bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling Gas Turbine Combustor Flow Fields in Isothermal Flow Experiments
Authors: Bicen A F , McGuirk J J , Palma J M L M 
Published: February 2007

Future designs of gas turbine combustors will demand an increasingly detailed understanding of their internal flow structure. Acquisition of complete velocity field information in realistic combustor geometries under burning conditions is, however, extremely difficult, if not impossible, and recourse will always be made to the study of isothermal, constant density systems. Exact similarity between isothermal and combusting flows is clearly not possible. A question is therefore raised as to the most suitable way in which an isothermal experiment may be tailored to make it as closely as possible a simulation of the equivalent burning flow. This is the issue addressed in this paper. A can-type combustor geometry is studied; this includes a swirler-driven primary zone and two rows of radially inflowing jets. Two flow splits are considered to simulate the burning flow in a geometrically similar combustor with transply walls for cooling. The first split simulates swirler-total and primary-dilution flow ratios. The second split concentrates on swirler-primary and dilution-cross-flow ratios. Laser Doppler anemometry measurements and flow visualizations obtained in a plexiglass water model show that the first flow split results in atypical and totally unsuitable flow patterns for modelling the burning flow. The second flow split produces much improved flow patterns in both primary and dilution zones. Measurements of both axial and swirl velocity components are provided to demonstrate the acceptability of the resulting flow structure.
Design of a Load Cell for the Wagner Distractor
Authors: Verkerke G J , Koops H Schraffordt , Veth R P H , Nielsen H K L , van den Kroonenberg H H , Grootenboer H J , de Boer L J , van Krieken F M , Wagner H , Pock H G 
Published: February 2007

A leg length inequality can be treated by using a Wagner distractor. With this apparatus, it is possible to extend the upper or lower leg slowly. By analysing the measurements of the axial force acting on the femur or tibia the treatment can be optimized and soft tissue damage prevented. To measure the axial force, a load cell has been designed and constructed. This load cell is built into a Wagner distractor and connected with a specially designed measuring amplifier. The load cell and amplifier do not interfere with the lengthening procedure. They are safe for the patient and have an acceptable error of 7 per cent.
Improved Techniques for Measuring the Indentation and Thickness of Articular Cartilage
Authors: Swann A C , Seedhom B B 
Published: February 2007

A review of the techniques previously employed in the indentation and measurement of the thickness of articular cartilage has led to new and improved techniques for performing both measurements. By utilizing high-speed, microcomputer-controlled data logging techniques, simultaneous monitoring of signals from a dynamic load cell and a displacement transducer could be made throughout an indentation test. The position of the indenter as it touched the articular surface could thus be determined automatically by identifying the moment at which a positive change in the load signal occurred. Less accurate and more time consuming techniques previously required for determining the position of the cartilage surface were hence avoided. The apparatus also included a critically damped dashpot which prevented any transient loads being applied to the cartilage. Depths of indentation could be measured to an accuracy of 0.005 mm with a measurement repeatability of 2.14 per cent. By replacing the indenter with a sharp needle, the apparatus was also capable of measuring the undeformed thickness of cartilage. An accuracy of ±0.012 mm could be achieved with a measurement repeatability of 1.2 per cent. The apparatus is particularly suited to survey work where large numbers of indentation tests are to be performed.
Correlation of Breath Sounds with Diagnoses of Lung Dysfunction: Experimental Observations
Authors: Stoneman S A T , Parker R , Jones A 
Published: February 2007

An investigation has been undertaken to determine whether there is any correlation between the spectral analyses of breath sounds at the mouth and the diagnosis of lung dysfunction in a small number of patients. The results of the investigation have shown that it is possible to differentiate between the spectral characteristics of the breath sounds of people who are: normal; asthmatic adult, both before and after the administration of a bronchodilator drug; asthmatic adult, treated with an inhaled steroid, both before and after the administration of a bronchodilator drug; asthmatic child, both before and after the administration of a bronchodilator drug. The possible applications of the technique are discussed.
The Potential of the Stirling Cycle Heat Pump
Authors: Rix D H 
Published: February 2007

An important potential application of the electrically driven Stirling cycle heat pump is in the field of industrial waste heat recovery. Here the temperatures and temperature lifts required are often outside the scope of existing types of heat pump. What has to be ascertained is whether the Stirling cycle heat pump can achieve a sufficiently high coefficient of performance. In the paper this question is examined by the use of a theoretical model. The model is first checked against measured results from an actual Stirling heat pump which has been built and tested, but which was of low COP. It is shown that for a temperature lift of WOK, it should be possible to construct a heat pump with a COP of about 3.5. It is also shown that under these conditions, the maximum attainable specific output of heat would approach 1 J/cycle cm3 of piston displacement.
Non-Linear Three-Dimensional Finite Element Analysis of a Cementless Hip Endoprosthesis
Authors: Tensi H M , Gese H , Ascherl R 
Published: February 2007

