bluuebunny/crossref_metadata_2025 huggingface dataset:
Speciated hydrocarbon emissions from a gas-fuelled spark-ignition engine with various operating parameters
Authors: Kim C. U. , Bae C. S.
Published: October 2002

For natural gas and liquefied petroleum gas (LPG), measurements of the concentrations of individual exhaust hydrocarbon (HC) species have been made under various engine operating conditions in a 2 litre four-cylinder engine using gas chromatography. Non-methane hydrocarbon (NMHC) in addition to the species of HC and other emissions such as CO2, CO and NOx were examined for natural gas and LPG at 1800 r/min for two compression ratios (8.6 and 10.6), various brake mean effective pressure (b.m.e.p.) values (250-800 kPa), spark timings (before top dead centre 10°-55°) and exhaust gas recirculation ratios up to 7 per cent. Fuel conversion efficiencies were also investigated together with emissions to study the effect of engine parameters on the combustion performance in gas engines, especially under the lean burn conditions.

It was found that CO2 emission decreased with smaller C value of fuel, leaner mixture strength, higher compression ratio, higher b.m.e.p. and the ignition near the maximum brake torque spark timing. HC emissions from the LPG engine consisted primarily of propane (C3 H8) (more than 60 per cent), ethylene and propylene (C3 H6), while the main emissions from natural gas were methane (more than 60 per cent), ethane, ethylene and propane. Natural gas was shown to have less of a tendency to form ozone than LPG. This was accomplished by reducing the emissions of propylene, which has a relatively high maximum incremental reactivity factor, and propane, which forms a large portion of LPG. In addition, natural gas shows a benefit in the other emissions (i.e. NMHC, NOx and CO2), specific reactivity and brake specific reactivity values except fuel conversion efficiency.
Numerical simulation of intake and compression flow in a four-valve pent-roof spark ignition engine and validation with LDV data
Authors: Kim W. T. , Huth K. Y. , Lee J. W. , Kang K. Y.
Published: October 2002

The intake and compression flows in a motoring four-valve pent-roof spark ignition engine are calculated and compared with the laser Doppler velocimetry (LDV) data. A simple valve treatment technique is used to avoid excessive difficulty in generation of a body-fitted grid for multiple moving valves. A constant-pressure boundary condition is applied at the intake port inlet. Results show good agreement for the fluctuation velocity, while there is some discrepancy in the mean velocity owing to uncertainty in the inlet boundary condition. The tumble ratio and the average fluctuation velocity remain approximately constant or rise slightly owing to the spin-up phenomenon near top dead centre (TDC) after rapid decay of the strong intake flow and turbulence in the compression stroke.
Stochastic prediction of cycle-by-cycle cylinder pressure fluctuations in a spark ignition engine
Authors: Jones J. C. Peyton , Roberts J. B. , Landsborough K. J.
Published: October 2002

The generality of recent stochastic models for cylinder pressure development is exploited, both to recreate or simulate cyclic datasets with similar statistical properties to real engine data, and to derive many of the more traditional statistics (e.g. standard deviations of maximum pressure, mean effective pressure, burn angle, etc.) directly from the parameters of the more general model form. The same approach also provides insight into the phasing of the cyclic process, since a number of statistics (such as the standard deviation of pressure or burn rate variations) can be computed directly as a function of crank angle. It is also straightforward to evaluate the contribution to such quantities from each of the physically meaningful model parameters, and thereby obtain some insight into the mechanisms involved.
Multidimensional numerical simulation of heat radiation in direct injection diesel engines
Authors: Chen S , Chan T. L. , Leung C. W. , Liu M. A. , Pan K. Y. , Zhou L. B.
Published: October 2002

A multidimensional theoretical model of radiation heat transfer in the cylinder of a direct injection (DI) diesel engine has been developed, which includes submodels of heat release, geometrical description, radiation temperature, soot formation and oxidation, the absorption coefficient and the Monte Carlo method for total exchange areas. In this code, the cylinder is divided into 10 surface zones and four gas zones. The Monte Carlo method integrated with a smoothing technique considering reciprocity and conservation is used to calculate the radiation total exchange areas directly for both the absorbing—emitting media and the complex structure of the cylinder. Using the multi—dimensional approach, the variation in radiant heat transfer with crank angle can be obtained across the whole combustion chamber. The computed results are analysed and discussed in the present study, and they are found to be in agreement with the experimental results.
Fabrication and characterization of polyurethane-coated fabrics for collapsible diesel tanks
Authors: Velan T. V. T. , Bilal I. M. , Arumugham S
Published: October 2002

