1,720,975 research outputs found
Optimizing the calibration of a turbocharged GDI engine through numerical simulation and direct optimization
No full textDifferent optimization strategies for the optimization of the calibration of a turbocharged GDI engine through numerical simulation were analyzed, aiming to evaluate the opportunities offered by direct optimization techniques.
A one-dimensional fluid dynamic engine model was used to predict engine performance, taking into account knock and exhaust temperature constraints.
Air fuel ratio, spark advance, boost pressure and cam phasing were optimized by means of different optimization strategies, including direct search as well as numerical methods.
Both full load (with maximum bmep targets) and part load (with minimum bsfc targets) were considered.
The potential for remarkable improvements (up to 10% bmep increase at full load and 8 g/kWh bsfc decrease at part load) in comparison with the baseline engine calibration was highlighted, and a ranking between different optimization methods was obtained, based on the requested computational efforts and on their capabilities to handle constrained optimization problems
Numerical Simulation of Cycle-to-Cycle Variation for Knock Prediction in a Turbocharged Spark Ignition Engine
No full textIn this paper a novel approach to mimic through numerical simulation Cycle-to-Cycle (CCV) Variations of the combustion process of Spark Ignition (SI) engines is described. The proposed methodology allows to reproduce the variability in combustion which is responsible for knock occurrence and thus to replicate the stochastic behaviour of this abnormal combustion phenomenon.
On the basis of the analysis of a comprehensive database of experimental data collected on a typical European downsized and turbocharged SI engine, the proposed approach was demonstrated to be capable to replicate in the simulation process the same percentage of knocking cycles experimentally measured in light-knock conditions, after a proper calibration of the Kinetics-Fit (KF), a new phenomenological knock model which was recently developed by Gamma Technologies.
Finally, the capability of the proposed methodology, coupled with the usage of the KF knock model, to correctly identify the Knock Limited Spark Advance (KLSA) on the basis of the CCV-replicating model was assessed over a wide range of different operating conditions, thus confirming its reliability and robustness
A methodology to mimic cycle to cycle variations and to predict knock occurrence through numerical simulation
No full textIn this paper a novel approach to mimic through numerical simulation Cycle-to-Cycle Variations (CCV) of the combustion process of Spark Ignition (SI) engines is described. The proposed methodology allows to reproduce the variability in combustion which is responsible for knock occurrence and thus to replicate the stochastic behavior of this abnormal combustion phenomenon.
On the basis of the analysis of a comprehensive database of experimental data collected on a typical European downsized and turbocharged SI engine, the proposed approach was demonstrated to be capable to replicate in the simulation process the same percentage of knocking cycles experimentally measured in light-knock conditions, after a proper calibration of the Kinetics-Fit (KF), a new phenomenological knock model which was recently developed by Gamma Technologies.
Finally, the capability of the proposed methodology, coupled with the usage of the KF knock model, to correctly identify the Knock Limited Spark Advance (KLSA) on the basis both of the CCV-replicating model and of a more traditional average-cycle simulation was assessed over a wide range of different operating conditions, thus confirming its reliability and robustness
A DOE Analysis of Compression Ratio, Injection Timing, Injector Nozzle Hole Size and Number on Performance and Emissions in a Diesel Marine Engine
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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