bluuebunny/crossref_metadata_2025_split huggingface dataset:
Paper 1: The Hydrodynamics of Flat Contacts: Friction Studies in the Pin and Disc Machine
Authors: Robertson W. G. , Spillman D. T. 
Published: June 2010

The friction of run-in flat steel specimens lubricated with plain mineral oils has been measured in a pin and disc machine over a wide range of operating conditions. The hydrodynamic region was identified with the aid of electrical contact measurements and the corresponding friction data were considered in terms of the various theories which have been proposed to explain hydrodynamic action in nominally flat sliding contacts. It was concluded that the Lewicki inflow, the surface roughness, and the viscosity-density wedge mechanisms could not explain the observed friction; but that it could be explained if the surfaces formed a wedge whose angle was constant over the whole range of operating conditions. It is suggested that the wedge may be formed during the running-in process by mechanical effects such as flexural distortion. Particularly striking is the strength of the hydrodynamics which can occur in such ‘flat’ contacts: in terms of the wedge analysis the contact was operating close to the maximum theoretical load-carrying capacity. The implications with respect to the use of the pin and disc machine as a test rig are discussed and it is suggested that there might be a practical application in the design of ‘self-adjusting‘ slider bearings.
Paper 12: A Comparison of Performance Predictions for Steadily Loaded Journal Bearings
Authors: Smalley A. J. , Lloyd T. , Horsnell R. , McCallion H. 
Published: June 2010

Various predictions of the performance of steadily loaded circular journal bearings, running in the laminar regime, are compared. The values of load, friction, peak pressure, and oil flow given result from the iterative numerical solution of the Reynolds equation subject to a number of different boundary conditions, which attempt to allow for oil-film disruption. The boundary conditions considered are: (1) That only the positive pressure region of the 360-degree full-film solution contributes to load carrying. (2) That the full-film is bounded, both at breakdown and at build-up, by the conditions that pressure and pressure derivative are zero. (3) That the pressure is zero along the line of maximum film thickness, this being the assumed build-up boundary, and the breakdown occurs when the pressure and pressure derivative fall to zero. (4) That the build-up boundary arises when the flow balance, allowing for the oil feed system, indicates a full-film, breakdown occurring as in (2) and (3) above. The influence of mesh size, convergence limit, and finite difference formulae on the accuracy of the solutions is also discussed. Finally a comparison is made with the results from the analytical solutions due to Sommerfeld and Ocvirk, which show large errors in load and in peak pressure. This led the authors to devise a new and accurate procedure for the prediction of load and peak pressure for finite bearings using simple formulae.
Paper 8: A Graphical Method for Predicting the Performance of Circumferentially Grooved Hydrodynamic Journal Bearings under Steady Loads
Authors: Martin F. A. 
Published: June 2010

This paper illustrates a procedure of bearing design which avoids the iterative process of conventional methods of determining the eccentricity ratio in a journal bearing. The iterative process results from the need to satisfy three simultaneous equations; in the method described, the equations are graphically defined on two sheets. The transparent sheet defines the bearing data and eccentricity ratio and the opaque sheet defines the viscosity-temperature characteristics of the oil chosen. The transparent sheet is moved over the opaque sheet according to a fixed locus till a point representing the bearing data is coincident with the oil inlet conditions. The eccentricity ratio can be read directly and power loss and oil flow calculations may then be carried out in the normal manner. Experimental results obtained from tests with circumferentially grooved bearings have been used to test the generality of the design method and also to check the assumptions relating to operating viscosities in the bearing.
Paper 6: Hydraulic Control of Valves in Tankers
Authors: Pomper Victor 
Published: June 2010

The 47 800-ton vessel Altair of the Compagnie Navale des Pétroles (C.N.P.) was the first oil-tanker to be equipped with a hydraulic remote-control system of cargo valves. The vessel was delivered at the beginning of May 1959. The opening and closing operations of the valves were controlled from a central panel which was fitted with manually operated directional control valves. The panel was located in the cargo valves' remote-control room which also housed the indispensable remote-controlled level-indicator board. Since then the application of hydraulic remote-controlled valves has become widespread and has taken one of two forms : that of a centralized control system or that of directional control valves located on the deck. Remote-controlled valves are either gate valves operated by a hydraulic cylinder, or butterfly valves operated by a hydraulic rotary actuator. The application of remote-control also allowed the setting up of the ‘free-flow’ system which uses hydraulically operated bulkhead valves. The first ‘free-flow’ oil-tanker was the Sirius of the C.N.P.; it was delivered in 1961. At present it appears that there exists an ever-increasing trend towards automation in the loading and unloading of tanker cargoes. This is accomplished by electrically operated directional control valves, which are connected with electrically programmed systems or with electronic servo-controls.
Paper 1: The Breathing and Combustion Requirements of the Small High-Speed Diesel Engine
Authors: Broome D. 
Published: June 2010

