bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Cold-Drawing on the Yield and Flow Behaviour of OFHC Copper under Combined Stress
Authors: Holloway G. , Shelton A.
Published: February 2007

Tests under combinations of tension, torsion and internal pressure have been performed at constant stress ratio on oxygen-free high-conductivity (OFHC) copper, previously annealed and then subjected to progressive reductions in the plug-drawing process.

The influence of cold-drawing was investigated by means of six reductions in area up to 81 per cent and this showed marked changes in the creep behaviour. Logarithmic creep no longer occurred and, in contrast to the annealed material, creep was observed at stresses well below yield when the latter is defined by the backward extrapolation method. The creep rate accelerated rapidly as the yield stress was approached and the creep strain became large compared with the instantaneous strain.

Under axial tension—internal pressure, symmetrical yield loci tending progressively towards the Tresca criterion were found for reductions up to 42.4 per cent. Asymmetry developed at the largest reduction and, in general, the normality rule was obeyed in subsequent plastic strain behaviour for all tests.

Under axial tension—torsion and internal pressure—torsion, almost identical elliptical yield loci were found for each reduction. These also tended towards the Tresca criterion for reductions up to 42.4 per cent and distortion was only observed at the largest reduction. Again, the normality rule was obeyed.

Yield criteria derived from the theory of Edelman and Drucker were in good agreement with experiment over all yield loci. Hill's theory showed good agreement with experiment under tension—torsion, except for the largest reduction, but was inadequate for those axial tension—internal pressure tests not in agreement with the Maxwell–Mises yield criterion.
Transient Response of the Miniature, Reversed Stirling-Cycle, Cryogenic Cooling Machine—An Empirical Approach
Authors: Organ A. J.
Published: February 2007

By regarding the ideal thermodynamic cycle as being artificially separated from the hardware, and by treating the former as a simple energy flux path, an energy-rate balance is set up for the miniature, reversed-cycle, Stirling cooling machine. Account is taken of thermal energy storage and release rates corresponding to the rates of change of temperature of regenerator and cylinder walls. There results a first-order, linear differential equation. Solutions are obtained numerically using the parameters of a tentative cooler design. The solutions are presented in the form of curves of temperature ratio, τ (=Tc/Te), against time, t, at uniform angular speed. Regenerator inefficiency, Ie, emerges as the parameter that is most critical in the achievement of desired heat-lifting capacity at cryogenic temperatures. For a machine of given thermal mass, both Ie and ηc (cycle efficiency relative to corresponding Carnot efficiency) strongly influence the cool-down rate. The treatment is capable of application to Stirling machines operating as prime movers.
Design of an Anthropomorphic Manipulator for Industrial Application
Authors: Vukobratović M. , Hristić D.
Published: February 2007

This paper presents a two-level manipulation concept, featuring minimal configuration for attaining the working point in the working space without obstacles, and the compensating part in the form of a gripper, by means of which the problem of the corresponding orientation is fully solved.

An industrial manipulator based on this concept is realized and the results of experimental trials using a microprocessor controller are given.
Effect of Surface Distortions upon the Thermal Resistance of Pressed Contacts
Authors: Al-Astrabadi F. R. , Jones A. M. , Prober S. D. , O'Callaghan P. W.
Published: February 2007

The thermal resistances of two pressed contacts, which under isothermal conditions were respectively between (i) a flat and a convex surface and (ii) nominally flat surfaces, have been predicted and the deductions compared with experimental measurements. The analysis evolved is useful in the design of thermal rectifiers.
Steady-State and Dynamic Behaviour of Multi-Recess Hybrid Oil Journal Bearings
Authors: Ghosh M. K. , Majumdar B. C. , Rao J. S.
Published: February 2007

A theoretical analysis of the steady-state and dynamic characteristics of multi-recess hybrid oil journal bearings is presented. A perturbation theory for small vibrations is used to solve an incompressible, finite journal bearing with a time-dependent term. Load capacity, attitude angle, friction parameter, stiffness and damping coefficients are evaluated for a capillary-compensated bearing.
Drop Coagulation in Cross-Over Pipe Flows of Wet Steam
Authors: Williams J. J. E. , Crane R. I.
Published: February 2007

A numerical technique is developed for predicting the evolution of drop-size spectra in turbulent, two-phase pipe flows. While relevant to many chemical engineering processes, it is applied here to the crossover pipes of a nuclear wet-steam turbine.