In this finite element study the stresses between a stem component of a cementless hip endoprosthesis (Young modulus of Co—Cr—Mo) and the human femur were calculated for two different loading types. Linear and non-linear models were used to simulate the interface implant bone. Two models, a stem with a porous coated surface over the entire length and a stem with a porous coated surface in the proximal region were compared regarding the load transmission to the femur. An additional calculation of an ‘isoelastic’ stem (Young modulus of cortical bone) was done to show the influence of the stem stiffness. A porous coated surface over the entire length causes principal shear stresses up to 2.75 MPa in the distal-medial region during level walking. The highest compressive stresses were calculated in the proximal-lateral region as 1.5 MPa in cancellous bone. A more physiological load transmission is obtained by limiting the coated area to the proximal region. All stresses in the two models are lower than experimentally evaluated strengths in the interface between implant and bone. A strong infuence of the Young modulus of the stem material on the interface stresses was found. An ‘isoelastic’ stem causes compressive stresses in the proximal-lateral region whose values exceed the experimental strength of cancellous bone.
Simulation and Experimental Verification of Completely Closed Cavity Die Forging on a Mechanical Press
Authors: Ibhadode A O A , Dean T A 
Published: February 2007

A mathematical model for mechanical press forging is developed and applied to solid cylindrical shapes forged in a sprung completely closed cavity die. It is used to investigate the effects of various process variables on the forging process. Cold and hot forging tests, using commercially pure aluminium and AISI 1045 steel respectively, were carried out on a 2000 kN mechanical press. Experimental results compared well with those obtained from the theoretical model.
Trends in Military Aircraft Propulsion
Authors: Denning R M , Mitchell N A 
Published: February 2007

The major factors determining the choice of engine cycle for a combat aircraft are the requirements of the design mission and those of aircraft speed and agility. The requirement for jet-borne flight in short take-off vertical landing (STOVL) aircraft imposes further demands on cycle and configuration. The changing nature of combat aircraft requirements is the reason for changes in engine design. Specific thrust is shown to be the major parameter defining engine suitability for a particular role. An examination of mixed turbofan characteristics shows that specific thrust is also the key to understanding the relationships between engine characteristics. The future development of combat engines is discussed, in particular the implications of stoichiometric limits on cycle temperatures and the benefits of variable cycle engines are examined. Recent work on advanced STOVL (ASTOVL) aircraft is reviewed and aircraft/engine concepts designed to meet the requirements of the role are assessed. Experience shows that the technology for these advanced engines must be fully demonstrated before production to minimize the risks and costs of the development programme.
The Life-Long Education and Training of Mechanical Engineers
Authors: Crossland B 
Published: February 2007

Without doubt Great Britain led the world into the Industrial Revolution, and for a considerable period up till the second half of the nineteenth century it could rightly consider itself as ‘the workshop of the world’. The author traces up till recent times why it was that Great Britain lost that position, mainly because of its reliance on engineers learning on the job by picking things up for themselves and learning by rule-of-thumb and ignoring the need for a soundly based education and well planned training. Since the end of World War II various attempts have been made to rectify this position, but without much success, until the Finniston Committee Report. The organization of the Engineering Council, set up in 1982 on the recommendation of the Finniston Committee, is considered, and in particular its responsibility for the engineering profession and for changing the public's perception of industry and the engineering profession. The author expresses his opinion on the initial education and training of engineers. He comments on the need to reconsider whether mechanical engineering as presently taught is a viable subject, or if a course spanning mechanical and electronic engineering is needed. He sees the objective of engineering education as being a design for total life cost, and he explores how this may be achieved within a total technology concept. Finally, he considers how to achieve better university/industry collaboration which is at the heart of effective education and training of engineers. He describes the Technology Centre concept recently set up in the Queen's University of Belfast, which integrates the services and resources provided for local industry and those required by the engineering departments of the University as well as providing for continuing education and training. He sees this as the way ahead in achieving close collaboration with industry.
OP-PLAN: An Automated Operation Planning System for Turned Components
Authors: Hinduja S , Huang H 
Published: February 2007

OP-PLAN is one of the modules of TECHTURN (1) which is a technologically oriented system for turned components. Given the geometry of the component, OP-PLAN recognizes, in the first instance, features such as threads, grooves and recesses, and then subdivides the rest of the component into volumes. A novel method is presented which determines simultaneously the optimum subdivision of the stock into volumes and the most suitable operation. In arriving at the solution, cost calculations are performed based on optimum cutting conditions calculated with standard tools having indexable inserts. For other features, preassigned operations are used. The sequence of operations is based on commonly accepted rules used in turning and care is taken to ensure that the technological requirements can be guaranteed. OP-PLAN caters for all axisymmetrical features and therefore it should be able to deal with a fairly large percentage of turned components found in industry. Three examples are included and they highlight some of the features of the system.
A Computer Aided Manufacturing Procedure for Experimental Two-Dimensional Aerofoils
Authors: Al-Kayiem H H , Day A J , Bruun H H 
Published: February 2007

