bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further Investigation of Conical Diffusers with Annular Injection
Authors: Duggins R. K. , Lampard D. , Sanders A. T. 
Published: February 2007

A comprehensive investigation is made, for a wide range of incompressible flows, into the merits of annular injection as a means of obtaining a high-performance diffuser with short axial length. Results show that injection yields considerable improvements in both the quality of the discharging flow and the magnitude of the pressure recovery. Accordingly, the technique is strongly recommended when a short, high-performance diffuser is required and when a suitable secondary supply is available. Recommendations are also made regarding the optimum cone angle and the geometry of the injection slot.
A Vibration Technique for Non-Destructively Assessing the Integrity of Structures
Authors: Adams R. D. , Cawley P. , Pye C. J. , Stone B. J. 
Published: February 2007

A method of non-destructively evaluating the integrity of structures is described and applied to structures for which a one dimensional analysis is satisfactory. It is shown how vibration measurements made at a single station in the structure can be used, in conjunction with a suitable theoretical model, to indicate both the location and the magnitude of a defect. Receptance analysis is used in this instance, but the principle is equally applicable to other techniques of mathematical analysis. Experimental results are obtained on a variety of components, including straight prismatic bars, a doubly-tapered bar, and an automobile camshaft, excellent agreement between the predicted and actual damage sites being obtained. The axial mode of vibration is generally used, although somes tests are also carried out successfully in torsion.
Investing in Ideas in an R & D Department
Authors: Leech D. J. , Smart P. M. 
Published: February 2007

This paper reviews some literature on project appraisal and concludes that most of the methods suggested have not been used in industry and that there are good reasons why they should not be used. One of the major criticisms of project selection methods is that most ignore the constraints imposed by limited resources. Many ignore the probabilistic nature of the problems. A simulation model is developed in order that methods of project selection may be tested. The methods tested are a simple economic ranking procedure and a stochastic LP procedure which takes account of resource limits. A random selection is also tested in order that the benefits of the formal selection techniques may be judged. Where the projects available are relatively small and numerous and are unlikely to cause scheduling problems in whatever order they are undertaken, the stochastic LP model does almost as well as an economic selection rule and significantly better than a random selection. Where scheduling problems may be encountered, the stochastic LP model can yield significantly better results than an economic model which ignores resource limitations.
An Investigation into the Dynamic Effects on the Track of Wheelflats on Railway Vehicles
Authors: Newton S. G. , Clark R. A. 
Published: February 2007

Wheelflats on railway vehicles are created by wheelslide in braking: the resulting imperfection in the running line generates dynamic forces and stresses at each subsequent revolution. The authors describe this problem and refer to earlier work on this topic. A field experiment is described, in which an irregularity in the railhead was used to simulate a wheelflat for a range of vehicles, and loads and rail stresses were monitored. The structure and solution procedures of three theoretical models of the vehicle/track system are outlined and typical results are compared with the experimental data to establish the adequacy and limitations of each of the models. Although this paper is primarily concerned with railway track dynamics, the mathematical techniques described could be applied to any problem involving the impact loading of beams.
On the Computation of Heat-Transfer Coefficients from Imperfect Temperature Measurements
Authors: Owen J. M. 
Published: February 2007

An approximate theoretical model is developed to estimate the effects of errors in temperature measurement on the computation of heat-transfer coefficients, h, from the numerical solution of Fourier's equation. The model predicts that, depending on the Biot number and the algorithm used, a small random error on temperature will produce an amplified random error on the calculated instantaneous value of h and a bias in the average value, <h>. ‘Experimental results’, simulated using Monte Carlo methods, are in reasonable agreement with the model, and it is shown that improved estimates of the heat-transfer coefficient can be obtained by using smoothing curves to minimize the effects of noise on measured temperatures. If the temperature measurements have a small positive bias, the theoretical model and ‘experimental results’ show that there can be a large negative bias in the calculated value of h. It is also shown that ‘missing thermocouples’ can be partially compensated for by using interpolation polynomials, but there are dangers that these will cause systematic rather than random errors.
Dynamic Synthesis of a Timing Device with Pulse Loading
Authors: Simandiri S. , Hahn E. J. , Kothari M. , Rao A. C. 
Published: February 2007

