bluuebunny/crossref_metadata_2025_split huggingface dataset:
Digital Computer Programmes for Steam Cycle Analysis
Authors:   Steam Plant Group, Turton P. J. 
Published: October 2007

Much of the published data on steam cycles cannot be applied to modern power stations owing to the advanced steam conditions and complex cycles now used. Plant optimization therefore requires the detailed analysis of a large number of cycles over a wide range of steam conditions Modern high-speed digital computers offer the engineer relief from the tedium of lengthy calculations and the uncertainty of broad simplifying assumptions. The Ferranti ‘Mercury’ computer is used in the present work and, for economy in computing time, separate boiler and turbine programmes are written and the results combined through a short desk calculation The turbine programme, which is applicable to both conventional and nuclear stations, is sufficiently general to deal with all anticipated steam conditions and cycle arrangements and it also takes account of minor cycle corrections. Possible variations in boiler design, however, make a similarly general treatment more difficult and several separate programmes are described here, each dealing with a steam cycle and boiler design suitable for use with the low-temperature gas-cooled reactors being built in Britain at present Application of the programmes to the design optimization of a complete nuclear power station is discussed
Interferometry Applied to the Study of Elastic Flexure
Authors:   Applied Mechanics Group, Duncan J. P. 
Published: October 2007

This paper describes briefly techniques for the rapid preparation of optically flat metal plates to an accuracy of approximately two interference bands over an 8-in. span. The construction and use of two large Fizeau interferometers for observing defections resulting from flexure is described The technique was developed 'as an experimental means of circumventing the very great theoretical complexity of analysing various forms of flexed multiply-connected plate occurring in engineering construction. It is illustrated qualitatively from studies of perforated circular plates subjected to lateral loading, of annular and triangular plates subjected to concentrated loads and of perforated bars subjected to pure bending Quantitative studies based on the method are to be described in subsequent papers
Gridwork Rigidity Determined by Interferometry
Authors:   Applied Mechanics Group, Duncan J. P. , Michejda O. 
Published: October 2007

An experimental method based on optical interferometry is applied to find the deflected shape of gridworks subjected to lateral loads These experimental results are compared with results obtained by moment distribution calculations and by the use of the equivalent elastic constants of Horvay and Malkin The technique itself, which has been developed by one of the authors as a general experimental method of studying the flexure of thin elastic plates, has been described in the accompanying paper
Hot-Starting Trials on Reheat Generating Units at Ferrybridge ‘B’ and Northfleet Power Stations
Authors:   Steam Plant Group, Austin P. E. , Beck J. S. , Dixon P. , Evans H. M. , Kalderon D. , Mathews H. L. , Parish A. H. , Payton E. J. , Weatherson J. 
Published: October 2007

The paper summarizes the results of a number of starting tests, after unit shutdowns of 6 and 36 hours respectively, conducted collaboratively by the manufacturers of the principal generating plant and the C.E.G.B. on a 100-MW reheat unit, in October-November 1959, and on a 120-MW reheat unit in June-July 1961. The units were extensively instrumented for the tests and many steam and metal temperature measurements on the boiler, pipework and turbine were taken at regular short intervals to determine the thermal condition of the unit during the shutdown and starting operation. The tests were conducted on the basis of carefully planned and agreed operational procedures, within the framework of the working limits recommended by the manufacturers of the principal generating plant. It was demonstrated that the units could be satisfactorily and quickly started up to full load with a drainage loss of about 22 000 lb, after a 6-h shutdown, and with a drainage loss of approximately 20 000 lb, and 52 000 lb, after a 36-h shutdown, for the 120-MW and 100-MW unit respectively, without exceeding the recommended limits. It was possible to operate the 100-MW unit at full load in 64 min, and 120-MW unit in 51 min from lighting the boiler, after a 6-h shutdown. The minimum turbo-generator loading times were 25 and 11 1/2 min respectively. After a 36-h shutdown the 100-MW unit was brought up to full load in about 200 min and the 120-MW unit brought up to full load in about 170 min from lighting the boiler. The corresponding loading times were 110 and 55 1/2 min respectively. Information obtained from the tests has been used in designing new plant. The paper includes descriptions of the plant installed, instrumentation used, and the development of the tests. The recommended procedures for two-shift operation of these units are also given, based on the results obtained.
Steam-Water Critical Flow through Pipes
Authors:   Thermodynamics and Fluid Mechanics Group, James Russell 
Published: October 2007

