bluuebunny/crossref_metadata_2025 huggingface dataset:
The Cooling of Methane with Vortex Tubes
Authors: Williams A.
Published: February 2007

Measurements have been made of the amounts of cold and heat produced by a vortex tube operated with methane containing some carbon dioxide, and with Algerian natural gas, which has a high methane content. The effects of gas supply temperature and pressure have been investigated. The contribution of the Joule–Thomson effect to the total cooling has been calculated and allowed for.

Vortex effect cooling decreases with lowering of the supply temperature and probably disappears at the gas liquefaction point. It is dependent on the pressure expansion ratio across the tube. The findings are compared with those of other workers and those predicted by vortex tube theories.
Hydraulic Jacking
Authors: Eliasson E. T.
Published: February 2007

The trend in modern plain journal bearing design is towards a reduction in the relative bearing width; this results in reduced machine bulk and bearing losses, but has the disadvantage of increased bearing wear, particularly at starting, stopping and the reversal of motion.

A method of reducing this wear problem is by means of hydraulic jacking, or the separation of the load carrying surfaces by the introduction of high pressure oil into the clearance space, through suitable feed grooves.

The article describes an analytical solution to the problem of hydraulic jacking. The following solutions are presented, giving full performance characteristics.

(1) Single- and twin-axial feed grooves, end leakage neglected.

(2) Single- and twin-axial feed grooves, concentric journal, finite length bearing (approximate solution).

(3) Single- and twin-axial feed holes, concentric journal, small diameter feed holes (approximate solution).

Some experimental verification is given for the theory of the axial feed groove arrangement, both the single grooved and the twin grooved arrangement.
The Plane Strain Indentation of Anisotropic Aluminium Using a Frictionless Flat Rectangular Punch
Authors: Venter R. , Johnson W. , de Malherbe M. C.
Published: February 2007

In Part 1, the slip-line field solutions and the associated load requirements necessary for the indentation of anisotropic solids are presented. The analysis is based on Hill's approach to the analysis of anisotropic material. All results are recorded in terms of a lumped anisotropic parameter, c.

In Part 2, the results of an investigation to determine the anisotropic parameters of a commercially available aluminium are reported. Specimens machined from the aluminium at selected orientations to the anisotropic axes were indented using a nominally frictionless flat rectangular punch. A comparison between the theoretical and experimental indentation loads is given.
Whirling of a Cantilever Elastic Shaft Subjected to External Pressure
Authors: Newland D. E.
Published: February 2007

This paper is a theoretical study of the whirling of a cantilever elastic shaft subjected to external pressure. The whirling speeds are shown to depend on the variation of pressure and area along the shaft and the lowest whirling speed is solved approximately by an energy method for a number of cases. When the external pressure is high enough., its effect may be important and the whirling speed may be raised or lowered, depending on the pressure distribution.
Analysis of Rotors Supported upon Many Bearings
Authors: Morton P. G.
Published: February 2007

This paper presents a technique for setting up a mathematical model of a rotor supported by many bearings. The technique takes into account the coupling between horizontal and vertical motions at the bearings, as well as inter-bearing couplings. The rotor, which is isotropic and undamped, can be of arbitrary stiffness and mass distribution. The economy and accuracy of the programme is demonstrated for the very complex case of a large turbo-set line-out in which the rotor is supported upon twelve bearings.
Free Convection in Open-Ended Rectangular Cavities-Inclination Dependence
Authors: Probert S. D. , Malde H. D.
Published: February 2007

Air pressure was employed as the variable to distinguish between the radiative, conductive and free convective components of the heat leak between the isothermal parallel plates of a rectangular cell. A steady-state temperature difference existed between the isothermal parallel plates. The radiative and, to a large extent, the gaseous conductive components were independent of cell inclination. However, for the chosen cell geometry (plates with inclined dimension 15 cm × channel length 12 cm × separation 2 cm) the mean slope of the convective component versus the logarithm of the air pressure exhibited minima at 27° inclination to the horizontal when the plates were at 200°C and 15°C respectively. This phenomenon is due to differing air circulation patterns predominating above and below this inclination.
Tests of some Taper-Hub Flanges with Narrow Gaskets
Authors: Fessler H. , Musson J. K.
Published: February 2007

Seventeen 4 in bore models having two pipe thicknesses, various flange thicknesses and hub lengths, made of spheroidal graphite (s.g.) iron, mild steel and bronze, were subjected to series of initial bolt tensions and, at each bolt tension, pressurized in stages to leakage or failure of the metal. Outer surface strains were measured at each stage. Elastic behaviour was also determined from some Araldite models using strain gauges or frozen stress photoelasticity.

