bluuebunny/crossref_metadata_2025 huggingface dataset:
In-cylinder studies of the effects of CO2 in exhaust gas recirculation on diesel combustion and emissions
Authors: Zhao H , Hu J , Ladommatos N
Published: October 2002

This paper reports the results of the effects of CO2 in exhaust gas recirculation (EGR) on diesel combustion and emissions. The experiments were carried out on a specially designed single-cylinder diesel engine. In-cylinder measurements were obtained from the optically accessible swirl chamber using high-speed shadowgraphy, the two-colour method and laser extinction. Furthermore, in-cylinder pressure measurements from the combustion chambers were used to derive the heat release rates during combustion.

Two experiments were carried out on the effects of CO2 on diesel combustion and pollutant formation. In the first series of experiments, CO2 was used to replace some of the oxygen in the intake mixture, which simulated the dilution effect of conventional EGR. This so-called replacement EGR method was characterized by the typical NOx and smoke trade-off, where NOx reduction was accomplished at the expense of exhaust smoke. In the second series of tests, CO2 was added to the intake charge so that the oxygen concentration in the combustion chamber was not affected. In this additional EGR method, CO2 was found to suppress both NOx and smoke emissions. The mechanisms of these two different EGR modes on diesel combustion and emissions were examined using the above in-cylinder measurement techniques and exhaust emission analysis.
Automotive box section design under torsion Part 2: Behaviour and implications on weight reduction
Authors: Lee M. M. K. , Pine T , Jones T. B.
Published: October 2002

A well-calibrated and validated finite element procedure, described in companion paper 1, was used in producing data on the stiffnesses, elastic limits and strengths of automotive box sections under torsion. The modelling procedure was first used in analysing all the experimental geometries, and these preliminary analyses helped to define the scope of further numerical work. This work, which consisted of 76 analyses, investigated the main effects identified—section thickness, cross-sectional area, model length and section design—and their interactions. Particular emphasis was given to quantifying the implications of the various effects on weight reduction by replacing spot welding with adhesive bonding as the fabrication technique. Further tests and analyses were also conducted to investigate the effects of weld pitch on torsional stiffness and to compare the properties of adhesively bonded, laser-welded and spot-welded sections.
A study of a Kalman filter active vehicle suspension system using correlation of front and rear wheel road inputs
Authors: Yu F , Zhang J-W , Crolla D. A.
Published: October 2002

Based on a half-vehicle model, an algorithm is proposed for a Kalman filter optimal active vehicle suspension system using the correlation between front and rear wheel road inputs. In this paper, two main issues were investigated, i.e. the estimation accuracy of the Kalman filter for state variables, and the potential improvements from wheelbase preview. Simulations showed good estimations from the state observer. However, if the wheelbase preview algorithm is incorporated, the estimation accuracy for the additional states significantly decreases as vehicle speed and the corresponding measurement noises increase. Significant benefits from wheelbase preview were further proved, and the available performance improvements of the rear wheel station could be up to 35 per cent. Because of the feasibility and effectiveness of the proposed algorithm, and no additional cost for measurements and sensing needs, wheelbase preview can be a promising algorithm for Kalman filter active suspension system designs.
Analysis of driveline loads in an automotive powertrain with multiple Cardan joints
Authors: Krishna V , Naganathan N. G. , Phadnis R , Dukkipati R. V.
Published: October 2002

A general equilibrium analysis of automotive drivelines with multiple universal joints and numerous supporting conditions is presented. For the analysis, components of the driveline in terms of their angular rotation, angular velocity and acceleration are defined. Using kinematic conditions and a known torque and speed, the angular speed of the axle output shaft and all intermediate shafts and forces at contact points are computed using software developed to perform the analysis. To perform a time domain analysis, the quasi-static equilibrium conditions are imposed on the system at an instant. The instantaneous behaviour of the system is determined as a function of the transmission output shaft rotation. Finally, a numerical example is provided to illustrate the analysis. The results of the numerical example are plotted with respect to time. The general behaviour of the forces is found to be oscillatory and harmonic in nature.
New results on an electropneumatic active seat suspension system
Authors: Stein G. J.
Published: October 2002

A vibration control system with an air spring as the actuator and proportional electropneumatic control has been developed at the Institute of Materials and Machine Mechanics, Bratislava. As the electropneumatic transducer, a proportional pressure control valve is used in contrast to the previously used proportional flow control valve. The vibration control is facilitated by a combination of a ‘sky hook’ feedback loop and a feedforward loop working on the so-called ‘sky cloud’ principle, compensating base vertical vibration. Good agreement between simulation results and measurement on a laboratory dummy system was observed. The dummy system was also subjected to narrow-band random excitation, prescribed for standardized laboratory tests of driver's seats. The improvement in driver's seat vibration control properties owing to the feedforward vibration compensation is 2.5-fold, i.e. by 8 dB in comparison with ‘sky hook’ feedback damping only. The system could be used for vibration control in automotive applications, especially for vehicles with an unsprung chassis (earth-moving machines, wheeled tractors) and in the heavy vehicles sector.
Experimental study on the combustion characteristics of emulsified diesel in a rapid compression and expansion machine
Authors: Park J. W. , Huh K. Y. , Park K. H.
Published: October 2002