Valid expressions for turbulent coagulation rate in the cross-over pipes are available only for drops below about 10 μm diameter in the core flow, and for those exceeding about 20 μm near the pipe wall. Using these expressions, it is found that the rapid formation of large drops in the core allows prediction for only a small fraction of the typical residence time in the pipe, but near the wall the volume median diameter of an initial 20 μm monodispersion can double in 100 ms. Further work is required to validate the technique and extend it to handle the intervening ranges of drop size and turbulence parameters.
Blade Bending Vibration Induced by Wakes
Authors: Matsuura T.
Published: February 2007

The amplitude of vibration of the blades of a compressor rotor due to upstream periodic wakes is investigated. Good agreement is found between the calculated results, using the unsteady force coefficients given by Smith (1)‡ and those obtained by experiment.
Static Stability Behaviour of Plate Elements with Non-Uniform, in-Plane Stress Distribution
Authors: Datta P. K.
Published: February 2007

The results of analytically and experimentally determined buckling loads of a rectangular plate, subjected to partial edge loading and mixed boundary conditions, are presented.
An Experimental Investigation of the Stability of Spiral Vortex Flow
Authors: Sorour M. M. , Coney J. E. R.
Published: February 2007

The hydrodynamic stability of the flow in an annular gap, formed by a stationary outer cylinder and a rotatable inner cylinder, through which an axial flow of air can be imposed, is studied experimentally. Two annulus radius ratios of 0.8 and 0.955 are considered, representing wide- and narrow-gap conditions, respectively. It is shown that, when a large, axial pressure gradient is superimposed on the tangential flow induced by the rotation of the inner cylinder, the characteristics of the flow at criticality change significantly from those at zero and low axial flows, the axial length and width of the resultant spiral vortex departing greatly from the known dimensions of a Taylor vortex cell at zero axial flow. Also, the drift velocity of the spiral vortex is found to vary with the axial flow. Axial Reynolds numbers, Rea, of up to 700 are considered.
Flow in Centrifugal Compressor Impellers: A Hub-to-Shroud Solution
Authors: Goulas A. , Baker R. C.
Published: February 2007

The matrix through-flow analysis is applied to the hub-to-shroud stream surface of a centrifugal compressor impeller. The k-ε turbulence model is used to calculate the stress tensor necessary to obtain a dissipation force. Integration of the streamwise equation of motion yields an entropy field in agreement with the dissipation force. The results are compared with isentropic flow solutions. Furthermore, the effect on the velocity field of the initial velocity profiles and turbulence levels at the eye of the impeller are studied, as is the influence of the shroud on the flow.
Dynamic Stability of Off-Shore Structures
Authors: Thomas J. , Abbas B. A. H.
Published: February 2007

This paper presents the results of an investigation of the dynamic stability of steel off-shore platforms subjected to vertical and horizontal forces. A computer program based on the finite-element method was developed to calculate the frequencies of vibration, the buckling load, and the regions of dynamic instability.
Generation of Streamwise Vorticity in an Asymmetric Swirling Flow
Authors: Greitzer E. M. , Hawthorne W. R.
Published: February 2007

A direct analogy is drawn between the streamwise vorticity generated in an asymmetric swirling flow and that developed in secondary flow in a curved duct.
Effects of Cathode-Mandrel Surface Irregularities on the Mechanical Properties and Structure of Electroformed Iron Foil
Authors: Crichton W. A. , McGeough J. A. , Thomson J. R.
Published: February 2007

Iron foil, of thicknesses between 003 and 0.15 mm has been electroformed at a current density of 30 A/dm2 and an electrolyte temperature of 100°C upon cathodes of surface roughness ranging from 0.04 to 4.4 μm Ra. The surface roughnesses of the face of the foil formed adjacent to the cathode, and of that electrode, are similar. The roughness of the reverse anodic face increases with increasing foil thickness, due to the increase in size of the crystal growth sites. The hardness of the cathodic face of the foil is unaffected by either cathode surface roughness or foil thickness. The hardness of the anodic face increases with both increasing cathode surface roughness and decreasing foil thickness, due to corresponding changes in grain size. A slight net decrease in tensile properties with increasing cathode surface roughness is attributed to the greater amount of stress concentration borne by the rougher foils. Young's modulus for the foil is not affected by cathode surface roughness.

The electroforming of foil upon a mandrel surface carrying an isolated V-shaped scratch, 0.14 mm deep and 0.28 mm wide, has also been studied by numerical and experimental methods. The cathodic surface of foil is found to adopt the shape of the scratch whilst its upper side becomes level. The effect upon the geometric configuration of the foil depends upon the relationship between current efficiency and current density for the electrolyte, and on the polarisation (overpotential) characteristics at the mandrel surface.
Measurements and Calculations of the Isothermal Flow in Axisymmetric Models of Combustor Geometries
Authors: Green A. , Whitelaw J. H.
Published: February 2007

Measurements with laser-Doppler anemometry and calculations with finite-difference solutions of the time-averaged Navier-Stokes equations and a two-equation turbulence model, have been obtained for the turbulent isothermal flow in an axisymmetric geometry related to gas-turbine combustors. The results quantify the flow patterns in the arrangement and demonstrate the extent to which they can be represented by calculation. The discrepancies between measured and calculated results are shown to depend more on the distribution of grid nodes than on the turbulence model. Even with a distribution of nodes which is considered to be near optimum, differences between measurement and calculation exist and are particularly significant in the regions of steep velocity gradient immediately downstream of the incoming annular jet. The general trends are, however, correctly represented, and the calculation method has been used to determine the influence of the width of the annulus and of the jet gap. The results provide information of relevance to the development of calculation methods for real combustors, and this is discussed.
An Inertial Relaxation Method of Curing Numerical Instability in Prediction of Flows Influenced by Severe Body Forces
Authors: Ideriah F. J. K.
Published: February 2007

