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In this study, a new submodel concerning fuel film formation process is proposed in order to simulate the behavior of diesel spray impingement on relatively low temperature wall surface. Here, super - heating degree of the surface, defined by the temperature difference between the wall surface and the fuel saturated temperature, is newly considered for the behavior of impinged liquid droplets. In this spray impingement submodel, fuel film formation process, droplet interaction, film breakup process, and velocity and direction of dispersing droplets were considered based on several experimental results. This new submodel was incorporated into KIVA-II code, and the results were compared with experimental data KIVA-II original code and the spray / wall impingement model proposed by Naber & Reitz. As a result, it is found that the calculated results of impinging spray behavior by the new model agree well with experimental results.

In this investigation computational methods for the atomization process of a liquid fuel jet and the secondary breakup of droplets have been developed and tested for non-evaporating, solid-cone diesel fuel sprays injected into a cylindrical constant-volume cell using a KIVA-3 based code. The breakup of the liquid fuel is computed based on the Taylor analogy breakup model. In this new approach the droplet breakup process has been improved to account for the different breakup regimes which occur in diesel engine environments. In addition, an appropriate choice of the initial drop deformation parameters allows the simulation of a fragmented liquid core at the nozzle exit. The model enhancements have been tested by comparisons with data from phase doppler anemometry. Specifically, the droplet radius and velocity distributions have been compared over two cross-sections in the near-field region of the spray.

The non-reactive diesel spray is studied in a constant volume combustion chamber. Droplet sizes and velocities are measured using Particle Doppler Analyzer instrumentation. The effects of aerodynamic drag and vaporization on the droplets size are emphasized. An increase of the mean diameters is observed downstream of the break-up region. The well known KIVA-II code is used to achieve spray computations. The break-up model is disabled and the spray is assumed to be already atomized at the nozzle exit. Size distribution and velocities of the injected droplets are deduced from downstream experimental data. A good agreement is obtained between numerical and experimental results. Size distributions at various locations and temperature conditions are correctly predicted. A diesel spray can be thus modeled in a satisfactory way, when we alleviate the complex processes of break-up, but with appropriate initial droplets conditions.

It is generally agreed that adequate resolution is required to reproduce the structure of spray and gas jets in numerical computations. It has not been clarified what this resolution should be although it would appear reasonable to assume that it should be such that the physical scales of the problem are resolved. In the case of a jet, this implies that near the orifice, the jet diameter has to be resolved since this is the appropriate length scale. It is shown in this work that if such a resolution is not used in computing transient jets, the structure of the jet is not reproduced with adequate accuracy. In fact, unexpected, erroneous and misleading dependence on ambient turbulence length and time scales will be predicted when the initial ambient turbulence diffusivity is small relative to the jet diffusivity. When the ambient turbulence diffusivity is of the same order as the jet diffusivity or greater, entrainment rates are significantly underpredicted.

This paper will focus on fuel flow analysis in nozzles, in particular, in the injection hole, a key component of Fuel Injection Equipment(FIE). Optimum controlled flow in the hole improves flow efficiency and atomization. To meet the emission regulations which will be introduced from the end of '90's to the 21st century, Diesel Engines require FIE to produce higher injection pressure which creates better atomization and higher utilization of air. But higher injection pressure results in increased pump driving torque, larger pump size and higher cost. We have studied the improvement in fuel flow characteristics of the nozzle, using an enlarged flow model and the theoretical analysis method. As a result, we have found that the cavitation, which occurs at the inlet of the hole, is affected by the configuration of the sac hole and injection hole. And, furthermore, the cavitation has a direct effect on the contraction and its recovery flow.

