Quantitative Measurements and Modeling in Partially-Premixed Cellular Tubular Flames

Vanderbilt University, Nashville TN

Investigators

Abstract

1606005 - Pitz To design efficient and clean combustors, simplified chemical kinetic and molecular transport models are needed for accurate and efficient prediction of combustion used for heating, land and air propulsion. Cellular tubular flames mimic practical flames and are an efficient platform to predict and experimentally validate simplified combustion models. The flame cells are arrayed in a cylindrically symmetric geometry that can be mathematically simplified and predicted on a desktop computer. The symmetrical flame cell pattern can be measured quickly in the laboratory with advanced laser methods to assess predictions using the simplified combustion models. Validated simplified chemical kinetic and molecular transport models can then be used in computer codes to accurately predict combustion and pollution emission in practical car engines, house furnaces and aircraft jet engines. Success of this research will lead to cleaner and more efficient combustion in the U.S. to help the economy and the environment. The project will study cellular tubular flames with quantitative measurements and modeling in order to evaluate simplified models of molecular transport and chemical kinetics. The detailed two-dimensional (2D) simulation will be validated with laser imaging and measurements of major species concentration by Raman scattering and radial species (OH, H, O) by laser-induced fluorescence (LIF) in cellular flames that are premixed, non-premixed and partially premixed. The H and O atom concentrations are measured with a femtosecond (fs) laser to avoid interference from laser photolysis that plagued earlier efforts. With the validated computationally efficient 2D tubular flame models, simplified models of molecular transport (e.g., mixture-averaged transport and approximate Soret effect models) and reduced species chemical kinetic mechanisms can be developed for more accurate turbulent combustion models burning hydrogen, methane and propane. Once the detailed 2D model is validated, simplified transport and chemical kinetic mechanisms will be developed and/or evaluated for use in turbulent combustion modeling. Quantitative 2D models verified by multi-scalar measurements of cellular structures will provide data for development of simplified models of hydrogen and hydrocarbon flames used for practical combustors in heating, energy production and propulsion. Development of H and O atom quantitative measurements with femtosecond lasers will lead to adoption of the fs-LIF method by other research groups in the world. Graduate students and undergraduate students will be involved in research with an emphasis in recruiting underrepresented minorities. Students will present their results at research conferences. Students will collaborate with the Air Force Research Laboratory/Spectral Energies in Dayton, Ohio on femto-second laser measurement giving them a broad exposure to the latest computer simulation and laser diagnostic facilities.