Polyurethanes synthesized from diols of low, medium and high molecular weight ( Mw = 1000, 2000 and 3000 respectively) with low free isocyanates were used to fabricate coated fabrics. The physical, chemical and mechanical properties of these coated fabrics and polymer films were studied to establish their suitability for fabricating collapsible fuel tanks to store diesel for long periods under adverse conditions. Fabrics coated with low molecular weight polyurethanes are found to be more suitable for storing diesel fuel compared with those coated with medium and high molecular weight polyurethanes.
Theoretical simulation of combustion processes of airbag inflators
Authors: Hsieh W. H. , Sun L. Y. , Chen J. K. , Wang S. W.
Published: October 2002

Combustion and inflation processes of pyrotechnic airbag inflators are simulated by a theoretical model and numerical code developed in this study. The theoretical model considers the ignition and combustion of gas generation propellants of an inflator located in a constant-volume discharge tank. The model is based on the transient conservation equations of mass, species and energy for the combustion chamber of the inflator and the discharge tank. In addition, the model also includes the propellant burning rate law, the ignition model of gas generation propellants, real gas equation of state, effect of mass and energy fluxes from the igniter to the combustion chamber, heat transfer correlations and filter clogging processes. The theoretical model is solved by a numerical code. The calculated results agree well with experimental data. Simulation results indicate that the gas properties in the combustion chamber and the discharge tank change in different fashions owing to the large difference in the volumes of the two regions. In general, the gas properties in the discharge tank vary slowly, continuously and almost monotonically. It is found that the increase in the pressure exponent of the burning rate law and the inertia coefficient of the filter will increase the peak pressures in both regions. The major effect of an increasing mass flowrate from the igniter is the introduction of a local pressure peak in the combustion chamber at the very beginning of the combustion processes.
Cycle analysis for fuel-inducted internal combustion engine configurations
Authors: Micklow G. J. , Owens B. , Russell M.
Published: October 2002

A quasi-one-dimensional computer code based on a fuel-air cycle analysis was developed to predict the performance of two- and four-stroke fuel-inducted engines. The analysis was developed to provide boundary conditions for a finite element analysis to predict thermal and mechanical loading of carbon-carbon pistons for use in advanced internal combustion engine concepts. The computer code can predict the required boundary conditions, which are gas pressure and temperature and heat transfer coefficients as a function of crank angle, along with engine indicated and brake power output, thermal efficiency and mean effective pressure. The code utilizes a variable specific heat calculation throughout the cycle. The compression of an air-fuel-residual gas mixture is calculated followed by a finite rate burn, where the burn duration is calculated on the basis of the turbulent flame speed and cylinder geometry. The residual gas content is calculated by an iterative technique. During combustion and expansion, ten equilibrium combustion product constituents are tracked. Engine friction, instantaneous heat transfer and blowby past the rings are calculated on the basis of empirical correlations. The tendency for engine knock or autoignition of the fuel is also calculated. Good agreement is obtained when compared with actual engine operation for power output, thermal efficiency and exhaust gas temperature.
Reduction of NOx, smoke and brake specific fuel consumption with optimal injection timing and emulsion ratio of water-emulsified diesel
Authors: Park J. W. , Huh K. Y. , Lee J. H.
Published: October 2002

This paper reports the test results of a diesel engine at different engine speeds, injection timings and emulsion ratios with water-emulsified fuel. Results show that both NOx and smoke may be reduced significantly at the same brake specific fuel consumption (b.s.f.c.) at high engine speeds above 1400 r/min. At low engine speeds below 1000 r/min NOx may be reduced slightly with minor penalty in the b.s.f.c. with no overall gain in use of emulsion fuel. In the tested range of water-oil ratio by volume of 0-40 there was no significant deterioration in the HC and CO emissions and the combustion stability in terms of cyclic variations of the peak cylinder pressure. It may be necessary to employ accurate electronic control of the injection timing as a function of load and speed to maintain the optimum operating condition with emulsion fuel.
Flame kernel formation and propagation modelling in spark ignition engines
Authors: Song Jeonghoon. , Sunwoo Myoungho.
Published: October 2002

One-dimensional, time-dependent numerical simulations of flame kernel growth produced by a spark in a combustible gasoline-air mixture are presented. This model accounts for the fundamental properties of the ignition system, the combustible mixture and flow fleld. Submodels representing the cylinder pressure and temperature, heat transfer to the cylinder wall and spark plug electrodes or ambient air, effects of the residual gas and so on. In addition, to research the effects of ignition energy, two kinds of ignition systems are used. The results show that the increased breakdown energy enlarges the plasma radius, which derives faster development of the initial flame kernel. The heat transfers to the electrodes and the cylinder wall also affect the growth of the kernel. These results appear to be coherent with previous experimental visualizations. The simulations are validated by different engine running conditions, for example air-fuel ratio, spark advance, engine speed and intake manifold pressure.
Study of the steady flow produced by direct injection diesel engine intake ports
Authors: Desantes J M , Pastor J V , Doudou A
Published: October 2002