Contributions intended for publication as Research Notes should preferably be limited in length to 1000 words and two illustrations, and should be addressed to the Manuscript Section, The Institution of Mechanical Engineers, 1 Birdcage Walk, Westminster, London SW1H 9JJ
Elastic, Finite Deflection and Strain Rate Effects in a Mode Approximation Technique for Plastic Deformation of Pulse Loaded Structures
Authors: Symonds P. S.
Published: February 2007

A general scheme is proposed for including effects of elastic deformation, finite geometry changes, and strain rate sensitivity in a simple approximate scheme for estimating maximum transient and permanent deformations in structures subjected to load pulses of high intensity. The method is applied here to fully clamped beams of mild steel subjected to explosive loading. Comparisons are made between estimates from the present method and test results, as well as with estimates by various rigid-plastic methods and (to a limited extent) with results from numerical methods.
The Turbulent Flow of Two-Phase Mixtures in Horizontal Pipes at Low Reynolds Number
Authors: Chisholm D.
Published: February 2007

Contributions intended for publication as Research Notes should preferably be limited in length to 1000 words and two illustrations, and should be addressed to the Manuscript Section, The Institution of Mechanical Engineers, 1 Birdcage Walk, Westminster, London SW1H 9JJ
Turbulent Flow over a Plane Normal Wall
Authors: Fraser S. M. , Siddig M. H.
Published: February 2007

A DISA two-colour back-scatter laser Doppler anemometer was used to take measurements of mean and fluctuating velocities of an air flow of 4.6 × 104 Reynolds number in a short duct with a normal wall fixed to one side. Walls of 30 and 20 mm height were investigated and the resulting flow patterns were compared.
Natural Transition of Boundary Layers—The Effects of Turbulence, Pressure Gradient, and Flow History
Authors: Abu-Ghannam B. J. , Shaw R.
Published: February 2007

Natural transition of boundary layers is investigated for a flat plate in a low-speed wind tunnel with free-stream turbulence intensities ranging from 0.3 to 5 per cent, and with pressure-gradient histories typical of turbomachinery blades without separation.

Empirical relationships are proposed for the prediction of the start and end of transition, as well as the development of the boundary layer during transition. These relations are based on the recent measurements made with a hot-wire anemometer, and augmented, mainly for the start of transition, by results of previously reported research.

Finally, these experimental relationships are used in conjunction with well established methods to predict the entire unseparated boundary layer. To utilize the prediction, all that is required is a knowledge of the free-stream turbulence level and the free-stream velocity distribution, which itself can be derived from potential flow theory.
Some Implications of Dundurs' Theorem for Thermoelastic Contact and Crack Problems
Authors: Barber J. R.
Published: February 2007

It is well known that a simply-connected isotropic elastic body in a state of plane strain and with traction-free boundaries remains free of stress if it is subject to steady-state heat conduction. A recent theorem due to Dundurs shows that in this state the curvature of any initially straight line element is proportional to the heat flux across the line element.

A closely related three dimensional result is proved for the sum of the principal curvatures of planes parallel to the faces of an infinite thick plate.

These results have certain implications for thermoelastic crack and contact problems. For example: (i) thermal distortion has no effect on the contact pressure distribution at an insulated interface or at an interface between two similar materials, (ii) the thermal stress in a cracked solid depends on the temperature field only through the value of a certain constant related to the average temperature difference across the crack, (iii) steady-state heat flow induces no stresses in an axisymmetric thick plate containing an external crack.
A Determination of Cavitation Interfaces in Fluid Film Bearings Using Finite Element Analysis
Authors: Hayashi H. , Taylor C. M.
Published: February 2007

The location of both rupture and reformation boundaries in liquid film bearings is important in determining overall performance characteristics. Finite difference approximations have been most widely used in the numerical analysis of hydrodynamic bearings, and the problem of determining cavitation interfaces may be trivial or extremely complex depending upon the physical model adopted. For some situations finite element analysis may offer an advantage and this possibility is investigated here.
Surface Vorticity Modelling of Separated Flows from Two-Dimensional Bluff Bodies of Arbitrary Shape
Authors: Lewis R. I.
Published: February 2007

A method is presented for the computation of separated flows past two-dimensional bodies of arbitrary shape. The surface vorticity technique is used to model the body flow and is combined with vorticity generation, shedding, and convection schemes which simulate the separation regime. The method is applied here especially to bluff body flows and illustrative examples have been limited to symmetrical or half plane flows only. An extension of the technique to free streamline flows is described and illustrated by comparison with the classical solution for free streamline separation from a flat plate.
Analysis of a Hydrodynamic Thrust Bearing Operated under Unsymmetrical Conditions
Authors: Safar Z. S.
Published: February 2007