The manufacture of experimental aerofoil sections to a specific profile is generally an expensive and time consuming part of aeronautical research. This paper describes a computer aided manufacturing procedure that has been developed for the production, in a small research engineering workshop, of experimental wing models required for investigation of the separation of flow from an NACA 4412 aerofoil section. A 2 1/2 axis CNC vertical milling machine has been programmed with coordinates generated by computer from the NACA 4412 defined profile, to produce aerofoil sections which are then built up into a wing model. The method is fast and accurate, enabling the time and cost of manufacture to be substantially reduced, at the same time improving the accuracy and quality of the model. The procedure has been developed as a computer program and is also used as a case study teaching aid in computer aided manufacture.
The Production and Properties of Copper-Iron Particulate Composite Wire
Authors: Lawal G I , Barton D C , Bramley A N , Nutting J 
Published: February 2007

A novel means of producing copper-based powder metallurgy wire containing sufficient iron in particulate form to impart useful magnetic properties has been investigated. The method, which involves encapsulating a powder mixture within a copper tube prior to rolling and die-drawing operations, has been successfully used to produce composite wire of diameter range 1.8-0.4 mm. Particular attention has been paid to the effect of composition, processing strain, heat treatment and iron particle size on the electrical, mechanical and magnetic properties of the wire. Microscopy studies have also been carried out to determine structural changes in the material during processing. It was found that the good conductivity and ductility of solid copper wire was not greatly reduced provided (a) the iron content of the composite wire was kept fairly low (<6 per cent) and (b) the annealing temperature was not sufficiently high for significant alloying to take place (650°C maximum). Saturation magnetization values increased with increasing process strain, as did the magnetic hardness. The latter, however, could be minimized by fully annealing the iron after processing the wire. The magnetic properties were undoubtedly influenced by the size and shape of the iron particles, smaller particles being more easily elongated and tending to give greater magnetic hardness.
Carrington: Innovative Change Transforms a Traditional Manufacturing Site
Authors: Cowl B J , Graham G N , Thomas C Curtis , Thompson R K 
Published: February 2007

This paper describes how a petrochemical plant at Carrington, near Manchester, has reversed spiralling losses and rescued both its economic viability and its self-esteem. It charts the steps taken to transform a traditional, hierarchical structure into an open, multi-skilled approach to chemicals manufacture, and it seeks to demonstrate how fundamental changes in work practices and organization have impacted on the financial performance of a manufacturing site.
Crack Propagation in Mixed-Mode Ductile Fracture with Continuum Damage Mechanics
Authors: Chow C L , Wang J 
Published: February 2007

This paper presents a crack propagation model based on an anisotropic theory of continuum damage mechanics proposed earlier by the authors capable of characterizing sub-critical crack growth in mixed-mode ductile fracture. The embedded β angles of mixed-mode specimens include 75, 60, 45 and 30 degrees. The crack growth criteria chosen are essentially those developed for crack initiation and are postulated as: 1. A crack propagates in the direction of maximum effective damage equivalent stress αd. 2. The threshold condition of crack initiation is satisfied when the overall damage w in an element ahead of the crack tip at the prospective crack growth direction reaches its critical value, wc. The crack growth behaviours of the mixed-mode specimens are analysed using a finite element formulation of the non-proportional loading based on the anisotropic model, and the predicted and measured results are found to be satisfactory. The proposed model is also adapted to predict the critical loads of unstable crack propagation and the results are compared favourably with those determined experimentally. Hence the application of the above two fracture criteria can be made to address the entire history of crack development from initiation to rapid growth.
Effect of Elevated Temperatures on Characterization of Rubber Fracture
Authors: Chow C L , Sze K Y 
Published: February 2007

The recent emphasis on improving tyre structure integrity against premature failures has led to an increased effort to study fracture behaviour of different carbon black reinforced tyre compounds. Due to the general hysteretic nature of tyre materials, the overall working temperature of a tyre is elevated under service conditions. Relative merits in the characterization of crack initiation in a typical tyre compound using the conventional quasi-static energy and J-integral approaches were first examined. The quasi-static energy method has been applied to evaluate the fracture toughness of materials exhibiting either linear or non-linear elastic behaviour within the confines of the linear elastic energetic approach. Based on the ease of analysis and ability to make multiple measurements on a single specimen, the quasi-static energy approach is chosen to measure the fracture toughness of the tyre material at temperatures of 23, 37, 52, 62 and 73°C. The fracture toughness measured for the tyre material has been observed to be inversely proportional to the temperature elevation. The observation agrees with earlier investigations that the crack growth rate of rubbers under fatigue loading decreased with an increase in temperature in the test materials.
An Investigation of the Liquid Petrol Wall Film in the Manifold of a Carburetted Spark Ignition Engine: Effect of Carburettor and Manifold Geometry on Wall Film Quantities, Engine Performance and Emissions
Authors: Hasson D A , Flint W L 
Published: February 2007

