. For a machinery user such as a navy there are some additional lubrication problems caused by the need to conserve space in machinery design and the need to proceed quietly. This paper will be concerned with five machinery lubrication problems arising from the marine environment. They may be considered typical of and peculiar to that environment. They are timely because their solutions must be shared in by those in research and design as well as by the machinery operators. The cases are as follows: (a) The protection of vapour spaces in operating turbines by volatile rust-inhibiting chemicals in the lubricating oil. (b) The operation of petroleum oil hydraulic systems in the presence of sea-water intrusion. (c) The selection of lubricating greases for quiet ball bearings. (d) The development of a lubricant for a ‘marinized’ aviation gas turbine. (e) The lubrication of diesel engines of such weight-to-output ratio as to be competitive with steam and gas turbine propulsion. Each case will be presented by reviewing the background of the problems, the approaches considered in their solutions, the status of the solutions and expected future developments.
Paper 19: Lubricants for Fluid Film and Hertzian Contact Conditions
Authors: Fowle T. I. 
Published: June 2010

Petroleum oils. Their nature, types, and method of refining are briefly introduced and followed by a discussion of their properties, constitution, and the important effects of their aromatic and of their non-hydrocarbon constituents. The effects of oil oxidation, including effects on bearing metals, and thermal decomposition are referred to and a number of the more important oil additives are described. An indication of useful oil life in relation to temperature and other conditions is given, and the importance of performance testing under rimulated service conditions is described. Water-containing lubricants. Water-in-oil, oil-in-water, and water–glycol solutions are described, together with their special properties such as fire-resistance. Their performances as lubricants, including effect on fatigue pitting, are briefly discussed. Synthetic oils. Dibasic acid esters, neopentyl esters, triaryl phosphate esters, chlorinated diphenyls, fluorocarbons, polyglycols, silicones, and polyphenyl ethers are described in terms of structure and physical properties. Their stability to oxidation, thermal degradation, and hydrolysis are discussed as are their effects on materials of construction, their load-carrying capacity under various conditions, and toxicity.
An Introduction to the Concepts Involved in Vehicle Testing
Authors: Macmillan R. H. 
Published: June 2010

Research covers a spectrum from pure research, through applied research and development, to market research. The most appropriate places for each kind to be pursued are discussed, together with the types of staff, instrumentation and facilities for testing that are essential to all research work. The three main areas of industrial research and testing are applied research, development testing and production testing; the particular requirements of each are considered. Applied research must be relevant to vehicle functioning, and projects may arise from new scientific discoveries, from novel ideas originating within a research organization, or from an urgent industrial need. In each case test techniques must be developed to obtain the data given in each category. Development testing requires the design and construction of laboratory rigs and proving facilities to obtain data in the most economical way. Production testing is directed mainly to the control of product quality and demands techniques and facilities which can be operated continuously and on a large scale. The types of facility needed for each of these applications are considered, with a view to giving an overall view of the matters discussed in detail in the papers of this Symposium.
Paper 5: Some Aspects of Tyre and Vehicle Vibration Testing
Authors: Barson C. W. , James D. H. , Morcombe A. W. 
Published: June 2010

Instrumentation techniques are discussed. Particular emphasis is given to those techniques which have been developed to give immediately interpretable results from complex vibration data. The relative merits of various test methods for the evaluation of tyre vibration performance are indicated. Of particular importance in this respect is the difference between rolling and non-rolling testing. This is illustrated during discussion of cross-ply/radial-ply comparisons using various test methods, and also comparisons between radial tyres of slightly different construction. A necessary vibration property of a tyre is its ability to absorb single obstacles such as ‘cat's eyes' or road joints. Attempts have been made to simulate such objects on a drum, and various methods of analysing the resulting impulse to the axle are compared. As yet no generally acceptable method of analysis has been found. The majority of vehicle testing is done using vibrator excitation, as this tends to minimize tyre differences. However, problems involving low frequency excitation due to once per wheel revolution inputs are usually investigated on both drums and vibrators. This type of problem often arises when longitudinal compliance has been introduced in the suspension. Typical curves from suspensions of this type are shown. An example showing one of the principal modes of oscillation of a tyre is given.
Paper 13: Liquid Metal Flow in a Complex System of Passages
Authors: Greene D. A. 
Published: June 2010

To achieve the necessary flow conditions in a particular liquid metal heat transfer experiment it has been necessary to design a rather complex pipework system. An analysis of the system has been made, and flow predictions in various parts of the system as functions of valve operation are given. Comparison is made with the experimental results obtained on the rig. The effect of various parameters such as thermal density changes and cavitating flow, caused by large temperature changes and driving pressure heads, is briefly discussed.
Paper 10: Pressure Losses in the Inlet and Outlet Casings of Axial Flow Turbines for Turbo-Chargers
Authors: Simpson C. W. , Scarlett D. E. Y. 
Published: June 2010

During initial design studies for a new range of turbo-chargers it was apparent that a considerable gain of efficiency could be achieved by a reduction of turbine casing losses. In this paper the theoretical and experimental pressure losses obtained from rig tests on the inlet and outlet casings for old and new designs will be presented. The inlet casing tests were completed on an axial entry casing with transition from circular to semi-annular section. The effect of this transition piece on gas incidences is also shown for the semi-annular nozzle entry. Studies on the outlet casing as a transition from annular through radial to axial flow have been completed and will be presented as a pressure loss coefficient for various designs. The tests have been undertaken with both convex and flat plate radial diffusers, with or without swirl. Different outlet ducts were used to determine the effects on pressure losses in the casings, and the results are discussed. Finally, the gains in overall turbine efficiency obtained by adopting the beneficial results from these tests are considered.
Paper 1: The Design and Development of an Inlet Volute for an Experimental Air Turbine
Authors: Ryan P. G. 
Published: June 2010

