Turbulence-Chemistry Interactions for Turbulent Lean Premixed Flames

Debolina Dasgupta, Georgia Institute of Technology

When:  Monday, August 13, 2018, 1:00 p.m.

Where:  Building 4100, Room J302


Turbulence has well-known impacts on the large-scale topology and wrinkling of a premixed flame, as well as on the internal structure of the flame through local, time-dependent strain and

Curvature.  Less, well-understood is the influence of turbulence on the chemical reaction pathways; this question is particularly significant given that kinetic mechanisms are generally validated and benchmarked with measured data from simple bomb reactors, steady laminar flames.  In addition, flamelet modeling approaches generally use libraries developed from laminar calculations for unstretched and stretched flames by solving the flamelet equations and it is essential to understand their validity in describing chemistry in highly turbulent flow fields.  This talk intends to answer these open questions in the turbulence-chemistry modeling community. Direct Numerical Simulations (DNS) are performed for different fuels such as hydrogen, methane and n-dodecane.  Laminar flame calculations for unstretched flames, stretched flames and perfectly stirred reactors are also performed to compare and contrast the results obtained from turbulent flames.

In an effort to simplify transport calculations in DNS, laminar calculations with constant Lewis numbers are also carried out for unstretched and stretched flames.  The results are compared with the mixture-averaged transport results obtained from DNS.  Comparison of the results from this model will also help in understanding the shift in the importance of species transport from molecular diffusion to turbulent diffusion.  Emphasis is put on the development and usage of multiple computational methods for extracting the required information from these complex high dimensional datasets.

Debolina Dasgupta is a 4th year PhD candidate at Georgia Institute of Technology working with Prof. Tim Lieuwen and is a recipient of the 2018 AIAA Martin Summerfield graduate award in the field of propellants and combustion. She completed her undergraduate studies at Jadavpur University in India where she worked on the development of a Navier-Stokes solver for microchannel flows. She completed her Masters in Technology at the Indian Institute of Technology, Madras. Her research there focused on flow-acoustics interactions to understand the hydrodynamic stability characteristics of flow configurations in a backward facing step combustor typically seen in afterburners. Debolina’s current research at Georgia Tech focusses on turbulent combustion and understanding turbulence-chemistry interactions using direct numerical simulations and comparing them with simplified 1D models with a strong emphasis on development of computational methods to understand these complex multi-dimensional data. Additionally, the work intends to suggest improved chemistry models for turbulent combustion simulations and test the validity of the current models