The elastic flange-hub fillet stresses due to initial tightening are compared with predictions based on Taylor-Forge and DIN methods of calculation. For different positions of gasket reactions, the effect of internal pressure on flange fillet stresses may be predicted from consideration of the external forces. Plastic-elastic behaviour is described; leakage and failure characteristics are presented.
Heat Transfer between Parallel Walls: An Interferometric Investigation
Authors: Brooks R. G. , Probert S. D.
Published: February 2007

The temperature fields and the transfer of heat within vertical, inclined and horizontal air layers are examined for each of three different heat transfer regimes. Experimental evidence is offered which explains the difference between the heat transfer correlations of previous investigations in which the Nusselt modulus is based on the heat flux leaving the heated wall and those in which the Nusselt number is based upon the rate at which heat is transferred to the cooled wall. It is also shown that some of the thermal boundary conditions which have generally been assumed in numerical studies are unrealistic.
Influence of Stream Turbulence and Pressure Gradient upon Boundary Layer Transition
Authors: Hall D. J. , Gibbings J. C.
Published: February 2007

In considering boundary layer transition, the available experimental data and prediction methods are reviewed and further experimental results are presented. Some empirical rules are suggested for the separate effects of stream turbulence and of pressure gradient and of both combined. The approximate nature of these rules is described and the causes indicated.
Vibration of Asymmetric Rotor through Critical Speed with Limited Power Supply
Authors: Iwatsubo T. , Kanki H. , Kawai R.
Published: February 2007

The non-stationary vibration of an asymmetric rotor with limited power supply is studied using the asymptotic method. The many factors which affect the transient vibrating behaviour of the asymmetric rotor in passing through critical speed are studied in relation to the amplitude of motion, phase angle, energy, etc. by numerical calculation; that is, stiffness ratio of the asymmetric rotor, damping coefficients, driving torque (during both acceleration and deceleration) and so on. The experimental study using a simple model is added.
A Numerical Solution of the Elastohydrodynamic Lubrication Problem Using Finite Elements
Authors: Taylor C. , O'Callaghan J. F.
Published: February 2007

This paper comprises a report on recent developments in the application of the finite element method in the analysis of elastohydrodynamic lubrication (e.h.l.) problems. The basic formulation is effected, using the Galerkin approach and the domain under investigation is discretized using isoparametric elements. The techniques used to locate the inlet and outlet boundaries and those employed during successive iterations are illustrated by application to particular examples.
Turn-Up and Turn-Down in Hot Rolling: A Study on a Model Mill Using Plasticine
Authors: Buxton S. A. E. , Browning S. C.
Published: February 2007

Turn-up and turn-down is a phenomenon which occurs in the hot rolling of flat products when the nose of a slab, or the whole slab, curls up or down upon emerging from the rolls and remains deformed unless subsequently straightened. Turn-up and turn-down can be troublesome to production, since it can cause damage to the mill rolls, housing, and run-out tables and can also cause production delays due to the difficulty of re-rolling a deformed slab.

The object of this paper is to determine the main factors governing the phenomenon, to obtain quantitative relationships between causes and effects, and to suggest means of preventing curvature occurring.

The best approach was considered to be a scale model using plasticine to simulate the hot metal. As a basis for the work, several dimensionless ratios are formed which have to be the same in both model and full size mill, if the model is to be both dynamically and geometrically similar. In the more important dimensionless ratios, account is taken of the plastic yield characteristics of the material, including the rate-of-strain component, of the stresses due to surface friction and gravity, and finally of the ratio of roll speeds. The results are compared with some previous work by others on steel slabs using a full size mill. In all respects, the results agree closely.

The most significant factor affecting turn-up and turn-down is the ratio of surface speeds of the two work-rolls. Curvature is proportional to this speed ratio, but slipping at the rolls may modify this relationship. For a given angle of entry, the ratio of torque upon each roll is a function of the speed ratio. Angle of entry has negligible effect on turn-up and turn-down, but has a powerful effect upon the torque ratio.

Slip is very undesirable and it appears that the roll surface finish should not be better than necessary if slip is to be avoided.

To produce a flat slab, a speed ratio of about 0·97 is required in the model. In practice, this may be achieved either directly by controlling the speed ratio, or indirectly by controlling the torque ratio, provided the angle of entry is constant.
Upper Bounds to the Load for the Plane Strain Working of Anisotropic Metals
Authors: Johnson W. , de Malherbe M. C. , Venter R.
Published: February 2007

The method of finding upper bounds to the load to work isotropic metals under conditions of plane strain using tangential velocity discontinuities is extended to include anisotropic metals. The theoretical foundations of the method are presented and three simple examples are given, followed by one which results in a solution identical to that given by the standard slip-line field approach. An approach for load bounding using isotropic slip-line fields is suggested.
Synthesis of Active Controllers for Vibratory Systems
Authors: Porter B. , Bradshaw A.
Published: February 2007

A systematic procedure for the synthesis of active controllers for vibratory systems is described. This method is based upon the use of modal control theory and is applicable to lumped-parameter linear systems possessing any number of degrees of freedom.
Billet and Die Temperatures in Hot Forging—A Theoretical Contribution
Authors: Kellow M. A. , Bannister F. K.
Published: February 2007

The theory concerns the unsteady conduction of heat occurring within and between billet and die during high-speed hot forging. The analysis comprises an extension of the Fourier heat soakage equation for axial symmetry so as to include the effects on heat flow, and hence temperatures, of the rapid plastic movements in the billet material. A step-by-step solution uses a modification of the Crank-Nicolson technique based on an iterative procedure. Using idealizing assumptions regarding the billet deformation, graphs are produced showing temperature changes in a cylindrical billet.
Unsteady One-Dimensional Compressible Frictional Flow with Heat Transfer
Authors: Issa R. I. , Spalding D. B.
Published: February 2007

The paper briefly describes a numerical procedure for solving problems of one-dimensional, unsteady, compressible, frictional flows with heat transfer. The procedure is based on the Hartree ‘hybrid’ method which combines the use of a rectangular grid with the use of characteristics. The main features of the procedure are its applicability and ease of adaptability to complex unsteady-flow problems. Another feature is the simplicity of its programming for a computer.