The use of small diesel engines in light highway vehicles has increased greatly in the last few years, and such engines exhibit some specialized characteristics. The performance requirements of these engines are outlined, and their dependence on the overall air consumption of the engine is emphasized. The latter is defined as the product of the breathing and combustion phases of the engine operation. For the breathing phase, the factors controlling the volumetric efficiency arc examined and the relative importance of heating and pressure effects estimated from the results of tests on a number of engines. The scope for further improvement is discussed in relation to these two factors, and the choice of valve timing. For the combustion phase, the requirements of the high-speed engine are listed and briefly discussed under eight headings, namely, the limiting air utilization; fuel consumption; flexibility of operation over the speed range; ease of starting; intensity of combustion noise; sensitivity to fuel quality; overall reliability; and ease of design and manufacture. The relative merits of direct and indirect injection systems for this duty are then examined with some reference to recent experimental work, and directions in which improvements are possible and desirable are indicated. On considering techniques which are useful in chamber development, a simple method of assessing the airflow pattern within indirect chamber layouts is described and illustrated by reference to test sequences obtained on two different combustion chamber forms. Some general notes on methods of expediting firing tests of new chamber systems are given.
Paper 2: Similarity Considerations in Assessing Diesel Engine Fuel Spray Requirements
Authors: Knight B. E. 
Published: June 2010

A simplified dimensional analysis has been made of the fuel-air mixing problem in diesel engines. The dimensionless variables describing the mixing pattern have been expressed in terms of the dimensionless variables describing the engine and fuel injection conditions by means of explicit equations with numerical values for the constants. A wide range of such equations has been derived and tables of numerical values are given as examples, together with examples of engine air motion calculations for comparison. A theoretical expression for fuel-spray penetration into a cross-wind has been compared with a few experimental results. Engine smoke and specific consumption measurements have been plotted against the appropriate dimensionless variables in two instances. In both instances the response of the engine to the variables is quite different. It is believed that the wide range of methods of engine performance data analysis outlined in this paper will make a significant contribution to progress in understanding diesel engine combustion.
Paper 3: An Experimental Study of Flow through Poppet Valves
Authors: Woods W. A. , Khan S. R. 
Published: June 2010

This report gives an account of steady flow tests carried out on poppet valves. The object of the investigation was to determine the boundary conditions for exhaust and inlet valves for subsequent use in the general programme of unsteady flow research. The exhaust valve was tested with and without pipes over a much wider range of pressure ratio and valve lift than has been carried out before and the boundary conditions have been found to be independent of the pipe and also almost independent of the position of the pressure tapping in the exhaust pipe. This result is very important and it will simplify subsequent boundary curve tests. Comprehensive tests have also been performed on the inlet valve and for reverse flow through each valve. The two usual mathematical flow models, namely, the constant pressure and the sudden enlargement, are discussed in detail and the concept of an effective area for a poppet valve is clearly explained. The effective areas for the exhaust and inlet valves for normal and reverse flow have been computed on the basis of the constant pressure flow model. The pressure ratio has been found to have little effect on the effective areas at low valve lifts but has considerable effects at high valve lifts. The results are presented graphically on a complete set of charts. It is illustrated in Appendix 3.II that the effective area of an exhaust poppet valve may be predicted for low valve lifts.
Paper 5: The Application of Some Analytical Techniques to the Study of Turbocharging the Automotive Diesel Engine
Authors: Garratt G. , Gee D. E. 
Published: June 2010

The scope of the paper is limited to a discussion of simple turbocharging (i.e. precluding multi-stage compressors or turbines, inter-cooling, etc.) and considers only four-stroke engines. On the basis of published information the constant-pressure and pulse-exhaust systems are re-examined in the light of the requirements of an automotive engine. It is concluded that the pulse system is essential for use with existing transmissions. Methods of assessing the thermodynamic performance of the compressor-turbine-manifold system, operating on the pulse principle, are reviewed and an overall coefficient defined. Existing methods of analysing the performance of exhaust turbines when operating in a non-steady flow field are discussed and the limitations noted. A slightly modified method, based on earlier work, is presented and should prove of value for direct application to an experimental turbocharged engine. A new method for determining the energy transmission efficiency of the exhaust manifold is derived and some preliminary results from a typical automotive engine are presented. The overall performance of a simple turbocharged engine is examined by the use of an analogue computer model and the importance of the manifold and turbine efficiencies emphasized. It is concluded that a complete solution of the torque-speed relationship problem is unlikely to be found using simple turbocharging alone, particularly with the 50 per cent reaction radial turbines at present in almost universal use. The analogue model of a turbocharged engine is likely to prove of increasing value and be a useful adjunct to experimental work.
Paper 6: Turbocharging the Automotive Two-Stroke Cycle Engine
Authors: Tryhorn D. W. 
Published: June 2010

