bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas Flow in Pipes and Tunnels
Authors: Bartlett H , Whalley R
Published: February 2007

Gas flow through interconnected ducts and pipelines of varying lengths and cross-sectional areas is considered. The distributed-lumped parameter model proposed by Whalley (1) has been extended to include the analytical determination of the responses of intermediate variables. To illustrate the procedure, a general two-stage distributed-lumped parameter model which is used to predict flow patterns following an input change is employed. Two specific applications are examined and simulated flow transient response records arising from pressure variations are presented.
A Note on the Stabilization of Continuous-Time Systems Using Discrete-Time Compensators
Authors: Szumko S , Husein S
Published: February 2007

Control systems are often designed on a continuous-time basis and, in practice, implemented in a discrete fashion. Feedback design guaranteeing the stability of the continuous-time closed-loop system may be lost when implementation is made in discrete form. This note makes some observations on the stability of continuous-time systems when use is made of discrete-time compensator state feedback. Exact and approximate conditions are given for system stability.
Adaptive Control of Robot Manipulators Using a Popov Hyperstability Approach
Authors: Yu H
Published: February 2007

A general adaptive control approach of robot manipulators using Popov hyperstability is proposed in this paper. The manipulator adaptive control problem is first formulated in a form suitable for the application of hyperstability theory. The adaptive control law is general, and most of the adaptive control laws that have been proposed are special forms of this adaptive control law. The adaptive controller takes advantage of the flexibility in the choice of the adaptive parameters and the controller structure. The adaptive controller guarantees globally asymptotic stability in the hyperstability sense. For input disturbances, the control law, with little modification, maintains satisfactory system performance. Simulation results are presented to evaluate the performance of the adaptive controller for a two link manipulator.
Self-Tuning Adaptive Speed Control of a Pump/Inverter-Controlled Hydraulic Motor System
Authors: Wu H-W , Lee C-B
Published: February 2007

In a hydrostatic transmission system the speed of the fixed displacement hydraulic motor can be controlled by varying either the pump displacement or the pump speed. The change of pump speed can be achieved via an inverter which governs the speed of an induction motor. In this paper, both the pump-controlled hydraulic motor system and the inverter-controlled hydraulic motor system are studied. A microcomputer-based self-tuning adaptive controller was designed and applied to both systems. A series of simulations and experiments was performed. The results show that both the pump-controlled system and the inverter-controlled system can be regulated to maintain a desired response under different speed commands, load inertias, oil temperatures and an external disturbance.
A Parity Space Approach to Robust Fault Detection in Generalized State Space Systems
Authors: Daley S , Wang H
Published: February 2007

Many sophisticated approaches have been proposed for fault detection in dynamic systems using standard model representations. In this paper, redundancy relations for fault detection in systems represented by a generalized state space description are presented. Conditions for the existence of a redundancy relation and the simplest form this can take for the generalized system are obtained. The design of the redundancy relation in the presence of model uncertainties is also considered and conditions for the existence of a perfectly robust solution obtained. For cases where this does not exist a procedure is defined for calculating an optimally robust solution. A simulation of a three-shaft gas turbine is used to demonstrate the potential of the method.
Discrete-Time System Identification for Electrohydraulic Servo Systems
Authors: Plummer A R , Vaughan N D
Published: February 2007

The application of system identification to an electrohydraulic servo system is described. Identified models are used to design pole-placement controllers for the system. A variety of parameter estimators and model structure selection techniques are compared by assessing the performance of the controllers designed from the estimated models. The least squares method processing filtered data is found to yield reliable models, and an appropriate model structure can be selected successfully by comparing prediction errors for models of different structure.
Comparative Studies between Finite and Infinite Time Interval Controllers for Flexible Joint Robots
Authors: Ge S S
Published: February 2007

Motivated by the work by Spong (1) on the control of flexible joint robots, an adaptive control law guaranteeing that statements from the Tychnov theorem hold on an infinite time interval is presented first. Computer simulation comparisons are then carried out between the proposed infinite time interval controller and the conventional finite time interval controller.
A Thin and Deep Hole Drilling Using a Fuzzy Discrete Sliding Mode Control with a Woodpeckering Strategy
Authors: Hwang C L , Hsu C W
Published: February 2007

In this paper, a thin and deep hole drilling (TDHD), which is one of the difficult operations in metalworking, is accomplished by a fuzzy discrete sliding mode control (FDSMC) which is a combination of the fuzzy control and the discrete sliding mode control. The kernel problems of TDHD are chip removal, heat buildup, drill life, drill vibration, hole finish, drill breakage, difficulties in modelling the dynamic system, and so forth. The advantageous features of the FDSMC are that it does not require a mathematical model and that it has the invariant properties to resolve uncertainties when the system state is on the sliding surface. Moreover, a woodpeckering strategy can help prevent chip congestion and drill breakage. Finally, the experimental results for a thin and deep hole drilling by the proposed fuzzy discrete sliding mode control using a woodpeckering strategy are presented to verify the usefulness of the system.
Experience of the Application of Intelligent Control Paradigms to Real Manufacturing Processes
Authors: West A A , Williams D J , Hinde C J
Published: February 2007

