Stringent emission regulations force the gas turbine combustor community to come up with new designs. Lean Premixed combustion (LPM) is gaining popularity to meet the emission regulations. However, lean combustion process is prone to other issues like combustion instabilities and noise.
Self-excited combustion instabilities in a gas turbine play a vital role in the lifecycle of combustor, noise generation and pollutant formation. If the instabilities in the combustor dominate at natural modes, there are risks of resonance that can lead to bursting damage to the combustors. Therefore, it is necessary to understand the combustion dynamics performance of a given lean premixed combustor.
Our team is contributing our best to develop methodologies using our tools for modeling combustion dynamics with a great confidence. On behalf of our team, I will be presenting some of our most recent work, a paper entitled: Mode Shapes and Dominant Frequency Predictions in a Swirl Stabilized Premixed Air-Methane Combustor Using Modal Analysis and Large Eddy Simulations (LES) at the upcoming ASME Turbo Expo — Technical session 4-38 Combustion Dynamics: Modeling III.
In this paper, I will be talking about modal analysis carried out using ANSYS Mechanical to predict the longitudinal and the transverse modes in a swirl-stabilized premixed methane-air combustor. Large Eddy Simulations (LES) with Flamelet Generation Manifold (FGM) combustion model in ANSYS Fluent were used to identify the instabilities and their sources. A couple of images from the simulation results are shown below.