Computations for flows in shock tubes are presented; they are in good agreement with previously published experimental data.
Performance of Truncated Conical Diffusers with Compressible Flow
Authors: Ferrett E. F. C. , Lampard D. , Duggins R. K.
Published: February 2007

The performance has been assessed for a variety of geometrical configurations and for inlet Mach numbers ranging from 0·2 to choking. Particular attention has been focused on the developing flow in the tailpipe.
Heat Transfer and Flow in a Short, Vertical, Internally Heated Annulus with a Rotating Outer Boundary
Authors: Coombs J. S. , Probert S. D.
Published: February 2007

Experimental determinations were made of the steady-state heat fluxes and velocity profiles in water between two vertical concentric cylinders, the heated inner cylinder being stationary while the outer cylinder was rotated in ambient temperature air. Secondary flows, due to end effects, existed in the annulus at all rotational speeds and profoundly influenced the rate of heat transfer across the annulus. When the circulation of the secondary flows opposed those due to natural convection, the mean Nusselt number decreased almost to unity.
Paper 1. Problems and Requirements of Directional Stability and Control of Surface Ships
Authors: Nomoto K.
Published: February 2007

This paper summarizes the stability and control problem for ships, and the various differential equations giving yaw dependence on rudder angle are developed. Experimental methods for evaluating the time constants are described. Non-linear behaviour is discussed.
Paper 2. Problems and Requirements of Directional Stability, Control and Manoeuvrability; High-Speed Craft
Authors: Eames M. C.
Published: February 2007

The problems of stability and control of high-speed craft are somewhat different for the various vehicle types.

The first part of this paper briefly compares characteristics of air-cushion vehicles and planing craft. This is followed by a more detailed discussion of the problems and requirements of hydrofoil craft.
Paper 4. Towed Bodies
Authors: Abkowitz M. A.
Published: February 2007

The problems of stability and control are surveyed for the system comprising towing body, connecting cable and towed body. Factors influencing the equilibrium configuration are first outlined, followed by a discussion of methods of stability analysis based on the assumption of a taut cable. Limitations of the assumption are indicated, leading to an appreciation of cable dynamics, and a summary of mathematical models of cables under hydrodynamic loads. The problems involved and directions for future research are suggested. Appendices 4.1 and 4.2 give extensive bibliographies on towed systems.
Paper 9. Model Testing
Authors: Burcher R. K.
Published: February 2007

This paper is an introduction to model test methods as a means of establishing the manoeuvring characteristics of ships. Consideration is first given to the reasons for the adoption of model techniques and the information to be obtained. The model techniques are considered under three sections: free models, constrained models and mathematical modelling. The standard tests employed are briefly described and the information that can be obtained, together with any problems. There is finally a short discussion of the problems of ship/model correlation.
Paper 10. On Manoeuvre Tests to Investigate the Course-Keeping Qualities of Ships
Authors: Fujii H.
Published: February 2007

Several model tests are outlined for evaluating the manoeuvrability and directional stability of full and large ships. The tests are classified into three groups according to the amount of helm involved. The modified zigzag test and the reversed spiral test using the oscillation method are described in detail. Problems of correlating model and full-scale behaviour are discussed.
Paper 11. Yaw Motion Stability; Twin-Screw, Twin-Rudder Ships—Some Model and Ship Results
Authors: Thurman G. D.
Published: February 2007

This paper describes the pull-out manoeuvre as an indication of yaw motion stability. Results of model tests at the Admiralty Experiment Works and full-scale trials data are presented as a demonstration of ship/model correlation; additional model test results are given to illustrate use of the manoeuvre for detecting changes in stability due to alterations in ship configuration.
Paper 13. Manoeuvring Research at Admiralty Experiment Works Using Free-Sailing Models
Authors: Hunt P. W.
Published: February 2007

Since June 1969 the Admiralty Experiment Works has been engaged in an investigation that is aimed at improving our knowledge of the facts affecting the yaw-motion stability of surface ships. The programme has involved extensive use of self-propelled, free-sailing models plus full-scale data from trials carried out by ships' officers and reported through the fleet organization. This paper will deal with the free model work to date and outline some of the questions raised, as well as information gained.
Paper 15. Some Aspects of Prediction and Simulation of Manoeuvres
Authors: van Leeuwen G.
Published: February 2007

Prediction and simulation are dependent on the knowledge gained from mathematical models. The choice and the form of the model is determined by the specific application and the accuracy required.