The application of conventional and intelligent control paradigms to the dispensing of adhesive in the manufacture of mixed technology printed circuit boards, a real process with real time constraints and error conditions, is outlined in this paper. A description of the process and its various operation and error states is followed by a brief discussion of the application of conventional (system identification and incremental proportional control) and intelligent (knowledge-based, fuzzy logic and neural network) controllers to the system. Comments on the control and timing performance of each paradigm are given.
A Three-Dimensional Analysis of Piston Ring Lubrication Part 1: Modelling
Authors: Ma M-T , Smith E H , Sherrington I
Published: February 2007

The study of piston ring lubrication in internal combustion engines has remained a very active area in tribology. Theoretical analyses have been developed by many researchers to predict the performance characteristics of piston rings, but almost all previous models established were based upon the assumption that ring/cylinder geometry was axisymmetric. This may not be adequate for modern-day engine design since it is well known that cylinder bores are not perfectly circular. They suffer radial distortions which arise for various reasons. In the current work, a three-dimensional model has been developed to account for the effects of bore out-of-roundness. In order to do this, the three-dimensional Reynolds equation was solved cyclically using the finite difference method in fully flooded lubrication conditions. In this part of the paper, the theoretical model is presented and the effect of bore shape on piston ring performance is examined with three proposed types of bore (circular, elliptical and four-lobe). The results have shown that piston ring performance is significantly dependent on the bore shape or bore out-of-roundness.
A Three-Dimensional Analysis of Piston Ring Lubrication Part 2: Sensitivity Analysis
Authors: Ma M-T , Smith E H , Sherrington I
Published: February 2007

A three-dimensional model, developed by the authors, incorporating axial and circumferential variations in film shape and squeeze effects has been presented in Part 1 (1). In order to verify this model, the minimum film thicknesses predicted by the authors' model are compared with the predictions of an axisymmetric (two-dimensional) theory and with experimental results presented by Brown (2). A sensitivity analysis is then presented. A number of important factors affecting piston ring performance are examined. They include ring lateral location, constant ring twist (or offset of the ring face profile), bore out-of-roundness, liner temperature distribution and barrel height of the ring face profile. The results indicate that most of these factors have a considerable influence on piston ring performance. Notably, it is shown that ring lateral displacement and bore distortion can have a favourable effect on energy consumption provided blow-by and excessive oil consumption are avoided.
Using Taguchi Experimental Design to Investigate Operating Variables That Significantly Affect Wear in Mud Pumps
Authors: Mok S H , Gorman D G
Published: February 2007

Maintenance of offshore drilling mud pumps is normally based on running hours. It is generally accepted, however, that time does not provide an accurate means of scheduling maintenance, given the varying operating conditions of the reciprocating mud pumps. The energy expended at the interaction of sliding surfaces is hypothesized to be a better alternative. The effects of operating variables on wear rates are investigated. A Taguchi experimental design was used to identify those factors that significantly affect wear. Within the confines of an experimental test rig, the normal load and abrasive sand content was found to have a significant effect on the specific wear rate of nitrile rubber sliding on steel in drilling fluid.
Prediction and Measurement of Surface Temperature Rise at the Contact Interface for Oscillatory Sliding
Authors: Tian X , Kennedy F E
Published: February 2007

Surface temperature rise due to frictional heating in oscillatory sliding is studied using Green's function method and a recently developed temperature model for finite bodies. The surface temperature solution in oscillatory sliding differs in two respects from that in unidirectional sliding: the heat source is time varying and the sliding motion is periodic. The magnitude of the heat flux determines the local or flash temperature rise, which is cyclic owing to the time-dependent nature of the heat source. The periodic sliding movement of the heat source is found to be responsible for an additional surface temperature increase which can be considered as a nominal temperature rise. Based on a new surface temperature model for a finite contacting body, a relatively simple method for predicting the maximum surface temperature rise for an oscillatory sliding system is presented. Experimental measurements of surface temperature rise during oscillatory sliding were carried out using thin-film thermocouple (TFTC) techniques. The measured surface temperature rise at the contact interface agrees well with the model's predictions.
Screw Compressor Bearing Failures on Process Plant: A Case Study And Some General Lessons
Authors: Summers-Smith J D , Taylor G
Published: February 2007

