bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting Changes in Operating Variables for Hydrostatic Thrust Pads Subjected to Tilt and Dynamic Action
Authors: Newton M. J. , Howarth R. B. 
Published: October 2007

Hydrostatic thrust bearings are frequently designed for static operation with parallel surfaces although, in practice, they are required to operate under dynamic conditions and probably in a tilted state. Introducing tilt and dynamic action may result in the operating variables being quite different from those predicted for parallel static conditions. Theoretical analyses of hydrostatic thrust bearings usually present the performance characteristics in a non-dimensional form. These describe the quasi-static operating conditions, but they do not give a direct indication of changes in individual operating variables because the parameters are interrelated. This paper utilizes the non-dimensional parameters in a small perturbation analysis that allows the changes in individual operating variables to be evaluated directly. The analysis gives results that are in reasonable agreement with those observed during experimental tests, both for small and large variations in operating parameters.
Experiments on the Accuracy of Holders Used in Gas Meter Calibration—Effects of Evaporation
Authors: Smith A. J. Ward , Martini J. D. 
Published: October 2007

Tests have been conducted on a 0·057 m3 (2 ft3) holder taken out of normal service and specially instrumented. The effects of water sealant temperature changes and evaporation on the volumetric readings of the holder have been measured. From these results, the mass transfer coefficient k, which is a measure of the rate of evaporation, has been evaluated. It is concluded that well-maintained holders, whether used for pressure or vacuum testing, give rise to insignificant errors in volume measurement under normal test conditions, such as those specified in B.S. 4161, in a room with reasonable temperature control. Only when a holder is used to measure low flow rates do evaporative effects give rise to substantial errors.
Die Variator Mandrel Forces Encountered in Blow Moulding Parison Control Systems—Computer-Aided Design
Authors: Parnaby J. , Worth R. A. 
Published: October 2007

In designing control systems for parison shape in the blow moulding process it is necessary to take into account the forces that act upon the movable mandrel inside the convergent annular die. These forces can be considered as consisting of two parts; firstly, a steady-state force acting along the axis of the mandrel whilst it is stationary and, secondly, an axial force Pertubation that arises as a consequence of controlled movements of the mandrel during the parison shape control process. The present paper deals only with steady-state axial forces and its aim is to assist the design engineer by showing him how to calculate mandrel forces and die pressure drops, using a digital computer, for dies having a form composed of a series of tapered and parallel annular flow passages. By careful design, under certain circumstances, an almost force-free arrangement can be obtained, so minimizing the power and strength requirements of the mandrel drive control system. The theoretical analyses used assume that the polymer being processed is described by a power-law equation relating shear stress and shear rate. This is typical of polymers such as high-density and low-density polyethylene.
The Rolls-Royce Rb 211 Turbofan Engine
Authors: Eltis E. M. , Wilde G. L. 
Published: October 2007

The lecture gives a technical account of the Rolls-Royce RB 211 42 000 lb thrust turbofan engine now powering the Lockheed TriStar passenger transport. This engine was the result of extensive preliminary design studies begun in 1960 to evolve a turbofan successor to the Conway bypass engine. The aim was to provide Rolls-Royce with a propulsion system that would give the United Kingdom the opportunity to share in the most important section of the air-transport market during the last quarter of this century. Low fuel consumption, low noise and low maintenance costs were the principal objectives. These studies led to the RB 211 three-shaft design which was specified for the Lockheed L1011 ordered in 1968 by a number of the larger U.S. airlines. An idea of the large scale of the RB 211 project is given and some of the development problems and lessons are discussed. There is a brief outline of the supporting component, rig and high-temperature turbine development and a summary of the engine's performance is given which includes thrust, specific fuel consumption and noise, all of which have met or beaten the design targets. A developed version of the RB 211, now being tested at over 50 000 lb thrust, is described, as well as the potential for further improvements in fuel consumption and for expected additional aircraft and industrial applications.
Influence of Spring-Back on the Characteristics of the Spiral Spring
Authors: Swift W. A. C. 
Published: October 2007

In this paper, the method of manufacturing the spiral spring is examined to develop a theory for this type of spring giving a closer agreement with practical tests than does the conventional theory. The theory makes use of Gardiner's (1***)† equation for spring-back to develop the equation of the free spiral of the spring and then considers that, in operation, the process of winding up or running down can be considered as the difference between winding up from the free spiral to the run-down state and winding up from the free spiral to the wound-up state. In the conventional theory for this type of spring, the active length is considered to be constant and equal to the strip length and the moment versus the rotation of the arbor plot (torque characteristic) is apparently always linear. In the theory presented below, the variation in active length is taken into account and non-linearities in the torque characteristic become evident. The theory assumes that the forming of the spring takes place under the action of pure bending without anticlastic curvature and the strip is assumed to behave as an ideal elastic-perfectly plastic material.
Synthesis of Complex Cam Mechanisms
Authors: Fawcett G. F. , Fawcett J. N. 
Published: October 2007

