Co-sponsored by Professor William H. Green, MIT, Professor Ronald K. Hanson, Stanford University, and Professor Hai Wang, University of Southern California.
Dr. Dames will apply recently advanced uncertainty quantification/minimization tools and determination of multi-species time histories behind reflected shock waves towards the development of high-fidelity kinetic models for combustion applications. The focus will lie on small (C1-C4) hydrocarbons, serving as a kinetic foundation for higher hydrocarbons and biofuels. This prospect offers the possibility for design of highly-accurate experiments to constrain model parameter uncertainties in a most efficient manner. It also allows for measurable progress in this area of research. The proposed approach and the toolkits developed will be combined with the Reaction Mechanism Generator software currently used by the CEFRC to produce kinetic models for various biofuels. The incorporation of this proposed computational package and the accompanying experimental database with RMG will allow for a novel methodology of kinetic model development for other compounds of interest to the CEFRC.
Co-sponsored by Professor Fokion N. Egofopoulos, University of Southern California and Professor Yiguang Ju, Princeton University.
Dr. Menon will utilize numerical simulations to study uncertainties introduced into fundamental combustion measurements such as flame speed and extinction rate due to non-ideal, multi-dimensional, fluid dynamic and thermodynamic effects. This is important given the fact that parameters such as flame speed and extinction rate are extensively used to develop and validate chemical reaction mechanisms. Following the development and validation of efficient techniques to couple multi-step reaction chemistry into fluid dynamic simulations, the codes will be used to study a well-characterized experimental setup. The results will be used to examine any uncertainties introduced into the measurement through non-ideal, higher-dimensional effects.
Co-sponsored by Professor William H. Green, MIT and Dr. Stephen J. Klippenstein, Argonne National Laboratory.
The purpose of Dr. Suleymanov's project is to generate the accurate theoretical estimates of the rate coefficients using state-of-art techniques of quantum chemistry and rate theory for reactions controlling concentrations of the HO2 radical. HO2 is one of the key chemical intermediates in various combustion and atmospheric oxidation processes. Sensitivity analysis indicates that reactions involving HO2 drive the output uncertainty of various combustion kinetic models. In this project I propose to focus on several important reactions of the HO2 radical with (i) biofuel radical and (ii) biofuel molecules for which direct experimental measurements and/or accurate theoretical calculations of the rate coefficients are not available. Because of a different nature of the intermolecular interactions (open shell-open shell, open shell-closed shell), these two classes of reactions will require the development and use of different theoretical methodologies.
Co-sponsored by Dr. Jacqueline H. Chen, Sandia National Laboratories and Professor Chung K. Law, Princeton University.
Dr. Valiev is working on investigation of various aspects of high-pressure combustion, both laminar and turbulent, by means of direct numerical simulation (DNS). With recent development of high-performance resources, peta-scale multidimensional DNS involving detailed chemistry has become a powerful tool for providing fundamental physical insight into multi-scale combustion problems. The goal is to perform DNS and extend theory and modeling of premixed flames at high pressure with or without turbulence and including intrinsic flame instabilities (hydrodynamic, diffusive-thermal, and pulsating), depending upon the Lewis number of the fuel. In particular, the effects of an unsteady flow field on the intrinsic pulsating instability of a premixed flame are studied using detailed hydrogen-air and hydrocarbon-air chemical kinetics.
Co-sponsored by Professor William H. Green, MIT and Dr. Stephen J. Klippenstein, Argonne National Laboratory.
Dr. Vandeputte’s research focuses on quantifying the effect of roaming mechanisms during combustion. Besides bond cleavage and molecular decomposition by tight transition states, roaming offers a new pathway for molecules to break apart. Roaming therefore has the potential of significantly altering the radical pool during combustion, affecting various combustion properties such as for example the ignition delay. From accurately mapped potential energy surfaces, rate coefficients and branching ratios will be derived using advanced transition state theories and the reduced dimensional trajectory framework, respectively. The final goal is to implement the calculated data in networks for the combustion of conventional fuels. Many of those networks still require some fine-tuning as simulated and measured data show discrepancies. In this regard, the feasibility of implementing roaming reactions in automated reaction network generators will be assessed.
CEFRC Research Fellows (Alumni)
Ionut Alecu, Manager of Research and Development, Hydrotex Partners Ltd.
Previously co-sponsored by Professor William H. Green, MIT and Professor Donald G. Truhlar, University of Minnesota.
