bluuebunny/crossref_metadata_2025 huggingface dataset:
Support vector machines for detection and characterization of rolling element bearing faults
Authors: Jack L. B. , Nandi A. K.
Published: April 2011

Artificial neural networks (ANNs) have been used to detect faults in rotating machinery for a number of years, using statistical estimates of the vibration signal as input features, and they have been shown to be highly successful in this type of application. Support vector machines (SVMs) are a more recent development, and little use has been made of them in the condition monitoring (CM) arena. The availability of a limited amount of training data creates some problems for the use of SVMs, and a strategy is offered that improves the generalization performance significantly in cases where only limited training data are available. This paper examines the performance of both types of classifier in one given scenario—a multiclass fault characterization example.
Piecewise linear reliability data analysis with fuzzy sets
Authors: Harris J
Published: April 2011

The Weibull three-parameter model is widely used in the analysis of reliability data, since it provides a good fit to many, but not all, data cases. In this work an analysis is presented in which locally constant hazard rate functions are applied in the analysis. By defining concomitant fuzzy reliability functions as overlapping fuzzy sets, the limited ranges may be conjoined to provide an extensive continuous reliability function. The efficacy of this treatment is tested with three different typical cases of published physical data that were previously the subjects of Weibull graphical analysis. It is found that in each case the treatment is effective. Different phases of the failure pattern of each case are identified and characterized by ‘time’ constants. The treatment is not limited to three parameters, as in the Weibull case, and it is therefore more flexible. It provides a deeper insight into the underlying failure mechanisms and may be expected to provide a wider range of applications, both within reliability data analysis and in other fields, and can form part of a knowledge-based system.
Effect of circumferential outlet distortion on the flow characteristics at the impeller exit of a centrifugal pump
Authors: Hong S. S. , Kang S. H.
Published: April 2011

Centrifugal impellers are exposed to downstream circumferential outlet distortions due to non-axisymmetric volutes or diffusers. This paper explores the effect of circumferential outlet distortion on the flow characteristics at the impeller exit of a centrifugal pump. A fence with non-uniform height was installed at the vaneless diffuser exit to create the outlet distortion, and then unsteady velocity and static pressure were measured at the impeller exit. The instantaneous and mean flow fields at the impeller exit varied with the circumferential position. Plots of the flows against the local flowrate showed hysteretic loops that deviated from the quasi-steady curves obtained from the flows without the fence. When the assumption of quasi-steady variation was applied to the present impeller-diffuser interaction, the prediction for the total and static pressure was reasonable but showed a phase difference for the absolute velocity.
Parametric study of the air-side performance of slit fin-and-tube heat exchangers in wet conditions
Authors: Wang C-C , Lee W-S , Sheu W-J , Chang Y-J
Published: April 2011

The air-side performance of three new slit fin-and-tube heat exchangers under dehumidifying conditions is reported. The effects of the number of rows of tubes, the fin pitch and the inlet relative humidity on air-side performance are reported. It is found that for type I slits, which are characterized by a small louvre angle (convex-louvre configuration), the test results show that the sensible heat transfer performances are relatively independent of fin pitch. However, for type III slits, which feature the smallest distance between adjacent slits, a drop of heat transfer performance for N= 1 and Fp = 1.81 mm is observed. It is very likely that this phenomenon is related to the ‘non-recovery wake effect’ caused by the slit geometry. A correlation is proposed for the slit fin configuration; the mean deviations of the proposed heat transfer and friction correlation are 8.0 and 8.1 per cent respectively.
Optimal synthesis of a spring-actuated cam mechanism using a cubic spline
Authors: Kim J H , Ahn K Y , Kim S H
Published: April 2011

This paper presents the optimal synthesis for a cam with non-constant angular velocity based on the dynamic model of a complete spring-actuated cam system. In order to satisfy asymmetric constraints and guarantee continuous contact at the cam-follower interface, the follower motion, which is dependent on the requirements during the closing period of a vacuum circuit breaker, is optimized using a cubic spline. The optimized cam is compared with a cam designed by assuming the cam angular velocity to be constant and with a polynomial cam. Simulation results reveal that the dynamic behaviours of the optimized cam are superior to those of the original cam and the polynomial cam.
Analysis of large-scale flow characteristics in a four-valve spark ignition engine
Authors: Li Y , Zhao H , Ladommatos N
Published: April 2011