In this paper laser Doppler anemometry is used to characterize the steady flow field inside the cylinder generated by the two intake ports of a four-valve diesel head over the whole valve lift range and to compare the patterns at two different sections commonly used for global characterization in order to decide which is more appropriate for cylinder head evaluation. A more detailed investigation is performed for two valve lifts where the change in the flow patterns is more evident by applying a spectral analysis with the local normalized slotting technique to study the turbulent structures accompanying the in-cylinder swirl development.
An adaptive sliding mode controller for air-fuel ratio control of spark ignition engines
Authors: Yoon P , Sunwoo M
Published: October 2002

An adaptive dynamic sliding mode fuel injection control algorithm based on the measurement of a binary oxygen sensor to reduce the exhaust gas emissions is proposed. The controller suggested in this paper is designed on the basis of the two-state dynamic engine model developed in the crank angle domain, and it is composed of an adaptation law for fuel delivery model parameters and measurement bias in mass air flowrate. The control algorithm is mathematically compact enough to run in real time, and it is robust to modelling errors as well as to rapidly changing manoeuvres of the throttle. The simulation and experimental results show that this algorithm can substantially reduce the transient peaks in air-fuel ratio (AFR) while maintaining robustness to model errors and measurement delay.
Vibration characteristics of steering columns with bellows
Authors: Kim K H , Han G H , Kim H K
Published: October 2002

Bellows can be used as collapse elements for automotive steering columns. The crash performance of the steering column can be significantly improved with the bellows. However, the bending flexibility of the bellows has negative effects on the vibration characteristics. An effort is made to improve the vibration characteristics of steering columns with bellows. To understand the effects of various design parameters on the collapse and vibration, sensitivity analyses are performed by the finite element method using Taguchi's scheme. It is shown that the structure of the upper mounting bracket is the most important parameter affecting the vibration characteristics. An optimal design is proposed for a lower tilt type steering column.
Axiomatic design of the motor-driven tilt/telescopic steering system for safety and vibration
Authors: Shin M K , Hong S W , Park G J
Published: October 2002

The design process of the motor-driven tilt/telescopic steering column is established by an axiomatic design approach in conceptual design. Since independent design parameters are defined for improving the performance of the steering system, each detailed design can be carried out independently. In detailed design, occupant safety in a crash environment and vibration reduction are considered. The occupant analysis code SAFE (Safety Analysis For occupant crash Environment) is utilized to simulate the body block test. Segments, contact ellipsoids and spring-damper elements are used to model the steering column in SAFE. The model is verified by the result of the body block test. After the model is validated, the energy absorbing components are designed using an orthogonal array. Occupant analyses are performed for the cases of the orthogonal array. Final design is determined for minimum occupant injury. For vibration analysis, a finite element model of the steering column is defined for the modal analysis. The model is validated by vibration experiments. Size and shape variables are selected for the optimization process. Optimization is conducted to minimize the weight subjected to various constraints.
A general theory for skid steering of tracked vehicles on firm ground
Authors: Wong J Y , Chiang C F
Published: October 2002

A general theory for skid steering of tracked vehicles under steady state conditions on firm ground, taking into account the shear stress-shear displacement relationship on the track-ground interface, is presented. The steering behaviour predicted using the general theory bears a strong resemblance to that observed in the field. The variations of sprocket torques for the outer and inner tracks with turning radius predicted by the general theory are in reasonably close agreement with available experimental data. On the other hand, predictions based on Steeds’ theory developed earlier differ greatly from measured results. Using the general theory, the lateral coefficient of friction used in the conventional method for predicting the moment of turning resistance of the track can be quantitatively determined as a function of turning radius. It is believed that the new theory presented in this paper provides a unified approach to the study of the mechanics of skid steering of tracked vehicles and that it may be extended to the study of transient handling behaviour of tracked vehicles.
The distribution of energy absorbed by a three-spoke steering wheel armature in an impact with a deformable chestform
Authors: Altenhof W. , Paonessa S. , Zamani N.
Published: October 2002

This research deals with experimental and finite element simulation of impacts occurring between a deformable chestform and an aluminium three-spoke steering wheel armature. Experimental testing was conducted to investigate the effect of impact location and armature orientation on the energy-absorbing capabilities of the automotive component. Numerical (finite element) models were developed to simulate the experimental process and to investigate further how the energy absorption abilities of the armature, and specific sections of the armature, vary with different impact situations. An excellent correlation between the experimental testing observations and numerical simulation results was observed for this highly non-linear problem. Most importantly, the finite element simulations have illustrated that the steering wheel armature hub and rim regions are the locations where most energy, because of plastic deformation in the structure, is absorbed. These observations provide an understanding of the characteristics of energy management in crash situations for the steering wheel armature.
Outline of a new control concept for power shifting of fixed step ratio automotive transmissions
Authors: Jacobson B.
Published: October 2002