Steam and steam-water flashing flow were used to obtain critical† discharge pressures for pipes over the stagnation enthalpy range 230 to 1200 Btu/lb and for the critical pressure range 14 to 64 lb/in2 abs. Pipe sizes used were 3, 6 and 8 in. in diameter. The following empirical equation covers the data with an accuracy of ±3 per cent: where G is mass-velocity, lb/sec.ft2, h is specific stagnation enthalpy, Btu/lb, and P is the critical discharge pressure, lb/in2 abs. It is also shown that the amount of energy flowing along a pipe can be obtained accurately to within ±10 per cent if the critical pressure only is known; that is, the stagnation enthalpy is not known.
Heat Exchange in Profound Hypothermia: Heat Exchanger Design for Blood during External Circulation
Authors:   Thermodynamics and Fluid Mechanics Group, Shore D. T. 
Published: October 2007

Profound hypothermia involves the cooling of a patient from 37°C to 13-15°C, using the patient's own blood as a secondary heat transfer medium. The problem presented is one of heat transfer in viscous flow, demanding apparatus of absolute reliability and ensuring thermal and hydrodynamic conditions which would in no way damage blood cells. Apparatus must be easily sterilized and all blood contact surfaces readily examined. The paper presents a solution using an annular heat exchanger design capable of cooling a patient weighing 10 stone in a period of 30 minutes, the same heat exchanger being suitable for body weights of between 8 and 186 lb. The heat transfer theory presented compares published work in this field, in particular the Graetz result for viscous flow. In the paper it is suggested that measurement of local heat transfer coefficients under similar conditions of both heat flux and velocity gradients gives a better approximation for design than lengthy arithmetic analysis of theoretical equations. Blood is a complex non-Newtonian fluid and consideration is given to viscosity variations with both temperature and rate of shear. Finally, there is a description of automatic controls installed with the heat exchanger unit now operating at the Westminster Hospital.
A Thermocouple for the Measurement of Gas Temperatures up to 2000°C
Authors:   Thermodynamics and Fluid Mechanics Group, Bertodo R. J. 
Published: October 2007

The present paper reviews the principal aspects of some work carried out between 1958 and 1961 to obtain a thermocouple capable of operating in the range of 1200-2000°C in the combustion chamber and reheat tailpipes of advanced turbojet aero-engines with an inherent accuracy of about ± 1 per cent. The work of previous experimenters is reviewed and a consideration of existing thermocouple combinations indicates that oxidation-resistant refractories might be well suited to the applications envisaged. A number of refractories and high-temperature metals and alloys were selected for evaluation on an oxidation-resistance basis, and their thermoelectric output against EY4 graphite (Morgan Crucible nomenclature) is presented. Thermocouple pairs were selected on the basis of the above tests and complete assemblies were evaluated in the laboratory and on test-bed engines, a total of over 1000 hours being accumulated for the final design. Such factors as repeatability, stability and response time are presented. It is concluded that in order to obtain adequate response times only refractories having a high thermal conductivity are suitable. Greater immersions are therefore required in order to avoid excessive cooling of the hot junction by conduction. This in turn requires greater strength in the thermocouple in view of increased stresses due to gas loading. As a result a refractory thermocouple will be dimensionally larger than conventional thermocouples, but the thermoelectric output will be one magnitude greater. By stringent control during sintering or hot moulding and subsequent selection, adequate accuracy may be maintained and repeatability achieved. Some limitations exist as regards shape and size in view of the difficulty in obtaining sintered or hot-moulded bodies of high length/diameter ratio. In view of the fact that the thermocouple impedance could be less than 10 Ω in conjunction with thermoelectric outputs of 200 mV or more, the possibilities of power generation are considered.
The Thirty-Fifth Thomas Lowe Gray Lecture: Design and Construction of Large Tankers in Japan
Authors: Yoshiki Masao 
Published: October 2007

This lecture first presents an outline of research work by which many troublesome problems in the design and construction of large tankers were solved, and secondly introduces the largest tanker ever built in Japan, the Nissho Maru, of 130 000 deadweight tonnage. With regard to design of such tankers, two points, that is, (1) reduction in length of ship ( L), and (2) increase in depth ( D), should be taken into account from the standpoint of weight saving and of easy fabrication. Researches into structural problems of tank parts and into the dynamic pressure of cargo oil tank, due to ship motions, are described briefly, and show that the maximum impulsive pressure in model tests may be up to 5 times the static fluid pressure and may be observed at the tank top when the natural period of fluid in the tank is resonant with the oscillation period of the ship. Special care should be taken in the detailed design of longitudinals, struts and so on, otherwise cracks will initiate easily at the point of stress concentration. As regards hull construction practices in such large tankers, there seem to be no special problems except in the fabrication and welding of very thick plate of up to 50 mm thickness. Very thick plates thus offer several problems to be solved such as groove shapes, application of ‘Unionmelt’, doubling plate, weld cracking, and back-wave welding technique, etc. Brief discussion and some test results on these problems are included and mention is made of the superiority of KZ-type groove for automatic single-pass submerged-arc welding and of ‘Uranami’ welding electrode (which offers a perfect one-side welding without backing plate). Finally, construction methods for large tankers are briefly introduced to give an idea of the hull construction of such large tankers in the building berth.
Second Paper: Deep Drawing and Free Forming Using a Water Hammer Technique
Authors: Vafiadakis A. P. , Johnson W. , Donaldson I. S. 
Published: October 2007

