For combustion occurring in high-speed flows, radical-formation time scales and ignition delay times may be similar to, or dominate, relevant flow time scales. Accurate modeling of induction and autoignition processes is critical to the prediction of combustor performance. The evolution-variable manifold (EVM) approach of Cymbalist and Dimotakis1 uses a transported scalar to explicitly track the evolution of induction leading to autoignition and subsequent robust combustion in its representation of autoignition-dominated combustion. In the present work, the EVM method is implemented in a computational fluid dynamics code and wall-modeled large-eddy simulations are performed for two ethylene-air high-speed combustion test cases. The detailed thermochemical state of the reacting fluid is tabulated as a function of a reduced number of state variables that include density, energy, mixture fraction, and a reaction-evolution variable. A thermodynamically consistent numerical flux function is developed and the approach for coupling the CFD to the EVM table is discussed. It is found that particular attention must be given to the solution of the energy equation to obtain accurate and computationally stable results. The results show that the LES-EVM approach shows promise for the simulation of turbulent combustion of hydrocarbons in high-speed flows that are dominated by ignition delay and have regions of thin reaction fronts as well as distributed reaction zones.
|Original language||English (US)|
|Title of host publication||46th AIAA Fluid Dynamics Conference|
|Publisher||American Institute of Aeronautics and Astronautics Inc, AIAA|
|State||Published - 2016|
|Event||46th AIAA Fluid Dynamics Conference, 2016 - Washington, United States|
Duration: Jun 13 2016 → Jun 17 2016
|Name||46th AIAA Fluid Dynamics Conference|
|Other||46th AIAA Fluid Dynamics Conference, 2016|
|Period||6/13/16 → 6/17/16|
Bibliographical noteFunding Information:
This work was sponsored by the Air Force Office of Scientific Research under grant FA9550-12-1-0461. The views and conclusions contained herein are those of the author and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the AFOSR or the U.S. Government. We would also like to thank Prof. Mirko Gamba of the University of Michigan for providing the code to compute the synthetic OH PLIF signal plots (Fig. 7), Drs. Matthew Bartkowicz and Travis Drayna of GoHypersonic Inc. for generating the grids used in this work, and Mr. Anand Kartha of the University of Minnesota for providing synthetic turbulent inflow code used for the University of Virginia simulations.
© 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.