Search Results

Engine knock is a major challenge that limits the achievement of higher engine efficiency by increasing the compression ratio of the engine. To address this issue, using a higher octane number fuel can be a potential solution to reduce or eliminate the propensity for knock and so obtain better engine performance. Methanol, a promising alternative fuel, can be produced from conventional and non-conventional energy resources, which can help reduce pollutant emissions. Methanol has a higher octane number than typically gasolines, which makes it a viable option for reducing knock intensity. This study compared the combustion characteristics of gasoline and methanol fuels in an optical spark-ignition engine using multiple spark plugs. The experiment was carried out on a single-cylinder four-stroke optical engine. The researchers used a customized metal liner with four circumferential spark plugs to generate multiple flame kernels inside the combustion chamber.

The conjugate heat transfer, which effectively integrates the heat conduction within the solid metal block of the so-called Water Spider Geometry (WSG) configuration and the fluid domain within it, is computationally investigated in the present work, allowing an accurate representation of the temperature conditions at the solid-fluid interface. The WSG configuration represents a specially configured tube geometry that effectively reproduces the flow behavior observed in cooling channels associated with Internal Combustion (IC) engines. The inherent high flow unsteadiness potential of the WSG flow configuration, resulting from the complex flow guidance involving phenomena such as flow impingement, bifurcation, multiple deflections and flow confluence, requires the application of a model capable of capturing turbulence fluctuations.

In 2012, Continental received an autonomous vehicle testing license from the US state of Nevada and has subsequently operated an automated driving vehicle on more than 15.000 miles of testing on public roads. The present paper describes the development of this vehicle by explaining the necessary system modules - structured along the signal processing chain from sensing and representing the vehicles environment up to a holistic actuator concept. Therefore, the functional specification for automated lateral and longitudinal vehicle guidance is addressed, also giving an answer on how to cope with challenging scenarios such as stop-and-go traffic and narrow road lanes. Focus is set on a hybrid environment representation, integrating model-based tracking for moving traffic participants and an occupancy grid for maneuvering space.

The extended steady state lap time simulation combines a quasi steady state approach with a transient vehicle model. The transient states are treated as distance dependent parameters during the calculation of the optimal lap by the quasi steady state method. The quasi steady state result is used afterwards to calculate a new dynamic behavior, which induces in turn a different quasi steady state solution. This iteration between the two parts is repeated until the dynamic states have settled. An implementation of the extended quasi steady state simulation is built up to determine the capabilities of the approach. In addition to pure steady state simulation abilities, the method is able to judge the influence of the transient or time variant vehicle states on lap time. Sensitivity studies are generated to analyze the influence of basic parameters like mass, but also the influence of parameters with transient interaction like vertical damping or tire temperature.

The introduction of CO₂-reduction technologies like Start-Stop or the Hybrid-Powertrain and the future emissions limits require a detailed optimization of the engine start-up. The combustion concept development as well as the calibration of the ECU makes an explicit thermodynamic analysis of the combustion process during the start-up necessary. Initially, the well-known thermodynamic analysis of in-cylinder pressure at stationary condition was transmitted to the highly non-stationary engine start-up. There, the current models for calculation of the transient wall heat fluxes were found to be misleading. But with a fraction of nearly 45% of the burned fuel energy, the wall heat is very important for the calculation of energy balance and for the combustion process analysis.