Dr. Alecu worked with Professor Truhlar of the University of Minnesota and Professor Green of MIT to accurately compute and/or directly measure the thermochemistry and rate coefficients over a wide temperature range for important reactions in the combustion of new and potential biofuels. The initial focus of Dr. Alecu’s research was to improve on the existing n-butanol combustion mechanism by refining the rate coefficients of several critical reactions through high-level quantum-chemistry-based direct dynamics calculations using variational transition state theory with a curvilinear dividing surface, a multi-structural treatment of torsions, and a multidimensional treatment of tunneling. In addition, the rate coefficients to which the overall combustion mechanism is the most sensitive was investigated further using the laser-photolysis experimental technique coupled with the laser-absorption and/or time-of-flight mass spectrometry detection methods. Additional research was aimed at developing and modeling mechanisms for the combustion of other alcohols using MIT’s Reaction Mechanism Generator. This modeling work complemented the quantum chemistry and experiments, and helped to ensure that effort was focused on the most important reaction steps.
Previously co-sponsored by Professor Emily A. Carter, Princeton University and Professor Donald G. Truhlar, University of Minnesota.
Dr. Oyedepo's research was in the systematic utilization of ab initio quantum mechanical and density functional methodologies as predictive tools in the determination of thermodynamic properties, reaction rates and mechanisms of innovative non-petroleum based resources for optimum integration of energy conversion and new fuel compositions.
Colin Smith, Thermal Engineer, Jet Propulsion Laboratory
Previously co-sponsored by Professor Ronald K. Hanson, Stanford University and Dr. Nils Hansen, Sandia National Laboratories.
Temperature sensing is critical for fundamental studies of combustion chemistry. In particular, a temperature distribution is a required input parameter for flame computations that are used to develop and validate chemical kinetic models. Dr. Smith was working on tunable diode laser absorption spectroscopy for thermometry in low-pressure, burner-stabilized flames.
Mruthunjaya Uddi, Postdoc, MIT
Previously co-sponsored by Professor Yiguang Ju, Princeton University and Professor Chih-Jen Sung, University of Connecticut.
Dr. Uddi studied high temperature (500-600K) oxidation mechanisms of fuels such as ethane, methane in nanosecond discharge plasma under various conditions of temperature and pressure. He used advanced laser diagnostics such as Mid-IR absorption, TALIF to measure important radical species’ temporal densities. He conducted similar studies in a rapid compression machine for biofuels (methyl esters and butanols).
Bin Yang, Research Scientist, Tsinghua University
Previously co-sponsored by Dr. Nils Hansen, Sandia National Laboratories and Professor Hai Wang, University of Southern California.
Dr. Yang conducted joint research at the Advanced Light Source (ALS) at LBNL and Sandia National Labs and at University of Southern California. His work included (I) MBMS study of low-pressure burner stabilized flames, (II) Ab initio calculation and Master equation modeling for thermal decomposition and (III) detailed kinetic modeling for small oxygenates and related hydrocarbons. The experimental and computational work focused on the development of a fundamental and predictive reaction model for the pyrolysis and oxidation of iso-butanol and furan.
Yue Yang, Assistant Professor, Peking University
Previously co-sponsored by Dr. Jacqueline H. Chen, Sandia National Laboratories and Professor Stephen B. Pope, Cornell University
Dr. Yang worked with with Professor Pope of Cornell University and Dr. Chen of Sandia National Laboratories on advanced simulations of turbulent combustion. The goal of his research was to assess and to improve the capabilities of LES/FDF by making detailed comparisons with DNS of the same flames and developing advanced SGS models. The performance of the LES/FDF was assessed via posteriori comparisons with DNS in turbulent lifted jet flames, premixed and stratified jet flames, and future simulations focusing on biofuels for transportation under engine conditions.
Bret Windom, Assistant Professor, University of Colorado at Colorado Springs
Previously co-sponsored by Professor Fokion N. Egolfopoulos, University of Southern California and Professor Yiguang Ju, Princeton University.
Dr. Windom worked with with Professor Egolfopoulos of University of Southern California and Professor Ju of Princeton University on experimental modeling studies of high pressure flames. Using optical diagnostics, his goal was to characterize flames by measuring temperatures, flow velocities, and stable and radical species concentrations for flames under pressures typically experienced in practical applications. Using simple and carefully designed counterflow and spherically expanding flame configurations this data is expected to aid in the development and confirmation of high-pressure combustion models. Simple fuels was investigated to create a framework of data for which complex high-pressure combustion models may be validated and built upon.
Peng Zhang, Assistant Professor, Hong Kong Polytechnic University
Previously co-sponsored by Dr. Stephen J. Klippenstein, Argonne National Laboratory; Professor Chung K. Law, Princeton University; Professor Stephen B. Pope, Cornell University; and Professor Hai Wang, University of Southern California.
Dr. Zhang worked with four principal investigators on two major collaborative efforts which share the element of high pressure combustion. The first involved the collaboration between Prof. Law of Princeton University and Prof. Pope of Cornell University on the modeling of turbulent flames at high pressures. The second involved the collaboration with Prof. Law, Dr. Klippenstein of Argonne National Laboratory and Prof. Wang of University of Southern California on the re-examination of the extent of validity of the various “laws” governing the transport and reaction of reactive flows at exceedingly high pressures.