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Sulfur containing species as well as other polar molecules provide lubricity and thermal stability to diesel fuels. During the refining process to produce low and ultra-low sulfur diesel fuels, these components are removed. As a result, fuel additives such as lubricity agents and antioxidant may be added to protect fuel stability and prevent fuel pump wear. Some lubricity additives, such as dimer acids, resulted in fuel filter plugging. The plugging mechanism was related to the capability of aliphatic acids to form agglomeration by interactions with the overbased detergents, delivered into the fuel as oil contaminants. Other sources of acids, derived from thermal degradation, can lead to the same problem. In this study, individual lubricant additives were mixed in the fuel to form single- and dual-component systems. Levels of compatibility and amounts of interaction products were evaluated for individual solutions.

The EPEFE study (European Programme on Emissions, Fuels and Engine Technologies), /1/ and other programmes have identified an increase in tailpipe NOx emissions with reduced gasoline aromatics content for modern 3-way controlled catalyst vehicles. This effect occurs with fully warmed-up catalyst under closed-loop operation. In order to understand the reasons for this effect VW and Shell have mechanistically investigated the effects of fuel properties on EMS (engine management system) and catalyst performance. Fuels with independent variation of oxygen, aromatics and mid-range volatility were tested in different VW engines. λ was monitored using sensors located both pre and post catalyst. The results confirmed that reducing gasoline aromatics content reduced engine-out emissions but increased tailpipe NOx emissions. It could be shown that differences in H/C ratio led to differences in the hydrogen content of engine-out emissions which affected the reading of the λ sensor.

This paper discusses road damage caused by heavy commercial vehicles. Chapter 1 presents some important terminology and a brief historical review of road construction and vehicle-road interaction, from ancient times to the present day. The main types of vehicle-generated road damage, and the methods that are used by pavement engineers to analyze them are discussed in Chapter 2. Attention is also given to the main features of the response of road surfaces to vehicle loads and mathematical models that have been developed to predict road response. Chapter 3 reviews the effects on road damage of vehicle features which can be studied without consideration of vehicle dynamics. These include gross vehicle weight, axle and tire configurations, tire contact conditions and static load sharing in axle group suspensions. The dynamic tire forces generated by heavy vehicles are examined in Chapter 4.

Turbulent flame speeds have been measured in a single cylinder S.I. engine and in a stationary atmospheric burner. One- and two-point LDA has been used to measure turbulence intensities and integral length scales. Stretching, in terms of Karlovitz numbers could be estimated from these measurements. The influence of moving average filtered turbulence on the flame speed in the S.I. engine is in agreement with the burner experiments. Previously reported signs of quenching of small flames in the S.I. engine, due to excessive turbulence could not be found for larger flames.

This paper presents an analytical treatment of a mechanical-mathematical model of an air bag inflation process integrated with a model for the interaction between the air bag and a standing child dummy. The inflation model consists of a one-dimensional gas dynamics analysis of the flow system which delivers the gas to inflate the bag. The interaction model then provides a method for calculating the forces exerted by the inflating bag on the standing child. The results show that the unacceptably high contact forces recorded in standing-child air bag tests are due to impact of the unopened portion of the bag on the standing child. A single-membrane concept is thus suggested to reduce this impact severity.

Past experiments have shown that numerous micro-hole sprays in close proximity produce drop sizes that are sensitive to the nozzle arrangement. Numerical studies have been performed to identify the interaction mechanisms between closely spaced sprays. It is shown that nozzle configurations can lower the drop-gas relative velocity and droplet Weber number, leading to reduced atomization intensity. However, the collisions involving droplets from neighboring sprays have a much greater effect on droplet size. Thus, neighboring sprays primarily interfere with each other through droplet collision.

Two imaging techniques are used to investigate the interaction between developed combustion from earlier injections and partially oxidized fuel (POF) of a subsequent injection. The latter is visualized by using planar laser induced fluorescence (PLIF) of formaldehyde and poly-cyclic aromatic hydrocarbons. High speed imaging captures the natural luminescence (NL) of the prevailing combustion. Three different fuel injection strategies are studied. One strategy consists of two pilot injections, with modest separations after each, followed by single main and post injections. Both of the other two strategies have three pilots followed by single main and post injections. The separations after the second and third pilots are several times shorter than in the reference case (making them closely-coupled). The closely-coupled cases have more linear heat release rates (HRR) which lead to much lower combustion noise levels.

