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A crevice blow-by model has been developed for a Rapid Compression Expansion Machine. This device can be used to study chemical kinetics with application to Homogeneous Charge Compression Ignition and other alternative combustion processes. In order to accurately resolve the ignition conditions and understand the oxidation process, accurate models for heat transfer and crevice flow, including blow-by past the ringpack, must be utilized. Crevice flows are important when high compression ratio or boosted operation is investigated. In previous work the heat loss characteristics of the RCEM were characterized; this study concerns the crevice flows within the RCEM. A ring-dynamic model, first developed at MIT and recently modified at UIUC to account for circumferential flow pas unlubricated rings, was employed.

Knock integrals and corresponding ignition delay (τ) correlations are often used in model-based control algorithms in order to predict ignition timing for kinetically modulated combustion regimes such as HCCI and PCCI. They can also be used to estimate knock-inception during conventional SI operation. The purpose of this study is to investigate the performance of various τ correlations proposed in the literature, including those developed based on fundamental data from shock tubes and rapid compression machines, those based on predictions from isochoric simulations using detailed chemical kinetic mechanisms, and those deduced from data of operating engines. A 0D engine simulation framework is used to compare the correlation performance where evaluations are based on the temperatures required at intake valve closure (TIVC) in order to achieve a fixed CA50 point over a range of conditions.

A floating-stroke, free-piston internal combustion reciprocating engine (FS-FPE) is currently under development with the primary goal of high engine efficiency, along with ultra-low emissions. High compression ratio, boosted, lean operation is targeted with kinetically-modulated combustion expected to be utilized as a principal mode of operation. To aid the engine's preliminary design stage modeling is conducted in order to explore the engine's operational characteristics and charge conditioning needs. Natural gas and gasoline are considered as potential fuels. A single-zone, homogeneous reactor model (HRM) is employed to approximate the in-cylinder processes, especially the ignition chemistry (timing) which is important for operation under these conditions. Sub-models are integrated into the HRM to describe fuel evaporation, heat transfer, and piston crevice / ringpack flows.

Of late there has been a resurgence in studies investigating parameters that quantify combustion knock in both standardized platforms and modern spark-ignition engines. However, it is still unclear how metrics such as knock (octane) rating, knock onset, and knock intensity are related and how fuels behave according to these metrics across a range of conditions. As part of an ongoing study, the air supply system of a standard Cooperative Fuel Research (CFR) F1/F2 engine was modified to allow mild levels of intake air boosting while staying true to its intended purpose of being the standard device for American Society for Testing and Materials (ASTM)-specified knock rating or octane number tests. For instance, the carburation system and intake air heating manifold are not altered, but the engine was equipped with cylinder pressure transducers to enable both logging of the standard knockmeter readout and state-of-the-art indicated data.