This paper describes the experimental investigations which were conducted to verify existing theoretical vibration-amplitude predictions for centrally-preloaded, squeeze-film-bearing-supported rigid rotors. Very good agreement was obtained with all aspects of these predictions, including the degree of pressurization needed to achieve full-film lubrication and the complicated bistable operation behaviour. By developing the theoretical model for the more general case of a rigid rotor supported by unequal squeeze-film bearings at the ends, it is shown how existing theoretical data, derived on the basis of a symmetric rotor with symmetric motion, are readily applicable to the case of a rotor supported by squeeze-film bearings at one end only. The experimental rig consisted of such a rotor, and, although the results are based on a given bearing having a length-to-diameter ratio of 0.167, and did not allow for any significant variation in the radial support stiffness, nor for variation in the bearing dimensions, and the rotor speed did not exceed 7500 rev/min, it is concluded that the theoretical data predictions are valid in general. Their validity is questionable, however, should conditions be such that turbulence and/or unaccounted-for cavitation effects become significant. Squeeze-film bearing behaviour under such conditions warrants further investigation. Slider-crank mechanisms are often used as timing devices, for example, to open and close valves at specified times. Such mechanisms are subject to pulse loads and their design is difficult. Here, a slider-crank mechanism with a flexibly-attached slider subjected to pulse loading is synthesized for position co-ordination. The pulse loading is expressed in the form of a Fourier series so as to simplify the analysis. A worked example is given to illustrate the synthesis procedure.
Interaction and Wall Corrections for the Slow Motion of Two Fluid or Solid Particles Parallel to the Axis of a Circular Cylinder through a Viscous Fluid
Authors: Greenstein T. 
Published: February 2007

Numerical values are provided which enable the drag force on the reference spherical fluid or solid particle, and the torque on the reference spherical solid particle, to be computed for the particular case when two spherical particles move in a direction parallel to their line of centres parallel to the axis of a circular cylinder. Results for this motion are also expressed in terms of the ratio of drag forces experienced by (1) the particle of arbitrary shape in a bounded, two particle system, and the particle in an unbounded, two particle system, and (2) the particle in a bounded, two particle system, and the particle moving alone with the same speed and orientation in the same, but unbounded, fluid. The computation furnishes the interaction and wall corrections correctly to the first-order in the ratios of characteristic particle dimension to characteristic distance of the particle from both another particle and from the cylinder wall. The axisymmetric problem was extended to the more general case where the two particles may be placed eccentrically within the cylinder and the torque was also computed. Furthermore, the two particles may be fluid droplets as well as solid particles.
Design of Planetary Cams for Short Period Events
Authors: Turnbull S. R. 
Published: February 2007

A cam mechanism is described in which a planetary cam operates in sequence a number of equally spaced radial translating followers, the lift and return of the followers taking place during a small angular rotation of the arm which carries the planetary cam. Equations for the synthesis of the planetary cam are developed, along with those for the sliding velocity between cam and follower. A method for allowing small variations in timing is described and some experimental results are given for a number of cams operating two different types of translating follower.
A Theoretical Analysis of the Twin-Land Type of Oil-Control Piston Ring
Authors: Ruddy B. L. , Dowson D. , Economou P. N. 
Published: February 2007

Cyclic variations of the important operating characteristics of the twin-land type of oil-control ring have been analysed by considering radial and torsional equilibrium of the ring cross-section. The assumed form of the face profiles of the lands are related to measurements of worn oil-control rings and the analysis includes the effect of surface roughness in the mixed lubrication regime. The results show that oil-control rings may operate with fluid film, mixed, or boundary lubrication, depending upon the land profiles, the attitude of the ring, and the surface roughnesses on liners and rings. A small height difference between the lands is shown to have a significant effect upon the calculated volume of lubricant passing the ring and the analysis has provided the basis for further rational design of this important machine element.
Drain Discharge Characteristics of Horizontal Drums
Authors: Cranfield R. R. 
Published: February 2007

An investigation is made of the normal steady drainage of water from horizontal drums freely discharging in a steam atmosphere via vertical drains. The flow to the drain orifice in a horizontal drum is asymmetric. At the drain the discharge flow may have several forms; however, there are two basic regimes. At low discharge rates it resembles flow over a weir, whereas with increasing flow there is a transition to a form of orifice flow when discharge is as a jet. In both cases the discharging water is free from entrained steam and vortex formation. Correlations are given to determine the regime and, hence, the applicable head/discharge relationship for drain/drum radius ratios from 0–08 to 0–25.
Theoretical Analysis of the Electroforming Process
Authors: McGeough J. A. , Rasmussen H. 
Published: February 2007