Analytical solutions for the pressure, load capacity, friction, and flow of a Michell thrust bearing in asymmetric operation are presented. The flow developed in this bearing is asymmetric because the surface rotation axis is offset from the bearing sector axis. These bearings are used with circular saws to constrain transverse displacement of the blades. The pressure, load capacity, friction, and flow increase significantly with offset of the bearing and rotation axes, and they are sensitive to the sector orientation. Results are presented for two sector angles and a complete range of orientations.
Analysis of Hydrodynamic Journal Bearings Having Non-Newtonian Lubricants (Prandtl Model) by a Finite Element Method
Authors: Tayal S. P. , Sinhasan R. , Singh D. V.
Published: February 2007

Additives are used to improve the performance of commercial lubricants. These lubricants behave like non-Newtonian fluids (shear thinning or shear thickening). The effect of the nonlinear behaviour on the performance characteristics of finite width journal bearings is investigated using the Prandtl model. The finite element method, using Galerkin's technique, has been used to solve the Navier-Stokes equations in cylindrical coordinates, representing the flow-field in the clearance space of a bearing using Newtonian fluids, and the non-Newtonian effect is introduced by modifying the viscosity term for the model in each iteration. The results applicable to shear-thinning (pseudoplastic) and shear-thickening (dilatant) lubricants are compared with the established results for Newtonian lubricants.
The Effects of Projectile Speed and Medium Resistance in Ricochet off Sand
Authors: Baif Y. L. , Johnson W.
Published: February 2007

It has been observed experimentally that when a sphere ricochets off water or sand the critical impact angle depends on the impinging velocity.

To explain this, a model is developed which takes into account the weight of the sphere and the static resistance of the medium into which penetration occurs. The proposed model can also treat processes in which the angle of impact is large and where the velocity of the sphere undergoes considerable change. Projectile trajectories which have been calculated for various conditions are presented and discussed. Numerical results for steel, aluminium alloy, and lead spheres are in good agreement with such experimental results as are available.
Energy Dissipation in Gyromechanics through the Concept of Intervalwise Rigidity
Authors: Rimrott F. P. J.
Published: February 2007

In the interpretation of the energy sink hypothesis the real body has in the past been approximated by two or more rigid bodies, connected in such a fashion that damping forces acting between them dissipate energy. This approach suffers from several shortcomings, and a more rational treatment of the problem can be achieved by assuming intervalwise rigidity.
A Study of Diffuser/Rotor Interaction in a Centrifugal Compressor
Authors: Fisher E. H. , Inoue M.
Published: February 2007

Experimental flow data recorded on a low speed centrifugal compressor rig are compared with theoretical predictions of the diffuser field. Results for four diffuser geometries are presented covering variation of the blade number, stagger angle, and radial separation of the rotor and diffuser. The theoretical predictions are based on an extension of the Martensen surface singularity theory.

The diffuser is found to play a major role in establishing the circumferential variation in the mean flow at impeller outlet. Large pitch wise variations are observed, which may be explained by consideration of the flow round the leading edges of the diffuser blades. Experiments and potential flow theory show good agreement, except for cases where the diffuser shows signs of separation. These are clearly identified from the theoretical predictions by Carter's lift coefficient criterion.

Although the absolute flow at rotor outlet is markedly time-dependent owing to the passage of the rotor, it would appear that the averaged flow conditions may be predicted by the steady-state singularity program. Unstalled diffuser flows are accurately predicted and stalled flows, which are generally to be avoided, may be anticipated from the lift coefficient criterion. The designer thus has the option of reducing pitchwise velocity and pressure variations at rotor outlet to acceptable amplitudes.
Analytical Theory of Three Dimensional Flow in Centrifugal Compressors
Authors: Bosman C.
Published: February 2007

Inviscid, compressible flow along a rotating elemental stream-tube is taken as a model for flow through a turbomachine blade passage. For this model an analytic expression for the relative secondary vorticity of the flow is derived which permits the mean stream-surface twist about the tube axis to be evaluated. This twist implies a migration of the fluid particles from one tube corner to the contiguous tube corner, a flow feature suppressed by all existing stream-sheet flow calculations in turbomachine blade rows. The analysis is applied to a centrifugal compressor configuration where the effects on the secondary flow of hub/shroud geometry, blade shape, compressibility, and meridional diffusion are investigated. The stream-surface twist, not being primarily dependent upon the elemental nature of the stream-tube is taken as a measure of stream-surface twist and consequent surface flow migration in finite blade passages. The levels of twist obtained from the analysis are similar to those obtained in three dimensional flow calculations using primitive variables as illustrated by Bosman (1) (2)‡ and show that existing streamsheet and streamsheet stacking methods, all of which suppress the relative passage vortex are an inadequate model of the flow in centrifugal compressors. The analysis clearly shows that contrary to common assumption, centrifugal compressor impellers are capable of generating a passage vortex in the same direction as that of blade rotation.
An Estimate of the Effect of Back Spin on the Critical Angle in the Unyawed Ricochet of a Cylinder
Authors: Bai Y. L. , Johnson W.
Published: February 2007