Earlier work on a water-hammer technique for high-rate forming of sheet metal has been extended to include work on deep drawing using lead plugs. A study of the pressure-time history of a deforming blank during its initial movement is reported. An assessment of the overall efficiency of the process has been made and is found to be about 50 per cent; this is an order of magnitude better than that found with comparable electro-hydraulic and explosive methods.
Experience in the Use of a Digital Computer for Predicting Steam-Turbine Performance
Authors: McCrae R. U. , Montague A. , Douglass M. 
Published: October 2007

This paper describes a number of programmes for digital computers that have been developed by the authors' firm to eliminate many of the tedious hand calculations which are encountered in the preliminary stages of steam-turbine and condenser design. By their use a considerable amount of the designers' time is saved and fatigue is reduced. These programmes also eliminate mistakes and inaccuracies which may occur in long calculations made by hand. The programmes described have been chosen as being representative of the range of programmes used in preliminary turbine design and optimization and are as follows: a programme to enable steam properties to be calculated, based on the formulae given in the Keenan and Keyes Steam Tables; a programme which can be used to determine the efficiency of small industrial turbines; a feed-heating programme which will carry out the calculations necessary to determine the preliminary energy balance for a feed-heating cycle; a detailed energy-balance programme incorporating turbine-efficiency calculations; a condenser-optimization programme for determination of the ideal parameters to be used in the design of a condenser. The programmes are arranged so that unskilled operators can run them on the computer without the help of an experienced programmer. Facilities are also made available for writing programmes in a simplified form called ‘autocode’ which can be used by an engineer after the briefest of trainings. Some programmes are described in considerable detail to assist others who may wish to write a similar programme or to compare them with programmes of their own. All these programmes have been in regular use for more than three years and have greatly enlarged the scope of investigations which may be carried out in the project stage of the design of a steam-turbine generator and associated power-station equipment.
Development of a Small Single- and Two-Shaft Gas Turbine for Military Applications
Authors: Petrie K. 
Published: October 2007

In the last two decades there has been a progressive increase in the scope of small gas turbine development and application, both in commercial and military fields. Technological advances in the military field have created demands for prime movers able to meet more stringent operational requirements. An environment now exists in the U.S. Armed Forces conducive to the acceptance and use of small gas turbines that can be adapted to the many specialized applications demanding distinctive physical characteristics. In 1957, the U.S. Bureau of Naval Weapons entered into a contract with Solar, a Division of International Harvester Company, for the design and development of a small, lightweight, single-shaft gas turbine engine to power a one-man helicopter. Rated at 55 s.h.p. for 100°F ambient conditions, the engine design requirements were based on simplicity of operation and maintenance, low production cost, and a short development time. These factors were considered more important than optimum specific power, fuel consumption and weight. A two-shaft version of this engine was also required to power a one-man flying platform. To facilitate the required low engine airflow, weight and rugged characteristics, a single-stage centrifugal compressor and radial inflow turbine, mounted back to back, were selected. A unique feature of the two-shaft engine was the simple method of achieving two-shaft capability by using the exducer portion of the radial turbine as a power turbine. This design resulted in both engines having the same nominal performance, weight and envelope dimensions, with maximum component interchangeability. A comprehensive aerodynamic development programme was undertaken to improve component efficiencies and various aspects of this programme are discussed. Based on favourable results from this programme, the building and development of an uprated engine was undertaken. By incorporating a modified compressor, a 38 per cent increase in s.h.p. and a 6 per cent decrease in specific fuel consumption (s.f.c.) was obtained. Probably the most important factor in the choice of a small gas turbine for military applications is its ability to develop more power, per unit weight and volume, than other engine types. In general, the specific weight of reciprocating engines, in the same power class as the subject gas turbine, average about 10–15 lb/hp with specific volumes ranging from 0.220 to 0.30 fr3/hp, compared to values of 0.53 lb/hp and 0.027 ft3/hp for the turbine. Over 20 different variations of this engine have been produced for such diverse applications as small aircraft and boat prime movers, aircraft and helicopter auxiliary power plants, mobile generator sets, and ‘winterization’ kits for U.S. Army field service. Intensive efforts are being made by companies on both sides of the Atlantic to develop the small gas turbine for a variety of applications. It seems reasonable to predict that these efforts will ultimately lead to the development of units with improved performance and lower initial cost.
The Effect of Hydrostatic Pressure on the Plastic Flow and Fracture of Metals
Authors: Pugh H. Ll. D. , Green D. 
Published: October 2007