One of the problems which arose during the design of an experimental air turbine was the design of a suitable inlet volute. It was considered that to obtain reliable flow measurements within the turbine without laboriously traversing around the complete turbine annulus, a smooth, evenly distributed flow at inlet was imperative. An analytical approach was considered in the first instance, but the problem appeared so complex that it was decided to perform a purely experimental investigation. This paper outlines the reasons for selecting a particular type of volute for the purpose, and describes the initial design, aerodynamic tests on a quarter-scale model, and the subsequent modifications which led to a final design of volute.
Paper 12: Fluid Flow Losses in A.C. Generator Stator Ventilating Ducts
Authors: Carew N. J. , Freeston D. H. 
Published: June 2010

This paper reports an experimental investigation into the ventilation characteristics of the air gap/radial duct combination in electrical machines. The problem is basically of the manifold type in which the machine air gap is compared to the supply duct and the radial ventilating ducts represent the branches. The factors affecting the pressure drop and flow distribution arising from the change in air direction from circumferential in the air gap to radial in the ventilating ducts are examined. First, the influence of slot wedge and duct spacer position, relative to the air gap, was observed in a qualitative manner using a water table model; the resulting flow patterns are illustrated. Second, the same duct configurations were tested in a model of a stator segment using air as the working fluid. The results of pressure drop and mass flow distribution are presented for variations in gap static and dynamic pressures together with curves showing the distribution of pressure losses along the ducts. Finally comparisons are made between model and full-scale measurements with a brief assessment of instrument problems.
Paper 7: Fluid Flow Losses Associated with the Cooling of Electrical Machines
Authors: Bennett R. B. , Poole R. M. 
Published: June 2010

One of the limitations in the design of electrical machines is that of the temperature rise of the machine components. The most effective method of limiting the temperature rise is to duct the cooling medium to the source of loss, without unduly inhibiting the electrical design. This often results in complicated fluid flow paths, which cannot be designed exclusively from the point of view of maintaining ideal flow conditions, in both stationary and rotating members. As the fluid flow conditions, generally, are not ideal, the only effective method of determining the loss factors is by practical means. To establish the duct losses and flow distribution under simulated conditions, full-size and scale models of components of electrical machines (e.g. direct hydrogen-cooled turbine generators, a.c. machines, and d.c. machines) have been made and tested. The loss factors which have been obtained are compound factors for a particular geometry and result from the effects of entry and exit conditions, changes of section and, where applicable, the effects of rotation. No attempt to separate the losses has been made, except where well-documented losses, such as friction, are involved. This paper illustrates the types of fluid flow paths encountered in electrical machines and presents the loss factors, obtained from tests, for some of these arrangements.
Paper 8: Pressure Losses and Erosion in Condenser Tube Inlets
Authors: Tucker A. C. N. 
Published: June 2010

From water model studies of two types of power station condenser, it has been deduced that the erosion of condenser tube inlets is due to a non-uniform inlet water-box flow distribution which results in damaging impingement flows in tube entries. The impingement flow can be reduced either by fitting bell-mouths to the tubes, or by deflection of the cooling water flow at the condenser inlet to prevent it crossing the faces of tubes. Some assessment has been made of the pressure losses in tube inlets, and these losses have been translated into drops in operational efficiency.
Paper 11: Diffuser Performance with Distorted Inflow
Authors: Tyler R. A. , Williamson R. G. 
Published: June 2010

A series of conical and annular diffuser geometries was tested in the National Research Council's 10 ft ×20 ft propulsion tunnel, under conditions of non-uniform inlet velocity distribution, generated by the operation of a short entry pipe in cross flow. The results suggest a wide applicability of the simple distortion factor, defined by the ratio of maximum to mean velocity in the inlet cross-section, to the prediction of pressure recovery in diffusers and diffuser exit settling pipes. A marked effect of inflow distortion on optimum diffuser geometry was indicated. The correlation of Sovran and Klomp was corroborated for the range of inlet distortion factor pertaining to the original data.
Paper 3: Steady Flow Tests on Twin Poppet Valves
Authors: Woods W. A. 
Published: June 2010

This paper presents the results of an experimental investigation of steady flow through a pair of exhaust poppet valves. An account is given of the gas exchange process on engines which use poppet valves and the reason why pressure losses should be kept to a minimum is explained. Tests carried out on the cylinder head of a uniflow two-stroke cycle engine are described following a brief description of the apparatus used. The results of a simple analysis of incompressible flow are also given. It is shown that the two previous models of flow through a valve, namely the sudden enlargement and constant static pressure, both give unrealistic pressure losses for large area ratios, i.e. at high valve lifts. A new model is introduced which leads to realistic pressure losses at small and large area ratios, i.e. at low and high valve lifts. Effective areas for the present tests are calculated on the basis of the constant pressure model, and details of calculation of pressure losses are outlined. The blockage effect caused by placing the exhaust valves near the cylinder wall is given in the discussion of the test results. This is zero for 0 < l/d < 0·08, but reaches a maximum blockage of 10 per cent at l/d = 0·28. With unrestricted twin valves the effective area is about twice that of a single valve up to l/d = 0·18 with a progressively larger effective area at lifts up to 13 per cent higher at l/d = 0·4. A comparison is also made with other data readily available. The pressure losses determined from the tests were analysed using a parameter derived in the simple theory. The parameter used is found to be almost independent of pressure ratio and the results are presented by means of this pressure loss parameter as a function of valve lift. The representation provides a quantitative method of comparing the performance of a given configuration of valve and port. On this basis the twin poppet valves are shown to give a slightly higher pressure loss than a single valve.