Prediction of autoignition in a lifted methane/air flame using an unsteady flamelet/progress variable model
- Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)
An unsteady flamelet/progress variable (UFPV) model has been developed for the prediction of autoignition in turbulent lifted flames. The model is a consistent extension to the steady flamelet/progress variable (SFPV) approach, and employs an unsteady flamelet formulation to describe the transient evolution of all thermochemical quantities during the flame ignition process. In this UFPV model, all thermochemical quantities are parameterized by mixture fraction, reaction progress parameter, and stoichiometric scalar dissipation rate, eliminating the explicit dependence on a flamelet time scale. An a priori study is performed to analyze critical modeling assumptions that are associated with the population of the flamelet state space. For application to LES, the UFPV model is combined with a presumed PDF closure to account for subgrid contributions of mixture fraction and reaction progress variable. The model was applied in LES of a lifted methane/air flame. Additional calculations were performed to quantify the interaction between turbulence and chemistry a posteriori. Simulation results obtained from these calculations are compared with experimental data. Compared to the SFPV results, the unsteady flamelet/progress variable model captures the autoignition process, and good agreement with measurements is obtained for mixture fraction, temperature, and species mass fractions. From the analysis of scatter data and mixture fraction-conditional results it is shown that the turbulence/chemistry interaction delays the ignition process towards lower values of scalar dissipation rate, and a significantly larger region in the flamelet state space is occupied during the ignition process. (author)
- OSTI ID:
- 21350364
- Journal Information:
- Combustion and Flame, Vol. 157, Issue 10; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
Similar Records
A Novel In Situ Flamelet Tabulation Methodology for the Representative Interactive Flamelet Model
Fluid age-based analysis of a lifted turbulent DME jet flame DNS [Residence Time-Based Analysis of a Lifted Turbulent DME Jet Flame]
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
LARGE-EDDY SIMULATION
AUTOIGNITION
METHANE
AIR
MIXTURES
COMBUSTION
FLAMES
EXPERIMENTAL DATA
FORECASTING
CHEMICAL REACTIONS
SCALARS
TURBULENCE
TIME DEPENDENCE
MASS
TEMPERATURE RANGE 1000-4000 K
TRANSIENTS
MATHEMATICAL MODELS
Turbulent combustion
Lifted flames
Non-premixed combustion
Unsteady flamelet modeling