Large Eddy Simulation: An Approach to Simulate Non-Premixed and Partially Premixed Natural Gas Combustor

Abstract

This paper highlights on the large eddy simulation approach for non-premixed and partially premixed combustor. In the case of large eddy simulation, mainly two scalars are taken into consideration that is mixture fraction and the other one is the progress variable mixture fraction, which tracks the mixing of fuel and the oxidizer, and a progress variable which tracks the global extent of reaction of the local mixture. In the case of non-premixed combustion, there are two ports provided for fuel and oxidizer and the mixing of fuel with oxidizer takes place inside the combustor and due to diffusion this mixing takes place and two scalars considered in the case of non-premixed are the mixture fraction and probability density function (PDF). Whereas in the case of partially premixed combustor there is single port provided for both the fuel and the oxidizer which get into the combustor and energy production takes place. Most of the combustion processes are highly turbulent, so the effect of turbulence, combustion and interaction are very important factors and has to be taken into consideration. Non-premixed combustion are based on the mixture fraction where is it is to be assumed that the inner turbulence diffusion term is not interrupted by the turbulence but in the case of partially premixed combustion, there is progress variable c which is introduced with only two possible states, i.e., 1 for burnt and 0 for unburnt gas. This paper mainly focuses on the Large Eddy Simulation approaches for solving non-premixed and partially premixed combustor.