Measurements of crank angle resolved air velocity and fuel droplet velocity inside the intake port of a six cylinder four valve production engine were performed using two component Laser Doppler Velocimetry (LDV). Prior to the engine measurements the fuel injector was characterized by determining time resolved droplet sizes and velocities with Phase Doppler Velocimetry (PDV) at an injector test rig with complete optical access. PDV results indicate that during spray penetration into quiescent air at atmospheric pressure (test rig conditions) large droplets move at the tip of the spray while small droplets due to their low force of inertia are slowed down by aerodynamic pressure and pile up at the end of the spray. Mean values of the droplet diameter rise with the distance from the injector because the smallest droplets do not reach the downstream measurement locations.

This paper describes a study of the incidence of drug use among drivers and pedestrians killed in fatal crashes in Melbourne. Australia. Overall, 42% of the study population had been drinking and 66% had used drugs other than alcohol, caffeine and nicotine. Blood alcohol concentration was significantly related to the road users' liability for the crashes in which they were killed. However, there was no relationship between liability and use of other drugs. Only 11% of the study population had used alcohol in combination with other drugs and individuals with zero blood alcohol levels were more than twice as likely to have used other drugs as those who had been drinking. No drinking road users who were deemed not liable for the crashes in which they were killed had combined alcohol with use of other drugs. The implications of these data to development of relevant countermeasures to crashes in which cannabis or medication are factors has been discussed.

The aim of this study is systematically to evaluate and quantify the influence of interaction of car passengers in impacts. Within this programme 70 car tests were performed. The impact speeds were 30 and 60 km/h for the frontal and rear and 30 and 45 km/h for the lateral impacts. Impact angles were as follows: frontal: 0° and 30° left; lateral: 60° and 120° left, 90° right; rear: 180° and 150° left. Test cars were of subcompact type bought on the car market. Impacting vehicle was a rigid moving barrier according to SAE J 972a. Each of the 14 configurations was repeated 5 times. The effects of interaction were studied on 50 percent male PART 572 dummies. The significant effect of interaction is the change of direction of acceleration in the additionally loaded occupant, because the interaction forces are effective in the opposite direction of the primary impact forces.

The aim of this study is to evaluate the interaction of car passengers in side collisions. In 12 side impact tests, four newly developed side impact dummies (APROD 82, HSRI, MIRA, ONSER) were positioned at the impact side of the car, with the interacting dummy - a Hybrid II dummy - on the offside. The velocity of the impacting rigid barrier was 45 km/h. Each test configuration with each side impact dummy was repeated three times. They are compared with tests of the same configuration but without an interacting Hybrid II dummy. The kinematics of the side impact dummies are more humanlike in side impacts than those of the Hybrid II dummy which was used in a previous test program on the impact side. Each side impact dummy showed interaction effects and loads in different measuring parameters.

Traffic flow rates and speeds have been measured on two types of road to determine how CV's affect traffic flow. A comparison of the behaviour of CV and car drivers during braking was also made

This study reflects on two areas of vehicle aerodynamics, optimising cooling performance and features that will improve the handling of the car. Both areas will have a significant impact on the overall performance of the car and at the same time these areas are linked to each other. The considered vehicle in this study was the Chalmers Formula Student 2011 Formula SAE car and the flow field was analysed using both numerical simulations as well as performing wind tunnel experiments on a 1:3-scale model of the car. The focus on increasing downforce without increasing the aerodynamic drag is particularly good in Formula SAE since fuel economy is an event at the competition. Therefore, the intention of this work is to present a study on how undertrays with different design such as added foot plates, diffuser and strakes can improve the downforce and reduce the drag.

The four-screw propulsion vehicle has high traffic performance and strong maneuverability on the fluidized soft terrain. However, the interaction mechanism between the four-screw vehicle and the soft terrain is quite complicated. The driving performance of the screw vehicle on the soft terrain are not clear, and it is difficult to achieve accurate dynamic control of the four-screw vehicle. The mechanical relationship and motion mode of the four-screw propulsion vehicle-soft terrain interaction are theoretical analyzed, the force characteristics of the screw drive wheel under each motion mode of the vehicle are obtained. The interaction model between soft terrain of tailings dam and four-screw vehicle is established by using smooth particle hydrodynamics (SPH) and finite element method (FEM).