Model techniques, such as horizontal oscillation tests, provide the means of finding the coefficients of extensive non-linear models, though for other purposes, such as simulation, there is also a need for simpler, empirical models. To determine the coefficients of such models, free-running full-scale or model tests are necessary.
Paper 17. Some Aspects of the Stability of Automatic Course Control of Ships
Authors: Bech M. I.
Published: February 2007

A short discussion of the ship's transfer function is given, based on the second-order differential equation. The influence of the steering gear is pointed out. Based on Bode diagram representation, the principal requirements to the controller transfer function are deducted in conjunction with a short discussion of the total closed-loop block diagram. The target for control and a possible optimization criterion is suggested.
Paper 18. Improvement of Course Stability and Control by a Subsidiary Automatic Control
Authors: Koyama T.
Published: February 2007

An investigation has been made to improve the course-keeping capabilities of an unstable ship by adding a subsidiary automatic control to the manual steering. For this, use has been made of results of full-scale experiments with a 200 000 d.w.t. tanker and a simulation study. Some instructive results have been obtained.
Paper 19. Hydrodynamic Characteristics of Flapped Rudders
Authors: Kerwin J. E. , Mandel P. , Lewis S. D.
Published: February 2007

Water-tunnel experiments were performed to determine the free-stream characteristics of a series of 12 rudders with systematic variations in the amount of flap area and flap balance. The results include lift, drag, rudder moment and flap moment coefficients for a range of angles of attack and flap deflections. A comparison is made of the effectiveness of all-movable rudders, rudders with a fixed skeg and movable flap, and rudders with movable skegs and flaps. The latter were found to be by far the most effective. Rudders with fixed skegs are inferior to all-movable rudders unless the proportion of flap is very large. Flap balance does not appear desirable. Maximum flap moments, even with zero balance, are generally less than or comparable to the maximum moment of an ideally balanced all-movable rudder.
Paper 23. A Rational Combination of Directional Stability and Turning Capacity
Authors: Yudin E. B. , Firsoff G. A. , Pershits R. Y.
Published: February 2007

It is necessary in the design of any ship to compromise between the conflicting requirements of directional stability and manoeuvrability. Thus the less stable a ship is, the more readily it can be turned by a given rudder. This paper is concerned with a rational assessment of these requirements and the associated design of an effective rudder.
Paper 24. Stability and Control Problems Associated with Acceleration and Deceleration
Authors: Jourdain M.
Published: February 2007

This paper gives a general survey of the behaviour of surface vessels subjected to accelerations in a horizontal plane. There are two different cases which frequently occur in combination but which, for convenience, are treated separately. First, longitudinal acceleration is considered, including positive or negative acceleration in the fore and aft plane; problems of stability and manoeuvrability and means of improving directional control are discussed. Next, the manoeuvring problem associated with transverse accelerations is described, with particular emphasis on the use of auxiliary devices, such as side thrusters, and modified propulsive arrangements.

Finally, the influences of currents, winds and restricted depth on manoeuvrability are outlined.
Paper 25. Course Stability While Stopping
Authors: Smitt L. Wagner , Chislett M. S.
Published: February 2007

This paper contains the results of captive model tests with an 8-m model of a 190 000 d.w.t. tanker. The tests were made with HyA's new large amplitude Planar Motion Mechanism and the test programme was designed to provide information on the influence of speed and propeller revolutions on the course stability of the vessel. The rudder effectiveness and the side force and turning moment induced by the propeller at full astern revolutions were also measured.
Paper 27. The Stability of a Ship in a Simple Sinusoidal Wave
Authors: Price W. G.
Published: February 2007

The linear differential equations governing the motion of a ship in a sinusoidal wave disturbance are derived from the principles of rigid body dynamics. Stability criteria are obtained when the linear differential equations have ( a) constant coefficients and ( b) periodic time-dependent coefficients that are needed to describe the ship in a following sinusoidal wave. The frequency of encounter between ship and wave is not necessarily zero.
Thermal Insulation Provided by Vertical, Annular, Air-Filled Cavities
Authors: Sadhu D. , Probert S. D.
Published: February 2007

Steady-state rates of heat transfer outwards across vertical air-filled annular cavities, with aspect ratios (i.e. height divided by annular gap) which ranged from 16·0 to 70·3, were measured for several pressures of the contained air between 10-3and 760 torr. The chosen temperature difference between the isothermal cylindrical walls ranged from 20 to 180 K. For constant values of the temperature difference the gaseous conductive, convective and radiative components of the heat leaks across the air gap to the outer cylindrical wall were distinguished and evaluated using a technique which employed the air pressure as the variable. Convection of the air ensued throughout the whole height of the cavity when the Rayleigh number attained a value of 1·6 × 104. The optimal separation for maximum thermal resistance greatly exceeded the 6 mm annular gap recommended for chimneys in British Standard 4076:1966 (1)‡.
A Hydrodynamic Theory of Radial-Face Mechanical Seals
Authors: Stanghan-Batch B. , Iny E. H.
Published: February 2007

