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A simple model to simulate cycle-by-cycle variation that is suitable for use in Monte-Carlo approaches has been developed and validated with a wide range of experimental data. The model is intended to be diagnostic rather than predictive in nature, with a goal of providing realistic in-cylinder pressures. The individual-cycle cumulative rate of heat release was curve fit with a four-parameter Wiebe function. It was found that the distribution of the Wiebe b-parameter was quite small, so its value was obtained from the ensemble-averaged condition. The remaining three Wiebe function parameters, θig, θcomb and m were found to be distributed over a moderate range, and were linearly correlated to each other. Using the cumulative density function of θig, and the linear fit of θcomb and m to θig, with a random component added, a Monte-Carlo scheme was developed.

Airborne compression-ignition engine operations differ significantly from those in ground vehicles, both in mission requirements and in operating conditions. Unique challenges exist in the aviation space, and electrification technologies originally developed for ground applications may be leveraged to address these considerations. One such technology, electrically assisted turbochargers (EATs), have the potential to address the following: increase the maximum system power output, directly control intake manifold air pressure, and reignite the engine at altitude conditions in the event of an engine flame-out. Sea-level experiments were carried out on a two-liter, four-cylinder compression-ignition engine with a commercial-off-the-shelf EAT that replaced the original turbocharger. The objective of these experiments was to demonstrate the technology, assess the performance, and evaluate control methods at sea level prior to altitude experimentation.