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MODELING AND SIMULATION OF REACTING FLOWS IN LEAN-PREMIXED SWIRL-STABLIZED GAS TURBINE COMBUSTOR

TOKEKAR, DEVKINANDAN MADHUKAR
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1141412599

Abstract Details

2006, MS, University of Cincinnati, Engineering : Mechanical Engineering.
Combustion in a lean pre-mixed (LPM) combustor may become unstable due to small changes in geometry and the manner in which reactants are introduced. This may lead to excessive thermal loads and possible off-design operation. A comprehensive understanding of combustion instability is therefore needed. The present study aims to analyze the flow and flame dynamics in a model LPM gas turbine combustor in LPM combustion. Fluent is used as the flow solver for the present study. The 3-D Navier-Stokes equations are solved along with finite-rate chemical reaction equations and variable thermo-physical properties. Large-eddy-simulation (LES) technique is used to model turbulence. The dynamic version of the Smagorinsky-Lilly model is employed to describe subgrid-scale turbulent motions and their effect on large-scale structures. At first a non-reactive LES was performed in model round and LM6000 combustor. The results for time averaged mean velocity are compared with the previous LES work by Grinstein et al. and Kim et al. Using non-reacting case for LM6000, reactive simulation was initiated, with lean methane-air mixture with equivalence ratio 0.56. Species transport equation is solved for global methane-air two-step reaction with six volumetric species to predict the local mass fraction of each species. The reaction rates that appear as source terms in the species transport equation are computed using finite-rate/eddy-dissipation model, which computes both, the Arrhenius rate and the mixing rate and uses the smaller of the two. It is observed that as the flow enters the chamber, it bifurcates in two shear layers forming a prong like structure. The layers further tend to reattach to the wall at a distance approximately equal to 3D. Counter-clockwise recirculation zones are formed in the corners, whereas clock-wise toroidal vortex structure is formed in the center. The flame is located in between these vortex structures and thus experiences shear-layer instabilities. It is also noticed that the eddy structure in case of reacting case is thicker than that of the non-reacting case. This is mainly due to the temperature dependent viscosity, which has a stabilizing effect on the flow.
Dr. Urmila Ghia (Advisor)
115 p.
Large Eddy Simulation; LES; Lean Pre-mixed; LPM; Gas Turbine Combustor; Combustion; Reacting Flows

Recommended Citations

Citations

  • TOKEKAR, D. M. (2006). MODELING AND SIMULATION OF REACTING FLOWS IN LEAN-PREMIXED SWIRL-STABLIZED GAS TURBINE COMBUSTOR [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1141412599

    APA Style (7th edition)

  • TOKEKAR, DEVKINANDAN. MODELING AND SIMULATION OF REACTING FLOWS IN LEAN-PREMIXED SWIRL-STABLIZED GAS TURBINE COMBUSTOR. 2006. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1141412599.

    MLA Style (8th edition)

  • TOKEKAR, DEVKINANDAN. "MODELING AND SIMULATION OF REACTING FLOWS IN LEAN-PREMIXED SWIRL-STABLIZED GAS TURBINE COMBUSTOR." Master's thesis, University of Cincinnati, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1141412599

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.