This paper reports on the investigation of injection pressure upon the droplet behavior in transient diesel sprays. Phase/Doppler results for a Diesel spray with a maximum fuel injection line pressure of 105 MPa are compared with previously acquired droplet size and velocity measurements for a Diesel spray with an injection pressure of 21 MPa. All measurements reported here were made in atmospheric conditions at a position near the nozzle. It is shown in these results that the droplet velocity and size profiles do maintain similarity despite the substantial change in injection pressure. Specific characteristics, for example, the appearance of subtle waves in the time-dependent spray data, are present in both data sets. Comparison of the measured droplet velocities and diameters with Weber number based stability criteria shows that increased injection pressure produces a higher percentage of droplets that are likely to breakup.

An axi-symmetric, five-hole V.C.O. nozzle mounted on an electro-injector was used to analyze the spray produced by each hole varying feeding pressure, injected quantity and timing. An advanced experimental apparatus has been used to investigate particle size and velocity of the sprays. The investigation comprized a hydraulic characterization, a photographic one with back-light technique, the analysis of the droplet size distribution through laser diffraction technique via MALVERN 2600 SERIES and the analysis of particle size and velocity using PDPA technique (AERMETRICS DSA 4000) with the extremely dense spray produced by the common-rail electronically controlled injection system. Four feeding pressures (25, 30, 90, 120 MPa) and five injected quantities (2, 4, 10, 25, 40 mm3/shot) were chosen to characterize the nozzle behavior. Sprays from different holes appeared different in shape but very similar in the droplet size distribution.

An original calculation model based on the acoustic-wave theory is presented in this paper, capable of calculating the overall dimensions of an optimum intake manifold, with the aim of improving the gas exchange process in the engine. Some parameters depicting the dynamic interaction between the engine and the manifold are defined, which also allows the assessment of the manifold quality. By employing these parameters, the model can be applied in two complementary modes: the acoustic analysis of an existing manifold and the synthesis of an optimum geometry according to the design requirements and restrictions. The model results are assessed by the test on engine of some prototype intake manifolds, designed following the guidelines of the model.

Elastomeric components are used extensively in the construction of the modern automobile to accommodate relative movement between metal parts, absorb shocks and to provide isolation from undesirable vibrations. Their small-amplitude dynamic stiffness and damping characteristics are the key mechanical properties most influencing vehicle NVH performance. Their large-amplitude static force-deflection characteristics are crucial for vehicle ride and handling performance. On the other hand, when a vehicle is driven on a rough road durability course at a proving ground, all elastomeric components experience large-amplitude dynamic loads. The durability loads transferred through each elastomeric component highly depend on the stiffness and damping characteristics of these components.

This paper describes the ride and handling development process used for the 1997 Corvette. Three levels of suspension are available for the 1997 Corvette: base (FE1), sport (FE3) and RTD or Real Time Damping (F45) suspensions. All suspensions will be discussed in this paper A review of the development and vehicle integration tradeoffs for each of the specific chassis components is included. Control arm bushings, springs, jounce bumpers, anti-roll bars and insulators, tires, shock mounts, shock absorber valving, real-time damping, steering development, alignment and measurements are discussed.

This paper describes the performance attributes of the all-new front and rear SLA (short-long arm) suspensions, steering system, and tires of the 1997 Corvette. The process by which these subsystem attributes flowed down from vehicle-level requirements for ride and handling performance is briefly described. Additionally, where applicable, specific subsystem attributes are rationalized back to a corresponding vehicle-level performance requirement. Suspension kinematic and compliance characteristics are described and contrasted to those of the previous generation (1984 to 1996 Model Year) Corvette. Both synthesis/analysis activities as well as mule-level vehicle development work are cited for their roles in mapping out specific subsystem attributes and related vehicle performance.

This paper discusses the approach to acquire base data regarding suspension travel, spring force, damping force and velocity which are essential for the design of suspension system and chassis. Strain measurement technique was used to obtain the data. Strain gauge locations were decided based on the sensitivity to spring and damping force. Methods used to calibrate the system and validate the technique are described. Data acquisition on different types of public roads and the behaviour of the parameters on these roads are elaborated. Displacement derived from acceleration signal at the wheel and suspension top mounting point, gave good correlation with the displacement derived from strain signals on different roads. Damping velocity (derived from displacement) and the damping force showed good proportionality on various roads. This technique was used successfully to establish the suspension parameters.

