Diesel and biodiesel combustion in a light duty compression ignition engine were simulated during a closed cycle, using a commercial computational fluid dynamics (CFD) code, CONVERGE. The corresponding computational domain was constructed for the engine based on combustion chamber geometry and compression ratio measurements. Submodels were calibrated for simulation. The results were able to capture the experimental pressure and apparent heat release rate trends for both fuels over a range of engine loads and fuel injection timings. NOx emissions trends were captured for diesel, while under-predicted for biodiesel. The NOx trends were also analyzed based on the thermal NO mechanism. A new modular tool in Matlab was developed for studying the residence time. It was found that high in-cylinder temperatures and their residence time are critical in NOx formation.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Note:

A method to efficiently introduce supersonic drag predictions from computational fluid dynamics (CFD) calculations in a combined aerodynamic-structural optimization of a High-Speed Civil Transport (HSCT) is presented. To achieve this goal, the method must alleviate the large computational burden associated with performing CFD analyses and reduce the numerical noise present in the analyses. This is accomplished through the use of response surface (RS) methodologies, a variation of the variable-complexity modeling (VCM) technique, and coarse grained parallel computing. Variable-complexity modeling allows one to take advantage of the information gained from inexpensive lower fidelity models while maintaining the accuracy of the more expensive high fidelity methods. The utility of the method is demonstrated on HSCT design problems of five, ten, fifteen, and twenty design variables. Motivation for including CFD predictions into the HSCT optimization comes from studies detailing the differences in supersonic aerodynamic predictions from linear theory, Euler, and parabolized Navier-Stokes (PNS) calculations for HSCT configurations. The effects of these differences in integrated forces and distributed loads on the aircraft performance and structural weight are investigated. These studies indicate that CFD drag solutions are required for accurate HSCT performance and weight estimates. Response surface models are also used to provide useful information to the designer with minimal computational effort. Investigations into design trade-offs and sensitivities to certain design variables, available at the cost of evaluating a simple quadratic polynomial, are presented. In addition, a novel and effective approach to visualizing high dimensional, highly constrained design spaces is enabled through the use of RS models. <i>NOTE: An updated copy of this ETD was added in July 2012 after there were patron reports of problems with the original file.</i> / Ph. D.