A digital particle image velocimetry (PIV) measurement has been carried out to study the large-scale flow characteristics in a single-cylinder engine with a production-type four-valve cylinder head under one intake port deactivation. The measurement plane was located 12 mm below the cylinder head parallel to the flat piston top. Two-dimensional velocity fields from 100 consecutive cycles were acquired at every 30 crank angle interval in the compression stroke to analyse ensemble-averaged mean velocity, cyclic variation of the swirl motion, low-frequency and total velocity fluctuations and their integral length scales. The analysis shows that as one intake port is deactivated, strong swirl forms at the end of the intake stroke and sustains its flow pattern up to the late stage of the compression stroke with the precessing of the swirl centre. Both swirl ratio and swirl centre show significant cyclic variations in the compression process. A low-frequency component with spatial frequency below 0.05 mm-1 (corresponding to a large-scale structure with a spatial scale over 20 mm) is absolutely predominant in the flow field and therefore the low-frequency large-scale flow behaviour determines the basic characteristics of the total in-cylinder flow. The flow field is considerably anisotopic because the integral length scale of any velocity fluctuation components along any direction is different. However, the velocity fluctuation field in the horizontal plane will gradually become homogeneous as the piston moves up in the compression stroke. The integral length scale is in the range of 4-10 mm at an engine speed of 600 r/min. When the engine speed is doubled, flow velocity in the cylinder nearly doubles and velocity fluctuation kinetic energy more than triples though the flow pattern hardly changes.
The effect of active control on stability characteristics of hydrodynamic journal bearings with an axial groove
Authors: Rho B-H , Kim K-W
Published: April 2011

Results of theoretical investigations on stability characteristics of an actively controlled hydrodynamic journal bearing are presented. Proportional, derivative and integral controls are adopted for a hydrodynamic journal bearing with an axial groove. Furthermore, a cavitation algorithm, implementing the Jakobsson-Floberg-Olsson boundary condition, is adopted to predict cavitation regions in a fluid film more accurately than the conventional analysis, which uses the Reynolds condition. Using the bearing's linear dynamic coefficients, which are evaluated from the perturbation method, the stability characteristics of a rotor-bearing system are investigated using the Routh-Hurwitz criteria. It is shown that the instability threshold speed of a rotor-bearing system can be greatly increased and the unbalanced responses of the system can be markedly decreased by both proportional and derivative control of the bearing. Results show that active control of a hydrodynamic journal bearing can be adopted for stability improvement and reduction of the unbalanced whirl amplitude of a rotor-bearing system.
A mathematical model of a cc-type single-screw compressor
Authors: Yang S-C
Published: April 2011

In this paper, a method is proposed for determining a basic profile of a cc-type single-screw compressor including the gate rotor and the screw rotor. The cc-type has a cylindrical screw and two cylindrical gate rotors. Based on this method, a mathematical model of the meshing principles of a cc-type screw rotor meshed with a gate rotor, that has either straight edge teeth or conical teeth, is presented.

The inverse envelope concept is used to determine the cutting-edge curve of a gate rotor. Based on this concept, the required cutter for machining a cc-type screw rotor can be obtained by the envelope of a one-parameter family. The obtained screw rotor is an envelope to the family of the gate rotor's surfaces. The obtained envelope becomes the generating surface. The inverse envelope can be used to obtain the envelope to the family of generating surfaces. Then the profile of a gate rotor cutting-edge curve can be easily obtained.

The surface analysis including contact lines is shown for the design and manufacture of a screw compressor. As an example, the cc-type single-screw compressor with a compressor ratio of 11:6 was determined with the aid of the proposed mathematical model. Using rapid prototyping (RP) and manufacturing technology, a cc-type single-screw rotor with a gate rotor was designed.

The RP primitives provide an actual full-size physical model that can be analysed and used for further development. Results from these mathematical models should have applications in the design of cc-type single-screw compressors.
Geometry analysis and optimal design of Geneva mechanisms with curved slots
Authors: Lee J-J , Huang K-F
Published: April 2011

A systematic procedure is proposed for the design of Geneva mechanisms with curved slots. Based on the theory of conjugate surfaces, mathematical expressions for the slot profile, pressure angle and cutter's location for manufacturing are presented. In addition, to evaluate the combined kinematics and structural performance of the mechanism, the maximum contact stress and degree of wear are established as the performance index. Effects of variations in various design parameters on the values of the performance indices are investigated. Using the indices as the objective function, the optimum design that takes into account the initial crank angle, offset and roller radius is performed.
Thermal design for the Beagle 2 landed test environment
Authors: Shaughnessy B M
Published: April 2011

Beagle 2 is a British-led mission to place a scientific Lander on Mars to search for evidence of past or present life and to conduct geochemical and environmental investigations. It was launched aboard the European Space Agency's Mars Express on 2 June 2003.