Power shifting transmissions, e.g. automatic transmissions, are traditionally shifted from gear A to B by disengaging a clutch belonging to gear A and engaging a clutch belonging to gear B. This paper tries out the idea of employing a third clutch. In practice, such a third clutch can be one of the clutches which is traditionally used only for other gears. This means that the new concept can be used with only a control software update in an ordinary gearbox. The trade-off between comfort and wear, which is experienced in the traditional control concept, becomes less troublesome. The wear, or the discomfort, can be reduced to roughly half of that corresponding to a traditionally controlled upshift. The work finds the largest potential in using an extra clutch which belongs to a gear higher than the high gear in an upshift. The theoretical study is carried out with a general and simple model, but a simulation example is added using a more detailed model of an existing gearbox.
Cold start and drivability characteristics of an ethanol-methyl-t-butyl ether blend fuelled vehicle
Authors: Silva N. R. , Sodré J. R.
Published: October 2002

An ethanol-methyl- t-butyl ether (MTBE) fuel blend was used as a substitute for hydrated ethanol to improve the vehicle cold start and drivability characteristics during the warm-up period. The vehicle was tested in a cold box, reaching a lower ambient temperature limit of -6deg;C, which represents the most severe weather condition experienced in Brazil. Different concentrations of MTBE in ethanol were investigated. The results show satisfactory drivability characteristics for the tested conditions, comparable with those found in gasoline-fuelled vehicles, thus overcoming the existing cold start difficulties in production ethanol-fuelled vehicles.
Combustion modelling for direct injection diesel engines
Authors: Micklow G. J. , Gong W.
Published: October 2002

Successful modelling of combustion systems depends on an adequate as well as a computationally efficient description of the reaction mechanisms. For a typical medium speed compression ignition direct injection (CIDI) engine under normal operating conditions, from 70 to 95 per cent of the injected fuel is in the vapour phase at the start of combustion and 10-35 per cent of the vaporized fuel has mixed to within flammability limits. This indicates that both a premixed combustion mechanism and a diffusion combustion mechanism are important to model CIDI engines. In the early stages of combustion, a premixed combustion mechanism should be utilized while, late in the combustion process, a diffusion-based mechanism will be dominant. The former is chemically based, while the latter is physically based. In this article, the two combustion mechanisms mentioned above and various combinations of the two mechanisms for the intermediate stages of combustion are investigated. The study was done on a Caterpillar 3401 diesel engine. It was found that by utilizing a hybrid scheme whereby the premixed combustion mechanism is employed up to a user-specified crank angle, beyond which point a diffusion combustion method is utilized, reasonable agreement for both in-cylinder pressure and heat release rate with experimental data could be obtained.
Optimization of the intake port shape for a five-valve gasoline engine
Authors: Lee K , Lee C , Joo Y
Published: October 2002

For the development of a high efficiency gasoline engine, the optimization of the intake port shape for a five-valve engine has been studied. Intake multivalve cylinder heads were manufactured by using a three-dimensional computer-assisted design program, and steady state flow experiments and flow visualization experiments have been performed with these cylinder heads. The five-valve engines, which have larger valve opening areas, have larger intake flowrates and higher tumble ratios than the four-valve engines. The effects of intake port design parameters of a five-valve engine on the intake flowrate and tumble were studied, and the design guidelines for the five-valve engines were established.
Theoretical and experimental study of a power split continuously variable transmission system Part 1
Authors: Mantriota G
Published: October 2002

Continuously variable transmissions (CVTs) have made notable progress, especially in the automotive industry, over the past years. In this paper the results of a theoretical and experimental study of an original power split CVT (PS-CVT) system are obtained. The main advantage of the proposed solution is to improve the efficiency of the CVTs by means of a power flow without recirculation using two separate phases of operation. The kinematic characteristics of the single-component devices are obtained. Using a special test rig, the power flows and the efficiency of the PS-CVT system are experimentally determined in the first operational phase. The results are compared with those obtained by a theoretical model. The advantages are therefore shown, in terms of power and efficiency, of the PS-CVT system proposed in this paper in comparison with the single CVT.
Will radar-based vision enhancement make driving safer? An experimental study of a hypothetical system on a driving simulator
Authors: Stanton N. A. , Pinto M
Published: October 2002

