Search Results

Fuel injection during negative valve overlap offers a promising method of controlling HCCI combustion, but sorting out the thermal and chemical effects of NVO fueling requires knowledge of temperatures throughout the cycle. Computing bulk temperatures throughout closed portions of the cycle is relatively straightforward using an equation of state, once a temperature at one crank angle is established. Unfortunately, computing charge temperatures at intake valve closing for NVO operation is complicated by a large, unknown fraction of residual gases at unknown temperature. To address the problem, we model blowdown and recompression during exhaust valve opening and closing events, allowing us to estimate in-cylinder charge temperatures based on exhaust-port measurements. This algorithm permits subsequent calculation of crank-angle-resolved bulk temperatures and residual gas fraction over a wide range of NVO operation.

The efficiency and durability of catalytic converters for automobiles are determined by several heat and mass transport mechanisms acting in concert. This study characterizes these mechanisms with measured temperature and concentration profiles throughout a large-scale catalytic passage at fixed wall temperature. The increased passage size allows the concentration field within the passage to be accurately monitored. A small isokinetic sampling probe and laser positioning system enable the concentrations to be spatially resolved to within 0.04 mm and ten transverse locations are sampled at each axial station. The active walls are coated with a Pt catalyst over a production alumina washcoat containing 28% Ceria on a metal substrate. The walls are 2 cm apart, which is roughly 16 times larger than in a conventional monolith passage, so the Reynolds number is adjusted for scale similarity with commercial devices.

Global regulations intended to enhance pedestrian protection in a vehicle collision, thereby reducing the severity of pedestrian injuries, are presenting significant challenges to vehicle designers. Vehicle hoods, for example, must absorb a significant amount of energy over a small area while precluding impact with a hard engine compartment component. In this paper, a simple passive approach for pedestrian protection is introduced in which thin metal alloy sheets are bent to follow a C-shaped cross-sectional profile thereby giving them energy absorbing capacity during impact when affixed to the underside of a hood. Materials considered were aluminum (6111-T4, 5182-O) and magnesium (AZ31-O, AZ61-O, ZEK100) alloys. To evaluate the material effect on the head injury criterion (HIC) score without a hood, each C-channel absorber was crushed in a drop tower test using a small dart.