381 research outputs found
Comparative Investigation of the High Pressure Autoignition of the Butanol Isomers
Investigation of the autoignition delay of the butanol isomers has been
performed at elevated pressures of 15 bar and 30 bar and low to intermediate
temperatures of 680-860 K. The reactivity of the stoichiometric isomers of
butanol, in terms of inverse ignition delay, was ranked as n-butanol >
sec-butanol ~ iso-butanol > tert-butanol at a compressed pressure of 15 bar but
changed to n-butanol > tert-butanol > sec-butanol > iso-butanol at 30 bar. For
the temperature and pressure conditions in this study, no NTC or two-stage
ignition behavior were observed. However, for both of the compressed pressures
studied in this work, tert-butanol exhibited unique pre-ignition heat release
characteristics. As such, tert-butanol was further studied at two additional
equivalence ratios ( = 0.5 and 2.0) to help determine the cause of the
heat release.Comment: 4 pages, 4 figures, presented at the 2011 Meeting of the Eastern
States Sections of the Combustion Institut
Accelerating moderately stiff chemical kinetics in reactive-flow simulations using GPUs
The chemical kinetics ODEs arising from operator-split reactive-flow
simulations were solved on GPUs using explicit integration algorithms. Nonstiff
chemical kinetics of a hydrogen oxidation mechanism (9 species and 38
irreversible reactions) were computed using the explicit fifth-order
Runge-Kutta-Cash-Karp method, and the GPU-accelerated version performed faster
than single- and six-core CPU versions by factors of 126 and 25, respectively,
for 524,288 ODEs. Moderately stiff kinetics, represented with mechanisms for
hydrogen/carbon-monoxide (13 species and 54 irreversible reactions) and methane
(53 species and 634 irreversible reactions) oxidation, were computed using the
stabilized explicit second-order Runge-Kutta-Chebyshev (RKC) algorithm. The
GPU-based RKC implementation demonstrated an increase in performance of nearly
59 and 10 times, for problem sizes consisting of 262,144 ODEs and larger, than
the single- and six-core CPU-based RKC algorithms using the
hydrogen/carbon-monoxide mechanism. With the methane mechanism, RKC-GPU
performed more than 65 and 11 times faster, for problem sizes consisting of
131,072 ODEs and larger, than the single- and six-core RKC-CPU versions, and up
to 57 times faster than the six-core CPU-based implicit VODE algorithm on
65,536 ODEs. In the presence of more severe stiffness, such as ethylene
oxidation (111 species and 1566 irreversible reactions), RKC-GPU performed more
than 17 times faster than RKC-CPU on six cores for 32,768 ODEs and larger, and
at best 4.5 times faster than VODE on six CPU cores for 65,536 ODEs. With a
larger time step size, RKC-GPU performed at best 2.5 times slower than six-core
VODE for 8192 ODEs and larger. Therefore, the need for developing new
strategies for integrating stiff chemistry on GPUs was discussed.Comment: 27 pages, LaTeX; corrected typos in Appendix equations A.10 and A.1
UConnRCMPy: Python-based data analysis for rapid compression machines
The ignition delay of a fuel/air mixture is an important quantity in
designing combustion devices, and these data are also used to validate chemical
kinetic models for combustion. One of the typical experimental devices used to
measure the ignition delay is called a Rapid Compression Machine (RCM). This
paper presents UConnRCMPy, an open-source Python package to process
experimental data from the RCM at the University of Connecticut. Given an
experimental measurement, UConnRCMPy computes the thermodynamic conditions in
the reaction chamber of the RCM during an experiment along with the ignition
delay. UConnRCMPy implements an extensible framework, so that alternative
experimental data formats can be incorporated easily. In this way, UConnRCMPy
improves the consistency of RCM data processing and enables the community to
reproduce data analysis procedures.Comment: 8 pages, 3 figures, presented at the 10th US National Combustion
Meetin
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