A series of thrust bearing failures occurred on two large screw compressors on a chemical plant, resulting in serious production losses. In such circumstances those most closely involved are under extreme pressure to restore production and are not necessarily best placed to investigate the underlying causes of the problem. This case study shows the importance of maintaining good plant records and highlights the role of the independent consultant, able to adopt a more systematic approach uninhibited by the myths and prejudices of those more directly concerned.
Predicted Performance of a Tri-Taper Journal Bearing Including Turbulence and Misalignment Effects
Authors: Hargreaves D J
Published: February 2007

The performance predictions of a particular tri-taper journal bearing are shown to confirm known operating conditions. The importance of manufacturing tolerances on the resulting performance characteristics are highlighted. Design guidance for a family of these bearings including journal misalignment and lubricant inertia effects is also provided.
The Kinetics of Gas-Phase Lubrication in the Orthogonal Machining of an Aluminium Alloy
Authors: Wakabayashi T , Williams J A , Hutchings I M
Published: February 2007

Tetrachloromethane (carbon tetrachloride) has been used as a model gas-phase lubricant to investigate the kinetics of lubrication in the low-speed orthogonal machining of a precipitation-hardened aluminium alloy, in a controlled low-pressure environment. The dependence of cutting force on lubricant gas pressure, feed (that is depth of cut in these experiments), cutting speed and interfacial temperature was investigated. The results are not consistent with previous theories of vapour-phase lubrication in which transport of the lubricant molecules is assumed to control the reaction rate. A new model is proposed involving activated chemisorption of the lubricant at the tool-chip interface. The predictions of this model are in good agreement with the experimental observations and an activation energy of 18.4 kJ/mol has been derived for the relevant reaction.
Investigation of Factors Affecting Wear Characteristics in Rubber–Metal Sliding Contact
Authors: Mok S , Gorman D G
Published: February 2007

This paper examines the correlation between volumetric wear loss and the energy expended at the interface of nitrile rubber sliding on steel in the presence of drilling mud and abrasive sand. The measurement of energy expended at the material interface is investigated as an alternative for monitoring the extent of wear damage due to operating conditions. This is contrasted with running hours, as is typical of reciprocating mud pumps used in oil and gas drilling operations. It is found that increased deterioration and wear loss resulted from the combined effects of load and sand. The volumetric wear loss was found to increase at the rate of 16.8 per cent per 1 per cent sand and is specific to the type of sand used and the test configuration employed.
Influence of Surface Roughness and Oil Ageing on Various Ceramic-Steel Contacts under Boundary Lubrication
Authors: Denape J , Masri T , Petit J-A
Published: February 2007

The friction and wear behaviour of four structural ceramics (two aluminium oxides of different purity, a silicon nitride and a tetragonal zirconia polycrystal) have been investigated under boundary lubrication against a 100C6 hard steel (52100 steel). The effect of three initial surface roughnesses of the ceramics is studied. Lubrication is by a commercial oil used ‘as received’ (new oil) and ‘aged’ (used oil). Tests are performed on an alternating ‘pin-on-plate’ tribometer. The friction and wear responses are analysed in terms of three main parameters depending on the mechanical preparation mode of the ceramics surface: the roughness magnitude, the morphology of the asperities (sharps or blunts) and the mechanical strength of the asperities. The evolution of these parameters during sliding leads to significant changes of tribological behaviour and contact pressure. The friction and wear transitions result from changes of the lubrication mode where roughness and oil have a competitive action.

The wear processes of the ceramic surfaces include fracture mechanisms of the asperities and/or polishing by the mechanochemical action of the lubricant and submicronic ceramic wear debris. The worn surfaces of steel exhibit either abrasion grooves or a continuous metallic layer covering the steel. A running-in effect is observed on both silicon nitride and zirconia but does not occur on aluminas. The stronger running-in effect is observed with used oil. The used oil can lead to a very smooth sliding surface on the ceramic and allows particularly low friction coefficients and steel wear, but only after a more severe initial degradation process ESCA analyses on steel reveal the occurrence of a reaction film generated through chemical reactions with the oil.
Dynamic Analysis of a Thrust Bearing—Effect of Misalignment and Load
Authors: Iordanoff I , Stefan P , Boudet R , Poirier D
Published: February 2007

The ABG SEMCA, specialists in air-conditioning machinery, has considered the concept of small turbines with high rotation speeds (50 000–80 000 r/min). Air radial and thrust bearings are particularly well adapted for this kind of turbine. The load on the thrust bearing can be directed on one way or en the other. Therefore two thrust bearings are needed in order to support a bidirectional load However, some problems of stability have been found in the non-loading thrust bearing. This paper deals with a dynamic analysis of a thrust bearing and outlines the bad effects of misalignment on the unloaded thrust bearing and the importance of the sector angle on stability.
Analysis of a Grease-Lubricated Roller Bearing under Arctic Conditions
Authors: Östensen J O , Åström H , Höglund E
Published: February 2007

This paper summarizes measurements of starting torque and motion of the rollers in a roller bearing during start-up at a temperature of − 30°C. The bearing was lubricated with three different greases and the tests were carried out after a running-in procedure at + 20 °C. The results were compared with measurements obtained at +20°C and with results from one base oil at +20°C. A model for the roller motion was also built and simulations of the roller motion were compared with the measurements.