Due to the design of lightweight, high speed driveline system, the coupled bending and torsional vibration and rotordynamics must be considered to predict vibratory responses more realistically. In the current analysis, a lumped parameter model of the propeller shaft is developed with Timoshenko beam elements, which includes the effect of rotary inertia and shear deformation. The propeller shaft model is then coupled with a hypoid gear pair representation using the component mode synthesis approach. In the proposed formulation, the gyroscopic effect of both the gear and propeller shaft is considered. The simulation results show that the interaction between gear gyroscopic effect and propeller shaft bending flexibility has considerable influence on the gear dynamic mesh responses around bending resonances, whereas the torsional modes still dominate in the overall frequency spectrum.

Nineteen sled impact tests were conducted simulating a frontal collision exposure for an unrestrained driver. The deceleration sled buck configuration utilized the passenger compartment of a late model compact passenger vehicle, a rigid driver's seat, and a custom fabricated energy-absorbing steering column and wheel assembly. Sled impact velocities ranged from 24.1 to 42.6 km/hr. The purpose of the study was to investigate the kinematic and kinetic interaction of the driver and the energy-absorbing steering assembly and their relationship to the thoracic/abdominal injuries produced. The similarities and differences between human cadaver and anthropomorphic dummy subjects were quantified.

The in-cylinder charge motion during the compression stroke of an optically accessible engine equipped with direct injection of hydrogen fuel is measured via particle image velocimetry (PIV). The evolution of the mean flow field and the tumble ratio are examined with and without injection, each with the unmodified 4-valve pent-roof engine head and with the intake ports modified to yield higher tumble. The measurements in the vertical symmetry plane of the cylinder show that intake modification produces the desired drastic increase in tumble flow, changing the tumble ratio at BDC from 0.22 to 0.70. Either intake-induced flow is completely disrupted by the high-pressure hydrogen injection from an angled, centrally located single-hole nozzle. The injection event leads to sudden reversal of the tumble. Hence the tumble ratio is negative after injection. However, the two intake configurations still differ in tumble ratio by about the same magnitude as before injection.

This paper aims to study numerically the influence of the number of fuel sprays in a single-cylinder diesel engine on mixing and combustion. The CFD simulations are carried out for a heavy-duty diesel engine with an 8 hole injector in the standard configuration. The fuel spray mass-flow rate was obtained from 1D-simulations and has been adjusted according to the number of nozzle holes to keep the total injected fuel mass constant. Two cases concerning the modified mass-flow rate are studied. In the first case the injection time was decreased whereas in the second case the nozzle hole diameter was decreased. In both cases the amount of nozzle holes (i.e. fuel sprays) was increased in several steps to 18 holes. Quantitative analyses were performed for the local air-fuel ratio, homogeneity of mixture distribution, heat release rate and the resulting in-cylinder pressure.

Rapid opening, closing and rebounds of needle from seat and stopper plate give rise to fluid transients in fuel injectors, which are strongly coupled to the dynamics of needle and body motions. A mathematical model, based on unsteady compressible flow in the injector and steady incompressible flow in inlet and outlet section in conjunction with the equation of motion for needle and body, allows the quantitative description of the injector operation cycle. Agreement between prediction and experiment in terms of needle motion, needle velocity and pressure history is good. The mathematical model is used to show the effects, which various contributions to the hydrodynamic interaction force have on the needle motion, on pressure history and on injected mass.

The theme of this work is the interaction of the part geometry, material properties, forming severity and tooling design for box-shaped stampings. It is shown that the forming severity decreases with the increase of material normal anisotropy and corner radius. The lower the material normal anisotropy, the larger are the required tooling clearances and the thickening of the material under the blankholder. Understanding these relationships is of primary importance in applications requiring a major change in material properties, such as cold-rolled to hot-rolled conversion of products, or product shape redesign. The work also introduces a new type of idealization to metal forming problems. Beside the traditional continuum mechanics axisymmetric and plane strain idealizations, the work introduces the “corner analysis” approximation.