The combustion characteristics of emulsified diesel fuels are investigated in a rapid compression and expansion machine (RCEM). Among the test cases, the 40 water-oil (W/O) fuel injected at 20° before top dead center (BTDC) has shown the best performance with respect to efficiency and NOx and soot emissions. The pressure trace of the 40 W/O fuel is characterized by a longer ignition delay and a lower rate of pressure rise in premixed combustion. High-speed photographs show reduced flame luminosity and lower flame temperature with increasing W/O ratio. Microexplosions of emulsified fuel droplets, which affect the local shape and brightness of the flame, are identified in magnified flame images.
Alternative methods of traffic characterization in flexible pavement design
Authors: Collop A. C.
Published: October 2002

This paper investigates the way in which traffic data are used in flexible pavement design and analysis procedures. A deterministic long-term pavement performance model (LTPPM) is used to calculate flexible pavement damage caused by trafficking from three realistic fleets of commercial vehicles. The fleets have been modelled using seven-axle group models representing steer axles, drive axles (single or tandem) and trailer axles (tandem or tridem) with either steel suspensions or air suspensions. Results are compared with the calculated flexible pavement damage caused by a fleet of 80 kN standard axles and predictions from the currently used method of traffic characterization for UK pavement design procedures. Results show that pavements that fail by rutting last longer when trafficked by the realistic vehicle fleets compared with the fleet of 80 kN standard axles whereas the pavements that are predicted to fail by fatigue last longer when trafficked by the fleet of 80 kN standard axles. Results also show that current UK pavement design procedures are more sensitive to differences in the vehicle fleet compared with LTPPM predictions.
Determination of air brake adjustment from air pressure data
Authors: Kandt L. D. , Reinhall P. G. , Scheibe R. R.
Published: October 2002

Continuing research in brake condition monitoring for vehicles equipped with air brakes considers the feasibility of using air pressure data to determine brake stroke, a vital parameter in determining the effectiveness of the total braking system. Recent statistics show there is an alarming number of vehicles operating with brakes that are out of adjustment even with the introduction and requirement of automatic slack adjustment in 1994. The importance of brake stroke information is thus highlighted. To address this problem, a mathematical model of an air brake chamber is developed and used to investigate parameter sensitivity. A method capable of indirectly determining brake stroke by examining air pressure data is formulated and its effectiveness is proven through simulation and testing.
An investigation of in-cylinder tumbling motion in a four-valve spark ignition engine
Authors: Li Y , Liu S , Shi S-X , Feng M , Sui X
Published: October 2002

The formation and break-up of the tumble in the cylinder were studied in a single-cylinder four-valve spark ignition engine using laser Doppler anemometry (LDA) measurements and multidimensional numerical simulations. The flow structure generated by the tumble break-up was also analysed using the cycle-resolved LDA data processing method. These results show that, during the intake stroke, two counter-rotating vortices are generated in the cylinder by the intake flow along the two sides of the cylinder. They then gradually evolve into the tumble vortex at the initial stage of the compression stroke. Tumble motion can be strengthened by increasing the intake flow going along the surface of the exhaust valves and/or decreasing the intake flow descending directly along the cylinder wall on the side of intake valves. Although a partially decayed tumble vortex still exists in the central part of the combustion chamber near the end of compression, in other parts of the combustion chamber the tumble distorts and breaks up into small vortices and eddies so that the root mean square velocity fluctuation increases. The flow structure generated by the tumble break-up has a characteristic of lower frequency and larger eddy scale.
Comparison of audible and digital techniques for the determination of gasoline octane rating in production engines
Authors: Hudson C. , Gao X. , Stone R.
Published: October 2002

A microprocessor-based knock measuring system has been developed and tested for use in fuel rating and octane rating increase tests. Tests have been conducted with eight knock raters, and this has shown inter-rater and intra-rater variability. It has also been shown that there is no absolute standard by which knock can be measured. However, it has been argued that, as long as a consistent measuring system is used, comparative fuel testing can be undertaken with greater repeatability by using the microprocessor-based knock detector.
Effect of synchronized secondary air injection on exhaust hydrocarbon emission in a spark ignition engine
Authors: Sim H. S. , Min K. , Chung S. H.
Published: October 2002

A synchronized secondary air injection (SAI) method has been proposed to reduce hydro- carbon (HC) emission by injecting secondary air intermittently into the exhaust port. The method has been tested in a single-cylinder spark ignition engine operating at cold-steady/cold-start conditions. HC concentration and exhaust gas temperature were monitored with a fast-response flame ionization detector and with thermocouples respectively. Effects of exhaust air-fuel ratio (A/F), engine A/F, spark timing and air injection timing have been investigated and the results are compared with a continuous SAI method and the baseline condition.