The rate of deposition on the manifold wall of liquid droplets from the multi-component, two-phase stream of fluid flowing in the inlet manifold of a carburetted petrol engine and the re-entrainment of droplets into the stream from the liquid film which flows on the walls have been investigated using a single cylinder crossflow engine. The effect of throttle opening, straight manifold length, a smooth bend and a mitre bend is reported: measurements of exhaust emissions and cycle-to-cycle pressure variation of cylinder pressure are related to wall film quantities. It was found that throttle position was important in determining the initial wall film, that the average thickness of the film decreases with length along the straight manifold and that droplet re-entrainment from a sharp bend is greater than from a smooth bend. Removal of the wall film yields a significant reduction in the emission of unburned hydrocarbons and virtually eliminates cycle-to-cycle variations of pressure in the engine cylinder.
The Use of Viscous Couplings to Alleviate Transmission Wind-Up in Military Vehicles When Driven On-Road
Authors: Hall L C , Moss P J 
Published: February 2007

Many of the high-mobility wheeled vehicles used by the British Army employ permanent all-wheel drive transmission systems with just one transverse differential. Since all the wheels on each side of the vehicle rotate at the same angular velocity severe transmission wind-up can be developed on roads. The possibility of using viscous couplings to alleviate this problem has been investigated by computer simulation backed up by practical trials on a 4 × 4 armoured reconnaissance vehicle. The results suggest that with a suitable choice of coupling characteristic this solution can dramatically reduce the wind-up torque during low-speed manoeuvres with no significant effect on off-road mobility or handling on roads. It can reduce the wind-up caused by non-uniform tyre wear but not to the extent anticipated. To safeguard handling stability under heavy braking there may be a need to bias the brake effort distribution to the front.
A Study of the Correlation between In-Cylinder Air Motion and Combustion in Gasoline Engines
Authors: Kyriakides S C , Glover A R 
Published: February 2007

This paper describes an investigation into the effects of in-cylinder air motion at the spark plugs on gasoline engine performance. Measurements of combustion angles have been made in a single-cylinder four-stroke disc combustion chamber engine at part load and MBT ignition timing. Seventeen in-cylinder air motion regimes have been produced using masked valves. The air motion in each build has been evaluated by making laser Doppler anemometry (LDA) measurements of mean velocity and turbulence intensity at the spark plug position under motored conditions. It has been shown that there is a strong correlation between turbulence intensity and 10–90 per cent burn angle. It is demonstrated that for this combustion chamber geometry a tumbling air motion is a more effective means of generating turbulence at TDC than swirl.
A Review of the Role of Vehicles in Agriculture
Authors: Dwyer M J 
Published: February 2007

Agricultural tractors have been developed over the years to carry out almost every operation on the farm. However, they are not ideally suited to all these tasks and it may be more economical, in certain situations, to use more specialized vehicles. In the extreme, one could perhaps imagine four different types of agricultural vehicles, for heavy draught work, transport, low ground pressure applications and materials handling. Computer models are being developed to evaluate the potential economic benefits that might be achieved by the introduction of such specialized vehicles on particular farms. Models already exist for predicting tractive performance and average speed over different types of terrain. Further models are needed for manoeuvrability and some other aspects of performance. Mechanization of farming throughout the world has been based on the agricultural tractor. Introduced originally as a replacement for draught animals, it has now been adapted to carry out almost every job on the farm. Nevertheless, it is still the requirement to pull ploughs and other cultivation implements that mainly determines its design specification. This has led to the development of a slow, heavy, unsprung vehicle with large diameter, low inflation pressure driving wheel tyres. This design, with two driving wheels at the rear for the lower power ranges and all four wheels driven for higher powers, is reasonably well suited to carrying out heavy draught operations in the field while maintaining sufficient mobility to be useful for other jobs. The range of other jobs for which the agricultural tractor has been adapted has increased steadily over the years so that it would not be difficult to list perhaps forty or fifty. As far as their effect on the vehicle design specification is concerned, however, they can be grouped into relatively few classifications. Apart from cultivations, they comprise operations where transport of large quantities of materials is an important component—operations such as harvesting, spraying and fertilizer distribution, where neither tractive effort nor transport of materials is a major part, and materials handling. Obviously these are not strictly defined categories and many tasks will contain some elements of two or more of these classifications. However, they are useful in considering the design specifications for agricultural vehicles.