A method is described for giving an estimate of the effect of back spin on the critical angle for the ricochet of a cylinder off water. The method incorporates both the spin and the weight of the projectile into the Birkhoff et al theory, as described by Johnson and Reid (1) ‖ for a sphere. The differences and predictions concerning hydrodynamic pressure and lift, etc., are compared with those made by several other authors. A comparison of our new results with some available experimental results has also been made.
Dynamic Performance of Hydraulic Buffers of Unequal Rating in Series
Authors: O'Carroll M. J.
Published: February 2007

Standard hydraulic buffers are designed to produce a nearly uniform force so that the work load is equitably shared over the whole stroke. Such designs depend upon the impact mass to be presented to the buffer. If the actual impact mass is greater than the design value then the resulting force has a high peak at closure of the buffer. Occasionally impact conditions have two buffers of different mass-rating in series. This paper shows that such combinations behave like a single uniform-force buffer until one of them closes. The safe impact mass of the combination is established.
On the use of Equilibrium Axes and Body Axes in the Dynamics of a Rigid Ship
Authors: Bishop R. E. D. , Price W. G.
Published: February 2007

Although it is natural and usual to employ body axis in the theory of ship manoeuvring and directional stability, the motions concerned are performed in the ‘rigid body modes’ of hydroelasticity theory and the theory of seakeeping, in which equilibrium axes are used. The dynamics of a rigid ship can therefore be approached from two standpoints. The theory of body axes is summarized and the less familiar theory of equilibrium axes is developed in a simple way from first principles. The two approaches are then compared. The transformations that are needed to adapt hydrodynamic data for use with the two types of axes are examined. These are of considerable practical importance in view of the present scarcity of data.
Porous Retainers for Rolling Bearings
Authors: Gohar R. , So H.
Published: February 2007

A theoretical analysis is made for the lubrication of ball bearing retainers made of porous material. The results show that at low Sommerfeld reciprocals, the eccentricity ratio tends to unity with a high coefficient of friction. At a certain critical value of the reciprocal, a minimum friction occurs, thereafter followed by hydrodynamic operation. The critical value depends on the permeability parameter of the porous matrix and increases with its porosity. Experiments suggest that at low Sommerfeld reciprocals or with the oil supply coming only from the retainer pores, mixed film lubrication occurs, friction being less than that obtained theoretically. Such a lubrication regime would still allow sufficient oil to be carried by the balls to the races for their lubrication.
Prediction of Stall Type (Abrupt or Progressive) for a Single Compressor Rotor
Authors: Al-Daini A. J.
Published: February 2007

The performance of four single compressor rotors in rotating stall is described. Using an earlier work, Al-Daini and Railly (1)‡, theoretical maps of performance are constructed using a blockage factor αm (related to losses) for each of the tested rotors. It is shown that these maps may be used to give a good indication of whether a single compressor rotor will experience progressive or abrupt stall.
An Interaction Effect Consideration in Cumulative Damage in Metals Due to Creep
Authors: Bui-Quoc T. , Biron A.
Published: February 2007

An interaction effect between stresses is considered in cumulative creep damage tests with two levels to explain the deviation of the summation of time ratios from unity. With the cumulative damage concept previously suggested for the creep process, empirical relations have been established in order to take this effect into account. The parameters considered are the difference between stresses and the damaging time ratio. Essentially, this approach gives a theoretical value of the sum of time ratios greater than unity for decreasing stresses, whereas this value is smaller than unity for increasing stresses. The correlation between predictions and some published experimental results is discussed.
Cyclic Softening and Over-Softening of a 1 Percent Cr-Mo-V Steel at Elevated Temperature
Authors: Gardiner T.
Published: February 2007

Detailed results are presented of shear stress range variation during cycling of 1 per cent Cr-Mo-V test specimens within controlled total shear strain limits at 565°C. The cyclic softening induced during continuous and two-step cycling are compared. A saw-toothed pattern for the strain was maintained for each cycle giving a constant straining rate. Normal cyclic softening was found throughout the tests but another phenomenon of over-softening occurred during the two-step tests when high strain cycles took place first. A permanent history effect had been produced within the steel. This over-softening did not depend on the straining rate of the cycling or the magnitude of the initial cycle ratio. The generally accepted method of determining cyclic stress-strain curves using continuous cycling is shown to be invalid when over-softening is present.
A Novel Technique of wire Drawing
Authors: Hashmi M. S. J. , Symmons G. R. , Parvinmehr H.
Published: February 2007

In the conventional wire drawing process the reduction is achieved by pulling the wire through a tapered die. The minimum bore size of such a die is always smaller than the inlet wire diameter. A suitable lubricant is used to reduce the die wear and drawing load and to produce a good surface finish. Nevertheless, the problem of die wear and wire breakage during start-up is always present.