Results show that HC reduction rate and exhaust gas temperature are sensitive to the timing of synchronized SAI. Two optimum SAI timings are observed which are at 100° crank angle (CA) after top dead centre (ATDC) and 230° CA ATDC depending on spark timing. At the cold-steady condition, the synchronized SAI is found to be more effective in HC reduction and also has much higher exhaust gas temperature than either the continuous SAI or the baseline condition. At the cold-start condition when a catalyst is not used, the accumulated HC emission during the first 120 s decreases by about 55 per cent with the synchronized SAI compared with that of the baseline condition, while the result with the continuous SAI is comparable with the baseline condition.
The turbulence measurement during the intake and compression process for high-turbulence generation around spark timing
Authors: Song Y. S. , Hong J. W. , Lee J. T.
Published: October 2002

In-cylinder turbulence of an engine was generated by an intake pressure effect and inertia effect during the intake process and it was generated and decreased by the compression effect of a piston during the compression process. The separate measurement of the turbulence generated by these factors during each process was necessary to generate high turbulence around the spark timing. A single-shot rapid intake compression expansion machine (RICEM) was manufactured and evaluated for this purpose. The RICEM could carry out the intake and compression processes separately or in a row. It was proved that the RICEM simulated not only high temperature and high pressure field but also the same flow pattern as a real engine. The turbulence generated by each factor was measured in the swirl field of the RICEM. As the result, it was also found that enhancing the turbulence by the compression effect of a piston with improvement of the flow at the beginning of the compression process was desirable.
Prediction of wet band brake dynamic engagement behaviour Part 2: Experimental model validation
Authors: Fujii Y. , Tobler W. E. , Snyder T. D.
Published: October 2002

A wet (oil-lubricated) band brake in a vehicle automatic transmission system exhibits widely varying engagement behaviour under different operating conditions. In recent years, analytical evaluation of the band engagement behaviour has become increasingly important to improve automatic transmission shift quality. Thus, a mathematical tool which accurately captures band engagement physics is indispensable in a transmission design process. This paper describes experimental validation of the dynamic band engagement model which includes the physics of squeeze film, asperity deformation, porous oil diffusion, heat transfer and loading pressure distribution caused by a selfenergizing mechanism. The model is implemented as a stand-alone computer program to predict the band engagement behaviour on an inertia absorption type band engagement test stand. Simulation results show good agreement with experimental torque profiles over a wide range of operating conditions. The model provides an analytical interpretation of the widely varying engagement behaviour resulting from the effects of oil temperature, friction material permeability and drum speed. The successful model validation demonstrates that the dynamic band engagement model serves as a valuable tool to assist band design and shift calibration processes of automatic transmission systems.
A suspension system with a variable roll centre for the improvement of vehicle handling characteristics
Authors: Lee U , Han C
Published: October 2002

In this paper, the improvement of vehicle handling characteristics using variable roll centre suspension (VRCS) is investigated. A vehicle with VRCS can improve stability and ride comfort by automatically controlling suspension geometry in accordance with the running conditions of the vehicle. To achieve this, a variable roll centre concept in the McPherson strut suspension system is suggested, while the two parts most sensitive for controlling the roll centre are suggested. One is between the vehicle body-side connecting portion of the lower arm and the vehicle body (control input, LCZ), and the other is between the vehicle body-side connecting portion of the strut and the vehicle body (control input, STY). Kinematic roll centre analysis, based on the analytic half-car model, shows that the use of two control inputs, LCZ and STY, can decrease migration of the roll centre and centre of gravity according to the side force. In order to quantify the relationship between roll centre and geometry control input and evaluate handling performance, a full vehicle model of 15 degrees of freedom (DOF) is constructed using multi-body dynamic analysis software, ADAMS. In step steering and double lane change manoeuvres, simulation results demonstrate that a vehicle with VRCS adjusts roll centre migration, and handling characteristics such as roll angle, lateral acceleration and yaw rate are much improved.
Kinematics of fibre optics sensory systems for control of a natural gas engine
Authors: Nwagboso C. O. , Pendlebury M. A.
Published: October 2002