During 2002 tests were undertaken at the Rutherford Appleton Laboratory, UK, to verify the Lander thermal design under simulated Martian environmental conditions. A pre-requisite was the design and commissioning of the test facility required to achieve the stringent test requirements. This paper describes the development of the test facility and the supporting thermal design and analysis.
An experimental investigation of the heat transfer due to multiple jets impinging normally on a dimpled surface
Authors: Kanokjaruvijit K , Martinez-Botas R F
Published: April 2011

A dimpled surface, used as a turbulence promoter, was combined with jet impingement to investigate the potential for heat transfer enhancement. An eight-by-eight jet array was used to impinge a staggered dimple surface, both on the dimples themselves and on the flat portions adjacent to the dimples. The heat transfer coefficient was measured using the transient wide-band liquid crystal method. The jet-to-plate spacing (H/D) studied was 2, 4 and 8. Two dimple geometries were tested: hemispherical concavities and cusped elliptical shapes. All the results were normalized by those from a flat plate. The results varied depending on the H/D spacing and the flow scheme for the exit (one-way, two-way and four-way exits); the effect of geometry variation (hemispherical or cusp shapes) was secondary. The maximum exit flow scheme (four-way exit) achieved the highest enhancement of heat transfer. The combination of dimples and impingement can lead to significant enhancement, but careful optimization of the location of impingement would be required.
Annulus wall temperatures and heat transfer coefficients in aeroengine compressors deduced from engine measurements
Authors: Lewis L , Provins J , Fisher L
Published: April 2011

Surface-mounted thermocouples were located on the annulus walls of every stator stage in both core compressors of a large civil aeroengine. The relationships of the steady state wall temperatures to the compressor inlet and exit air temperatures are shown, as is their variation with engine rotational speed. The transient response of the thermocouples to fast engine throttle manoeuvres was measured, for acceleration to full power, deceleration to idle and for both acceleration and deceleration to two intermediate power levels.

Heat transfer coefficients are deduced from the matching of a thermal finite element model to the measured transients and are expressed as factors with respect to the standard free-disc formula. The variations in the factors through the compressor and through the speed range are shown. The advantages and disadvantages of using an alternative standard formula, based on duct flow, are discussed. Finally, the importance of understanding the transient local air temperature response arriving at a compressor stage due to upstream slugging is shown.
Computational simulations of buoyancy-influenced turbulent flow and heat transfer in a vertical plane passage
Authors: Wang J , Li J , He S , Jackson J D
Published: April 2011

Computational simulations are reported of some recent experiments on turbulent variable-property mixed convection to air flowing upwards and downwards through a vertical plane passage, one wall of which was uniformly heated. In addition to heat transfer from that wall by convection, there was some radiative heat transfer to the opposite wall. In the experimental study, measurements were made of profiles of velocity and turbulence within the flow, and also local values of convective heat transfer coefficient were determined along the heated wall. The Reynolds number was varied from 44000 down to 7000 and the Grashof number from 3.0 × 108 to 9.0 × 09. To simulate the experiments by computational means, the governing equations for variable-property buoyancy-influenced two-dimensional turbulent flow and heat transfer in Reynolds-averaged form were solved using an elliptic formulation in conjunction with two well-known low-Reynolds-number k-e turbulence models. In this paper, results from the computational study are compared directly with experiment. In general, the observed effects of buoyancy on flow and heat transfer were satisfactorily reproduced but there were some clear discrepancies between the predictions and the experimental results, especially with downward flow under conditions where the influence of buoyancy was strong.
Dynamic modelling of flexible structures using a local frame formulation
Authors: Chochia G A , Chawdhry P K , Burrows C R
Published: April 2011

In this paper a new finite element formulation for slender beams is suggested that is valid for large rotations and deflections. Traditional formulations such as the floating frame approach and the incremental method are limited to small deflections, which restricts the scope of their applicability to small accelerations. In the local frame formulation no simplifying assumptions are made in accounting for the inertia forces. As the formalism remains consistent with large deflections it can be used for accurate evaluation of deformations caused by inertia forces at large accelerations. The paper is concerned with multibeam plane motions. The new formulation is implemented as a computer algebra tool that generates dynamic equations of flexible multibody systems from specifications. A number of case studies related to high-speed machinery are presented.
Vibration of non-homogeneous plates using two-dimensional orthogonal polynomials as shape functions in the Rayleigh—Ritz method
Authors: Chakraverty S , Petyt M
Published: April 2011

This paper presents the use of two-dimensional boundary characteristic orthogonal polynomials as the shape functions in the Rayleigh—Ritz method to study the vibration of non-homogeneous plates with a curved boundary, and of elliptical plates in particular. The non-homogeneity considered here is a sort of generalized radial tapering that belongs to a special class such that the taper always extends to zero elasticity and zero density at the plate edges. The first five natural frequencies are reported here for various combinations of the degrees of non-homogeneity. Plots have been presented to show the effect of the aspect ratio on different modes of vibrations for various shapes of elliptic plates and degrees of non-homogeneity. The results for non-homogeneous elliptical plates are entirely new and are not available elsewhere. Comparison can only be made for homogeneous plates, and in this case the results have been found to be in exact agreement with the results of available literature.
Free vibration analysis of composite sandwich plates
Authors: Meunier M , Shenoi R A
Published: April 2011