Technological progress is suggesting dramatic changes to the tasks of the driver, with the general aim of making the driving environment safer. Before any of these technologies is implemented, empirical research is required to establish whether these devices do, in fact, bring about the expected improvements. Initially, at least, simulated driving environments offer a means of conducting this research. The study reported in this paper concentrates on the application of a hypothetical radar-based vision enhancement system within the risk homeostasis paradigm. It was expected, in line with risk homeostasis theory (RHT), that the drivers would compensate for the reduction in risk by increasing their speed. The results of this study support the hypothesis although, after a simulated failure of the vision enhancement system, drivers did reduce their speed owing to reduced confidence in reliability of the system. Suggestions for new design solutions are given.
A direct injection diesel combustion model for use in transient condition analysis
Authors: Cui Y , Deng K , Wu J
Published: October 2002

A phenomenological multizone combustion model is developed for use in the transient condition analysis of a turbocharged direct injection (DI) diesel engine. The main processes in the cylinder, such as spray penetration, droplet evaporation, air-fuel mixing, spray wall interaction, ignition and fuel combustion, are taken into consideration. In order to predict cylinder pressure and NOx emissions in a wide range of engine speeds, loads and air-fuel ratios under transient conditions, the model has been improved in many respects, especially in the velocity distribution of fuel spray, zonal entrainment and the calculation of gas properties and chemical equilibrium compositions of combustion products including solid carbon. With respect to the turbocharged engine with a high pressure in the cylinder, the compression factor is added to the ideal gas equation of state in order to simulate cylinder pressure accurately. Cylinder pressure, heat release and NOx emission histories for different operating conditions are calculated for two types of engines. The agreement between calculated and measured results is good for a wide range of operating conditions. This indicates that the model has the ability to predict cylinder pressures and NOx emissions in both steady state and transient operating conditions.
Fuel losses to the crankcase and hydrocarbon return with recirculated oil and ventilation flow
Authors: Winborn L. D. , Shayler P. J.
Published: October 2002

Gasoline fuel losses to the crankcase, fuel/oil interactions and fuel return as unburned hydrocarbons (HCs) in the crankcase ventilation flow and recirculated oil films have been investigated for a contemporary spark ignition (SI) engine. The results of engine tests under motored and firing conditions have been used to develop a detailed description of the fuel transport path. This has then been applied to predict the level and rate of fuel accumulation in the oil sump. Fuel transported past the piston with blow-by is the major source of HCs in the crankcase ventilation flow. During cold operation, a large proportion of this is retained by oil films along the blow-by path, thus contributing to bulk oil dilution. At elevated engine temperatures, this absorption mechanism becomes considerably less effective, and the majority of blow-by fuel is transported directly through to the crankcase vent. The return of fuel hydrocarbons from the oil takes place via desorption into the crankcase gas, which makes a further small contribution to the HC concentration in the ventilation flow, and desorption from oil recirculated to the cylinder wall films. Crankcase ventilation flow generally accounts for the majority of the desorbed fuel, which is then recirculated to the cylinders and assimilated into the fresh charge. Fuel desorption from the liner oil films consists of smaller flowrates but can contribute directly to feedgas HC emissions. The evidence strongly suggests that the in-cylinder desorption primarily involves the heavier fractions of the injected fuel.
Comparison and evaluation of contemporary restraint systems in the driver and front-passenger environments
Authors: Kent R. W. , Crandall J. R. , Bolton J. R. , Duma S. M.
Published: October 2002

Restrained driver and passenger kinematics and injury outcome in frontal collisions are compared using US fatality field data and post-mortem human surrogate sled tests. The fatality data indicate that a frontal airbag may provide greater benefit for a passenger than for a driver. The thoracic injuries sustained by passenger-side surrogates restrained by a force-limited, pre-tensioned belt and airbag are evaluated, and kinematics are compared with driver-side subjects exposed to a similar impact. Driver and passenger kinematic differences are identified and the implications are discussed with respect to the injury-predictive ability of existing thoracic injury criteria. The chest acceleration of the passenger-side subjects exhibited a bimodal profile with an initial (and global) maximum before the subject loaded the airbag. A second acceleration peak occurred as the subject loaded both the belt and the airbag. A similarly restrained driver-side subject loaded the belt and airbag concurrently at the time of peak chest acceleration and therefore did not exhibit this biomodal chest acceleration. While the injury-causing or injury-mitigating significance of this bimodal response is not known, its significance with respect to thoracic injury prediction is discussed.
A new strategy for improving the warm-up performance of a light-off auto-catalyst for reducing cold-start emissions
Authors: Jeong S-J , Kim W-S
Published: October 2002

Light-off catalysts are often used to minimize cold-start emissions. The improved coldstart performance of light-off catalysts (LOCs) needs the optimal design in terms of flow distribution, geometric surface areas (GSA), precious metal (PM) loading, cell density and space velocity (SV). In this study, these influential factors are numerically investigated using an integrated numerical technique by considering not only the three-dimensional fluid flow but also the heat and mass transfer with chemical reactions. The present results indicate that uneven catalyst loading by depositing highly active catalyst materials upstream of the monolith is beneficial during the warm-up period, but its effect is severely deteriorated when the SV is above 100 000 h-1. To maximize light-off performance, this study suggests that:

(a) the LOC be designed as a double-substrate type;

(b) a substrate with high GSA and high PM loading at the face be placed at the front;

(c) the cell density of the rear monolith be lower to reduce the pressure drop.