The paper deals with the problems of turbocharging the two-stroke cycle engine. Obtaining a sufficiently rapid drop in the pressure of the cylinder contents after exhaust port opening is chiefly dependent on obtaining a high turbocharger efficiency. However, exhaust-pipe design can be very important in this process, and a system is described which permitted the use of simple turbocharging from light load to 200 lb/in2 b.m.e.p. Good starting and acceleration demanded that energy be fed into the charging system and so the normal engine-driven Roots blower was then fitted as a second stage. This spoiled the good natural match of the turbocharger and engine but it was discovered that by control of air recirculation through the Roots blower a good match could be obtained. The work showed that the best match leads towards a constant horsepower type of engine torque curve, and this fact should be recognized for future vehicle design. The use of two turbochargers in series offers very high outputs with good efficiency but will require a new generation of engines to withstand the high pressures and thermal loading.
Paper 14: Acoustic Detection of Cavitation
Authors: Pearsall I. S. 
Published: June 2010

The onset of cavitation in a hydraulic machine can be determined visually and its effect on performance by performance tests. It would be convenient to have an alternative method that required neither transparent sections nor expensive tests. Initial tests have been made measuring noise over a frequency range of 20 c/s-20 kc/s in one-third octave bands, on a number of pumps and turbines. An accelerometer attached to the casing was used. The tests indicated that, generally, the onset of cavitation was accompanied by a rise in the high-frequency noise, whilst the low-frequency noise increased as the cavitation developed. A maximum of cavitation noise was reached before the efficiency and load fell off. In some cases difficulty was experienced because blade cavitation was drowned by noise caused by other cavitation, such as the vortex in a Francis turbine. It also appears that the noise following the onset of cavitation is at the frequency which is used as a critical frequency in accelerated erosion tests. Further development of techniques is required, but the initial tests are encouraging.
Paper 9: Instrumentation for the Measurement of Hydraulic Noise in Centrifugal Pumps
Authors: Wood F. J. , Corkill J. 
Published: June 2010

For a programme of research into hydraulic noise generation in centrifugal pumps, it was necessary to develop special measuring equipment for use in conjunction with existing equipment designed for the measurement of air-borne and structure-borne noise. Small hydrophones, less than 0.5 in in diameter, in which the piezo-electric sensitive element was an axially polarized lead-zirconate-titanate disc, were designed and developed. In the design, reliability, implying both mechanical and electrical stability, was considered to be more important than extreme sensitivity; ease of construction and low cost were also taken into account. The final design, in which a thin stainless steel diaphragm was used, proved very stable and reliable and has a sensitivity of over 250 mV/lb in2 into a 200 megohm load. Commercial tape recorders, considerably modified, were used as a cheap method of recording all data on 1/4 in magnetic tape for subsequent analysis. A time-delay tape deck was also constructed for use in conjunction with a small special purpose computer to evaluate the cross-correlation function from the outputs of two hydrophones spaced a known distance apart. Methods of hydrophone calibration were devised, and the results agreed closely with the theoretical figures derived from the piezo-electric constants of the ‘crystals’ used. Special consideration was given to methods of automatically recording the results of one-third octave and discrete frequency analyses in forms which would provide the maximum amount of easily assimilable information.
Paper 13: Influence of the Casing on the Calculation of the Critical Speed of Multi-Stage Pumps
Authors: Domm U. , Dernedde R. , Handwerker Th. 
Published: June 2010

Pump impellers and pump casings are considered as simultaneous beams coupled through the bearings, the stuffing-box and the radial clearances acting as hydrostatic bearings. Lomakin has given a relation for the restoring forces in smooth clearances, according to which these are to be taken as springy supporting bearings the spring constants of which are proportional to the pressure. Small clearances therefore raise the critical speed. The procedure is a method of residues in which the estimated natural frequency is varied until the residual value diminishes. In the case of multiple masses and supports the calculation necessitates the use of digital computers. The critical speed is calculated by extending the matrix-method known from the single beam to systems of two parallel beams. Because of the analogy of the differential equations for the shaft operating with critical speed and for the transversally vibrating beams, rotation of one beam is allowed also. By special transposition matrices, single masses, spring-elastic couplings between the two beams may be considered. The coupling forces according to Lomakin, already explained above, being proportional to the product from deflection and square of speed, formally correspond to the loading of the shaft by apparent negative masses. In the case of very close clearances the critical speed may be almost completely suppressed.
Paper 12: Generation of Hydraulic Noise in Centrifugal Pumps
Authors: Simpson H. C. , Macaskill R. , Clark T. A. 
Published: June 2010

