Numerical Study Of Stability Of Premixed Combution

In recent years, with the enhancement of awareness of environmental protection, countries around the world have developed strict emission standards for air pollution. The development of clean and efficient gas turbine has drawn wide attention, carrying out the study on high efficient and low emission combustion, the investigation of new device is very necessary. Premixed combustion technology can lower the peak combustion temperature, thus enabling to lower NOX emissions. But the development of premixed combustion technology is limited by the combustion instability. So the purpose of this thesis is to research characteristics of premixed combustion instability.In this paper, a 2D combustor is set up in the light of some gas-turbine combustor parameters. With this model, stability of premixed combustion can be presented. Using CFD software, under the same boundary conditions, the flow field, temperature field and emission of the combustor are numerically simulated through changing the shape of the combustor, velocity of inlet methane-air and equivalent ratio of methane-air. During numerical calculation, finite volume method is utilized, the RNGκ-εturbulent transport is utilized for the closure of the time averaged governing equation. Finite Rate/Eddy Dissipation model is utilized for turbulent premixed combustion. Effective algorithms for the study of combustion instability were raised, applying the curvilinear coordinate system for the complex geometry of chamber, using QUICK difference scheme and SIMPLE algorithm, using a less relaxation method for strong nonlinear source terms.2D calculation simulation is used for gas-turbine premixed combustion with the model and method presented.The calculated results present that premixed combustion can decrease NOX emission efficiently, the stability of premixed are significantly affected by the inlet velocity and equivalent ratio of methane-air.