The existence of a lubricating fluid film between the faces of a mechanical seal has been amply demonstrated, but the mechanisms of lubrication and sealing have yet to be convincingly established. Experimental evidence to show that mechanical seal faces are most probably lubricated by a hydrodynamic action induced by the waviness of one of the surfaces has recently been published by the authors. Following this work a modified form of the narrow bearing approximation to Reynolds' equation for hydrodynamic lubrication has been applied to an idealized wavy faced seal. The resulting theory of seal face lubrication has been extended to include radial flows in the fluid film and predicts a net inward flow of fluid which may be utilized to oppose the flow due to the sealed fluid pressure. Predicted lubrication and sealing characteristics are in substantial agreement with measured values. It is suggested that the performance of mechanical seals can be improved by giving one face an appropriately wavy surface at the time of manufacture; a number of other observations on mechanical seal design are also made.
Post-Buckling Behaviour of Rectangular Orthotropic Plates
Authors: Prabhakara M. K. , Chia C. Y.
Published: February 2007

An analysis is presented for the post-buckling behaviour of a simply supported, rectangular, orthotropic plate subjected to biaxial compression. The solution of von Karman-type large deflection equations of the plate satisfying the prescribed boundary conditions is expressed in the form of a double Fourier series for the transverse deflection and a double series for the stress function consisting of the appropriate beam functions. The effect of plate properties on stresses and deflections has been studied for three fibre-reinforced materials. Numerical results indicate good convergence of the present series solution and are compared with the available data.
Design and Analysis of an oil Cushion
Authors: Satter M. A.
Published: February 2007

The dynamic characteristics of an oil cushion, which was originally designed to eliminate impactive excitation to a mechanical lever and thereby achieve noise reduction, have been studied both theoretically and experimentally. The system motion is represented by a second order non-linear differential equation which can be reduced to a first order linear differential equation by changing the variables. An approximate but simple solution to the non-linear equation has also been presented. Theoretical and experimental results have good agreement.
A Graphical Method for Synthesis of Crank-Links
Authors: Mruthyunjaya T. S.
Published: February 2007

A graphical method is presented for three- and four-precision-position synthesis of the crank-link where the displacement of the free end is co-ordinated with angular rotation of the crank.
Correlation of the Damping Capacity of Cast Iron with its Mechanical Properties and Microstructure
Authors: Fox M. A. O. , Adams R. D.
Published: February 2007

Cast irons were produced with variations in quantity and shape of the free graphite inclusions and in matrix structure in order to determine their effect on the damping and dynamic modulus characteristics in both shear and direct loading conditions. Static mechanical behaviour, represented by the strength, the ductility, the initial modulus and the 0·1 per cent proof stress was obtained in shear and in tension. A significant improvement in mechanical properties could be obtained for a given damping capacity by ensuring that the matrix was pearlitic and not ferritic. Otherwise, high damping could only be obtained at the expense of the mechanical properties and vice versa.
Experimental Technique for Minimizing Resonance within a Ducted Fluid
Authors: Reed E. W. , Gill K. F.
Published: February 2007

Presented is an experimental method that enables practical pipe systems to be de-tuned so that resonance can be reduced to an absolute minimum. The technique employed is to correlate pseudorandom binary sequence pressure disturbances which are deliberately introduced into the pipe system. It is believed that this is the only method yet available to achieve this minimization of resonance phenomena. The experiment does not require fragile equipment and can be used in two phase flow work. The procedure is unsophisticated and directly applicable to engineering systems requiring this adjustment. The rapid response of the measuring technique makes the approach suitable for automatic control applications. Further extensions of this technique that give a greater insight into the practical behaviour of sonic waves are highlighted in the paper.
Solids Conveying in a Single Screw Extruder; the Rôle of Gravity Forces
Authors: Lovegrove J. G. A. , Williams J. G.
Published: February 2007

A theoretical analysis is given which illustrates the rôle of gravity forces in solids conveying. A one-dimensional solution for flow in an extruder channel is used to investigate the nature of the solution and a more precise, two-dimensional, version is then developed.
Fluid Oscillations in a Pitot Tube in Unsteady Flow
Authors: Horlock J. H. , Daneshyar H.
Published: February 2007

An analysis is presented for the response of a pitot tube placed in an unsteady flow and connected to a liquid manometer. The error in time mean total pressure recorded by the system is negligible unless its natural frequency is close to that of the flow oscillations or unless the density of the measuring fluid is close to that of the fluid whose total pressure is being measured.

The results of the analysis are broadly confirmed by experiment.
Transverse Modes and Frequencies of Beams Translating between Fixed end Supports
Authors: Simpson A.
Published: February 2007

The effects of longitudinal steady translational motion on the vibration frequencies and modes of simple Euler beams are outlined. An example shows that the natural frequencies decrease monotonically with increasing translation velocity, while the mode shapes are complex, indicating significant phase disparities from point to point across the span. Divergence is shown to occur when the translation velocity is greater than the fundamental flexural wave propagation velocity.