In this paper, some initial results towards a new strategy of dual substrates are also reported to shorten the light-off time and improve conversion efficiency during warm-up. The proposed approach was very effective in reducing back pressure and cold-start emissions during the early seconds of engine operation.
Robust roll control of a vehicle: Experimental study using a hardware-in-the-loop set-up
Authors: Kim H-J , Yang H. S. , Park Y-P
Published: October 2002

This paper presents a simcopy IMulation and experimcopy IMental study of a vehicle with an electrically actuated roll control system. The controller is designed in the framework of an output feedback H∞ control scheme based on the three-degree-of-freedom linear vehicle model. Various parameters which affect the roll dynamics are considered for robust stability and disturbance rejection. In order to investigate the feasibility of the active roll control system, its performance is evaluated by simcopy IMulation in a full vehicle model with non-linear tyre characteristics. After that, an electrically actuated roll control system is devised, which imcopy IMproves the high frequency isolation during inoperative periods. Finally, its performance is investigated by experimcopy IMental work using a hardware-in-the-loop set-up with the devised control system.
Simulation of the operation of a climatic wind tunnel
Authors: Hanby V. I. , Roberts E. C. , Fletcher D. W. , Jones D. N. T.
Published: October 2002

The climatic wind tunnel (CWT) is a facility which is widely used in vehicle and component manufacturing to reduce product development times. In view of the wide range of temperatures, humidities and wind speeds required for testing, the energy cost can be a significant part of the overall cost of testing. The paper describes a project which was primarily concerned with the development of a detailed, component-based model of a climatic wind tunnel, its associated plant and the test vehicle. The model was tested against measured plant performance and shown to give a satisfactory representation of plant performance. The potential uses of the model are illustrated by the exploration of alternative control strategies and plant configurations.
Braking performance simulation for a tractor-semitrailer vehicle with an air brake system
Authors: Suh M-W , Park Y-K , Kwon S-J
Published: October 2002

Recently safety systems for commercial vehicles have been developed rapidly. However, there are still many problems in the vehicle stability and the braking performance. In particular, a commercial vehicle may meet a dangerous braking condition when the vehicle is lightly loaded or empty and when the road is wet or slippery. Under these conditions, the truck can spin out, the tractor can jackknife or the trailer can swing out. To design an air brake system for a commercial vehicle, since the air brake system has many design variables, there must be intense research on a method on how to prevent dynamic instability and how to maximize vehicle deceleration. In this study, mathematical models of the tractor-semitrailer and the air brake system including an antilock brake system controller have been constructed for computer simulation. Also, simcopy IMple examples are applied to show the usefulness of the program. Designers can use this simulation program for understanding the braking characteristics such as trajectory, braking distance, longitudinal deceleration, lateral deceleration and yaw rate under various braking conditions.
The rapid development of a vehicle electronic control system and its application to an antilock braking system based on hardware-in-the-loop simulation
Authors: Li J. , Yu F. , Zhang J-W. , Feng J-Z. , Zhao H-P.
Published: October 2002

The paper describes in detail a rapid development system for vehicle electronic control systems by using real-time hardware-in-the-loop (HiL) simulation technology. This system can be used in parallel with the development of a new vehicle electronic control product. Once desired simulation results are achieved from the real-time HiL simulator in laboratory environments, control system design can be verified by setting up the same configuration in the new product in-vehicle test. The correlation between HiL simulation results and vehicle field test data can thereby be evaluated. The feasibility and effectiveness of the rapid development system have been demonstrated through the development of a vehicle antilock braking system (ABS) control algorithm. A significant reduction in development cycle time and cost has been achieved with the aid of this powerful tool, and the effectiveness of the ABS algorithm has been validated in vehicle field tests. The proposed ideal and approach can also be applied to develop other control systems, such as a traction control system, a vehicle stability control system, etc.
Objective evaluation of handling quality
Authors: Data S , Frigerio F
Published: October 2002

