Combustion dynamics in a lean premixed gas turbine combustor

摘要

Large eddy simulations of flame behavior in a lean premixed gas turbine combustor have been conducted to understand unstable combustion dynamics toward future active control implementation. The target combustor is a swirl-stabilized gas turbine combustor using methane as fuel. Inside the combustor, longitudinal acoustic resonance modes are formed and the basic mode is the quarter-wave mode. The acoustic pressure propagation causes the flow velocity field to fluctuate and periodic vortex shedding occurs from the combustion chamber entrance. The flow velocity fluctuations make the flame shape and location change continuously. This lead to heat release fluctuations. The pressure and heat release fluctuations are in phase to sustain the unstable behavior of flame. Calculations under different conditions imply that the flow filed can be changed by manipulating flow conditions and active control will lie in how to change these links properly.