More general equations of motion, governing the translating Timoshenko beam under axial loading, are derived in Appendix 1.
Stress Distribution in a Wedge for Boundary Conditions Approximating to the Rake-Face Loads on a Metal Cutting Tool
Authors: Thomason P. F.
Published: February 2007

An analysis of published experimental and theoretical slip-line field results for the metal cutting process suggests that, when the tool and workpiece are of high elastic modulus, a reasonable first approximation to the rake-face loading will consist of uniformly distributed normal and tangential stresses over the contact length. An indication of the form of the stress distribution at the tip of a cutting tool is therefore obtained from an isothermal–elastic solution for a two-dimensional infinite wedge, loaded antisymmetrically by uniform normal and tangential stresses adjacent to the apex.

Only a preliminary assessment of the results is made, in relation to cutting tool wear and fracture problems, since a more detailed assessment will await a complete thermoelastic solution to the problem.
Axisymmetric Vibrations of Ring Stiffened Circular Plates
Authors: Jain R. K.
Published: February 2007

The free-flexural vibrations of elastic circular plates with an attached axisymmetric ring stiffener are considered on the basis of both classical as well as improved theories of plates. Effects of symmetric as well as eccentric stiffeners on the frequencies in the first four modes of axisymmetric vibration are investigated for various plate and stiffener dimensions.
Void Fraction during Two-Phase Flow
Authors: Chisholm D.
Published: February 2007

From consideration of the homogeneous equation for frictional pressure gradient, and the relation between friction and void fraction, an equation for the ratio of the phase velocities during two-phase flow, is developed which is interesting in form, easy to use, and agrees with experiment.
Cross Flows in Bounded Three-Dimensional Turbulent Boundary Layers
Authors: Horlock J. H.
Published: February 2007

A study is made of the flow normal to the mainstream direction (cross flow) that takes place in three-dimensional ‘bounded’ turbulent boundary layers near a wall, i.e. boundary layers restricted by the presence of bounding surfaces normal to that wall. Such boundary layers are present in the flow through rows of blades in a turbo machine.

Analytical expressions for the cross-flow velocity profiles are derived for these ‘bounded’ boundary layers and are compared with experimental data.
Transient Stress Distribution Caused by Water-Jet Impact
Authors: Tohnson W. , Vickers G. W.
Published: February 2007

A water jet of 50 mm diameter is used in conjunction with a calibrated split-platen pressure cell to determine how the normal and shear stresses engendered during perpendicular and inclined impact against nominally rigid surfaces, vary with time.
Correlation Method for Measuring Reflection Coefficients of Sharp-Edged Orifices for small-Amplitude Pressure Waves
Authors: Ali M. A. , Reed E. W. , Gill K. F.
Published: February 2007

A correlation technique using pseudo-random binary-sequence pressure-pulse testing is used to measure reflection coefficients of sharp edged orifices at the end of a duct. Within the range of the incident pressure-wave amplitude investigated in this paper it is believed that no other experimental means has yet been devised. A simple formula is derived from one-dimensional flow theory which gives values showing close agreement with the experimental results. End conditions for non-reflection are established to create an analogy to the hypothetical ‘infinite pipe’.
Relationship between the Steady-Handling Characteristics of Automobiles and Their Stability
Authors: Sharp R. S.
Published: February 2007

Analyses of the steady-state handling behaviour of an automobile and the stability of its steady-turning motion, based on a three degree of freedom mathematical model, are used to show that the steady behaviour and the stability are related similarly in the nonlinear region as in the well documented linear one. It is concluded that analysis and measurement of the steady behaviour will yield information on the stability of automobiles.
Changes in Water Level Due to Swell in a Pool-Boiling Plant
Authors: Poon K. L. , Chiu P. C.
Published: February 2007

A theory for bubble-flashing dynamics based on mass exchange between the bubble and the bulk water in the water phase is presented. Analytical methods for the steam-void dynamics are developed by considering two alternative models for bubble–mass exchange rate, i.e. distributed and lumped parameter models. The water-level swell dynamics are then determined by combining bubble flashing, steam void and boiler dynamics. A small boiler plant was constructed and experimental work was carried out by applying a step change on the valve position for various boiler pressures.
Transfer-Function Identification Using a Complex Curve-Fitting Technique
Authors: Mannetje J. J. 't
Published: February 2007

The mathematical analysis and synthesis of linear-dynamic systems, based on experimental test results, often requires that the frequency response of the system be fitted by an algebraic expression. The form in which this expression is usually desired is that of a ratio of two frequency-dependent polynomials.

In this paper, a method based upon the minimization of the weighted sum of the squares of the differences between the measured data and the approximating function is presented as a means for the evaluation of the polynomial coefficients of the approximating function.