Vehicle roll behavior has a large influence on how drivers evaluate handling performance. This paper describes an approach to quantifying roll behavior experimentally and presents a method for designing suspension properties to improve the sensation of roll. In this study, it was found that using pitch motion as an evaluation index results in good correspondence with subjective evaluations. To obtain acceptable roll behavior, it is important to control pitch motion during roll to a lower mode at the front end relative to the rear. This desirable behavior can be achieved by designing suitable roll center characteristics, nonlinear load changes and damping force coefficients.

In this paper the criteria and the requirements for the approval of the service strength and the durability of vital car suspension components are treated. The overview of the main influences on the fatigue life is given and the methodology for the design evaluation and a reliable time and cost saving development, including durability approval, are described. These include: Description of representative, customer related loading Procedure for design evaluation based on customer usage Corresponding test programs for durability approval including the requirements for statistical validation and quality assurance of manufacturing. On two examples - a wheel and a suspension arm - the procedure including individual steps is explained.

This paper describes the hardware execution of the front and rear suspensions of the all new 1997 Chevrolet Corvette. Topics covered include: alternative design trade-off, mass optimization, alignment and trim, structural interfaces, shared components, component design and a review of the overall design of the front and rear suspensions. Two case studies are detailed for the front upper and rear lower control arms. The systems engineering process used for suspension design is described throughout the paper.

This paper presents two fuzzy logic based systems, developed by Valeo Thermal Systems and PSA Peugeot-Citroën, for controlling the thermal environment in a car cabin. This study aimed to simplify the control systems set up, while improving the cabin passengers comfort by taking into account the subjectivity of thermal sensation. The first system regulates the internal cabin temperature from a temperature fixed by the user on the climate control panel. The second system proposes a new “intelligent” control panel in order to ensure a better thermal balance for the car passengers. The two systems were installed and tuned on a Peugeot 605 vehicle, on which a standard automatic controller is already available. So, it was possible to compare the fuzzy and the classical series controllers on the same vehicle. The results show good regulation performances and demonstrate that the use of fuzzy logic reduces the development time.

An investigation of the effect of rack-housing rubber bushings on the handling characteristics of a vehicle is presented using a sophisticated three-dimensional vehicle model based on multibody dynamic analysis method. Previous research on this problem has been limited to a transfer function model for a simplified one- or two-dimensional steering subsystem. This paper uses a multibody modeling approach to find the effects of the steering-system compliance on the complete vehicle system. Sample simulations for circular cornering and pulse steering show that the steering-system compliance is the source of the frequency peak in the yaw rate to hand-wheel angle response function.

Compliance elements such as bushings of a suspension system play a crucial role in determining the ride and handling characteristics of the vehicle. In this research, a general procedure for the optimum design of compliance elements to meet various design targets is proposed. Based on the assumption that the displacements of elastokinematic behavior of a suspension system under external forces are very small, linearized elastokinematic equations in terms of infinitesimal displacements and joint reaction forces are derived. Directly differentiating the linear elastokinematic equations with respect to design variables associated with bushing stiffness, sensitivity equations are obtained. The design process for determining the bushing stiffness using sensitivity analysis and optimization technique is demonstrated.

The chracteristics of a steering system, such as steering stiffness, power steering assisting force, gear ratio and friction, have been known as an influencing factor on the vehicle handling. Especially, the driver's feeling during straight running, so called on-maneuver feel, is of interest to investigate the steering effects on the handling qualities. This paper introduces a steering system modelling using the multi-body simulation program AUTOSIM.

Front Mac Pherson suspensions are widely used by the car manufacturers. The quality of this suspension depends in part on low friction in the shock absorber. Among all the solutions proposed up today, none are giving full satisfaction. To remedy the problem, ALLEVARD has developed calculations and new types of springs in order to minimize the frictions in the shock absorber and to reduce the space required and the mass of the spring.