Scott Martin

Reacting Unsteady Reynolds-Averaged Navier–Stokes with the Tabulated Premixed Conditional Moment Closure Method

The tabulated premixed conditional moment closure model has shown the capability to model turbulent, premixed methane flames with detailed chemistry and reasonable run times in a Reynolds-averaged Navier–Stokes formulation. The tabulated premixed conditional moment closure model is a table lookup combustion model that tabulates species, reaction rates, and thermodynamic data for use by the computational-fluid-dynamics code during run time. In this work, the tabulated premixed conditional moment closure model is extended to unsteady Reynolds-averaged Navier–Stokes. The new model is validated against particle image velocimetry and laser Raman measurements of an enclosed turbulent reacting methane jet from the German Aerospace Center. The flame’s reaction progress variable, its variance, and the scalar dissipation rate are calculated by the computational fluid dynamics in three dimensions. These three parameters are used to index detailed species information from the table for use by the computational-fluid-...

LES Simulation of an Enclosed Turbulent Reacting Methane Jet With the Tabulated Premixed CMC Method

The Tabulated Premixed Conditional Moment Closure Method (T-PCMC) has been shown to provide the capability to model turbulent, premixed methane flames with detailed chemistry and reasonable runtimes in a RANS environment [1]. Here the premixed conditional moment closure method is extended to Large Eddy Simulation. The new model is validated with the turbulent, enclosed reacting methane backward facing step data from El Banhawy [2]. The experimental data has a rectangular test section at atmospheric pressure and temperature with an inlet velocity of 10.5 m/s and an equivalence ratio of 0.9 for two different step heights. Contours of major species, velocity and temperature are provided.The T-PCMC model falls into the class of table lookup turbulent combustion models where the combustion model is solved offline over a range of conditions and stored in a table that is accessed by the CFD code using three controlling variables; the reaction progress variable, variance and local scalar dissipation rate. The local scalar dissipation is used to account for the affects of the small scale mixing on the reaction rates. A presumed shape beta function PDF is used to account for the effects of large scale turbulence on the reactions. Sub-grid scale models are incorporated for the scalar dissipation and variance. The open source CFD code OpenFOAM is used with the compressible Smagorinsky LES model. Velocity, temperature and major species are compared to the experimental data. Once validated, this “low runtime” CFD turbulent combustion model will have great utility for designing the next generation of lean premixed gas turbine combustors.Copyright