Independent of temperature and lubricant the rollers rolled in the loaded zone and slipped, more or less, in the unloaded zone. The degree of sliding in the unloaded zone was found to be governed mainly by the local lubricant distribution and the position of the roller in the cage pocket. Some differences are also seen in the slide-roll ratio between the lubricants. A roller diameter difference of 1.3 pm gave a significant difference in roller motion, with the slightly thinner roller slides more in the unloaded zone of the bearing.
The Elastohydrodynamic Lubrication of Elliptical Point Contacts Operating in the Isoviscous Region
Authors: Hooke C J
Published: February 2007

The elastohydrodynamic lubrication of point contacts is examined and results for the minimum film thickness are presented for a wide range of radius ratios and operating conditions. The results are compared with the predictions of the appropriate regime formulae. Although these formulae give a reasonable estimate of the contact's behaviour, the actual clearances are often substantially different, particularly close to the regime boundaries.

Interpolation equations for seven values of radius ratio are given and these should be sufficient to allow the minimum clearance to be estimated for most isoviscous point contacts.
Prediction of Film Thickness in an Elastohydrodynamic Point Contact Lubricated with a Viscosity Index Improved Base Oil
Authors: Östensen J O
Published: February 2007

A simple iterative method is used for the computation of the central film thickness in a fully flooded elastohydrodynamic (EHD) point contact lubricated with a polymeric viscosity index (V1)-improved base oil. The shear stress dependence of the Vl-improved base oil is included in the iterative method. Experimental data are presented on temporary viscosity loss and central film thickness at different temperatures from —8 to 40° C.

A good approximation of the central film thickness in an EHD point contact lubricated with V1-improved oil is given by using an iterative method involving the temporary viscosity loss of the Vl-improved base oil. The central film thickness depends on the mean shear stress at the inlet of the contact, and this shear-thinning effect has been accounted for in the calculations.
Dynamic Behaviour of Tilting-Pad Journal Bearings
Authors: Pagano S , Rocca E , Russo M , Russo R
Published: February 2007

The dynamic behaviour of a rigid rotor on tilting-pad journal bearings system is analysed for balanced and unbalanced rotors. The study mainly regards a two-pad journal bearing symmetric with respect to the external static load.

Both linear and non-linear behaviours have been analysed, with particular reference to the stability of the journal and pads equilibrium positions in the case of balanced or slightly unbalanced rotors, and to the stability of their synchronous motions in the case of considerable unbalance.
Wear and Seizure of Aluminium-Silicon Piston Alloys in Reciprocating Motion against Steel
Authors: Reddy A Somi , Murthy K S S , Biswas S K
Published: February 2007

Aluminium-silicon alloy pins were dry slid in unidirectional and reciprocating sliding against steel counterfaces in a normal pressure range of 0.39–26 M Pa and a sliding speed range of 0.6–1.8 m/s. Changing the mode of sliding from unidirectional to reciprocating as well as an increase in reciprocating speed were found to affect wear and seizure resistances adversely. Alloying additions of copper and magnesium to the base metal, on the other hand, were found to improve both of these properties. The temperature rise of the pin during sliding and the mechanical behaviour of the test alloys in compression in a temperature range of 25 300 °C and a strain rate range of 0.1–100/s were recorded and the data incorporated into a qualitative model to account for the wear and seizure behaviour of the test materials.
A Knowledge-Based Decision Support System for Combined Heat and Power Investment Appraisal and Plant Selection
Authors: Hughes R A , Ramsay B , Rossini C
Published: February 2007

Combined heat and power (CHP) can, in the most suitable cases, reduce a consumer's total energy costs by up to 40 per cent. It is important to stress that CHP is not viable at all sites and further that poor choice of CHP plant often results in inefficient and uneconomic operation. It is therefore vitally important to build a clear picture of what specific factors determine the profitability of a CHP scheme. The development of an accurate, reliable economic model is necessary for any sector where a potential market for CHP exists. Conventional economic models have a number of limitations, particularly where situations involve a high degree of risk and uncertainty. This paper shows how decision analysis techniques can be combined with a conventional spreadsheet to overcome these weaknesses and demonstrates the power and flexibility of the resulting model with a case study.
Dynamic Characteristics of a Small Fixed-Bed Gasifier Stove
Authors: Beedie D , Syred N , O'Doherty T
Published: February 2007

This paper describes work directed at characterizing the dynamic behaviour of a small gasifying fixed-bed biomass stove. The system comprises a primary gasification chamber, followed by a multi-stage secondary combustor which can allow for the considerable variation in quantity and calorific value of fuel gas produced by forming a series of flamelets which move along the length of the secondary combustor as a function of the local mixture ratio. The typical cycle time is about 60 minutes and once warmed up the unit is capable of operating with low emissions, providing appropriate guidelines are followed.