A fibre optics combustion intensity detection sensor is developed for the purpose of monitoring and controlling natural gas engines. The sensory system, which is based on the detection of the intensity of the combustion event, is mounted on the top of the engine block. Prior to implementation of the detection system, the accurate kinematics of the sensor probe within the combustion chamber needs to be identified while taking account of the geometric complexity of the engine design. This requires the understanding of the kinematics of probe position within the spatial relations of the engine block geometry that is likely to give a good coverage of the combustion processes. This paper therefore presents a new model that was implemented on natural gas engines but could also be used for identifying the appropriate location within the combustion chamber of any modern engine. An application example using the model is presented. The model provides the ability to monitor completely the stages of combustion within the cycle-to-cycle operation of the engine and use the signal thereof for management and control of the engine. Experience gained from the application of the model resulted in the development of the probe deployment rule discussed in this paper.
An investigation of optimal fuel injection conditions for the reduction in hydrocarbon emission
Authors: Lee K , Lee C , Joo Y
Published: October 2002

Growing international concern about environmental issues in recent years has led to new proposals for strengthening exhaust emission standards and fuel economy requirements throughout the world. To cope with these standards, a reduction of hydrocarbon (HC) emission is the most important thing for the automotive industry to address because HC emission levels are more severe than the emission levels of any other components. In this paper, an apparatus for visualizing the wall film flow in an intake port and a spark plug with optical fibre for detecting the signal from the diffusion flame are developed to investigate the HC formation mechanism. A high-speed camera system is also used to elucidate the correlation between wall film flow and the diffusion flame. Using these methods, the effects of fuel injection systems such as injection direction, spray angle, atomized injector and ambient temperature on HC emission levels are investigated. Consequently, the optimal fuel injection conditions for minimizing the wall film flow and reducing HC emissions are found through this research.
Crash analyses and design of a belt integrated seat for occupant safety
Authors: Park Y-S , Park G-J
Published: October 2002

The performance of a belt integrated seat (BIS) is evaluated by using a sled test and occupant analysis software. The seat belt is attached to the seat back in the BIS to improve occupant safety. A simulation model of a BIS is established by using an occupant analysis program, SAFE. The model is constructed on the basis of data obtained from the structural investigation and a frontal sled test of a BIS. The numerical result from the simulation model is validated for consistency by comparison with high speed photographs taken during the sled test. Characteristics of both the conventional seat and the BIS are discussed. It is shown that occupant safety can be improved considerably with the BIS. A parametric study is conducted for various seat belts and a recommendation for an appropriate one is proposed. Structural analysis and optimization of the BIS are performed to establish the preliminary design trend considering occupant safety. A finite element model of the BIS is created, and the structure is optimized by the structural analysis and optimization program GENESIS. The seat components are reinforced on the basis of the shape of the existing BIS product. The results are discussed and a design recommendation for a BIS is made.
Unobtrusive drowsiness detection by neural network learning of driver steering
Authors: Sayed R , Eskandarian A
Published: October 2002

The purpose of this study is to detect drowsiness in drivers unobtrusively to prevent accidents and to improve safety on the highways. A method for detecting drowsiness/sleepiness in drivers is developed. This method is based on an artificial neural network (ANN). Steering angle signals are preprocessed and presented to the ANN which classifies them into drowsy and non-drowsy driving intervals. The method presented here relies on signals from the vehicle steering only (steering angle) and thus presents no obstruction to the driver. A feedforward ANN was trained using an error back-propagation algorithm and tested. The training and testing data were obtained from a previous experiment in a driving simulator driven by 12 drivers, each under different levels of sleep deprivation. The network classifies driving intervals into drowsy and non-drowsy intervals with high accuracy.
Gaussian networks for fuel injection control
Authors: Manzie C , Palaniswami M , Watson H
Published: October 2002

This paper proposes a radial basis function (RBF) based approach for the fuel injection control problem. In the past, neural controllers for this problem have centred on using a cerebellar model articulation controller (CMAC) type network with some success. The current production engine control units also use look-up tables in their fuel injection controllers, and if adaptation is permitted to these look-up tables the overall effect closely mimics the CMAC network. Here it is shown that an RBF network with significantly fewer nodes than a CMAC network is capable of delivering superior control performance on a mean value engine model simulation. The proposed approach requires no a priori knowledge of the engine systems, and on-line learning is achieved using gradient descent updates. The RBF network is then implemented on a four-cylinder engine and, after a minor modification, outperforms a production engine control unit.
Effect of coolant additives on thermal loading of a diesel engine
Authors: Selim M. Y. E. , Helali A-H B
Published: October 2002

An experimental investigation has been carried out to evaluate the heat transfer performance of three engine coolants and their mixtures with distilled water under real engine conditions. The coolants and their mixtures with water are used in a single-cylinder diesel engine running on gas oil fuel. Heat flux and wall temperatures were measured in the critical areas of the cylinder liner and cylinder head using traverse thermocouple probes. Coolant performance is defined as the ability to maintain a lower wall temperature for a given heat flux. Test parameters included coolant concentration in distilled water, engine load (heat flux), coolant flowrate and coolant type under forced convection and subcooled boiling conditions. Results showed that the coolant performance is critically affected by the coolant constituents, heat flux transferred and flow velocity. The best coolant for the cylinder head and cylinder liner is put forward.
Optimum control of an automotive direct injection diesel engine for low exhaust emissions
Authors: Capobianco M
Published: October 2002

