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To determine the appropriateness of specifying the allowable amount of hydrogen leakage upon collision based on the amount of leakage with generated heat equivalent to that of gasoline vehicles and CNG vehicles, we investigated the safety of each type of fuel when flame ignites. Our results confirm that the flame lengths for hydrogen and methane are almost equal, and there is no remarkable difference between them in terms of the distance for assuring safety. Furthermore, we confirmed that the irradiant heat flux from the mixed burning of hydrogen flame with liquid flammable materials is almost equal to that of the spray flame of gasoline. Thus, no clear difference was found between various types of fuel. Therefore, it is appropriate to specify the allowable amount of hydrogen leakage based on the amount of leakage with generated heat equivalent to that of other types of fuel.

In this study, hydrogen was leaked using a nozzle that simulated an actual leak port (with varied materials and diameters), and the possibility of ignition was verified to collect data useful for establishing standards for the allowable flow rate of hydrogen leakage on receptacle. With the flow rate of a hydrogen leak set at 250 mL/h(NTP) (hereinafter mL/h is NTP condition) or less, ignition of leaked hydrogen with an electric spark and a small methane-fueled flame was attempted. The results confirmed that ignition of 200 mL/h of hydrogen was not achieved under tested conditions. In some cases, hydrogen at a flow rate of 250 mL/h was ignited. Tissue paper placed in contact with the flame at a flow rate of 250 mL/h combusted, resulting the flame went out almost immediately. Therefore, it was determined that a hydrogen leak at approximately 200 mL/h that occurred in this test is a very low possibility of ignition or spreading.

This paper focuses on the applicability of numerical prediction of sound radiation caused by an axial vehicle cooling fan. To investigate the applicability of numerical methods, a hybrid approach is chosen where first a CFD simulation is performed and the sound radiation is calculated in a second step. For the acoustic simulation an integral method described by Ffowcs-Williams-Hawkings is used to predict the sound propagation in the far-field. The simulation results are validated with experiments. The corresponding setup in experiments and simulation represents an overall system which includes the cooler, the cooling fan and a combustion engine dummy. To optimize the economical applicability in terms of simulation setup and run time, different approaches are investigated. This includes the simulation of only one blade using a periodic boundary condition as compared to the whole fan geometry. In the CFD simulation an SAS-turbulence-model is applied.

The optimization of mixture formation in diesel engines requires precise knowledge of the mechanisms of spray atomization and the correlation between injection and engine operating conditions and the parameters of the injection spray. The influence of the fuel properties will be shown considering both the temperature in the high-pressure chamber and the injection pressure as important variation parameters. A global temporally resolved visualization of the injection sprays is realized and information about the droplet size distributions in the spray are obtained by means of locally highly resolved laser-based measurement techniques. The low proportion of low-boiling components in heavy fuels is a significant cause for a deteriorated mixture formation. Higher temperature in the combustion chamber and higher injection pressure have a positive influence on the spray development as well as fuel evaporation.

The drag reduction effect was investigated with regard to the bed and rear flap variation for a pickup truck through design of experiments process. The design factors were the bed length, bed height, rear flap length, and flap inset with three levels, and the noise factor was the yaw angle. The signal-to-noise ratio calculation was introduced to evaluate the low-drag performance under a crosswind. Analysis of variance indicated the significant interaction effect between the bed length and bed height. Since the bed flow of the short with low bed was attached to the tailgate, which increased the drag coefficient and lowered the S/N ratio. The rear flap add-on at the rear edge of a roof was effective to reduce the drag coefficient. However, the sensitivity of the flap length variation on the drag reduction was not significant. The flap inset had a negative effect on the drag reduction as it lowered the inset area pressure of the cabin back surface.

In recent years three-wheel camber vehicles, with two wheels in the front and a single rear wheel, have been growing in popularity. We call this kind of vehicle A “Leaning Multi Wheel category Vehicle” (hereinafter referred to as a “LMWV”). A LMWV has various characteristics, but one of them stands out in particular. When a LMWV is cornering, if one of the front wheels passes over a section of road surface with a low friction coefficient, there is very little disturbance to the vehicle’s behavior and can continue to be driven as normal. However, there has been no investigation into why these vehicles have this particular characteristic. Consequently, in this paper an investigation was carried out in order to determine the behavior of a LMWV in this situation. First, measurements were taken using an actual vehicle to confirm the situation described above.