Correlation of temperature and gas concentration measurements on the unit with velocity and flow visualization measurements on a perspex model of the secondary combustor show that improvements can be made to the flow patterns in the bottom of the secondary combustion chamber by reducing the size and shape of the recirculation zones formed and revising the location of the mid-section secondary air inlet. Control of the system is indicated using a simple measurement of temperature in the secondary combustor to determine appropriate air supply rates.
The Use of Palm Oil as Diesel Fuel Substitute
Authors: Sapuan S M , Masjuki H H , Azlan A
Published: February 2007

The high cost of energy supplies as well as the concern over the availability of oil have brought much pressure on many countries to search for renewable energy sources, especially after the oil crisis in 1973. Vegetable oil fuels such as palm oil fuel provide one of the alternative forms of energy that are currently being studied, particularly as a diesel fuel substitute.

The purpose of this note is to review the potential of palm oil as an alternative fuel in automotive and industrial diesel engines with respect to its performance and tribological, environmental, economic and social implications.
A Rotating Facility to Study Heat Transfer in the Cooling Passages of Turbine Rotor Blades
Authors: Morris W D
Published: February 2007

This paper describes a new research facility designed to study the effect of rotation on heat transfer in the cooling channels of gas turbine rotor blades. Rotation influences cooling performance via secondary flows generated because of Coriolis forces and centripetal buoyancy. The resulting complex three-dimensional flow creates asymmetric heat transfer over the channel surface. The research facility has been designed to permit experiments to be undertaken that are near to actual engine conditions. The paper includes details of the design philosophy, construction and commissioning of the facility, together with a selection of experimental data.
The Influence of Detailed Blade Design on the Aerodynamic Performance of Straight-Bladed Vertical Axis Wind Turbines
Authors: Coton F N , Galbraith R A McD , Jiang D
Published: February 2007

The recent development of an unsteady, three-dimensional aerodynamic model has provided the opportunity to determine the influence of detailed blade geometry on the performance of straight-bladed vertical axis wind turbines. In particular, the present paper examines the effect of blade pitch, twist, taper and aerofoil section by comparison with a simplistic baseline configuration. The study concentrates on the low tip-speed ratio regime where the blade aerodynamics are inherently unsteady and the most severe loadings are experienced. In general, the effects of pitch and twist are similar, with both presenting only limited scope for enhanced design. Moderate taper is shown to improve the overall aerodynamic performance while having the structural benefit of reducing the bending moment at the cross-arm. The potential of a blade with varying cross-section to produce passive stall regulation is also demonstrated. Finally, the influence of unsteady blade stall is considered in more detail for each of the configurations.
Piston Steam Engine Innovation
Authors: Stokes P R
Published: February 2007

By the introduction of an insulating liner, the efficiency of a low pressure reciprocating steam engine has been increased and fuel consumption reduced by some 28 per cent.
Fluid Power Systems Design—Bramah's Legacy
Authors: Burrows C R
Published: February 2007

This paper gives a brief historical survey of fluid power systems. It shows that many current applications can be traced to ideas embedded in the pioneering work of Bramah and later contributors. The demand for high dynamic performance has been satisfied by advances in components and the fusion of technologies. A central theme is the importance of developing effective tools for system synthesis. It is shown that research in progress will ensure a future for fluid power in the twenty-first century.
Numerical Evaluation of Plate Heat Exchanger Performance in Geothermal District Heating Systems
Authors: Karlsson T
Published: February 2007

This paper describes the performance of plate heat exchangers in residential water radiator heating systems receiving their heat from geothermal resources. Radiator theory is reviewed and determination of annual hot water requirements for space heating is discussed. Performance evaluation is made of plate heat exchangers and results obtained by means of two equations commonly used for this purpose, the Sieder–Tate and the Dittus–Boelter equations, compared to results obtained with a simplified equation where heat transfer in the heat exchanger is assumed to depend only on the fluid mass flow on both sides. It is found that for prevailing temperature ranges in Icelandic geothermal systems the mass flow approximation gives results very close to those determined by the more complicated conventional equations.
Design Methods of Volute Casings for Turbocharger Turbine Applications
Authors: Chen H
Published: February 2007

This paper discusses aerodynamic design methods of volute casings used in turbocharger turbines. A quasi-three-dimensional (Q-3D) design method is proposed in which a group of extended two-dimensional potential flow equations and the streamline equation are numerically solved to obtain the geometry of spiral volutes. A tongue loss model, based on the turbulence wake theory, is also presented, and good agreement with experimental data is shown.
Surface Convection Coefficients for Building Facades with Vertical Mullion-Type Protrusions
Authors: Taki A H , Loveday D L
Published: February 2007

