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The charge dynamics within a Rapid Compression Expansion Machine (RCEM) have been investigated using an integrated computational fluid dynamics / chemical kinetics code, KIVA3V/CHEMKIN. A 0D ring-dynamic model, first developed at MIT, and subsequently modified at UIUC to include circumferential flow past unlubricated rings, was added to the code in order to account for flow into, out of and past the piston's ringpack. Simulations were conducted using two different compression ratios (25:1 and 50:1) for an unreacting (‘motored’) charge and at 38:1 for a reacting (‘fired’) charge, in this case with a lean H2/air mixture. A 19-step detailed kinetic mechanism was employed for the reacting simulation. The effects of various modeling parameters, including the mesh configuration, ring-dynamic parameters and turbulent/laminar assumptions were explored; the simulation results were compared to experimental data from the RCEM.

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.

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.

A free piston, internal combustion (IC) engine, operating at high compression ratio (∼30:1) and low equivalence ratio (ϕ∼0.35), and utilizing homogeneous charge compression ignition combustion, has been proposed by Sandia National Laboratories as a means of significantly improving the IC engine's cycle thermal efficiency and exhaust emissions. A zero-dimensional, thermodynamic model with detailed chemical kinetics, and empirical scavenging, heat transfer, and friction component models has been used to analyze the steady-state operating characteristics of this engine. The cycle simulations using hydrogen as the fuel, have indicated the critical factors affecting the engine's performance, and suggest the limits of improvement possible relative to conventional IC engine technologies.

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.