The paper presents the latest results of a wide investigation performed at the University of Genoa on the control of automotive direct injection (DI) diesel engines. A dedicated procedure was developed which enables analysis of the behaviour of engine operating parameters as a function of two control variables with a limited amount of experimental information and the definition of proper control strategies. A first application of the procedure is presented in the paper with reference to a typical turbocharged DI diesel engine for automotive applications. The exhaust gas recirculation (EGR) rate and the position of the turbocharger waste-gate regulating valve were assumed as control variables and the behaviour of the most important engine parameters was analysed in a wide range for 15 steady state operating conditions related to the European driving cycle. Particular attention was paid to the most significant pollutant emissions and to the exhaust boundary conditions for the application of a low temperature lean de-NOx catalyst. Two different control strategies were also developed by which the catalyst conversion efficiency and the NOx engine tail pipe emission were individually optimized, taking account of some operating limits for specific parameters.
Design improvement of a high-pressure fuel pump for gasoline direct injection engines
Authors: Na B. C.
Published: October 2002

Gasoline direct injection (GDI) engines, considered to be one of the leading candidates for the next-generation engines of passenger cars, are able to reduce exhaust emissions and fuel consumption radically. The GDI engine requires a high-pressure gasoline supply system that enables the direct injection of fuel into combustion chambers. The high-pressure fuel pump is considered to be one of the key technologies in the development of GDI engines. However, because of the low lubricating ability of gasoline, a wide clearance is needed between the plunger and barrel. This clearance should be wide enough to create hydrodynamic lubrication between the sliding elements. As such, it is difficult to generate the high pumping pressure required in the GDI fuel pump owing to the large amount of leakage flowing through this gap. In this study, an optimum plunger design is presented to maximize pumping pressure in the aspect of flow control. This paper analyses leakage flow characteristics in the clearance of the plunger and barrel in order to improve the pumping performance of GDI fuel pumps. Design parameters have been introduced to maximize pumping pressure in a limited space, and a geometrical optimization has been conducted. Evaluations of pumping performance are determined by the degree of pressure drop in the leakage path assuming a constant leakage flow. Both turbulence and incompressible models are introduced in computational fluid dynamics (CFD) analysis. On the basis of the results of CFD analysis in various geometrical cases, optimum groove depths have been found to generate maximum pumping pressure. This analysis demonstrates that an improvement in plunger design achieves superior pumping pressure over that of conventional pumps.
An alternative semiactive control method for sport utility vehicles
Authors: Simon D. E. , Ahmadian M.
Published: October 2002

Many investigators have predicted that the performance gains attainable with a semiactive suspension are comparable with those possible with a fully active suspension. To achieve this, one of the crucial factors is the method by which the damper is controlled. This study is an investigation, through simulation, into the effectiveness of a number of basic control strategies in controlling vehicle dynamics, particularly roll. In addition, this study examines the effect of changing the vehicle mass on the effectiveness of selected semiactive control policies. The model represents a sport utility vehicle (SUV), a class of vehicles that regularly sees widely varying vehicle weight and exhibits undesirable levels of vehicle roll. In this study, a four-degree-of-freedom vehicle roll plane model is subjected to a variety of road- and driver-induced inputs, and the vehicle response with different semiactive control policies is characterized. The semiactive control policies investigated are tuned and modified such that the best possible performance with each is attained, and then they are compared. In addition, the effect of variations in vehicle weight on the performance of each semiactive control method is investigated. In this investigation, two basic skyhook control strategies are investigated, and two modified strategies are proposed. It is found that the performance achievable with each of the different control strategies is heavily dependent on the properties of the controllable damper. The properties that were particularly important were the upper and lower levels of force that the controllable damper was able to apply. The controllable dampers were tuned for each control system, and the results indicate that a velocity-based skyhook control policy, in conjunction with force control, is most effective at controlling both road-induced vibration and driver-induced roll. Furthermore, the results show that such a control policy is relatively insensitive to variations in vehicle weight.
Simulation on the characteristic of gas flow and mixing for the location of the oxygen sensor in the exhaust system
Authors: Park S. , Chung Y. H. , Cho Y , Chang G. H.
Published: October 2002

One of the methods for reducing engine exhaust emission is to use a close-coupled catalytic converter (CCC). To obtain the maximum conversion eYciency in a CCC, the exhaust gas should be uniformly distributed across the frontal area of the catalytic substrate as much as possible, and the engine should be operated at a condition close to the stoichiometric air/fuel ratio by using an oxygen sensor in the exhaust system. A theoretical and computational study on three-dimensional unsteady compressible non-reacting flow for three kinds of exhaust manifold and a CCC system was performed to understand the flow characteristics and estimate the eVects of geometric change. In each case, the oxygen sensor location where the local exhaust gas can represent the average flow of exhaust is proposed.
Investigation into steering wheel nibble
Authors: Neureder U
Published: October 2002