General equations are developed describing the kinematic behaviour of two rigid bodies in contact. The case of planar motion is then considered in more detail and the equations are developed in a form which is useful in synthesizing cam mechanisms. Examples of the application of the general equations to synthesizing the profiles of rolling contact cams and of cam profiles for use with flat and circular followers are given. Use of the general equations in cases where the follower has a complex profile is also described.
Experience Relating to the Steady Performance of Aerostatic Porous Thrust Bearings
Authors: Taylor R. , Lewis G. K. 
Published: October 2007

Good agreement between calculated and actual performance of aerostatic porous thrust bearings is possible provided account is taken of several practical influences. Those considered are elastic deflection of the porous pad, sheer distortion of the pad bond, surface finish of the pad and nature of the gas flow through it. The effect of surface finish on effective film thickness is accounted for by a new method based on a knowledge of film-pressure distribution. A criterion for viscous-dominated flow through the pad has been formulated and accurate values of both viscous and inertia permeabilities for the pad are readily derived from a simple flow test.
Aspects of Pole Vaulting Mechanics
Authors: Johnson W. , Al-Hassani S. T. S. , Lloyd R. B. 
Published: October 2007

The general and historical background to pole vaulting is discussed and the energy lost at impact is assessed. A description of the different actions of rigid and flexible pole vaulters is given and measurements of the flexural rigidity of typical aluminium and fibre glass vaulting poles are reported. The path of the hand hold and the hip of a vaulter have been followed and plotted using a camera and compared with previous conjectures. An estimate of the compressive force in the pole is made. A discussion of the factors which make for the height cleared by a vaulter is given.
Pneumatic Transportation of Coal and Ash in Industrial Boiler Plant-Experience with a Prototype Programme-Controlled System
Authors: Hunter J. 
Published: October 2007

The system has been fitted to two 905 kg/h steam boilers at a mine in Fife and has run for approximately two years. It consists of a pneumatic system for conveying coal, automatically, from the coal store to the main boiler hopper and an integral system for conveying ash away from the boilers, all to a programmed cycle of operations. The paper describes the plant in detail, experience in operation and reports on the results of tests on fuel degradation, pressure loss and air-flow measurements, performance of the coal- and ash-handling sections, plant wear and electrical running costs, in addition to other data. It concludes that continuing the development of coal-fired plant along the lines laid down in the paper could lead to packaged, shell and large sized industrial water-tube plant, which are low in capital and running costs and are automated in line with modern oil- and gas-fired plant.
Stresses in a Medium Speed Diesel Engine Frame
Authors: Fessler H. , Perla M. 
Published: October 2007

SYNOPSIS The bedplate, column, cylinder casings, bearing caps and crankshaft of a model of one bay of a Vee type medium speed Diesel engine have been made in epoxy resin and joined by compression springs simulating the appropriate bolt forces and stiffnesses. The model has been loaded by freely hanging weights simulating firing and reciprocating inertia forces and subjected to frozen stress loading. Stresses obtained from numerous slices cut from these components are analysed and related to the designer's qualitative understanding of the load paths.
Effect of Unbalance on a Journal Bearing Undergoing Oil Whirl
Authors: Barrett L. E. , Akers A. , Gunter E. J. 
Published: October 2007

SYNOPSIS A time-transient nonlinear analysis has been developed to examine the dynamical limit cycle motion of a plain journal bearing. The effect of unbalance and ambient pressure on the journal limit cycle motion below and above the linearized stability threshold speed is examined. The short bearing approximation is used, and the assumption of a 180° oil film has been relaxed. An arbitrary film extent based upon the instantaneous values of journal displacement, velocity, and ambient pressure is used. It has been found possible to optimize the unbalance to minimize the amplitude and the force transmitted for limit cycle operation above the stability threshold speed. Below this optimum value the whirl is fractional frequency and above this value it is synchronous. It has been found that when the journal is operating above the stability threshold speed, rotor unbalance may result in a smaller limit cycle than the balanced rotor. The effect of a non-zero ambient pressure at the optimum value of unbalance is to increase the size of the limit cycle and make the motion nonsynchronous.
A Study of Nucleating and Wet Steam Flows in Turbines
Authors: Bakhtar F. , Young J. B. , Ghoneim Z. 
Published: October 2007