The computer programme used will be discussed and the modifications that improve the accuracy of the calculated coefficients, although the data points may be subject to measurement inaccuracies.
Experimental Investigation of the Parameters Affecting the Castor Stability of Road Wheels
Authors: Roe G. E. , Thorpe T. E.
Published: February 2007

The experimental testing of a model castoring wheel on a moving road surface is described. The stability of this steerable wheel was investigated as a function of various geometrical and physical parameters. A most important parameter was found to be the lateral stiffness of the system relative to the steering axis. Previous work has explained instability in terms of tyre behaviour, notably for aircraft landing gear, but in these tests a tyre-less wheel was used in an attempt to find a more fundamental cause. It was concluded that the overall lateral stiffness of the wheel system, of which tyre stiffness is one component, is important. The graphical results form a basis for improving the design of motorcycle and motor car front wheel assemblies.
Traction, Load and Film Thickness in Lightly-Loaded Lubricated Point Contacts
Authors: Dalmaz G. , Godet M.
Published: February 2007

Theoretical results, i.e. pressure distribution, load and traction for given film thicknesses, were obtained for rigid point contacts under equiviscous and piezoviscous conditions. Reynolds' boundary conditions are used and integration domain is shown to sizeably influence traction and load. Tests were conducted for a contact formed by a sphere and a transparent fixed plane for light and medium loads and for four oils of identical viscosity, but of different nature. The results obtained cover the equiviscous and piezoviscous hydrodynamic and elastohydrodynamic ranges. Good correlation between theoretical and experimental results is obtained in the first two regimes. Traction measurements did not allow us to differentiate between the rheological behaviour of straight mineral oils and oils highly loaded with polymers. Starvation observed in this study leads to a flattening of the contact zone and to an increase of the traction force.
Balancing of Flexible Shafts Rotating in Massive Flexible Bearings
Authors: Parkinson A. G.
Published: February 2007

A process of modal balancing has been developed in recent years for rotors whose modal deflection shapes ψ1( x), ψ2( x), …, are orthogonal. If a shaft is rotating in massive flexible bearings, these shapes are not orthogonal, so that the correctness of modal balancing for such rotors requires investigation. It is shown that modal balancing is permissible, provided that the functions ψ1( x), ψ2( x), …, are linearly independent and not necessarily orthogonal. The linear independence of the modal deflection shapes is proved for many forms of flexible support.
Tensile Stiffness of a Thermoplastic Reinforced with Glass Fibres or Spheres
Authors: Ogorkiewicz R. M. , Weidmann G. W.
Published: February 2007

Stiffness under uniaxial tension of injection-moulded polypropylene was found to increase much more rapidly with the addition of glass fibres than with the same amounts, by weight, of glass spheres and to decrease in both cases with strain. The observed increases in stiffness due to the fibres correlated closely with the results obtained from a simple model of a two-phase material, when allowances were made for the apparently low degree of alignment of the fibres which decreased with increasing fibre content. The stiffening effect of the fibres was virtually constant over the strain range considered. The lower increases in stiffness due to the glass spheres also correlated with the results obtained from the simple model but only for strains of less than 0.5 per cent: at higher strains the inclusion of glass spheres reduced the stiffness of the polypropylene.
An Improved Method for Calculating the flow in Turbo-Machines, Including a Consistent loss Model
Authors: Bosman C. , Marsh H.
Published: February 2007

The basic principles of the through-flow theory of turbomachines are described and an improved method of analysis is developed which includes a consistent loss model. The application of this new method requires only a minor modification to existing computer programs for calculating turbomachinery flow patterns.
Thermal Resistance and Directional Index of Pressed Contacts between Smooth Non - Wavy Surfaces
Authors: O'Callaghan P. W. , Probert S. D.
Published: February 2007

More than 800 measurements of the thermal resistance for seven fully specified single contacts between non-wavy surfaces of both metals and non-metals in vacua (∼10−5torr) have been obtained and analysed. The effects of period of heating, vacuum pressure, thermal and load cycling, mean contact temperature and heat flux were also determined. Previous correlations obtained using data for rougher surfaces in contact were corroborated. For fully bedded-down contacts, i.e. the majority encountered in engineering practice, the deformation behaviour under load is elastic. Theories based on plastic deformation of the asperities are only applicable to the first loading of freshly assembled contacts.
An Analytical Study of the Compression Ignition Characteristics of H2-O2-N2 Mixtures in a Reciprocating Engine
Authors: Karim G. A. , Rashidi M. , Taylor M.
Published: February 2007

A large portion of the literature about the use of hydrogen as a fuel in air-breathing reciprocating engines is devoted to the problems of auto-ignition and knock. Operation with oxygen-enriched air or pure oxygen, which in principle can reduce or even eliminate the production of oxides of nitrogen, is expected to be potentially more troublesome in this respect. The paper describes an analytical approach, incorporating detailed chemical kinetics, to the combustion of H2-O2-N2 mixtures in a reciprocating engine. The role of various operating parameters was determined primarily in relation to the length of the ignition delay and the associated peak values of cylinder pressure and temperature. Also, the extent of production of oxides of nitrogen in the exhaust was examined in terms of cycle parameters and the oxygen index of the charge.
A Three-Dimensional oil film Temperature Distribution in Tilting Thrust Bearings
Authors: Tieu A. K.
Published: February 2007

The oil film temperature and pressure distributions of the finite width Michell tilting thrust pad are determined from a numerical scheme based on the finite element method. These computed results correlate very well with those obtained from the experiment.
A Reference Stress Approach to Creep Bending of Straight Tubes
Authors: Fairbairn J.
Published: February 2007

Reference-stress parameters, based on the Norton constitutive equation, are developed for creep bending of circular and elliptical tubes. The parameters are presented in the form of a design chart.

