Transported PDF simulation of auto-ignition of a turbulent methane jet in a hot, vitiated coflow

Abstract

In the current work, the auto-ignition of a turbulent round methane jet is studied numerically by means of a transported probability density function (PDF) method. The methane jet is issued into a hot, vitiated coflow, where it ignites to form a steady lifted flame. For this flame, experimental data of hydroxyl, temperature and mixture fraction are provided in the area where the fuel auto-ignites. To model this experiment, the transport equation for the thermochemical PDF is solved using a hybrid finite volume / Lagrangian Monte-Carlo method. Turbulence is modeled using the k-ε turbulence model including a jet-correction. Computational results are compared to experimental data in terms of mean quantities, variances and liftoff height. Moreover, the structure of the one-point, one-time marginal PDF of temperature is analyzed and compared to experimental data which are provided in this work. It is found that the transported PDF method in conjunction with the k-ε model is capable of reproducing these statistical data very well. In particular the effect of ignition on the marginal PDF of temperature can be well reproduced with this approach. To further analyze the relevant processes in the evolution of the temperature PDF, a statistically homogeneous system is studied both numerically and analytically.

Performance Comparison of CFD Microbenchmarks on Diverse HPC Architectures

“…The combustion chamber investigated by the DLR Institute of Combustion Technology is simulated. Detailed information about the experimental setup is reported in the literature [14]. A pre-chamber exists below a top vessel.…”

Non-Premixed Filtered Tabulated Chemistry: Filtered Flame Modeling of Diffusion Flames

“…This mechanism has been developed to simulate natural gas mixtures, it is characterized by a comprehensive range of validated applicability, and for its low tendency to run into stiffness problems [1]. For this reason it has been widely employed, a non exhaustive list of applications includes the CH 4 -Air chemical database generation for a novel coupled Principal Components Analysis (PCA)-LES model [39], NO x prediction [40], cryogenic CH 4 -O 2 flames [41], auto-ignition of CH 4 in hot vitiated coflow [42], and biomass-derived syngas modeling [43]. The progress variable is computed according to Equation (6), the selected species i are CO 2 , H 2 O and H 2 , and the weight factor γ * i = 1/MW i is the inverse of the molecular weight as proposed in [33], though highly promising techniques such as PCA [44] might as well offer appealing alternatives to be appraised in future studies.…”

The impact of molecular diffusion on auto-ignition in a turbulent flow

“…A related approach was applied by Fiolitakis et al [35] in the context of moment methods to compute near-wall flows and a hydrogen-jet flame in order to analyse the impact of differential diffu-sion. Fiolitakis and Arndt [36] further used the approach to analyse the auto-ignition of a turbulent methane-jet at a Reynolds number of 16,000 issuing into a vitiated coflow in the geometry investigated experimentally by Arndt et al [37,38]. Particular attention was focussed on marginal PDFs for which encouraging agreement was shown.…”