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A technique was developed for measuring the Laminar Burning Velocity (LBV) of multi-component fuel blends for use in high-performance spark-ignition engines. This technique involves the use of a centrally-ignited spherical combustion chamber, and a complementary analysis code. The technique was validated by examining several single-component fuels, and the computational procedure was extended to handle multi-component fuels without requiring detailed knowledge of their chemical composition. Experiments performed on an instrumented high-speed engine showed good agreement between the observed heat-release rates of the fuels and their predicted ranking based on the measured LBV parameters.

A large amount of the heat generated during the engine combustion process is lost to the coolant system through the surrounding metal parts. Therefore, there is a potential to improve the overall cycle efficiency by reducing the amount of heat transfer from the engine. In this paper, a Computational Fluid Dynamics (CFD) tool has been used to evaluate the effects of a number of design and operating variables on total heat loss from an engine to the coolant system. These parameters include injection characteristics and orientation, shape of the piston bowl, percentage of EGR and material property of the combustion chamber. Comprehensive analyses have been presented to show the efficient use of the heat retained in the combustion chamber and its contribution to improve thermal efficiency of the engine. Finally, changes in design and operating parameters have been suggested based on the analytical results to improve heat loss reduction from an engine.

A combined, experimental and numerical program is presented. This work summarizes an internal research effort conducted at Southwest Research Institute. Meeting new, stringent emissions regulations for diesel engines requires a way to reduce NOx and soot emissions. Most emissions reduction strategies reduce one pollutant while increasing the other. Water injection is one of the few promising emissions reduction techniques with the potential to simultaneously reduce soot and NOx in diesel engines. While it is widely accepted that water reduces NOx via a thermal effect, the mechanisms behind the reduction of soot are not well understood. The water could reduce the soot via physical, thermal, or chemical effects. To aid in developing water injection strategies, this project's goal was to determine how water enters the soot formation chemistry.

Southwest Research Institute (SwRI) is exploring the feasibility of extending the performance and fuel efficiency of the spark ignition (SI) engine to match that of the emission constrained compression (CI) engine, whilst retaining the cost effective 3-way stoichiometric aftertreatment systems associated with traditional SI light duty engines. The engine concept, which has a relatively high compression ratio and uses heavy EGR, is called “HEDGE”, i.e. High Efficiency Durable Gasoline Engine. Whereas previous SwRI papers have been medium and heavy duty development focused, this paper uses results from simulations, with some test bed correlations, to predict multicylinder torque curves, brake thermal efficiency and NOx emissions as well as knock limit for light and medium duty applications.

Tremendous amount of useful information can be extracted from the cylinder pressure signal for engine combustion control. However, the physical cylinder pressure sensors are undesirably expensive and their health need to be monitored for fault diagnostic purpose as well. This paper presents the results of the development of a virtual cylinder pressure sensor (VCPS) with individual variable-oriented independent estimators. Two neural network-based independent cylinder pressure related variable estimators were developed and verified at steady state. The results show that these models can predict the variables correctly compared with the extracted variables from the measured physical cylinder pressure sensor signal. Good generalization capabilities of the developed models are observed in the sense that the models work well not only for the training data set but also for the new inputs that they have never been exposed to before.

Recent advances in Variable Valve Actuation (VVA) methods have led to development of optimized valve timing strategies for a broad range of engine operating conditions. This study focuses on the cold-start period, which begins at engine cranking and lasts for approximately 1 minute thereafter. Cold-start is characterized by poor mixture preparation due to low component temperatures, aggravated by fixed valve timing which has historically been compromised to give optimal warm engine operation. In this study, intake cam phasing was varied to explore the potential benefit in hydrocarbon emissions and driveability obtainable for cold-start. A simple experimental approach was used to investigate the potential emissions benefits realizable through intake cam phasing. High speed cylinder pressure and Fast Flame Ionization Detector (FFID) engine-out hydrocarbon (HC) measurements were made to characterize instantaneous cold-start emissions and driveability.

Large reductions in low-load NOx emissions can be obtained by replacing conventional Diesel or spark ignited combustion by HCCI combustion in reciprocating engines. Currently, HCCI combustion is limited to operating conditions with lean air/fuel ratios or large amounts of EGR. However, a numerical model shows that, even if high equivalence ratio HCCI operation were satisfactorily attained, the NOx reduction potential vs. DI-Diesel combustion would be much smaller. Thus, high-load HCCI operation may best be obtained through highly boosted fuel-lean operation. Alternatively, HCCI combustion may be suited well for “dual mode” engine applications, in which spark ignition or conventional Diesel combustion is used to obtain full load. Avoiding wall impingement with heavy fuels is critical for achieving good emissions and fuel consumption, and it appears that a large degree of mixture inhomogeneity can be tolerated from a NOx benefit standpoint.