SYNOPSIS This paper describes a study in which nucleation theory has been applied to the flow in turbines. The treatment is one dimensional and use is made of friction coefficients to allow for the aerodynamic losses. The experimental results quoted have been obtained independently from tests on a model turbine. The results of a dry run have been used to obtain friction coefficients which have then been adopted in the prediction of the wet test. The theoretical results are extracts from the computer prints out, the comparisons are with the turbine wet efficiency and the agreement obtained is remarkably good.
The Analysis and Design of a Fire Engine Safety Cab Using Finite Element Methods
Authors: Miles J. C. , Wardill G. A. 
Published: October 2007

A three dimensional structural collapse analysis computer program is described, and illustrated by reference to a safety vehicle structure analysed and designed using the program. The particular problems of large displacements and material non-linearity are accounted for, and a method of estimating the permanent set which results after impact is described. Based on an incremental formulation of the conventional finite-element method, the computer program is capable of tracing the complete load deflection characteristics of a structure up to and beyond the point of collapse.
An Engineer's Approach to Company Appraisal
Authors: Parker E. J. 
Published: October 2007

In the past the engineer's role in company appraisal has been restricted to that of a technical adviser but with need to become conversant with the disciplines which impinge on his work he has now acquired such a depth of knowledge and experience as to justify his acceptance in the leading role. This paper is intended to provide a guide for those engineers who are called upon to assume the principal role in company appraisal. It emphasises the need for clear terms of reference, the importance of planning and briefly describes the main headings against which the appraisal is conducted.
The Stress Analysis of Crankshafts
Authors: Hildrew B. 
Published: October 2007

The paper reviews the fatigue problems of the main shafting in ships and in particular those associated with the crankshaft of a diesel installation. A description is given of an investigation on the bending moments and torques in multi-throw crankshafts. Details are given of bending and torsion tests on single throw cranks leading to the determination of correction factors for crank radius and crankpin length. A multi-throw shaft was then installed in a purpose-built rig and bending moments and torques were measured on crankpins and journals when loads were applied to the crankpins. A computer programme was developed which utilized the three factors determined from the single throw work to calculate these same bending moments and torques. Satisfactory comparative tests were carried out and the results from one typical series of tests are detailed.
Concrete, an Alternative Material
Authors: Pomeroy C. D. 
Published: October 2007

If ordinary Portland cement had been an expensive product it would still have been widely used, but much more highly respected. While its dominant use is as a structural material in civil engineering there are many other applications that can be made in which cement-based materials are economically and technically sound. Cement is also a material that can be made from raw materials that are universally abundant and when diluted by the addition of an aggregate the concrete is a low energy product, an extremely important factor in the current energy conscious society. Some of the ways in which the properties of concretes can be controlled and modified are discussed and the properties are compared with those of competitive materials. Examples will be given of the ways that these properties can be exploited in the manufacture of articles or components that have traditionally been made in other materials. In particular the use of concrete to replace cast-iron and steel structural components in the machine tool industry is discussed.
Sampling Gasborne Solids: Some Factors Affecting the Characteristics of Miniature Cyclones
Authors: Littlejohn R. F. , Smith R. 
Published: October 2007

Investigation of a technique for measuring the solids burden of gases described in BS 3405 has shown that 30% oversampling is possible. In tests using BS pitot-static tubes (1) and BCURA cyclones (2) under conditions typical of plant practice the presence of solids in the gas stream had negligible effect on the pitot reading but increased the flow through the cyclone corresponding to any given pressure drop across it. The increase varied with solids concentration, particle size and the material used. The mechanisms of the effect was not investigated but the observations suggest that it is caused by a small quantity of solids remaining airborne within the cyclone.
Lumped Parameter Model of Planetary Gear Systems
Authors: Polder J. W. 
Published: October 2007

A model system is described by parameters for shafts, planetary gear trains and nodes. Moments of inertia, spring stiffnesses and damping coefficients are assigned to the shafts; gear ratios and efficiencies are assigned to planetary gear trains. The equivalence of angular velocities and torques is demonstrated for shafts (vibration model), as well as for planetary gear trains and nodes (configuration of the system). This brings about a new view on the concept of degrees of freedom. The close relationship between gear ratios and torque ratios yields identical functions for these ratios when applied to the input and output shafts of a system. The full use of this relationship requires strict conventions of signs and an extension of the interpretation of values. The introduction of a new concept, named responsivity, expresses the relationships between torques and between powers of arbitrary shafts. With suitable equations, it becomes possible to investigate torque and power distributions exhaustively.
The Management of Information Flow in a High Technology Development Environment
Authors: Pearson D. S. 
Published: October 2007