The reference stress methods apply also to other simple constitutive equations of the power law, exponential and hyperbolic sine forms, and also to two complex equations describing creep behaviour over the entire range from primary to tertiary. In these equations the functions of stress and time are not separable and reference stress techniques provide a convenient method of evaluating stationary stress distributions and investigating the variation of these stresses with time.

Aluminium alloy tubes were creep tested with cyclic uniform bending moments. Creep strains to fracture were measured by an end-rotation method.

The creep behaviour of the tubes was well predicted by reference-stress cyclic tensile creep tests.
Separation Cavitation in Lightly Loaded Fluid Film Bearings with Both Surfaces in Motion
Authors: Taylor C. M.
Published: February 2007

For lightly loaded fluid film bearings in which gaseous cavitation occurs, application of the continuity boundary condition at the liquid-gas interface is not satisfactory. Two alternative boundary conditions have been postulated. The purpose of this paper is to examine the separation boundary condition; in particular, the effect of both bounding surfaces being in motion is studied. This situation might be used as a basis for experimental work designed to select the most appropriate boundary condition for lightly loaded bearings.

In Part 2, the boundary condition is used to analyse the cylinder-plane and journal bearing configurations. The theoretical predictions for the operating parameters are examined to see if their magnitudes and/or trends could be used for comparing the available cavitation boundary conditions.
The Effect of Inlet Disturbances on Turbulent Pipe Flow
Authors: Weir J. , Priest A. J. , Sharan V. K.
Published: February 2007

Disturbances near the entry to a pipe are shown to effect significantly the development of the turbulent velocity profile. The attainment of a ‘fully developed’ profile at a Reynolds number of 4 × 105 takes rather longer than is often assumed. Consequently, some care is required when designing test facilities with entry pipes (or channels) providing inlet conditions for internal flow component investigations.
Fluctuating Lift Coefficient for a Circular Cylinder in Cross Flows
Authors: Kacker S. C. , Pennington B. , Hill R. S.
Published: February 2007

Fluctuating lift forces experienced by cylinders of diameters 1, 1.125, 2, 3 and 4 in, and length-to-diameter ratios ( l/d) of 0.25 to 9 have been measured for Reynolds numbers in the range Re = 104to 2.5 times 105. Fluctuating lift and drag coefficients for the limiting case of l/d ŕ 0 were obtained by integrating measured values of the fluctuating surface pressure at points distributed around a horizontal section of the tube. At lower Reynolds numbers, lift coefficients for cylinders having l/d < 1 were found to agree within the limits of experimental accuracy with the values obtained by surface pressure measurements. However, at the Reynolds number of 105, the lift coefficient for cylinders of l/d = 0 were much higher than the lift coefficients for cylinders of l/d = 1; this clearly demonstrates the incoherence of the flow at Re = 105.

A measure of the extent to which vortex shedding is in phase along the length of a tube is obtained as a length scale for the coherence of vortex shedding. This was inferred from the variation of the measured value of the lift coefficient as a function of l/d. Within this length scale there is a high degree of correlation between signals from two points. Direct measurement of the length scale obtained by measuring u' correlations gave a value of the same order of magnitude but some 50 per cent lower than the length scale obtained from the measurements of the lift coefficient.
Film Rupture for a Lubricated Cylinder Lightly Loaded against a Plane
Authors: Taylor C. M.
Published: February 2007

Two alternative approaches for considering gaseous cavitation in lightly loaded bearings are examined for the case of a lubricated cylinder sliding against a plane. Despite the disparate natures of the methods, it is shown that essentially similar design predictions are forthcoming. This, however, does not give an insight into the physical understanding of the situation.
The Lubrication of Porous Elastic Solids with Reference to the Functioning of Human Joints
Authors: Higginson G. R. , Norman R.
Published: February 2007

The paper describes computational and experimental results for a simple mechanical model which has some features in common with load-bearing human joints. The normal approach of two rigid solids, one of which is covered by a layer of flexible porous material, is analysed; the gap between the bodies is filled with a viscous fluid. The rate of approach of the bodies is calculated and measured. Agreement between experiment and calculation is quite good, and some tentative conclusions are drawn about the lubrication of human joints, particularly in connection with the role played by the permeability of the cartilage layer.
A Critical Review of the Theorems of Thermodynamic Availability, with Concise Formulations
Authors: Haywood R. W.
Published: February 2007

In the study of availability, an evaluation of the effects of irreversibility on work output or input is of equal importance to the derivation of the expressions for reversible work reviewed in Part 1 of this paper (see last issue). In Part 2, means of evaluating these effects in a simple way are reviewed, both as regards the local and overall effects of irreversibility in multi-process plant. A critical, historical review of the entire subject appears in Appendix 4.