The fibre reinforced plastic (FRP) composite materials configured as sandwich panels are finding increased usage in a variety of structural applications. An important facet in correct usage is an understanding of the dynamic behaviour of such structural configurations. This paper addresses the issue of natural frequencies of sandwich plate panels. The closed-form solutions are obtained using Reddy's first- and higher-order shear deformation theories. The approaches are validated against results from a standard, commercially available finite element analysis package. The paper concludes with a detailed investigation of the influence of variation in material property parameters and plate geometry variables on the natural frequency.
A slip with entrained liquid fraction approach to compressible two-phase flow in nozzles
Authors: McNeil D A
Published: April 2011

Ideal flow theory adequately predicts pressure drops, critical mass flowrates and critical pressure ratios for single-phase gas flows in nozzles. A model based on these principles has been developed for two-phase, gas-liquid flows using a slip with entrained liquid fraction approach. The method relies on being able to establish the momentum flux of the fluid in the upstream supply pipe and therefore allows pipe flow correlations for slip ratios and entrained liquid fractions to be used at the nozzle inlet. Choking conditions are established from an isentropic pressure pulse approach. This produces a speed of sound for the two-phase mixture that gives choking conditions that are compatible with the end-limits of the momentum and energy equations used to estimate the pressure drops for non-choked compressible flows. This allows a consistency in approach between non-choked compressible and choked flows. The model predictions of pressure drops, critical pressure ratios and critical mass flowrates compare well with data sources and are an improvement on those made by other models available in the open literature.
Evaluating waste vegetable oils as a diesel fuel
Authors: Murayama T , Fujiwara Y , Noto T
Published: April 2011

The research into turning a vegetable oil into an alternative fuel has been underway for some time [1-5]. Although some countries have begun to use some biomass as a fuel for the automobile, the wide use of an alternative fuel has been difficult without substantial subsidies owing to the cost of the biomass which is 3-5 times higher than that of fossil fuel.

However, the cost of waste vegetable oil is competitive with that of fossil fuel and, in the collection of waste vegetable oil, there is an additional advantage of being able to prevent its illegal dumping. Furthermore, the reuse of the oil will improve the profitability of its collection.

This research focused on the engine performance and emission characteristics of methyl-esterified vegetable oil when it is used in a diesel engine of an automobile. The research conducted with direct injection (DI) and indirect injection (IDI) diesel engines revealed that, for engine performance, the alternative fuel was on a par with light oil. For the emission of particulates, with the IDI diesel engine there was no significant difference between the light oil; however, the DI engine proved to emit a much larger quantity of particulates in the low to middle load range. The research also revealed the necessity for countermeasures against solidification of the fuel during the winter months, the generation and emission of aldehyde and benzene, which are typical of oxygenated fuel, and the tempuralike smell caused by propionaldehyde.
The k - ε turbulence modelling of heat transfer and combustion processes in a Texaco controlled combustion stratified charge engine
Authors: Mansouri S. H. , Bakhshan Y
Published: April 2011

In this investigation, a model has been developed to predict the performance of a Texaco controlled combustion stratified charge engine (TCCS). This model uses the k - ε turbulence model to determine characteristic velocities for heat transfer calculations, which has only one empirical constant, in contrast to Woschni's equation in which separate constants are used for each process in the four-stroke cycle to determine the velocity for use in Reynolds number calculation. The modified Keck and Blizard model is used for combustion calculation by considering the rapid compression effects on turbulence intensity. Comparison of the model predictions with available experimental data shows a good agreement. Moreover, the program has a high flexibility for parametric studies to calculate performance parameters such as thermal efficiency, pressure, specific fuel consumption, temperature, fluid flow into and out of the cylinder, friction losses, heat transfer, flow field in the cylinder and so on.
Handling and driving characteristics for six-wheeled vehicles
Authors: Huh K , Kim J , Hong J
Published: April 2011

Handling performance of six-wheeled special-purpose vehicles is investigated in this study. Six-wheel drive (6WD) vehicles are believed to have good performance in off-the-road manoeuvring and to have fail-safe capabilities when one or two of their tyres are blown. However, the handling performance of six-wheel steering (6WS) vehicles is not yet well understood in the relevant literature. In this paper, six-wheeled vehicles are modelled as an 18 degree-of-freedom (DOF) system that considers non-linear vehicle dynamics, tyre models and kinematic effects. The vehicle model is constructed into a simulation tool using MATLAB/SIMULINK so that input/output and vehicle parameters can be changed easily using the modulated approach. Handling performance is analysed not only from the frequency domain but also from the time domain. Simulation results demonstrate that the effect of middle-wheel steering is not negligible from the viewpoint of handling characteristics such as yaw rate, lateral acceleration, etc. The simulation tool is also utilized for the manoeuvring analysis over a rough rigid surface, where the separation between the wheels and the road can be considered. In addition, a new 6WS control law is proposed in order to minimize the sideslip angle. Lane change simulation results show the advantage of 6WS vehicles with the proposed control law.
Ignition source characteristics for natural-gas-burning vehicle engines
Authors: Yossefi D , Maskell S. J. , Ashcroft S. J. , Belmont M. R.
Published: April 2011