In this paper a new technique of wire drawing is being reported which eliminates the problem of wear and breakage during start-up and also the need to have the diameter of the leading end of the wire reduced for easy insertion through the die. The reduction of the wire diameter is affected by means of the hydrodynamic action of a polymer melt lubricant in conjunction with a long tapering tube, the diameter of the tube being greater than the nominal wire diameter. Reductions in area of up to 21 per cent can be obtained in one single pass using this dieless reduction unit.
The Preliminary Analysis of Axial Turbines by a Simplified Throughflow Procedure
Authors: Mitchell N. A.
Published: February 2007

A new iterative scheme for calculating the axisymmetric flow through a turbine, which converges to a given value of turbine exit pressure, is described. It is intended to be used at a preliminary stage in a turbine design procedure instead of a one-dimensional calculation, since it enables spanwise variations of turbine performance to be calculated with reasonable accuracy and with minimum data preparation in approximately 1/30 of the computer time of a conventional axisymmetric calculation. The method solves the full axisymmetric flow equations on three streamlines through the machine at hub, midspan, and tip, although an approximation is introduced regarding the curvature of the centre streamline. Agreement with a full streamline curvature analysis is shown to be good, and comparisons with a one-dimensional Ainley-Mathieson based performance calculation show how the method is sensitive to root and tip behaviour.
Static Deflections and Stresses in Sandwich Beams under Various Boundary Conditions
Authors: Sharma S. R. , Rao D. K.
Published: February 2007

Expressions for deflections and stresses of sandwich beams are derived for all practically important boundary conditions for both uniform as well as concentrated loads. The energy method is used in deriving the differential equations governing deflection which are then solved by using the Laplace transform method. The influence of system parameters on deflections and stresses is illustrated for important boundary conditions by means of graphs and formulae. These investigations reveal that riveting an edge can reduce the deflections and stresses by as much as 40 per cent.
The Normal Impact of square Section long rods on ‘Rigid’ and ‘Soft’ Targets
Authors: Sengupta A. K. , Wigglesworth C. J. , Ghosh S. K. , Johnson W. , Reid S. R.
Published: February 2007

Studies of long rod impact are almost invariably associated with rods of circular cross-section, but in this paper experiments are described in which square cross-section long rods were made to impinge normally on nominally rigid target plates as well as on ‘soft’ targets of comparable strength. Plasticine has been used as the model material to simulate metallic projectiles and targets. The various modes of deformation and flow associated with square section rod projectiles have been identified and compared with those observed earlier by Johnson et al. (5)¶ in a study using long rods of circular cross-section.
The Prediction of Film Thickness in a Mechanical face Seal with Circumferential Waviness on both the face and the seat
Authors: Ruddy A. V. , Dowson D. , Taylor C. M.
Published: February 2007

The effect of two-period waviness on both the face and the seat of a mechanical face seal is examined theoretically in this paper. A closed-loop cyclic solution of the two-dimensional Reynolds' equation including squeeze-film effects is described. Results for a 45 mm diameter seal are presented which show that squeeze-film effects play an important role in protecting the fluid-film over parts of the cycle where the entraining effect is small. The analysis can be extended to allow for misalignment of the sealing faces and for the incorporation of mixed-lubrication theory.
The Dynamic Response of Railway Track to High Frequency Vertical Excitation
Authors: Grassie S. L. , Gregory R. W. , Harrison D. , Johnson K. L.
Published: February 2007

Two new dynamic models of railway track are presented, one continuous and the other incorporating the discrete mass of the sleepers. These models include the effect of the railpads which exist between rail and sleeper on modern track, and are used to calculate both the response of the track alone and the contact force between a moving wheel and the rail. There is good agreement between calculation and experiment in the frequency range from 50 to 1500 Hz, and it is shown that the railpad is of fundamental importance in attenuating dynamic loads in this frequency range.
The Dynamic Response of Railway Track to High Frequency Longitudinal Excitation
Authors: Grassie S. L. , Gregory R. W. , Johnson K. L.
Published: February 2007

The dynamic response of railway track to longitudinal forces is investigated. A model is presented of the rail as a uniform infinite bar resting on a continuous support. There is good agreement in the frequency range 50–1500 Hz between experimental data and the response calculated using this model.