Accurate knowledge of the heat transfer processes that take place at the external surfaces of a building is necessary for thermal modelling and for design purposes. Using a heated test plate fixed at the sixth-floor level to the wall of an eight-storey building, correlations are presented for the external convection coefficient, hc, as a function of wind speeds measured 1 metre from the test surface and 11 metres above the roof in the free stream. The effects of vertical mullion-type protrusions on the value of hc are measured for a range of protrusion heights separated by a fixed spacing, the geometries tested relating to facade configurations which are commonly found in British commercial high-rise buildings. Regression correlations are derived which may be used by designers and thermal modellers for the prediction of hc values for a range of typical building facades with vertical mullion-type protrusions.
Review of Sorbent Injection Processes for Low-Cost Sulphur Dioxide Control
Authors: Sage P W , Ford N W J
Published: February 2007

Over recent years there has been growing public awareness world-wide that the use of fossil fuels can have damaging consequences for the environment. As a result increased efforts are being made to reduce such adverse effects. A range of low-cost sorbent injection techniques for abatement of sulphur dioxide applicable to combustion plant and other process operations are available and development is continuing. These techniques are generally characterized by modest SO2 removal and low capital cost.

The potential for application depends on a range of plant specific factors, although their market niche is likely to be limited to smaller industrial scale plant or existing plant with a low residual lifespan. The main barrier to their exploitation on such plant is considered to be the general lack of operational experience, which does not help their acceptance by plant operators as an alternative to established techniques such as spray drying and wet flue gas desulphurization.

This paper describes the options for sulphur dioxide abatement from combustion plant with particular reference to low-cost sorbent injection processes and discusses their applicability.
Combined Characteristics of Dissimilar Centrifugal Pumps
Authors: Ntoko N-M
Published: February 2007

It is shown that the dissipation characteristic of a centrifugal pump can be obtained from the normal characteristic of the same pump. Using the dissipation characteristic of the weaker of two pumps coupled in parallel and the normal characteristic of the larger of the two pumps, an expression for the combined characteristics of the pumps is then obtained. Graphical results are presented for two sets of pumps.
Sizing Ram Pumps
Authors: Young B W
Published: February 2007

Although a method for the optimal design of ram pump systems using a pump of given size now exists, there is no simple procedure for selecting the proper size of pump to provide a specific duty. This Technical Note shows how pump size may be determined from the required output power. The finding is supported by existing results and further tests on a 53 mm Wilcox pump. Examples are given to illustrate the sizing of small to medium pumps.

A cost analysis indicates that economy of scale applies to ram pumps and that the use of multiple pumps is not cost effective unless low drive heads have to be utilized.
Combining Different Intelligent Reasoning Techniques for Explaining Faults on Turbine Generators
Authors: Georgin E , McDonald J R , Ricard B
Published: February 2007

Expert systems have been developed for the diagnosis of turbine generators, and are heuristic-based systems. The level of diagnostic explanations they provide to their end users is questionable. This paper presents and discusses the results of case- and model-based reasoning techniques for diagnosing and explaining faults of turbine generators. The techniques provide explanations that match user's expectations and reflect less ‘human expert rules’. This also led to the design of a new generation of smart systems which will explain and persuade better plant operators that their diagnosis was correct.
Tadpole: A Design Problem in the Mechanics of the Use of Sea Wave Energy
Authors: French M J
Published: February 2007

A study is made of a device for obtaining electrical energy from sea waves, in which the problem of providing a reaction against the wave forces is met by a combination of a pendulum and gyroscopes. The mechanics is developed in a logical manner which gives a clear insight into the function, the pendulum providing the reaction force, which leaves an unbalanced moment to be countered by the gyroscopes, which also constitute the power take-off. The result is a relatively small machine with no external moving parts. The treatment requires no understanding of wave hydrodynamics.

It is felt this paper may be of special interest as a design study, in which the relation between the mechanics and the development of the concept is peculiarly cogent.
Simplified Analysis and Design of the Hydraulic Ram Pump
Authors: Young B W
Published: February 2007

Hydraulic ram pumps are currently of interest because they make use of a renewable energy resource and are environmentally friendly. Ram pumps are particularly appropriate for use in the developing world as their construction is basic and robust and they are inexpensive and easy to install and maintain. Numerous attempts to analyse the complex behaviour of a ram pump system have been made in the past, but few have been successfully translated into simple design procedures and none have resulted in a general method for a ram pump of any size.

