and Sjöblom B., “ Validation Rig: A Tool for Flame Studies,” International Society for Air-Breathing Engines Conference, International Soc. and Sankaran V., Proceedings of the Second Model Validation from Propulsion (MVP 2) Workshop, April 2018. and Sankaran V., Proceedings of the First Model Validation from Propulsion (MVP 1) Workshop, March 2017. for Air-Breathing Engines Paper ISABE-2011-1110, Sept. O., “ V-Gutter Stabilized Turbulent Premixed Flame and Lean Blowout,” International Society for Air-Breathing Engines Conference, International Soc. K., “ The Instability of the Shear Layer Separating from a Bluff Body,” Journal of Fluid Mechanics, Vol. 333, Feb. and Lieuwen T., “ Density Ratio Effects on Reacting Bluff-Body Flow Field Characteristics,” Journal of Fluid Mechanics, Vol. 706, Sept. C., “ The Influence of Reactant Temperature on the Dynamics of Bluff Body Stabilized Premixed Flames,” Combustion and Flame, Vol. 158, No. 12, 2011, pp. 2441–2457. E., “ A Mechanism for High-Frequency Oscillation in Ramjet Combustors and Afterburners,” Journal of Jet Propulsion, Vol. 26, No. 6, 1956, pp. 456–462. In spite of a lack of thermoacoustic oscillations, exit boundary condition effects are shown to be substantial, and errors in velocity statistics are minimized by extending the computational domain into the exhaust region. All three categories of sensitivities are identified as significant, and the dominant source of variation in the results depends on the resolution and flow variable of interest. Specifically, low grid sensitivities at the finest resolution indicate that notable discrepancies with the experiment are likely due to model or boundary condition errors.
Comparisons with experimental data are presented, and an analysis of the causes of the discrepancies is informed by the sensitivity analysis. To identify potential sources of this variation, three categories of sensitivities are assessed for a stable combustion bluff-body flame test case: exit boundary conditions, turbulent combustion closure models, and grid resolution. Past simulation results from many research groups on the same bluff-body flame test case demonstrate significant variation that is neither fully understood nor quantified. Bluff-body stabilized turbulent premixed flames represent a challenging canonical configuration for computational simulation and validation.