A theoretical model is developed for electroforming with a shaped, soluble anode-electrode. Cases are considered for which the electrode is either flat or conforms initially to the shape of the cathode-mandrel. The model is first analysed by a perturbation procedure for a case where the amplitude and slope of the surfaces of sinusoidally-shaped electrodes are small compared with the inter-electrode gap width. The analysis shows that for d.c. electroforming, when the soluble anode is initially flat, the upper surface of the electroformed metal can become fiat at some stage. After that stage has been passed, the amplitude of the metal layer increases indefinitely with time of electroforming. A uniform thickness for the electroformed metal layer cannot, therefore, be achieved, unlike the case for insoluble plane anodes. When a soluble anode which conforms initially to the cathode-mandrel is used, a fiat upper surface for the metal layer can be obtained. When periodic reversal of polarity is used with soluble anodes, a uniform thickness for the electroformed layer cannot be achieved. A numerical method of analysis of electroforming is proposed which removes the restrictions on the size of shape treated by the perturbation method. The latter method is then applied to the practical case of electroforming of a mould for a rubber ‘O’ ring. Conditions are investigated where the anode is (i) plane and insoluble, (ii) plane and soluble, (iii) and (iv) conforming initially to the mandrel-shape and either insoluble or soluble. The numerical method has revealed that a variation in the metal layer thickness occurs for all these types of anode, and that little marked improvement arises if the simplest type of anode—plane and insoluble—is replaced by any one of the others.
Analysis of a Centrally Loaded 120 Degree Partial Porous Journal Bearing Taking Tangential Velocity Slip into Account
Authors: Malik M. , Chandra M. , Sinhasan R. 
Published: February 2007

This paper presents the analysis of a partial porous journal bearing for its static and dynamic characteristics. Tangential velocity slip at the interface of the fluid film and the porous medium has been taken into account. The analysis is general and can be easily adapted to plane journal and non-circular bearing configurations. The results reported in the paper are for centrally loaded 120 degree partial bearings of aspect ratio equal to unity. These results include static as well as dynamic characteristics of the bearing. A wide range of permeability parameter and R/C ratio has been covered making the data quite comprehensive for design purposes.
The Behaviour of Circular Tubes with Large Openings Subjected to Axial Compression
Authors: Montague P. , Horne M. R. 
Published: February 2007

Circular, thin-walled, steel tubes, with elongated, non-axisymmetric openings subjected to compressive, longitudinal load are examined. Thirteen laboratory tests are described in which careful measurements were made of displacements and strains. The tested specimens were in two geometrically dissimilar groups and their modes of failure were found to be different; in one group the free edges of the openings buckled before failure of the tube and in the other group large displacements at the free edges coincided with the reducing axial stiffness of the tubes. Two theories are proposed to explain these different kinds of behaviour and their predictions compared with the experimental results.
On the Time-Dependent Spin Creep of a Railway Wheel
Authors: Newland D. E. 
Published: February 2007

This paper describes two theoretical calculations of the fluctuating spin creep of a railway wheel rolling on straight track. The first calculation is of the transient spin moment which occurs when a constant spin creep angular velocity is applied suddenly to a rolling wheel. This may occur, for example, when a wheel passes over a discontinuity in the rail and rolling contact is resumed suddenly. The second calculation is of the fluctuating spin creep moment which occurs when a coned railway wheel rolls along a slightly corrugated rail. The analysis is highly idealized, using the approximations of the simplified theory of Kalker and assuming that the area of slip is limited to a negligible proportion of the area of contact. In the first calculation, the area of contact is assumed to be circular; in the second calculation, it is assumed to be rectangular. Subject to these far-reaching assumptions, the results of the calculations suggest that oscillatory fluctuations in spin creep may be initiated by rail discontinuities and irregularities. Such oscillatory fluctuations in conditions at the contact patch may have a role in the development of rail corrugations.
The Measurement of Dynamic Cutting Force Data and its Application to the Prediction of Chatter
Authors: Burdekin M. , Kilic S. E. 
Published: February 2007

A method and the related equipment to obtain dynamic cutting force coefficients under simulated regenerative chatter conditions are described. The coefficients in both thrust (normal to the cut surface) and the main cutting (tangential) directions for orthogonal cutting are presented for various cutting conditions. An algorithm which is developed to predict chatter instability by combining the receptance of a machine tool with the dynamic cutting data is also presented. Comparison of experimentally-determined stability charts of a centre lathe with the predicted ones is made to evaluate the reliability of the method.
Cavitation in Vortex Diodes and Its Significance in Diode Pumps
Authors: Priestman G. H. , Tippetts J. R. 
Published: February 2007

Vortex diodes handling liquids are subject to the effects both of cavitation and Reynolds number. The apparent complexity of their characteristics makes design and simulation difficult. To some extent, however, this complexity is artificial and can be reduced. The effect of cavitation is most severe in the forward state. The usual characterization in terms of Thoma's cavitation number (based on pressure drop and downstream pressure) obscures a much simpler relationship using the upstream pressure explicitly. This yields simple equations which cover the cavitating regime. The non-cavitating characteristics are shown to be well predicted by established data on the operation of diffusers. Experimental data vindicating this is taken from Zobel, Syred et al, and our own experiments. Cavitation in the reverse state is not simplified but it is much less important for the diodes quoted. The practical implications of these results in diode pump applications are examined and quantified.
Construction of Power Stations Designed and Built as Single Units
Authors: Masding H 
Published: February 2007