Natural gas is a promising alternative fuel to petrol for vehicles. However, one of the factors hampering the design of natural gas burning engines for domestic cars is the long delay from the time of ignition to the commencement of significant heat release. This is mainly due to the substantially endothermic phase during the early development of the combustion in natural gas. It is well known that high-energy, extended or multiple ignition sources can reduce this problem. The present article uses a large-scale computer simulation of a natural gas engine to examine the issues affecting the optimization of such ignition sources.
The variable valve timing mechanism for the Rover K16 engine Part 1: Selection of the mechanism and the basis of the design
Authors: Parker P. H.
Published: April 2011

Variable valve timing has become an important feature of automotive engines as part of the search for a better compromise between performance, economy and emissions. This paper describes the Rover VVC system and has been written in two parts. The first part covers the initial feasibility study, the selection of the mechanism and the unique features evolved to suit the K16 engine. The second part covers the detailed mechanical layout, the development work undertaken and the performance obtained.
The variable valve timing mechanism for the Rover K16 engine Part 2: Application to the engine and the performance obtained
Authors: Parker P. H.
Published: April 2011

Part 1 of this paper described the principles and basic design of the Rover variable valve timing system (VVC). This second part describes in detail the mechanical design which was developed to suit the particular requirements of the planned 1.8 litre version of the Rover K16 engine. The testing programme undertaken to establish durability and prove the product is covered and the performance obtained from the VVC engine is compared with the corresponding base engine which uses standard valve gear.
Low-temperature drive characteristics of automotive power window systems
Authors: Kim K. H. , Jeon S. Y.
Published: April 2011

It is a common experience that some automotive power windows tend to be sluggish during cold weather. The drive current of the power window system increases sharply with decreasing temperature and the ascending speed of the power window glass is greatly reduced. There are several possible sources of such phenomena: performance characteristics of the geared motor, hardening of the glass run and internal friction of the cable and pulley type regulator. Experiments have been performed to study the contributions from each source. It is shown that the major contribution comes from the internal friction of the regulator. Suggestions are made regarding the improvement of power window performance at low temperature.
Fuzzy modelling approach to the prediction of journey parameters for hybrid electric vehicle control
Authors: Quigley C. P. , Ball R. J. , Jones R. P.
Published: April 2011

To enable maximized use of electrical energy during the control of a hybrid electric power train, it is desirable to have a priori knowledge of the characteristics for a given journey. Unfortunately this information is only known on the completion of the journey and therefore at best can only be intelligently estimated. This paper presents work that explores the possibility of prediction of journey distance and duration on journey departure. Usage data were collected from a number of vehicles with different usage characteristics over a period of 1 month each. A preliminary visual analysis of the data demonstrated that there were predictable patterns inherent within the usage data which allowed simple rules to be developed heuristically. A fuzzy modelling approach was then used to generate automatically rules for the prediction of journey distance and duration from departure time only. This approach showed that there were three classifications of vehicle user among those logged: one with reasonable success, while the others required further information to enable effective prediction.
The influence of slipstreaming on sports prototype race car performance
Authors: Dominy R. G. , Ryan A , Sims-Williams D. B.
Published: April 2011

The effect of slipstreaming on a Le Mans ‘LM’ GTP sports racing car has been investigated using a computational lap time simulation based on new wind tunnel data. The effects of changes of the aerodynamic characteristics when slipstreaming are clearly identified and the effects of those changes have been quantified in terms of the relative performances of two cars racing in close proximity.
Vibration monitoring as a predictive maintenance tool for reciprocating engines
Authors: deBotton G , Ben-Ari J , Sher E
Published: April 2011

The vibration signature of a four-stroke, four-cylinder carburetted spark ignition engine has been analysed. The significance and contribution of the signature components with respect to the overall information about the engine health have been explored. The engine block vibrations were recorded at four different locations, two in the vicinity of the rear crankshaft bearing and two at opposing sides of the engine block. The vibrations were measured along the three principal axes. It was found that the engine block side is the most sensitive location for collecting data and the direction transverse to the pistons’ movement plane is the most informative one. For the sake of simplicity in possible practical applications in the future the tests were conducted under idle conditions. The measured vibration waveform has been synchronized with the crankshaft position by using the primary coil signal and then transformed to the frequency domain by a fast Fourier transform procedure. Frequencies below 1 Hz and above 10 kHz were filtered out.