The analytical approach adopted in the present paper assumes constant friction loss in the drive pipe during acceleration and concentrates on zero recoil conditions at which optimum pump performance occurs. Four simple and general design equations are derived which incorporate conservative assumptions for the critical velocity in the drive pipe and the effect of system losses. Design examples are given and design predictions compared with new and existing test results. Conclusions are drawn regarding the relevance of traditional drive pipe length–drive pipe diameter (L/D) and drive pipe length–supply head (L/H) ratios.
Performance of a Mixed Flow Pump with Varying Tip Clearance: Part 1
Authors: Saha T K , Soundranayagam S
Published: February 2007

Measurements of the three-dimensional flow field entering and leaving a mixed flow pump of non-dimensional specific speed k = 1.89 [ Ns = 100 r/min (metric)] are discussed as a function of flowrate. Flow reversal at inlet at reduced flows is seen to result in abnormally high total pressures in the casing region, but causes no noticeable discontinuities on the head-flow characteristics. Inlet prerotation is associated with the transport of angular momentum by the reversal eddy and begins with the initiation of flow reversal.
Performance of a Mixed Flow Pump with Varying Tip Clearance: Part 2
Authors: Soundranayagam S , Saha T K
Published: February 2007

Measurements in a mixed flow pump of non-dimensional specific speed k = 1.89 [ NS = 100 r/min (metric)] are analysed to give loss distribution and local hydraulic efficiencies at different flowrates and values of tip clearance. Fairly close agreement is obtained between the relative flow angles leaving the blading as predicted by simple deviation and slip models and derived from the measurements. The head developed is broken up into two parts: that contributed by Coriolis action and that associated with blade circulation. It is suggested that lift coefficients based on blade circulation are of limited value in selecting blade profiles. The variation of pump efficiency with tip clearance is greater than that reported for centrifugal pumps.
Results of Regulatory Investigations as a Basis for Safety Improvements of Nuclear Power Plants
Authors: Berg H P , Volland U , Weil L
Published: February 2007

Nuclear safety is not only a matter of technical development but is also an important public issue. Therefore it is mandatory that the responsible regulatory state authority performs its own investigation programme in order to enhance the safety level. The purpose and main objectives of this German regulatory investigation programme as well as the subject of some investigations are presented.
A New Concept of Externally Heated Engine—Comparisons with the Stirling Engine
Authors: Brzeski L , Kazimierski Z
Published: February 2007

This paper presents a new concept of the externally heated valve (EHV) engine. Air can be used as a working medium in the closed cycle of this engine. Heat delivered to the working air can come from a combustion chamber or another heat generator of an arbitrary type. The engine construction and the thermodynamic cycle performed by it are original and entirely different from the well-known Stirling engine. The main disadvantage of the Stirling engine is its low power density, that is the low power obtained per litre of the engine cylinder volume. In the case of the engine presented here it is possible to achieve power density and efficiency similar to those typical of advanced internal combustion engines. Comparisons between the power of the Stirling engine and the power of the new engine have been performed for the same engine capacity, rotational frequency and maximum and minimum temperatures of the cycle. At the same minimum pressure of the working gas in both engines, the power of the EHV engine is several times higher than that of the Stirling engine, while, on the other hand, at the same maximum pressure of the working gas in both engines, the power of the EHV engine is 20 per cent higher than that of the Stirling engine power. The efficiencies of both engines do not differ significantly from each other.
Lift-Off Characteristics and Flame Base Structure of Coal Seeded Gas Jet Flames
Authors: Gollahalli S R , Prasad A , Gundavelli S
Published: February 2007

An experimental study of the burner rim stability characteristics and the flame base structure of flames co-fired with pulverized coal and propane gas is presented. Lift-off and reattachment characteristics are examined as functions of propane concentration in the jet stream for lignite, bituminous and anthracite coals. The effects on flame base structure are studied in terms of temperature, product species concentration and radiation profiles. The addition of lignite and anthracite coals favours the lift-off transitions. Bituminous coal, on the other hand, makes the flame more stable. The peak values of temperature and concentrations of major combustion product species in the flame stabilization region strongly depend upon the rank of coal. Among the coals tested, bituminous coal produces the highest peak temperature and its flame emits maximum radiation from the stabilization region. Anthracite and lignite coals produce somewhat comparable stability characteristics and structure of the flame base. The effects of coal rank are explained by the differences in volatile matter, moisture and pyrolysis characteristics of coals.
Phase-Averaged Temperature Characterization in Swirl Burners
Authors: Fick W , Syred N , Griffiths A J , O'Doherty T
Published: February 2007

Methods have been developed to represent the rotating temperature fields associated with a three-dimensional, time-dependent coherent structure, the precessing vortex core (PVC), formed in the exit of swirl burners. In conjunction with laser sheet visualization of the phenomenon and phase-averaged rotating velocity measurements a description of the phase-averaged rotating temperatures and associated flow fields has been made for the flow in a 100 kW swirl burner (modelled on a 2 MW system for the efficient combustion of low calorific value gases), fired on premixed natural gas and air with some 10 per cent of the fuel used being injected on the central axis as a pilot.

