A New Jet-Stirred Apparatus for Turbulent Premixed Flame and Chemical Kinetics Experiments
A new jet-stirred chamber (JSC) design incorporating multiple impinging turbulent jets is proposed as an apparatus for the study of turbulent premixed flames. ANSYS-FLUENT computations employing the RANS - Reynolds Stress Model were used to simulate the flows and identify an optimal configuration of jets and outlet ports providing the most nearly ideal flow, i.e. homogeneous and isotropic with large turbulence intensity compared to the mean velocity. Results showed that a configuration of 8 jets, each surrounded by a concentric annular outlet, at the corners of an imaginary cube circumscribed by a spherical chamber produced by far the most nearly optimal flow characteristics. The performance of this configuration, called Concentric Inlet And Outlet (CIAO), was also compared quantitatively to two popular fan-stirred chamber (FSC) designs and CIAO JSC was found to provide far more nearly ideal flow.
A comparison of simulated turbulent premixed flames at high Damköhler numbers (Da, ratio of chemical reaction rate to turbulent strain rate) in CIAO and an FSC showed that CIAO enabled far more nearly spherical expanding flames with nearly the same inferred turbulent burning velocity regardless of the value of the mean progress variable used to define the flame location, whereas in the FSC there was considerable variation depending on the definition. Computations also showed that the CIAO configuration provides more nearly homogeneous mixing of reactants and products at low Da and consequently can be used for chemical kinetics experiments (so-called “well-stirred reactors”) resulting in more accurate kinetic data than currently popular designs.
Paul D. Ronney is a Professor in the Department of Aerospace and Mechanical Engineering at the University of Southern California in Los Angeles, CA. Prof. Ronney received a Bachelor of Science degree in Mechanical Engineering from the University of California, Berkeley, a Master of Science degree in Aeronautics from the California Institute of Technology, and a Doctor of Science degree in Aeronautics and Astronautics from the Massachusetts Institute of Technology. He held postdoctoral appointments at the NASA-Glenn Research Center and the Laboratory for Computational Physics at the U. S. Naval Research Laboratory and a position as Assistant Professor in the Department of Mechanical and Aerospace Engineering at Princeton University before assuming his current position at USC. Prof. Ronney was the Payload Specialist Astronaut (Alternate) for Space Shuttle mission MSL-1 (STS-83, April 4 - 8, 1997) and the reflight of this mission (STS-94, July 1 - 16, 1997).