Vehicle dynamics quality is generally evaluated by two approaches: subjective evaluations using driver ratings and objective measurements of vehicle dynamics characteristics. In both approaches it is important to define features of vehicle dynamics in order to cover all aspects, but without redundancy. For this reason, the first part of the paper tries to summarize the principal qualities and to how they might be organized. In the second part, the paper describes those procedures that can be used to obtain objective quality indices. First of all, criteria used in subjective testing (questionnaire design, jury selection, etc.) are described. Then it is determined which manoeuvres can be performed, and which physical quantities should be considered, in order to obtain objective parameters that correlate with subjective evaluation. After this, the paper briefly describes the statistical technique used to identify which measured variables best correlate with vehicle dynamics qualities. In the third part, the paper contains a practical application of the objective index identification procedure regarding handling quality. Some examples are given about how these indices are used in different phases of a new car development, from target setting to target deployment, and in target achievement and verification during final tuning.
Vehicle dynamics modelling for the National Advanced Driving Simulator
Authors: Heydinger G J , Salaani M K , Garrott W R , Grygier P A
Published: October 2002

This paper provides an overview of the development of a vehicle dynamics simulation model for use on the National Highway Traffic Safety Administration's (NHTSA's) National Advanced Driving Simulator. The paper describes fundamental aspects of models used to represent rigid body chassis and suspension systems, powertrain, tyres, brakes, steering and aerodynamics. Representative data from laboratory measurements, instrumented field tests and simulation runs of a 1997 Jeep Cherokee Sport are presented to illustrate simulation development and validation efforts. A companion paper to this one also uses Jeep Cherokee data. Both papers highlight current capabilities and methodologies employed by two organizations that have worked, often collaboratively, to advance the state of the art of vehicle dynamics modelling and simulation validation. This paper features work done by NHTSA's Vehicle Research and Test Center; the companion paper reports on work done by Systems Technology, Incorporated (STI).
Validation of a non-linear vehicle dynamics simulation for limit handling
Authors: Wade-Allen R , Chrstos J P , Howe G , Klyde D H , Rosenthal T J
Published: October 2002

This paper discusses the validation of a ground vehicle dynamics computer simulation that includes complete models for sprung and unsprung masses, tyres, suspension, steering and brake systems, and power train including engine, transmission and differentials. The models have been developed over the last decade and have been applied to single-unit passenger cars, trucks and buses, and articulated tractor/trailer vehicles up to limit performance operating conditions. The tyre and vehicle models use composite parameters that are relatively easy to measure. However, the measurements must cover the key operating regime where the simulation is expected to be applied. For example, limit performance manoeuvring conditions require tyre data over large slip conditions and high normal load (beyond the design load) to cover the full range of dynamic operating conditions. Spring and damper response should also take into account large deflections and high velocities respectively to cover relevant non-linearities.
Dynamic testing of shock absorbers under non-sinusoidal conditions
Authors: Kowalski D , Rao M D , Blough J , Gruenberg S
Published: October 2002

This paper deals with the dynamic characterization of an automotive shock absorber, the continuation of an earlier work [1]. The objective of this ongoing research is to develop a testing and analysis methodology for obtaining dynamic properties of automotive shock absorbers for use in CAE-NVH low-to-mid-frequency chassis models. Stepped sine sweep excitation is currently used in industry to obtain shock absorber parameters along with their frequency and amplitude dependence. Sine-on-sine testing, which involves excitation using two different sine waves, has been done in this study to understand the effects of the presence of multiple sine waves on the estimated dynamic properties. In an effort to obtain all frequency dependent parameters simultaneously, different types of broadband random excitation have also been studied. Results are compared with stepped sine sweep tests. Additionally, actual road data measured on different road profiles have been used as input excitation to obtain the shock absorber parameters for broad frequency bands under realistic amplitude and frequency conditions. These results are compared with both simulated random excitation and stepped sine sweep test results.
New evaluation indices for bulk motion of in-cylinder flow through intake port system in cylinder head
Authors: Yun J-E
Published: October 2002

The purpose of this study is to find new evaluation indices for the bulk motion of in-cylinder flow instead of the current swirl or the tumble coefficient and ratio using a steady flow test rig on intake port systems. To do this, port flow rig tests were conducted on the double-overhead cam head. Finally, the angular flow coefficient (NA), the inclination angle (γ) the angular flow parameter (PA) and the flow angle (φ) were introduced as new evaluation indices for the bulk motion of in-cylinder flow.
Analytical efficiency comparison between gas turbine and gas turbine hybrid engines for passenger cars
Authors: Cheng W , Wilson D. G. , Pfahnl A. C.
Published: October 2002

The performance and emissions of two alternative types of gas turbine engine for a chosen family vehicle are compared. One engine is a regenerative 71 kW gas turbine; the other is a hybrid power plant composed of a 15 kW gas turbine and a 7 MJ flywheel. These engines would give generally similar vehicle performance to that produced by 71 kW spark ignition and compression ignition engines. (The turbine engines would be lighter and, with a free power turbine, would have a more favourable torque-speed curve (1), giving them some advantages.) Results predict that for long-distance trips the hybrid engine would have a considerably better fuel economy and would produce lower emissions than the piston engines, and that the ‘straight’ gas turbine would be even better. For shorter commuting trips the hybrid would be able to run entirely from energy acquired and stored from house electricity, and it could therefore be the preferred choice for automobiles used primarily for urban driving when environmental factors are taken into account. However, the degradation of remaining energy in flywheel batteries and thermal energy in the regenerator and other engine hot parts between use periods will result in more energy being used than for the straight gas turbine engine using normal liquid fuel. The higher initial cost and greater complexity of the hybrid engine will be additional disadvantages.
Divergence analysis of an emissions-based air—fuel ratio model and exhaust oxygen estimation
Authors: Chan S. H. , Zhu J
Published: October 2002