A description is given of an apparatus for carrying out tension tests under hydrostatic pressures of 60 ton/in2 or more. The results of an investigation of the effect of hydrostatic pressure on the tensile properties of a number of metals are given. It was found necessary to protect cast materials with a rubber sleeve. The fracture strain increased with hydrostatic pressure, but this increase was not linear but varied with the crystal structure of the metal. In zinc and Mazak a sudden transition from brittle to completely ductile behaviour occurred at a critical pressure; this was probably due to a flat stress/strain curve. It was found in tension tests under pressure that specimens could deform and neck in a characteristic tensile manner, even though all the stresses were compressive. Fracture also could occur when the axial stress was compressive. It was found that the present results on tension, and previous results in torsion on cast iron, conformed either to a criterion that fracture occurred when the largest tensile stress reached a critical value which decreased as the volumetric compressive stress increased, or to a maximum deviatoric stress criterion, the critical value increasing with volumetric stress.
Design Study of a Forge Cogging Unit
Authors: Hutson C. , Knowles K. 
Published: October 2007

Modern developments in forging equipment and techniques are combining to make the dimensional accuracy and surface quality of forged stock comparable with that of rolled products. The output of a conventional press forge, employed on the cogging of alloy steels, is comparatively modest, being of the order of 10 000 tons/annum, as compared with a rolling mill installation which has a capacity in the range 500 000 to 1 000 000 tons/annum. It follows that, for production requirements between these two extremes, a high productivity cogging forge unit costing substantially less than a cogging mill should prove to be a worthwhile investment for many alloy steel producers. This paper contains an account of a design study of a forging machine with an output of 50 000 tons/annum capable of cogging alloy steel ingots down to billets or bars. The performance is based on current industrial requirements and the design concept calls for a machine in which the forging and manipulative functions are fully integrated and controlled. To achieve this, new features in press design and manipulative equipment have been evolved. It is concluded that a specialized high productivity cogging unit is a practical and economic proposition for the range and quality of steels considered.
Railway Overhead Contact Systems: First Paper: An Experimental Study of the Overhead Contact System for Electric Traction at 25 kV
Authors: Sell R. G. , Prince G. E. , Twine D. 
Published: October 2007

Increasing train speeds and the use of multiple pantographs have emphasized some of the problems of ensuring good current collection from the light overhead contact system used for railway electrification at 25 kV in Britain and overseas. The development, in Britain, of instrumentation and test methods is described, and the problems which arise as a result of ‘hard spots' and resonance effects are referred to. Experimental investigation has shown that greatly improved current collection can be obtained, by suitable modifications, even at speeds exceeding 100 mile/h, and under features such as bridges with minimum clearance. The main principle employed, which has been called ‘stiffness grading’, is to ensure a smooth transition of stiffness, or compliance of the overhead contact system through such features. These are, of necessity, considerably stiffer than normal open route equipment because of the strictly limited electrical clearances. The result is achieved primarily by modifications to the geometry of the equipment. It has been shown that such modifications can reduce appreciably the tendency of the system to build up oscillations of large amplitude, particularly in sequences of spans of approximately equal lengths. This tendency is much more marked where multiple pantographs are used, especially at certain spacings. Such phenomena can be remedied even more effectively by introduction of damping into the system and this can be achieved more conveniently by use of viscous dampers on the pantograph rather than on the overhead contact system. Appendix I describes recent test results which show that modified simple catenary equipment may be suitable for British Railways ‡ requirements if a smooth pantograph trajectory is ensured by suitable control of contact wire profile. This can be achieved by the use of mid-span sag. It will give an appreciable reduction of cost.
The Scientific Investigation of Aircraft Accidents
Authors: Walker P. B. 
Published: October 2007

Aircraft accident investigation is here treated as a problem in detection, calling for observation and deduction, and sometimes for scientific experiments to test tentative explanations. After consideration of preliminaries, such as the discovery and retrieval of the wreckage and its reconstruction as a jig-saw puzzle, most of the principal methods for ascertaining the cause of an accident are described under separate heads. It is shown how the different lines of investigation may proceed more or less simultaneously, and may substantiate each other. They include the analysis of fractures and the study of scratches, marks and indentations. Disruption of mechanical and electrical components is considered and also the evidence of eye-witnesses. Consideration is also given to methods that can be used even when no wreckage is available. The treatment is essentially practical as it proceeds from one specific example to another, with several photographs taken from actual cases. The paper concludes with a few remarks on modern trends, which do not appear likely to upset any of the basic principles here described.