The resulting calibrated temperature maps show comparable patterns to the laser Doppler anemometry velocity measurements and some basic structures associated with the PVC can be identified. Past the burner exit the PVC is shown to precess about the central axis and create a crescent-shaped region of high-velocity flow close to the exit wall and extending over about 180°. This structure extends to about one exit diameter downstream. Two flame regions are formed in this system. An inner yellow diffusion flame forms on the boundary of the PVC due to its coherence as the 10 per cent of the gas introduced on the axis passes directly into this structure. A much larger diameter annular blue premixed flame forms, which encloses the inner flame, restricts the oxygen supply and gives good flow visualization.

The inner flame surrounding the PVC only breaks up when it hits the side of the reversed flow zone (RFZ) and bursts with the PVC, then coalescing with the outer flame. As a result of the PVC, uneven burning results on the outside of the flame with hot and cold regions corresponding to low- and high-velocity regions respectively. The PVC was found to be helical in shape with the helix angle (140° from x/De = 0.13 to x/De = 039 above the burner exit) acting in the opposite sense to that of the flame.

The work has relevance to many areas where swirl burners or swirl-assisted combustion devices are used. In particular, high levels of swirl are probably best used in primary stages of air-staged low NOx burners where high levels of flame stability are sought under fuel-rich conditions. Subsequent air stages at lower swirl levels will tend to even out the non-uniform burning processes. In terms of acoustic resonance care must be taken to mismatch the PVC frequency with any of the natural frequencies of the system, as otherwise large-scale pressure fluctuations can result.
Modelling of a Turbocharger Turbine Under Pulsating Inlet Conditions
Authors: Chen H , Hakeem I , Martinez-Botas R F
Published: February 2007

This paper describes the results of the simulation of a mixed flow turbine under pulsating inlet conditions. The volute casing of the turbine is simulated as a tapered duct with one-dimensional unsteady flow analysis applied to this duct, while one-dimensional steady flow analysis is used in a quasi-steady manner to simulate the flow through the rotor of the turbine. The physical model of the turbine is an improved version of that described by Chen and Winterbone (1), and its predictive capability is evaluated against experimental data of the turbine performance obtained in the Imperial College's unsteady flow turbocharger rig.
Measurements and Modelling of a Lean Burn Gas Engine
Authors: Stone C R , Mentis K J S , Daragheh M
Published: February 2007

Natural gas is an alternative fuel that has potential for low emissions and a high efficiency. This paper presents the experimental results and predictions from a computer simulation of a fast burn high compression ratio (FBHCR) combustion system intended for use in a lean burn natural gas engine. Comparisons are made between the FBHCR combustion system at two compression ratios, predictions made by a two-zone combustion model and measurements from the original combustion system, for the brake efficiency, brake mean effective pressure, maximum cylinder pressure and the brake specific NOx emissions. Experimental measurements of the unburnt hydrocarbon emissions, the burn duration and the cycle-by-cycle variations in combustion are also discussed from the original and fast burn combustion systems. The results show how the conflicting aims of low emissions and low fuel consumption can be satisfied using a lean burn combustion system. The computer predictions are shown to be reliable, and thus suitable for estimating the performance of other engine builds.
Designing for Quality—An Integrated Approach for Simultaneous Quality Engineering
Authors: Braunsperger M
Published: February 2007

Automobile industry practice has shown that it is not sufficient merely to apply familiar quality control methods such as FMEA (failure mode and effects analysis) or QFD (quality function deployment), to introduce development process (DP) systems or to adopt project management procedures when an improvement in product quality is required. More than this has to be done: the product development procedure must be better arranged and made capable of achieving preventive quality assurance.

This paper presents an all-areas quality assurance concept as drawn up in the body development area of the BMW AG company and implemented successfully in the course of several pilot projects prior to general introduction. It is intended to provide stimuli and encouragement for similar measures to be taken in other areas, for example in the machinery construction industry.
End-Milling Machinability of Inconel 718
Authors: Alauddin M , El Baradie M A , Hashmi M S J
Published: February 2007

Most published research works on machining Inconel 718 have been mainly concerned with turning, while the milling process has received little attention due to the complexity of the process. In this paper a series of end-milling experiments of Inconel 718 has been carried out in order to: (a) optimize cutting variables, (b) investigate tool life values and relationships and (c) investigate surface roughness. The machining parameters have been optimized by measuring cutting forces. Tool life tests have been carried out using carbide inserts and the surface roughness has been analysed.
Conformability Analysis in Support of Design for Quality
Authors: Batchelor R , Swift K G
Published: February 2007

Around 80 per cent of the costs and problems of quality are created in product development. The paper overviews a knowledge-based design technique for the prediction of potential variability risks in component manufacture and assembly, and presents a method for linking the risk metrics to notions of design acceptability and potential costs of quality in production and service. The paper considers issues related to application of the work to industrial products and describes its coupling with failure modes and effects analysis.