This paper sets out an assessment of the value and practicality of the construction of fossil fired generating plant designed and built as single units and includes a proposal for the design and layout of a single unit designed to maximize the benefits derived from this concept. The conclusion is that an acceptable design of power plant, based on the construction of single 600 MW units, can be developed for the UK system which could prove to be advantageous in construction time, in capital cost and in running cost. The layout applies equally effectively to large ‘green field’ sites or for replanting existing stations; in addition, the plant can be replicated in detail and thereby reduce design and engineering costs. Finally the layout can also be applied in principle to smaller units for overseas utilities as required by their system developments.
The Performance Potential of Limited Cooled Diesel Engines
Authors: Watson N , Kyrtatos N P , Holmes K 
Published: February 2007

A mathematical model is used to predict the performance of a turbocharged diesel engine with a partially insulated combustion chamber. The model is briefly described, with emphasis on heat transfer aspects and prediction of combustion chamber surface temperatures. First the trade-off between performance improvement (efficiency) degree of insulation, combustion chamber surface temperature and exhaust gas energy is examined. It is shown that the high surface temperatures in the cylinder, due to insulation, cause volumetric efficiency to fall. However, this reduction is offset by increased boost pressure from the turbocharger due to greater exhaust gas energy. The contribution to overall reduction in heat loss from cylinder head, piston and liner and their effect on engine efficiency are presented and discussed. Various turbo-compound systems are examined and it is shown that most systems become unmatched when working over the wide speed and load range necessary for vehicle application, unless a variable geometry turbine or a variable ratio gearbox (this maintains compound power at part load) are used. Furthermore, substantial overall performance benefits can only be obtained with very efficient turbomachinery. Rankine bottoming cycles are more effective than fixed geometry turbo-compounding at low load, but their normal efficiency is limited by high condenser temperature, and they would be difficult to install in a compact European truck. It is concluded that the ultimate improvement in engine specific fuel consumption of an adiabatic turbo-compound engine is 20 per cent (excluding the savings from fan and water pump). However, drastically new design concepts are necessary, if engines are to be built that approach this degree of insulation. Meanwhile redesigned conventional engine types will offer substantial reduction in cooling system requirements with more modest thermal efficiency benefits.
The Design, Development and Manufacture of a New and Unique Tennis Racket
Authors: Haines R C , Curtis M E , Mullaney F M , Ramsden G 
Published: February 2007

This paper describes how a revolutionary new process was devised for producing top quality tennis rackets from carbon fibre reinforced thermoplastic by a specially developed injection moulding process. The product and process were evolved following an initial study by a multi-discipline team in January 1978 which led to a fully engineered manufacturing process starting production in November 1980. The new racket undercuts the price of competitors' carbon fibre composite rackets in a market sector of growing importance, and the ‘added value’ of the product is significantly higher than that for conventional wooden rackets currently manufactured by the Company. When other comparisons are made with wooden racket manufacture, the new product and process show advantages in nearly every aspect of production efficiency. The new racket and process which are protected by three patents, won a Design Council Award in 1981 and was the winner of the Willis Faber Manufacturing Effectiveness Award organized by the Institution of Mechanical Engineers in May 1982.
Wealth Generation—Our Essential Task
Authors: Small B W 
Published: February 2007

Wealth generation is the responsibility of those who design and make our engineered products. Others can do nothing more than create a sympathetic environment. Improving our manufacturing effectiveness, in its broadest business sense, is essential and an absolutely practical proposition. If most of our engineering businesses and factories were as good as our best our share of world trade would quickly improve. Five actions are suggested as the ingredients of a revival programme. We need to: (i) accept that too many of our factories are obsolete; many of them, if designed anew for today's purpose, would not remotely resemble existing operations; (ii) stop being tolerant of the 15–30 per cent excess cost in our products; (iii) become more commercially aggressive in applying new technology such as CAD/CAM and FMS; (iv) substantially improve our national skills and capacity to plan and implement more competitive operations; (v) encourage every engineering business unit, that does not have at least one major radical improvement programme under way, to start one now. While most revival programmes will require investment, the imperative ingredient is people, especially the creative engineer. Wealth generation is our essential task.
Development and Application of Continuous Dress Creep Feed Grinding
Authors: Parrott E 
Published: February 2007

In 1979 Bristol University concluded some work, on behalf of Rolls-Royce, on continuous dress creep feed grinding. This work had only been applied to flat faces at that point. In November 1979 it was decided to embark on a production implementation plan based on profile work and involving development work in line with production implementation. This paper describes the theory of continuous dress creep feed grinding, explores the development work required and the implementation procedure and experience gained in the production of turbine blades in Product Centre 02 at Rolls-Royce, Derby.