Effective management of a gas turbine development programme under commercial airline pressures demands very careful balancing of two separate cycling commodities. One is experimental engines and component parts or ‘hardware’. The other is data, information and conclusions, hereafter referred to collectively as ‘decisionware’. While techniques for hardware management are well documented, equivalent techniques for planning, monitoring and motivating decisionware activities are less developed. This paper describes experimental methods which have been evolved, and applied to some development activities within the Derby Engine Group of Rolls-Royce Limited. These methods include simulation modelling and performance monitoring of a staff organization and aim to achieve higher combined effectiveness of the two meshing cycles described. The work occupied a period of one man year and has applications in development associated departments outside the original field of study.
Reliability Reviewed
Authors: Carter A. D. S. 
Published: October 2007

Using a conventional mathematical model it has been shown that a component can be designed so that it is ‘intrinsically reliable’ i.e. the failure rate will be zero for all practical purposes so long as the strength of the item remains constant. Failure can then only take place by wear-out as the strength deteriorates. Reference to field data shows that most, though by no means all, existing mechanical components conform to this pattern but fewer electronic items do. The behaviour of items which are not intrinsically reliable is shown to be substantially indeterminate and hence not amenable to assessment. It is claimed that the concept of intrinsic reliability leads to a more rational and quantifiable approach to the best existing practice. For example, the minimum safety margin for intrinsic reliability can be calculated in terms of loading roughness. No empirical subjective factors are necessary in the design process. Leading from the concept, recommendations are made for a more logical specification of reliability and more positive methods of interpreting prototype trials. Given an intrinsically reliable design, achieving reliability in the field depends on avoiding wear-out, i.e. on the maintenance activity. Consequently the roles of the designer and maintainer can to some extent be separated, allowing a more definite allocation of responsibilities.
Some Observations on the Analysis of High Temperature Steam Piping Systems
Authors: Carmichael G. D. T. , Edwards G. 
Published: October 2007

The effects on system stresses and terminal moments of some factors not normally considered in high temperature steam piping design have been assessed by analysing notional but representative pipe lines. The factors considered include bend flexibility, anchor stiffness, rotational restraint achieved during cold pulling, and extraneous loads introduced by hanger hysteresis. In addition, the influence of hanger lateral stiffness is quantified by evaluating the implications for thermal expansion stress/displacement ranges and cold pull design. Procedures are developed enabling cold pull distances to be calculated which either induce predetermined moments into the system or minimize the difference between moments at specified locations and a required set of values. It is established that certain of the factors considered can have an appreciable effect on terminal moments and system stresses. Consequently it is essential to include them in design analyses.
The Day after Tomorrow
Authors: Parker Peter 
Published: October 2007

“That man only is wise who does not dogmatise and who proclaims nothing is impossible.‘ The World in 2030 AD The Earl of Birkenhead 6 SUMMARY AND CONCLUSIONS I have tried to indicate that the way forward into the day after tomorrow, although paved with good intentions, could end up at a hell of a mess, unless we accept that change at all levels is essential to both national and industrial survival. Foremost, and I make no apology for giving it preeminence, I have argued that there is a new social dimension emerging which surrounds the technical and market led development process. Secondly, I have argued that despite these social changes the railway industry, like any other enterprise, has aims whose nature is enduring. These aims are about survival through service to the customer. I have defined what I believe is the nature of railway requirements from our R and D effort in meeting the enduring aims of the business; toughness and resilience, reliability, simplicity and economy. Fourthly, I have given some indication of the contribution made by R and D to the operation of the railway, bringing economic benefits to the industry and the community. I have illustrated that in looking at future R and D benefits, we are alive to the strategic issues ahead; organizing ourselves to deal with them, and including one of our most important areas of responsibility, our workforce, in our plans. Finally I have outlined the urgent need for transport as an industry to be seen as an essential ingredient of the wealth-creating process. Taken together, these points, I believe, are the framework for giving all of us involved in the railway industry clear direction on the way we need to commit our R and D resources to take us into the day after tomorrow. There will certainly be surprises, and a mark of good management is the masterful administration of the unforeseen. Our strategy for R and D will be to anticipate the unforeseen, to measure it and shape it so that the industry will be alive and well in the twenty-first century.
Development of a Visco-Plastic Lubricant Model for the Synthesis of High Pressure Rolling Contact Tractions
Authors: Lingard S. 
Published: October 2007

Experimental rolling contact traction data for the nominal point contacts of a steplessly variable ratio drive are presented. Operation is in the elastohydrodynamic lubrication regime with peak contact pressures of 1.5 to 3.0 GPa. Good agreement with the measurements is demonstrated by a visco-plastic lubricant model, and contrary to the conclusions of other recent work it is shown that the effects of elastic compliance of the fluid and rolling elements are small. The ability of the theory to account for the influence of the main operating variables, and its simplicity, should facilitate the solution of certain transmission design problems.