This paper claims that, instead of relying on direct fuel and air flowrate measurements, exhaust gaseous emissions analysis should be considered as the standard method for the determination of time-resolved air—fuel ratio (AFR), in particular for petrol powered engines.

Various sensitivity parameters are defined and the maximum possible relative divergences of the air—fuel ratio are calculated to support the above claim. It is proved that to obtain the air—fuel ratio with the same order of accuracy for a petrol engine near stoichiometric conditions, the resolution of the instruments used for fuel and air flowrate measurements should be at least ten times more accurate than the emission analysers.

Estimation of oxygen concentration is also conducted based upon other measurable emission constituents, viz. oxides of carbon (COx) and hydrocarbons. Two methods are proposed, one depends on known air—fuel ratio whereas the other one does not require that the air—fuel ratio is known. Estimation of oxygen concentration using the former method is not affected essentially by the effect of the presence of water vapour in the analyser on the measured emission constituents.
Shape design of an engine mount by a method of parametric shape optimization
Authors: Kim J. J. , Kim H. Y.
Published: October 2002

In order to obtain an automatically designed shape of engine mount, the authors introduce the shape design process using the method of parameter optimization. The optimization code is developed and used with a commercial non-linear finite element program to determine the shape that satisfies the stiffness requirements of engine mounts. A bush type engine mount used in a passenger car is chosen for the application model. The stiffness of the optimized model along the principal direction is compared to the design specification of the mount. The shape obtained from the parameter optimization is considered to be acceptable. It can be seen that a well-defined parametric approach is successful in the design of the basic shape of engine mounts.
An alternative force state map for shock absorbers
Authors: Duym S
Published: October 2002

Automotive shock absorbers are commonly characterized by their force-velocity diagram. Nevertheless, mainly due to gas entrapped in the damper fluid, hysteretic effects can be observed on the characteristic curve. In order to improve the accuracy of the description and possible simulations, the restoring force method was used to describe the damper force. According to the restoring force method or equivalent force state mapping technique, the damper force is fitted as a non-parametric function of both velocity and displacement. However, it is shown for a damper under test that a more appropriate choice would be to use velocity and acceleration as independent variables instead of displacement and velocity for broadband excitation signals.
Fuel saving by the optimized use of cab roof fairings for typical articulated vehicle operating cycles
Authors: Dominy R. G.
Published: October 2002

The aerodynamic benefits of cab roof fairings and the associated reduction of drag and fuel consumption have been well documented. Although considerable effort has been applied by many manufacturers and researchers to devise roof fairings of near-optimal design for individual cab-trailer combinations, published studies have taken little or no account of the proportion of operations that may be undertaken by a tractor either with poor fairing/trailer matching or without a trailer at all. Observed load factors have proved to be substantially lower than those quoted by fleet operators. Cycle simulations have been performed to revise the estimate of the potential gains that are available from aerodynamic fairings for realistic operating cycles and load factors. It is shown that even for high load factors significant cost savings may be made in some circumstances by the adoption of simple but easily adjusted fairings in place of more highly optimized but fixed geometry designs.
Experimental studies of a thermochemical store for automobile engines
Authors: Darkwa K
Published: October 2002

An experimental evaluation of a thermochemical energy store using inorganic oxides as the storage material has been carried out. The experimental data achieved an average deviation of 17 per cent from the theoretical values and accounted for about 8 per cent of uncertainties in the primary data. Given the configuration of the rig and the experimental conditions and errors, the experiment has proved that it is feasible to utilize a fixed bed thermochemical energy store for preheating an engine during cold starting. However, for practical application purposes, it may be desirable to redesign the reaction bed in order to achieve effective mass and heat transfer. Immediate action is therefore required to accelerate the penetration of such a system into the transport sector.
Automotive active suspensions Part 2: Practical considerations
Authors: Williams R A
Published: October 2002

Part 1 of the paper demonstrated the compromises required in suspension design brought about by the conflicting demands of ride and handling, and the constraints applied by the need to minimize body acceleration within a limited suspension travel. It then went on to show how a state feedback controller can be used to provide improvements in ride which are not achievable with standard passive components.

This 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 is assessed, together with the practical implications.