A reliable data persistence was obtained by averaging eight spectra. Spectral analyses of several common faults, such as disconnected spark plug, early spark timing, late spark timing, worn spark plug, fouled spark plug and loose support, have been carried out. Reflections of these faults have been revealed in the vibration signature. General evaluation criteria for the engine's health have been proposed. For example, the appearance of vibration components with unusual frequencies can provide an early warning that the engine is operating at abnormal conditions. The appearance of peaks at one-half or three-halves of the fundamental frequency indicates that a severe malfunction has developed in the engine. The appearance of a peak at the fundamental frequency implies that a mechanical looseness enables the engine to vibrate at the crankshaft frequency. In general terms, dispersion of the energy at subharmonic frequencies, or at six to eight times the fundamental frequency, indicates a developing malfunction.
Thermodynamics and charge exchange of the new BMW six-cylinder engine
Authors: Otto E , Rubbert S , Borrmeister J
Published: April 2011

The BMW in-line six-cylinder engine has been modified and introduced to production in the new BMW 3 Series model. Its major features include variable intake and exhaust camshaft timing, a new induction system with resonance charging, a turbulence-generating system in the intake ports and a new exhaust system with two closed-loop, coupled catalysts integrated into the exhaust manifold. The cam timing of both camshafts can be adjusted continuously within a range of 40° crank angle (CA) for the inlet cams and 25° CA for the exhaust cams. The turbulence-generating system supplies combustion air to the engine during part load operation and produces the necessary charge motion to run the engine with greater valve overlap at low loads and speeds. Its combination with variable camshaft timing results in lower fuel consumption and exhaust emissions that meet the LEV emission standard. In addition, the variable cam timing raises the torque curve of the unthrottled engine, particularly at low engine speed. The maximum values for torque and power output are unchanged, but maximum torque is reached 500 r/min earlier than with the previous engine.
Combustion characteristics of spark-ignition and pilot flame ignition systems in a model Wankel stratified charge engine
Authors: Muroki T , Moriyoshi Y
Published: April 2011

In a stratified charge engine, a glow plug pilot flame ignition system has been compared with a spark-ignition system for a model stratified charge Wankel combustion chamber. A motored two-stroke diesel engine was operated as a rapid compression and expansion machine with the cylinder head replaced by a model Wankel combustion chamber designed to simulate the temporal changes of air flow and pressure fields inside the chamber of an actual engine. It was found that the pilot flame ignition system had better ignitability and improved combustion characteristics, especially in the lean mixture range, relative to the spark-ignition system.
Internal combustion engine waste heat potential for an automotive absorption system of air conditioning Part 1: Tests on the exhaust system of a spark-ignition engine
Authors: Boatto P , Boccaletti C , Cerri G , Malvicino C
Published: April 2011

Measurements have been carried out on a four-cylinder spark-ignition engine to estimate the amount of heat recoverable in particular when the engine runs at low loads. Such heat is sufficient to feed an absorption cooling system for car air conditioning when the speed is over a threshold value. Data for the design of a heat recovery system are reported and discussed.
Internal combustion engine waste heat potential for an automotive absorption system of air conditioning Part 2: The automotive absorption system
Authors: Boatto P , Boccaletti C , Cerri G , Malvicino C
Published: April 2011

An automotive air conditioning system based on absorption cycles has been studied. Such a system uses the recovered heat available in the engine exhaust gas. The lithium bromide-water pair is recommended as the working mixture owing to its present technological application level. A possible arrangement of the absorption system for this purpose is proposed. The suitability of such a system has been investigated, taking operating conditions and other standard requirements into account. Finally, the particular features of the proposed scheme are pointed out, and a borderline (at least in stationary conditions) is located in the power-velocity diagram.
Technical Note: Comparison of the dynamic behaviour of two misaligned crankshaft bearings
Authors: Lahmar M , Harouadi F , Frihi D , Maspeyrot P
Published: April 2011

A comparison of the dynamic performance characteristics of two misaligned crankshaft bearings belonging to a four-stroke petrol engine is carried out in this paper. The misalignment considered varies in magnitude during the running cycle. Under the dynamic conditions, the performance characteristics such as minimum film thickness, shaft centre orbit, friction torque and flowrate are obtained by using the mobility method of Booker. The main results obtained show that the presence of even a small skew of the main journal axis can cause metal-to-metal contact at one of the bearing edges.
Substructure analysis of complex systems using rigid body information of components
Authors: Hwang W S , Lee D H
Published: April 2011

Frequency response function (FRF) based substructure analysis can predict the response of complex systems using the FRFs of substructures. It combines the FRFs of each substructure derived from finite element analysis or experiments depending on the situation. In general, the substructure with the excitation is separated from the others by rubber bushes to prevent the transmission of vibration from the source to the main structure. In this case, the substructure with the excitation shows rigid body motion up to the mid-frequency region. This paper presents a new FRF-based substructure analysis that uses the FRFs from the rigid body information not from the complex finite element model of the substructure with rigid body motion. The rigid body information including the mass, the moment of inertia and the coordinates of the mass centre comes from the computer-aided design data. Since the mechanism of this technique is very similar to the finite element formation, it can be applied to complex systems with ease. Through a simple example of a ladder structure and a practical example of the interior noise in a car, the accuracy and efficiency of this approach is proven.
Developments in car door latching systems
Authors: Attridge A , Walton D , Kalsi G
Published: April 2011