Many studies of mechanisms contributing to steering wheel nibble have been carried out in the past. This paper deals with some aspects that have not yet been studied, or those that have been presented by several authors but are deemed to be controversial. Firstly, an overview of stimulation sources (disturbance factors), and the significance these have with respect to steering nibble, is given. As an example of the controversial aspects of the problem, this paper deals with the assumption of dry friction in steering gear models and its conflict with the observed transfer of vibration caused by small (realistic) amounts of imbalance or tyre force variation. After modelling the steering gear resistance correctly, it is possible to identify, in the steering gear, a natural frequency that contributes reasonably to the nibble phenomenon. Based on this new model, a CAE study on parameter sensitivity, using the ‘design of experiments’ approach, is presented.
Modelling of turbocharged diesel engines in transient operation. Part 2: Wave action models for calculating the transient operation in a high speed direct injection engine
Authors: Payri F , Benajes J , Galindo J , Serrano J R
Published: October 2002

Part 1 of this paper analysed the physical phenomena involved in the transient operation of turbocharged diesel engines, together with the principles of diesel combustion characterization during the transient process. This second part describes a calculation model developed to predict engine transient performance based on an existing wave action code. Relevant improvements introduced are combustion process simulation and modelling of heat transfer, variable geometry turbine behaviour and mechanical losses. Experimental load transient tests with a high speed direct injection engine have been performed, with the aim of assessing the model accuracy. The main evaluation parameters were instantaneous variation during turbocharger rotating speed transient, boost pressure, air mass flow, injected fuel and exhaust pressures.
Analysis of flame kernel development with Schlieren and laser deflection in a constant volume combustion chamber
Authors: Song J , Sunwoo M
Published: October 2002

The purpose of this study is to investigate the relation between ignition systems (or energy) and flame kernel development. In this research, three different kinds of ignition systems and several different kinds of spark plug electrodes are designed and manufactured. The flame propagation velocity in a constant volume combustion chamber is measured by both a laser deflection method using an He-Ne laser and a Schlieren method using a high speed digital camera. In order to control the ignition energy, the dwell time is varied by a spark time controller.

The results indicate that, when the ignition energy is increased by extending the dwell time, flame kernel growth accelerates. As the electrode gap width is increased, the breakdown energy is also increased, which stimulates the initial kernel development. The materials, diameter and shape of the electrode affect the discharged energy, the energy transfer efficiency and heat losses and, thus, these also affect the flame kernel development. The average difference in measurement of the flame velocity by the laser deflection method and Schlieren method is only 1.73 per cent. The laser deflection method is found to be preferable because it is more effective and employs simpler means for the analysis of flame kernel development.
Differential stress modelling of turbulent flows in model reciprocating engines
Authors: Lea C. J. , Watkins A. P.
Published: October 2002

A study is made here of the application of a differential stress model (DSM) of turbulence to flows in two model reciprocating engines. For the first time this study includes compressive effects. An assessment between DSM and k-ɛ results is made comparing with laser Doppler anemometry experimental data of the mean flow and turbulence intensity levels during intake and compression strokes.

A well-established two-dimensional finite-volume computer code is employed. Two discretization schemes are used, namely the HYBRID scheme and the QUICK scheme. The latter is found to be essential if differentiation is to be made between the turbulence models.

During the intake stroke the DSM results are, in general, similar to the k-ɛ results in comparison to the experimental data, except for the turbulence levels, which the DSM seriously underpredicts. This is in contrast to a parallel set of calculations of steady in-flow, which showed significant gains from using the DSM, particularly at the turbulence field level. The increased number of grid lines employed in those calculations contribute to this apparent difference between steady and unsteady flows, but cycle- to-cycle variations are more likely to be the primary cause, resulting in too high levels of turbulence intensity being measured.

However, during the compression stroke the DSM returns vastly superior results to the k-ɛ model at both the mean flow and turbulence intensity levels. This is because the DSM generates an anisotropic shear stress field during the early stages of compression that suppresses the main vortical structure, in line with the experimental data.
Technical Note: The importance of turbulence intensity, eddy size and flame size in spark ignited, premixed flame growth
Authors: Ting D S-K , Checkel M. D.
Published: October 2002

The effects of laminar burning velocity, turbulence intensity, flame size and eddy size on the turbulent burning velocity of a premixed growing flame were experimentally separated in a 125 mm cubical chamber with lean methane-air mixtures spark ignited at 1 atm and 300 K. The turbulence was up to 2 m/s with 1 to 4 mm Taylor microscale. For the near unity Lewis number and near zero Markstein number mixture considered here, the turbulent burning velocity, St, can be approximated as: St = Sl + Cd(r/λ)u′, where Sl is the laminar burning velocity, r is the mean flame radius, λ is the Taylor microscale, u′ is the root mean square (r.m.s.) turbulence intensity and Cd is a constant of the order 0.02.
Indirect methods for assessing road friendliness of lorry suspensions
Authors: Potter T E C , Cebon D , Cole D J
Published: October 2002