In this work a new concept for GDI engines is presented. Concerning a stable ignition a main goal of the so called Bowl-Pre-chamber-Ignition (BPI) process is to reduce the influence of varying flow and spray effects. The characteristic signs of the concept are the dual direct injection, a centrally arranged piston bowl and the special pre-chamber spark plug, that partly dips into the bowl at TDC. During that process most fuel is injected early (intake stroke) into the intake manifold or directly into the cylinder to form a homogeneous pre-mixture. Later in the compression stroke, only a small amount of fuel is injected into the piston bowl. So formed locally stratified charge mixture is transported by the piston bowl to the pre-chamber-spark plug, the pre-chamber dips into the bowl and the mixture flows directly to the spark plug electrode. The result is a very stable lean combustion.

This paper describes the numerical results for a simplified underhood buoyancy driven flow. The simplified underhood geometry consists of an enclosure, an engine block and two exhaust cylinders mounted along the sides of the engine block. The flow condition is set up in such a way that it mimics the buoyancy driven flow condition in the underhood environment when the vehicle is parked in a windbreak with the engine shut down. The experimental measurements for temperature and velocity of the same configuration were documented in the Part I of the same title. Present study focuses on the numerical issues of calculating temperature and flow field for the same flow configuration. The predicted temperature and velocity were compared with the available measured data. The mesh sizes, mesh type and the orders of spatial and temporal accuracy of the numerical setup are discussed.

The results of thermal and flow studies for a ¼ scale model of an engine compartment are presented here. Using PIV and thermocouples, the mid-plane flow velocity and temperature of the buoyant underhood flow with engine block average surface temperature of 127°C and exhaust heaters (surface temperature ∼ 600°C) were measured. Thermocouples were also used to measure the steady-state temperature of the engine block surface and the enclosure outside and inside walls. The airflow in the engine compartment is steady, laminar and three dimensional as predicted by the Grashof and Reynolds numbers calculated for different simple geometries comprising the engine block and its exhausts. Three dominant vortices are found to exist at the top corners of the engine compartment. Thermal measurements on the engine block and enclosure surfaces support the temperature gradients expected given the specified geometry and boundary conditions.

Diesel powered underground mining equipment is presently the most productive and efficient type of equipment used in underground mining operations. Uncertainties regarding ventilating air levels, which will minimize the risk to health, focus on the role of diesel particulate, both as a toxic agent itself, and as a carrier for other exhaust constituents such as acid gases. This paper describes the application of Catalytic Trap Oxidizer (CTO) Systems for particulate emission control to a test-bed engine and a mining vehicle in service. Testing procedures and results are presented for both laboratory and in-service evaluations. Gaseous and particulate emissions are compared for baseline and CTO-equipped operation and correlation of laboratory and in-service test results is discussed. The CTO systems demonstrated significant reductions in total particulate emissions, the level of PAH's and Ames mutagenic activity.

This paper will focus on the spray characteristics of a high pressure (up to 155 MPa) accumulator type injector in a high pressure (chosen density) quiescent spray chamber. The injector uses a standard single orifice nozzle which produces a full cone spray. Using this apparatus, we are examining the fundamental aspects of high pressure spray formation under controlled conditions. Experimental data was collected using high speed photography (10,000 frames per second) which used a pulsed copper-vapor laser as a light source. Two photographic techniques are being utilized. Direct attenuation allows measurement of tip penetration, spray cone angle, and injection duration. Scattering from a sheet of laser light perpendicular to the camera field of view is being developed in an attempt to resolve inner spray cone structure. In addition to the quantitative data from the high speed photography, injector accumulator pressure, supply pressure and injection rate histories were recorded.

The results of an optical investigation into the combustion characteristics of GTL (Gas-To-Liquids) diesel fuel are presented. The investigation was carried out using a high pressure, constant volume combustion chamber with optical access, fitted with a modern diesel injection system. Combustion images were captured under conditions which simulate those present in a diesel engine. A low sulphur diesel fuel meeting the European EN590 specification was used as a reference. Image capture and subsequent analysis was performed by means of an AVL Visioscope system which used the two-colour method to yield quantitative information regarding flame temperature and soot concentration. Conditions in the combustion chamber are preset by combusting a pre-charge to generate the necessary pressure, temperature, and residual gas fraction. This allowed the effect of varying oxygen concentration at the start of diesel combustion to be investigated.

Partially Premixed Combustion (PPC) has shown its potential by combining high combustion controllability with emission characteristics that are close to those of an HCCI engine. In order to get PPC the ignition delay needs to be long enough for the fuel and air to mix prior to combustion. This can be achieved by injecting the fuel sufficiently early while running with high EGR. In order to find out where and how PPC occurs a map that shows the changes in combustion characteristics with injection timing and EGR was created. The combustion characteristics were studied in a six cylinder heavy duty engine where the Start of Injection (SOI) was swept from early to late injection over a wide range of EGR levels. The emissions were monitored during the sweeps and in the most promising regions, with low emissions and high efficiency, additional changes in injection pressure and engine speed were applied to get a more versatile picture of the combustion.