Throughout the history of the automobile, and during the past four decades in particular, the door latching systems employed by the various original equipment manufacturers have continually and considerably evolved. This evolution has encompassed both the mechanical components of the latch and, more recently, the means of actuation employed by systems such as central locking and double/deadlocking. Various factors have influenced the developments which have taken place, such as safety, security, ergonomics and economic considerations, and the resulting designs are often compromises based on which factors are considered to be of greatest importance at the time and which market the design is targeting. This paper charts the history of the car door latching system, from its initial conception, through the years to present-day systems, and the technologies employed. It also looks at concepts and technologies currently under development and attempts to predict the direction in which the industry is heading and the latching systems which may come on to the market in the near future.
Design and development of a new gasoline direct swirl injector
Authors: Park Y K , Moon S Y , Lee C W
Published: April 2011

Numerical and experimental analyses were carried out to design and develop the optimum geometry of a gasoline direct swirl injector. In the numerical analysis, the needle cone angle, swirler inclined angle and needle lift were changed with mass flowrate as design parameters to determine the optimum sizes. The critical sizes of the needle cone angle, swirler inclined angle and needle lift are 140°, 120° and 100 μm respectively. Thus, the optimum sizes may be 130°, 110° and 80 °m respectively. Experiments were performed to observe spray phenomena and to measure the dynamic flowrate, penetration of the spray tip and mainstream, spray angle and the mean drop diameter using an image processing method. The formation of a counter-rotating vortex appears in the steady state as a feature of the high pressure swirl injector spray. The calculated needle cone and swirl inclined angles as well as the cone-type needle reduce the non-swirl and sac volumes of the non-swirl region such that the reduced volumes restrict the penetration of the spray tip. The sizes of the mean drop diameter range from 20μm to 23μm and the spray angles range from 64° to 66°, which satisfy the requirements of a gasoline direct injection engine.
Automated tuning of an engine management unit for an automotive engine
Authors: Hardie C , Tait H , Craig S , Chase J G , Smith B W , Harris G
Published: April 2011

Modern automotive engines are digitally controlled using an engine management unit (EMU) that is typically manually programmed using an engine dynamometer to obtain desired levels of power, emissions and efficiency. Closed-loop control of an engine dynamometer and EMU, combined with an overall engine tuning algorithm, is used to automate the tuning of the engine map for a four-cylinder engine. The tuning algorithm determines the air-to-fuel ratio necessary for each region of engine speed and throttle position to obtain the desired performance, automatically moving to each operating region in the map. Preliminary automated tuning results produce power output curves comparable with those delivered using the original manufacturer tuned EMU. At lower engine speeds data filtering is required and results in power outputs slightly lower than the factory-tuned engine. At higher speeds small improvements in engine efficiency, for equivalent performance, can be found. The research presented clearly demonstrates that engine tuning to a very high standard, equivalent to original equipment manufacturer engine performance, can he successfully automated, saving time and adding consistency to the engine tuning process.
Accurate prediction of the rate of heat release in a modern direct injection diesel engine
Authors: Lakshminarayanan P A , Aghav Y V , Dani A D , Mehta P S
Published: April 2011

An accurate model for the heat release rate in a modern direct injection (DI) diesel engine is newly evolved from the known mixing controlled combustion model. The combustion rate could be precisely described by relating the mixing rate to the turbulent energy created at the exit of the nozzle as a function of the injection velocity and by considering the dissipation of energy in free air and along the wall. The complete absence of tuning constants distinguishes the model from the other zero-dimensional or pseudomultidimensional models, at the same time retaining the simplicity. Successful prediction of the history of heat release in engines widely varying in bores, rated speeds and types of aspirations, at all operating conditions, validated the model.
Measurements and predictions of diesel soot oxidation rates
Authors: Ladommatos N , Song H , Zhao H
Published: April 2011

The oxidation rate of diesel engine soot particles has been measured experimentally over a range of gas temperatures (1650-1820 K) and oxygen partial pressures (0.01-0.05 atm). Soot particles from the exhaust of a running diesel engine were oxidized in the post-flame gases from a premixed burner. Measurements made at different heights above the flame included the particle size distribution and velocity, the gas temperature and the oxygen concentration. The results showed that the measured oxidation rates were between the values predicted by the Nagle-Strickland-Constable formula and those predicted by the Lee formula. The experimental results from the present study were combined with those of other experimenters and used to modify the Nagle-Strickland-Constable and Lee formulae in an effort to improve their predictive capability.
Transient response of an erodable heat flux gauge using finite element analysis
Authors: Buttsworth D R
Published: April 2011