The production of hydraulic noise by two types of centrifugal pumps—volute pumps and diffuser pumps—was examined to determine the effect of design and operating conditions on the level of noise generated in the pumped liquid. Experimental work with hydrophones in the exit and entrance to the pumps showed that for both pumps, the dominant frequencies in the noise spectrum were at rotational speed and blade number times rotational speed. It was also found that the distance between cutwater and impeller tip is critical in a volute pump as far as blade frequency noise is concerned. Analysis of the relation between the noise measured by the hydrophones and the fluctuating pressure produced by the pump and the water flow in the inlet and outlet ducts showed that the noise can be interpreted as being directly related to the unsteady flow of water issuing from the impeller. Test results of blade frequency noise levels were correlated with a theoretical analysis for static pressure fluctuations in the pump exit and were shown to be in good agreement. A correlation of general hydraulic noise level with pump specific speed and power consumption was also developed and shown to be reliable to within +2 dB.
Paper 11: Variation of Hydraulic Pressure in Annular Space between Guide Vanes and Impeller of a Francis Turbine
Authors: Lund E. 
Published: June 2010

One of the main sources of vibration in Francis turbines is thought to be pressure-wave disturbances generated from the impeller and interference impulses between impeller vanes and guide vanes. A theory is developed which explains the occurrence of severe vibrations caused by the elasticity of the water as a resonance phenomenon between the disturbing impulses and normal modes of vibration in the space between the impeller and the guide wheel. The wave propagation in the fluid, which is assumed to be uniform with no steady flow, is thought to satisfy the well-known sound-wave differential equation without any damping effects. The natural frequencies for one- and two-dimensional pressure-wave oscillations are calculated. The calculations, based on prior knowledge of the velocity of sound-wave propagation, show that a simple theory of one-dimensional oscillations interpreted as rotating sound waves in the annular space is sufficient to predict critical speeds of the turbine. Measurements carried out on a laboratory model Francis turbine for a head of 4.5 m and a capacity of about 1.0 m3/s confirmed the presence of free oscillations and indicated the occurrence of a resonance phenomenon in the annular space.
An Investigation into the Performance of Dynamically Loaded Journal Bearings: Theory
Authors: Lloyd T. , Horsnell R. , McCallion H. 
Published: June 2010

The main and big-end bearings in reciprocating machinery are subjected to loads varying both in magnitude and direction. At present the only guidance available to the designer of such bearings may be a comparison of bearing performance in similar engines and it is fundamental to the introduction of improved design criteria that a prediction of the journal locus, peak pressures, and oil flow be readily available for a proposed geometry and loading. In this paper a numerical method of solution of this problem, utilizing a high-speed digital computer with a large one-level store, is described. The method rests on the assumption of isothermal conditions in the oil film and on the unimportance of the inertia forces associated with the journal accelerations. Numerical solutions of the Reynolds equation are obtained and stored for both wedge and squeeze film terms, at a number of journal eccentricities, by using an iterative method. The oil film force and the derivatives of this force with respect to both the journal centre position and its velocity are then found by summing these pressure distributions in the required proportions. At intermediate eccentricities, the required pressure distributions are obtained by interpolation before they are summed. The journal centre locus is obtained from a step-by-step solution of two simultaneous, ordinary differential equations involving the oil film data and the external load. In addition to the locus, the maximum pressure at any instant, the oil flow, and the friction work are calculated. For big-end bearings, journal rotational velocity is not constant and this is allowed for in the analysis. The computer program described needs no input apart from the bearing geometry and operating conditions and, because of refinement of the iteration and the integration procedures, it is economic to use for routine design studies.
Paper 8: An Investigation into the Performance of Dynamically Loaded Journal Bearings: Design Study
Authors: Lloyd T. , Horsnell R. , McCallion H. 
Published: June 2010

The objects of this paper are to demonstrate the use of the method described in Paper 6 and to give an indication of the effect of design parameters on the performance of a dynamically loaded bearing. An investigation into the main and big-end bearings of a diesel engine of modern design is described. The performance of a bearing is gauged by obtaining: (a) the minimum oil film thickness, (6) the maximum pressure developed within the oil, (c) the maximum load/projected area, and ( d) the bulk oil temperature rise. The influence of the engine design upon the big-end bearing performance for the particular engine under consideration is found by investigating the effects of the following parameters: ( a) bearing length-diameter ratio, (6) removal of centre-circumferential groove, ( c) inlet temperature, ( d) bearing clearance, and ( e) loading diagram. This last parameter is varied by changing in turn the piston mass, the connecting-rod mass, and the position of the connecting-rod centre of gravity. Finally, the effect upon the main bearing performance of various balance weight configurations is demonstrated. The usual assumption is made to obtain the main bearing loads: that loads imposed by a crank throw are equally distributed between neighbouring main bearings. General conclusions are made regarding the relative influence of certain bearing-design parameters upon the bearing performance.