The support is significant up to a frequency of about 200 Hz, above which the rail is effectively a dashpot. The discrete nature of the support on sleepers is relatively unimportant. The track moves very much less under longitudinal forces than it does under vertical forces at these frequencies.
The Behaviour of Railway Wheelsets and Track at High Frequencies of Excitation
Authors: Grassie S. L. , Gregory R. W. , Johnson K. L.
Published: February 2007

The dynamical response in the frequency range 50–1500 Hz is investigated of a railway wheelset resting on the track and excited vertically, laterally and longitudinally at a point of contact. A mathematical model of a railway wheelset is developed which comprises a few simple components to which analytical methods can be applied. Good agreement is obtained between experimental data and calculations made using this model. For a given sinusoidal displacement imposed between wheel and rail, the contact force is in general greatest longitudinally and least laterally.
Transient Extinction of Counter flow Diffusion Flame
Authors: Saitoh T. , Ishiguro S.
Published: February 2007

A transient analysis was performed for extinction of the counter flow diffusion flame utilizing the assumptions of inviscid, incompressible, and laminar stagnation-point boundary layer flows. The unsteadiness was induced via linear time variation of the stagnation point velocity gradient. The physical meaning of the middle solution of the quasi-steady theory was clarified. The effects of acceleration and deceleration of the flow were examined and it was found that strong acceleration tends to support the flame up to a small Damkohler number, which implies that the flame strength becomes large for flames under acceleration.
Investigation of a Rotor Bearing Assembly Incorporating a Squeeze-Film Damper Bearing
Authors: Holmes R. , Dogan M.
Published: February 2007

Squeeze-film damper bearings, when properly designed, are a simple means of curbing instabilities and reducing vibration in rotor-bearing assemblies. This paper describes vibration tests carried out on a rigid rotor — flexible bearing test rig incorporating a squeeze-film damper; comparisons are made with theoretical predictions.
Non-Newtonian Lubrication Theory for Rough Surfaces: Application to Rigid and Elastic Rollers
Authors: Sinha P. , Shukla J. B. , Singh C. , Prasad K. R.
Published: February 2007

To predict the consequences of the interaction of the lubricant rheology with surface roughness, the stochastic theory of lubrication for Newtonian fluid is modified to take into account the non-Newtonian behaviour of the lubricant, by considering the power law model. Generalized forms of the Reynolds equation for two types of roughness arrangements, viz., longitudinal and transverse, are derived. These equations are subsequently used to study the lubrication characteristics of infinitely long rough roller bearings, and two particular cases, namely pure rolling (rigid surfaces) and rolling with elastic deformation, are discussed.
Effect of Surface Roughness on the Squeeze Film between Rotating Porous Annular Discs
Authors: Prakash J. , Tiwari K.
Published: February 2007

The analysis of the squeeze film between two rotating annular discs, one with a porous facing is extended to include the effect of surface roughness.

A detailed study of the squeeze film characteristics for a wide range of operating parameters is made to illustrate the effect of rotation and surface roughness and their interaction.
On the Possibility of Balancing Rotating Flexible Shafts
Authors: Bishop R. E. D.
Published: February 2007

Van de Vegte (1)‡ discusses the balancing of a flexible multi-disc rotor supported in two bearings, using two motorized balancing heads. The underlying idea of the motorized balancing head is used in the present paper, but with a completely different line of theoretical reasoning. Modal analysis suggests that, provided certain requirements as to the nature of the bearings are met, the approach described by van de Vegte may be unnecessarily complicated, in that only one motorized balancing head need be used, while neither the reference to ‘discs’ nor the restriction to two bearings may be needed.
A Method of Limiting Intermediate Values of Volume Fraction in Iterative Two-Fluid Computations
Authors: Carver M. B.
Published: February 2007

Multidimensional computational analysis of fluid flow is usually done by segmented iterative methods, as the equations sets generated are too large to permit simultaneous solution. Frequently the need arises to compute values for variables which must remain bounded for physical reasons. In two-phase computation, for example, the volume fraction is restricted to values between 0 and 1, but iterative procedures often return intermediate values which violate these bounds. It is fairly straightforward to prevent negative values, however no satisfactory method of imposing the upper limit has been published. A method of smoothly applying the limit in reversible fashion is outlined in this note.
The Role of Impregnants in Determining the Behaviour of Mechanical Carbon Sealing Rings
Authors: Rabah M A , Eldighidy S M , Azim A A Abdul
Published: February 2007

The lifetime of mechanical carbon sealing rings fitted into crude petroleum oil pumps can be increased by a factor of 43 by multiple impregnation with coal tar pitch. For single impregnation, epoxy resin yielded the largest improvement. The results were interpreted on the premise that properties such as viscosity, adhesion forces, and coking value determine the effectiveness of the impregnant. The proper selection of the impregnant and procedure of impregnation is dependent on the pumping pressure and oil properties.
The Role of Research in Man's Use of the Oceans
Authors: Adye A M
Published: February 2007

The contribution of research towards innovation and growth in ocean-related activities over past centuries is explored through a number of case studies. This historic view is amplified by some of the author's own experiences relating to the more recent development of offshore oil and gas resources.

Some implications from recent and current research programmes and scientific experiments are reviewed in an attempt to identify possible pointers towards future changes and developments in ocean-going operations.