The transient response of an erodable ribbon element heat flux gauge has been assessed using a two-dimensional finite element (FE) analysis. Such transient heat flux gauges have previously been used for measurements in internal combustion (IC) engines. To identify the heat flux from the measurements of surface temperature, it is commonly assumed that the heat transfer within these devices is one-dimensional. A corollary of the one-dimensional treatment is that only one value of the thermal product, , is needed for identification of the transient heat flux, even though erodable heat flux gauges are constructed from at least two different materials. The current results demonstrate that two-dimensional transient heat conduction effects have a significant influence on the surface temperature measurements made with these devices. For the ribbon element gauge and timescales of interest in IC engine studies, using a one-dimensional analysis (and hence a single value of ) will lead to substantial inaccuracy in the derived heat flux measurements.
Chromatograph determination of total and speciated hydrocarbons in the exhaust of a spark ignition engine
Authors: Sodré J R
Published: April 2011

Gas chromatography tests have been applied to the exhaust gases of a spark ignition engine to determine the concentration of unburned fuel among the total hydrocarbons. The contribution of unburned fuel was determined with variation in several engine parameters. The fuel tested was isooctane. The varied parameters were the air-fuel ratio, engine speed, ignition timing, compression ratio and coolant and lubricant temperature. The results have shown that the unburned fuel is responsible for most of the HC emitted, 50-73 per cent, depending on the engine working conditions. Methane, acetylene, ethylene, ethane, propylene and isobutylene were also analysed, as well as isooctane. The total contribution of the lighter species remained practically unaltered when the parameters were varied, though their individual concentrations did change. Thus, the unburned HC was seen to determine all trends of exhaust hydrocarbons.
Changes at interfaces of friction components during braking
Authors: Holinski R , Hesse D
Published: April 2011

The energy generated during the braking procedure needs to be dissipated. As a result of energy adsorption, a number of physical and chemical effects occur that result in surface changes of friction elements. These changes determine the service life of friction components and the effectiveness of brakes. Some of the surface changes are detrimental while others are beneficial for a safe braking procedure. Some changes in interfaces have been studied. In particular, during wet seasons, metallization of brake components is encountered, resulting in surface destruction of brake components. It was found that water decomposes at frictional interfaces during braking. Hydrogen diffuses into the rotor surface, resulting in metallurgical changes. Thin metal foils of alpha-iron are sheared from rotor surfaces and are transferred to composite surfaces. Metallization of pad surfaces results in high noise and wear during braking. Transfer of composite material to the rotor surface leads to the formation of layers which reduces wear of friction elements. Controlled transfer of material is essential for good braking performance. It was found that, at rotor temperatures higher than 500 °C, composite material is no longer transferred to rotor surfaces; rather, the additives in the composite react chemically at rotor surfaces. Decomposition compounds from additives are found on brake discs. Transfer layers and chemical reactions on rotor surfaces have been studied.
A structural optimization design for an aluminum-intensive vehicle
Authors: Lee Dong-Chan , Lee Jeong-Ick
Published: April 2011

This paper describes an integrated structural optimization procedure using a multilevel decomposition technique and a domain mapping contour that can represent the production parameter region. At the upper level, the structural responses are represented in terms of global quantities, i.e. stiffness, stresses and weight. At the lower level, the structural responses are represented in terms of local quantities, i.e. the intermediate parameters or the detailed dimensions based on the production parameter region. This technique was applied to develop the aluminium vehicle structure. The crosssectional characteristics and joint stiffness of the vehicle structure are calculated from the vehicle structure model which is composed of shell-beam-spring elements. In comparison with the base model (steel structure), the bending stiffness and torsional stiffness of the developed aluminium vehicle structure increase by around 45 and 35 per cent respectively, and the weight reduction is around 30 per cent. The manufactured structure is also presented.
A driving cycle for electrically-driven vehicles in Rome
Authors: Alessandrini A , Orecchini F
Published: April 2011

In the research results presented here, an average driving cycle is synthesized for an electrically driven car moving in the city of Rome. The technique of Lyons et al. [1] for synthesizing a statistically representative driving cycle was used on a 5 week acquisition set of data collected with a duly equipped electric Citroen Saxo that was driven for over 3100 km by six different drivers in the months of May and June 2001 in Rome. The driving cycle developed is compared with the other available cycles, especially the European ones. The comparison highlights the need for this new dedicated cycle to represent the driving conditions of electric cars in Rome, with a lower value of the acceleration-speed product on account of the limited power of the electric vehicle, frequent changes in the acceleration sign, typical of the trafic in a big city, and a very high maximum speed, typical of the driving behaviour of the inhabitants of Rome.