Two methods for assessing the road damaging potential of heavy vehicles are described in this paper. The methods use a simple laboratory test to characterize vehicle dynamics. This information is then used to predict the dynamic tyre forces generated by the vehicle for typical highway conditions. A quarter car laboratory test rig fitted with a leaf spring suspension is used to investigate these methods. Step inputs are used to excite the rig, and various sensors measure the response. A linear technique using the convolution algorithm is investigated initially. A non-linear method using parameter estimation is then examined. The accuracy of both systems is determined by comparing tyre force data measured on the test rig with predicted tyre forces.
Drive-by-wire systems: Some reflections on the trend to automate the driver role
Authors: Stanton N , Marsden P
Published: October 2002

The purpose of this paper is to review critically the current trend in automobile engineering toward automation of many of the functions previously performed by the driver. Working on the assumption that automation in aviation represents the basic model for driver automation, the costs and benefits of automation in aviation are explored as a means of establishing where automation of drivers’ tasks is likely to yield benefits. It is concluded that there are areas where automation can provide benefits to the driver, but there are other areas where this is unlikely to be the case. Automation per se does not guarantee success, and therefore it becomes vital to involve human factors into design to identify where automation of driver functions can be allocated with a beneficial outcome for driving performance.
Indirect injection diesel engine operation on palm oil methyl esters and its emulsions
Authors: Masjuki H , Abdulmuin M Z , Sii H S
Published: October 2002

Results of exhaust emissions and lube oil analysis of a diesel engine fuelled with Malaysian palm oil diesel (POD or palm oil methyl esters) and ordinary diesel (OD) emulsions containing 5 and 10 per cent of water by volume are compared with those obtained when 100 per cent POD and OD fuel were used. Very promising results have been obtained. Neither the lower cetane number of POD fuel nor its emulsification with water presented any obstacle to the operation of a diesel engine during steady state engine tests and the 20 hour endurance tests. Polymerization and carbon deposits on fuel injector nozzles were monitored. Engine performance and fuel consumption for POD and its emulsions are comparable with those of OD fuel. Accumulations of wear metal debris in crank-case oil samples were lower with POD and emulsified fuels compared with baseline OD fuel. Both OD and POD emulsions with 10 per cent water by volume show a promising tendency for wear resistance. The exhaust emissions for POD and emulsified fuels are found to be much cleaner, containing less CO, CO2, HC, NOx, SOx and smoke level. Power output is slightly reduced when using POD and emulsified fuels.
Automotive active suspensions Part 1: Basic principles
Authors: Williams R A
Published: October 2002

Automotive suspension design is a compromise brought about by the conflicting demands of ride and handling. The past few years have seen the introduction of increasingly sophisticated, electronically controlled, components into automotive suspensions which redefine the boundaries of the compromise.

The paper has been written in two parts. This first part reviews the compromises which are required in the design of a conventional passive suspension. It then goes on to show how those compromises can be changed by the inclusion of active components.

The second part discusses the hardware employed which ranges from simple switched dampers, through semi-active dampers, and low bandwidth/soft active suspensions, to high bandwidth/stiff active suspensions. The benefits to be derived from each of the technologies will be assessed, together with their strengths and weaknesses.
A sliding mode controller for vehicle active suspension systems with non-linearities
Authors: Kim C , Ro P I
Published: October 2002

In this paper, the control of an active suspension system using a quarter car model has been investigated. Due to the presence of non-linearities such as a hardening spring, a quadratic damping force and the ‘tyre lift-off’ phenomenon in a real suspension system, it is very difficult to achieve desired performance using linear control techniques. To ensure robustness for a wide range of operating conditions, a sliding mode controller has been designed and compared with an existing nonlinear adaptive control scheme in the literature. The sliding mode scheme utilizes a variant of a sky-hook damper system as a reference model which does not require real-time measurement of road input. The robustness of the scheme is investigated through computer simulation, and the efficacy of the scheme is shown both in time and frequency domains. In particular, when the vertical load to the sprung mass is changed, the sliding mode control resumes normal operation faster than the nonlinear self-tuning control and the passive system by factors of 3 and 6, respectively, and suspension deflection is kept to a minimum. Other results showed advantages of the sliding mode control scheme in a quarter car system with realistic non-linearities.
Measurements of in-cylinder mixture strength and fuel accumulation in the inlet port of a gasoline - injected engine during very rapid throttle openings
Authors: Ladommatos N , Rose D
Published: October 2002

The mixture strength in a cylinder of a port-injected gasoline engine was monitored continuously during very rapid throttle openings. The data on mixture strength were combined with other engine data collected in order to obtain for each successive engine cycle: the air—fuel ratio within the cylinder and the change in the fuel mass accumulating on the inlet port of the cylinder being monitored.