The paper examines the motivation, organization and shaping of some current research activities, and concludes with some suggestions directed towards enhancing the national research effort and its potential contribution towards economic and responsible development of the oceans.
The Sensitivity of Heat Exchanger Calculations to Uncertainties in the Physical Properties of the Process Fluids
Authors: Haseler L E , Owen R G , Sardesai R G
Published: February 2007

The various processes occurring in shell and tube heat exchangers are examined for their dependence on the physical properties of the fluid streams. This dependence, coupled with estimates of likely uncertainties in the various properties, is used in developing a simple procedure for evaluating the resultant uncertainty in heat exchanger design calculations. Two case studies, which use a well-tested computer program, have shown that the above procedure adequately quantifies the uncertainties in the calculation of heat transfer area and pressure drop.
Increased Manufacturing Effectiveness in the Production of Steam Generating Equipment
Authors: Mclntyre J , Greenwood J H , Harper J L
Published: February 2007

The paper describes the reorganization of a factory producing steam generating equipment for electricity generation to enable it to meet their foreseen requirements up to the year 2000. Plant and working practices were updated by capital investment to improve the effectiveness of management systems and that of the work-force. As a result the output of the machine shop was increased by 30 per cent on 45 per cent less area with 42 per cent fewer machine tools and 35 per cent fewer indirect shop floor personnel. As a consequence, whereas two years previously the Company was consistently ranked sixth or seventh on price, now it is more often second.
The Application of a Production Database to Select Key Machined Components
Authors: Kilmartin B R , Leonard R
Published: February 2007

This paper is the first of two concerned with the selection of computer numerically controlled (CNC) turning and machining centres by use of a systems approach. The work is based on collaborative research carried out by Simon Container Machinery and the University of Manchester Institute of Science and Technology. The first paper describes how computer-assisted modelling was developed in order to identify ‘key’ machined components from a sales forecast for a defined product mix. The second paper discusses how data derived from these components were used to formulate the specifications and make the final selection on a number of CNC machine tools.
An Approach for Dynamic Analysis of Mechanical Systems with Multiple Clearances Using Lagrangian Mechanics
Authors: Bahgat B M , Osman M O M , Sankar T S
Published: February 2007

The paper develops a general procedure for the dynamic analysis of planar mechanisms with multiple clearance. The analysis mainly relies on determining the clearance angles βi at mechanism revolutes for each phase of the analysis. The governing equations of each clearance angle are developed using Lagrangian mechanics. The solution is obtained in the form of sufficient number of harmonic terms and used to evaluate systematically kinematic and dynamic quantities of the mechanism. A slider-crank mechanism with three revolute clearances is analysed to illustrate the procedure.
Performance Characteristics of Centrifugal Pumps When Handling Non-Newtonian Homogeneous Slurries
Authors: Walker C I , Goulas A
Published: February 2007

The change in performance characteristics of centrifugal pumps when handling fine granular or homogeneous type non-Newtonian slurries has been investigated using two different slurry pumps handling mixtures of coal/water and kaolin/water. A test loop was used which allowed pump performance to be determined at various pump speeds, with many different mixture concentrations and rheologies.

The test work indicated two main changes in the pump performance compared to the water characteristics: (i) a large drop in pump developed head at low flowrates (creating an unstable curve), and; (ii) a reduction in the pump efficiency at flowrates near the best efficiency point.

The results show that the pump performance is dependent on the slurry's rheological properties, with pump Reynolds number giving generally good correlation with the change in performance. Methods of performance correlation used for Newtonian fluids were found to give good results provided that a suitable value for the viscosity could be chosen.
Radioisotope Techniques for Problem-Solving in the Chemical Industry
Authors: Charlton J S
Published: February 2007

Radioactive isotope techniques are now being applied routinely to the study of a wide range of problems on industrial process plant. The expansion of these activities has been stimulated both by the comparative ease with which measurement can be carried out on full-scale plant and by the ability of radioisotope techniques to diagnose plant faults while the plant is still on-line. This latter attribute can result in substantial economic benefits in terms of saved down-time.

This paper reviews the ways in which radioisotopes are used by ICI to solve problems on large-scale process plants. Recognizing that the field of application is extremely wide attention has been concentrated upon those techniques which have been found to be of greatest use. This selection is made on the basis of the work spectrum of ICI's Physics and Radioisotope Services, an organization which each year carries out more than 1500 applications for customers both within and external to ICI. The techniques described fall into two major categories: sealed source techniques and methods involving radioactive tracers. Applications from each category are described and, where appropriate, indications of the resulting economic benefits are given.
The Problems of New Technologies in a Rapidly Changing Energy Scene
Authors: Hill John
Published: February 2007

After an analysis of the world energy scene the paper concentrates upon the problems of the energy industries in having to build few, but very large and complicated, units.
Experience Gained in Constructing and Commissioning Two Medium Sized Wind Turbines
Authors: Wilson R R , Brown A
Published: February 2007

James Howden have designed a 300 kW wind turbine specifically for use in isolated sites, with the first such machine being installed on Burgar Hill, Orkney. The Company were also responsible for supplying the Central Electricity Generating Board (CEGB) with an American design of wind turbine; this is the 250 kW machine which has been installed at Carmarthen Bay, Wales.

This paper outlines the design features of these two wind turbines and describes the difficulties encountered and the lessons learned in constructing and commissioning the machines.