Advances in rapid compression machine studies of low- and intermediate-temperature autoignition phenomena

© 2017 Elsevier Ltd Rapid compression machines (RCMs) are widely used to acquire experimental insights into fuel autoignition and pollutant formation chemistry, especially at conditions relevant to current and future combustion technologies. RCM studies emphasize important experimental regimes, characterized by low- to intermediate-temperatures (600–1200 K) and moderate to high pressures (5–80 bar). At these conditions, which are directly relevant to modern combustion schemes including low temperature combustion (LTC) for internal combustion engines and dry low emissions (DLE) for gas turbine engines, combustion chemistry exhibits complex and experimentally challenging behaviors such as the chemistry attributed to cool flame behavior and the negative temperature coefficient regime. Challenges for studying this regime include that experimental observations can be more sensitive to coupled physical-chemical processes leading to phenomena such as mixed deflagrative/autoignitive combustion. Experimental strategies which leverage the strengths of RCMs have been developed in recent years to make RCMs particularly well suited for elucidating LTC and DLE chemistry, as well as convolved physical-chemical processes. Specifically, this work presents a review of experimental and computational efforts applying RCMs to study autoignition phenomena, and the insights gained through these efforts. A brief history of RCM development is presented towards the steady imp rovement in design, characterization, instrumentation and data analysis. Novel experimental approaches and measurement techniques, coordinated with computational methods are described which have expanded the utility of RCMs beyond empirical studies of explosion limits to increasingly detailed understanding of autoignition chemistry and the role of physical-chemical interactions. Fundamental insight into the autoignition chemistry of specific fuels is described, demonstrating the extent of knowledge of low-temperature chemistry derived from RCM studies, from simple hydrocarbons to multi-component blends and full-boiling range fuels. Emerging needs and further opportunities are suggested, including investigations of under-explored fuels and the implementation of increasingly higher fidelity diagnostics

Unraveling the role of EGR olefins at advanced combustion conditions in the presence of nitric oxide : ethylene, propene and isobutene

202406 bcchOthersUS Department of EnergyPublished24 monthsGreen (AAM

Chemical kinetic interactions of NO with a multi-component gasoline surrogate : experiments and modeling

202406 bcchOthersUS Department of EnergyPublished24 monthsGreen (AAM

Replicating HCCI-like autoignition behavior : what gasoline surrogate fidelity is needed?

202406 bcchVersion of RecordOthersUS Department of EnergyPublishedC

From electronic structure to model application of key reactions for gasoline/alcohol combustion : hydrogen-atom abstractions by CH3Ȯ radical

202306 bcchNot applicableRGCOthersFundamental Research of Free Orientation from Central Government; Supercomputing Lab and Clean Combustion Research Center; U.S. Department of Energy, Argonne National Laboratory; Laboratory Computing Resource CenterPublished24 month

Finding a common ground for RCM experiments. Part B : benchmark study on ethanol ignition

202406 bcchVersion of RecordSelf-fundedPublishedC

Turbulent swirling flow in a dynamic model of a uniflow-scavenged two-stroke engine

It is desirable to use computational fluid dynamics for optimization of the in-cylinder processes in low-speed two-stroke uniflow-scavenged marine diesel engines. However, the complex nature of the turbulent swirling in-cylinder flow necessitates experimental data for validation of the used turbulence models. In the present work, the flow in a dynamic scale model of a uniflow-scavenged cylinder is investigated experimentally. The model has a transparent cylinder and a moving piston driven by a linear motor. The flow is investigated using phase-locked stereoscopic particle image velocimetry (PIV) and time-resolved laser Doppler anemometry (LDA). Radial profiles of the phase-locked mean and rms velocities are computed from the velocity fields recorded with PIV, and the accuracy of the obtained profiles is demonstrated by comparison with reference LDA measurements. Measurements are carried out at five axial positions for 15 different times during the engine cycle and show the temporal and spatial development of the swirling in-cylinder flow. The tangential velocity profiles in the bottom of the cylinder near the end of the scavenge process are characterized by a concentrated swirl resulting in wake-like axial velocity profiles and the occurrence of a vortex breakdown. After scavenge port closing, the axial velocity profiles indicate that large transient swirl-induced structures exist in the cylinder. Comparison with profiles obtained under steady-flow conditions shows that the scavenge flow cannot be assumed to be quasi-steady. The temporal development of the swirl strength is investigated by computing the angular momentum. The swirl strength shows an exponential decay from scavenge port closing to scavenge port opening corresponding to a reduction of 34 %, which is in good agreement with theoretical predictions.ISSN:0723-4864ISSN:1432-111