The four-cylinder spark-ignition engine used had a displacement of 1.6 litre, four valves per cylinder and multipoint sequential fuel injection controlled by an electronic management system programmed for three - way catalyst operation. All tests were conducted with the engine coolant at the temperature of 90°C and at a constant engine speed of 2000 r/min. The engine transient involved very rapid throttle openings which were completed within about 15 ms. Small and large throttle openings were investigated along with the effect of altering the type and condition of the fuel injectors.

The engine response to the fast throttle opening comprised a sharp rise in the air—fuel ratio (maximum gravimetric air—fuel ratio of around 25:1) which lasted for only a single cycle, followed by a drop in the air-fuel ratio (minimum air—fuel ratio of about 10:1) and, subsequently, a gradual rise towards a stoichiometric air—fuel ratio within about 10 engine cycles.
Optimization of the tractive performance of four-wheel-drive tractors: Theoretical analysis and experimental substantiation
Authors: Wong J. Y. , McLaughlin N. B. , Knezevic Z , Burtt S
Published: October 2002

The results of a theoretical analysis reveal that, for a four-wheel-drive tractor to achieve the optimum tractive performance under a given operating condition, the thrust (or driving torque) distribution between the front and rear axles should be such that the slips of the front and rear tyres are equal. For four-wheel-drive tractors with rigidly coupled front and rear drive axles, this can be achieved if the theoretical speed (the product of the angular speed and the free-rolling radius of the tyre) of the front and that of the rear wheels are equal or the theoretical speed ratio is equal to 1.

Field test data confirm the theoretical findings that, when the theoretical speed ratio is equal to 1, the efficiency of slip and tractive efficiency reach their respective peaks, the fuel consumption per unit drawbar power reaches a minimum, and the overall tractive performance is at an optimum.
Kinematic considerations for reducing the circulating power effects in gear-type continuously variable transmissions
Authors: Dooner D , Yoon H-D , Seireg A
Published: October 2002

The present study deals with the kinematic analysis and design considerations of a continuously variable transmission (CVT) utilizing non-circular gear (NCG) sets with phase shift and summing differentials. The kinematic relationships are developed with emphasis on the effect of the different design parameters on reducing the circulating power inherent in this type of system. The study shows that a compromise has to be made between the number of non-circular gear sets to be used and the circulating power generated in the system. For the illustrative example of a 200 hp (149 kW) system it is shown that, for a gear ratio range from 1 to 4 and the considered characteristic curve on the non-circular gears, four sets of summing differentials are estimated to be required and the maximum instantaneous circulating power at the worst condition would be approximately 6 times the output power. The circulating power changes from its minimum of 1.5 to its maximum value with an average circulating power of 2.8 times the output power.
Fast optimization of mechanical designs using computer aided design/computer aided engineering emulation: A case study
Authors: Bates R. A. , Gilliver R , Hughes A , Shain T , Sivaloganathan S , Wynm H. P.
Published: October 2002

The use of emulator methods in mechanical engineering design is more limited than in electrical and electronic engineering. The concept is to replace a computer aided engineering simulator with a fast statistical emulator built using a designed computer experiment, which can then be used to facilitate optimization and robust engineering design. This case study draws out lessons for application in mechanical design.
Development and characterization of high-performance hybrid adhesive for fuel filters compatible with diesel fuel
Authors: Alagar M , Velean T V Thanikai , Bilal I Mohammed , Mohan V
Published: October 2002

For the fabrication of fuel filters, especially for diesel fuel, ten different combinations of hybrid Acranol 295D (BASF, Germany—a mixture of acrylic monomers), polyvinyl pyrrolidone (PVP)/polyvinyl alcohol (PVA) and melamine formaldehyde adhesives have been developed. Preparation of these hybrid adhesives involves three stages: preparation of a stabilized Acranol-PVP/PVA premix, preparation of a melamine formaldehyde prepolymer and preparation of hybrid Acranol-PVP/PVA-melamine formaldehyde. The properties of the prepolymers (viscosity, percentage solids content and pH) are determined by standard methods. The hybrid Acranol-PVP/PVA-melamine formaldehyde adhesive is applied between the filter material using a drum press and is cured at 120°C for 60 min. These adhesive systems are perfectly stable and have no sign of failure towards hot diesel during the test conditions. Results obtained from solvent resistance studies show that, among the adhesive systems developed, system IV and system VIII are perfectly suitable for application as fuel filter adhesives. However, system VIII is cost effective compared with system IV. Monoisopropanolamine stabilizes the Acranol-PVP/PVA prepolymer better than ammonium hydroxide.