The combustion propagation mechanism of homogeneous charge compression ignition combustion was investigated using planar laser Rayleigh scattering thermometry, and was compared to that of spark-ignition combustion. Ethylene and dimethyl ether were chosen as the fuels for SI and HCCI experiments and have nearly constant Rayleigh scattering cross-sections through the combustion process. Beam steering at the entrance window limited the load range for HCCI conditions and confined the quantitative interpretation of the results to local regions over which an effective beam steering correction could be applied. The SI conditions showed a clear bimodal temperature behavior with a well-defined interface between reactants and products. The HCCI results showed large regions that were partially combusted, i.e., at a temperature above the reactants but below the adiabatic flame temperature. Dual-imaging experiments confirm that the burned region was progressing towards the fully burned state.

The tradeoff between NOx emissions and combustion instability in an engine operating in the dual-fuel Reactivity Controlled Compression Ignition (RCCI) combustion mode was investigated using a combination of engine experiments and detailed CFD modeling. Experiments were performed on a single cylinder version of a General Motors/Fiat JTD 1.9L four-cylinder diesel engine. Gasoline was injected far upstream of the intake valve using an air assisted injector and fuel vaporization system and diesel was injected directly into the cylinder using a common rail injector. The timing of the diesel injection was swept from −70° ATDC to −20° ATDC while the gasoline percentage was adjusted to hold the average combustion phasing (CA50) and load (IMEPg) constant at 0.5° ATDC and 7 bar, respectively. At each operating point the variation in IMEP, peak PRR, and CA50 was calculated from the measured cylinder pressure trace and NOx, CO, soot and UHC were recorded.

The combustion mechanism of a fuel droplet cloud was studied by numerical simulation. We investigated how the flame front speed and combustion products changed depending on the equivalence ratio and initial temperature. Modeling was performed using the KIVA-III software package, a three dimensional analysis software used mainly for internal combustion engine applications. The computational domain was a horizontal 1x1x100 cell sector of a spherical combustion chamber and the fuel was n-decane. Results showed that when all the fuel droplets were assumed to have evaporated, the flame front speed increased from 28 cm/s to 152 cm/s as the equivalence ratio increased. The maximum flame front speed was reached at ϕ=1.1, beyond which it decreased (at richer overall equivalence ratios). With a constant equivalence ratio, the flame front speed decreased near the outside region, because the unburned gas was compressed by the expanding burned gas.

Dimethyl Ether (DME) is one of the major candidates for the next generation fuel for compression ignition (CI) engines. It has good self-ignitability and would not produce particulate, even at rich conditions. DME has proved to be able to apply to ordinary diesel engines with minimal modifications, but its combustion characteristics are not completely understood. In this study, the behavior of a DME spray and combustion process of a direct injection CI engine fueled with DME was investigated by combustion observation and in-cylinder gas sampling. To distinguish evaporated and non-evaporated zones of a spray, direct and schlieren imaging were carried out. The sampled gas from a DME spray was analyzed by gas chromatography, and the major intermediate product histories during ignition period were analyzed.

Often the perceived annoyance of noise does not correspond with the A-weighted sound pressure level. The disagreement is because of the unique directional and pattern-recognition properties of human hearing. Therefore the importance of psychoacoustic attributes, such as perceived loudness (considering masking effects) roughness (modulation of tonal components), sharpness (relationship of high-frequency components to low-frequency ones), harmony (distribution of tonal components), spatial selectivity and so on, is becoming appreciated. The correlation of objective measurement and subjective classification of noise can be improved by considering the final receiver, “human hearing”, and developing methods of deriving and analyzing metric data based on human hearing.

In modern compression ignition engines, the dense liquid fuel is directly injected into high pressure and temperature atmosphere, so the spray transitions from subcritical to supercritical conditions. To gain better control of the spray-combustion heat release process, it is important to have a physically accurate description of the spray development process. This work explored the effect of real-fluid thermodynamics in the computational prediction of multiphase flow for two non-ideal situations: the cryogenic nitrogen and non-cryogenic n-dodecane and ammonia sprays. Three real-fluid equations of state (EoS) such as the Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), and Redlich-Kwong-Peng-Robinson (RKPR) coupled with the real-fluid Chung transport model were implemented in OpenFoam to predict the real-fluid thermodynamic properties. Validations against the CoolProp database were conducted.

Advances in instrumentation, equipment, and techniques now allow a more in-depth analysis of cylinder head motions during internal combustion engine operation. Extensive measurements of these motions were taken on a specific bimetal engine. These measurements were taken during both actual and simulated engine operations. Capacitance probes and eddy current sensors were used to measure large scale motion. The eddy current sensors were also used to measure small scale or micro motion. The results of these measurements are discussed.