Numerical Prediction and Suppression of Thermoacoustic Longitudinal Mode in Annular Combustor

Abstract

Many industrial applications, such as gas turbines or aeroengines, are subject to thermoacoustic instability, especially in the lean combustion regime. In this paper, the linearized Navier–Stokes equations (LNSEs) framework is applied to predict the acoustic liner damping effects with real geometry and different bias flow velocities. The results show that the LNSEs can capture the tilt angle effect of the orifice or grazing and bias flow coupling phenomenon. The forced large-eddy simulation results of premixed methane flame present the same trend in gain and phase of the flame transfer function with the equation. Then, the flame response model is coupled into the Helmholtz and LNSE solvers. The mean flow from Reynolds-averaged Navier–Stokes calculation is used in the LNSEs, and no assumption of liner geometry is made. The linear stability analysis reveals that the velocity fluctuation in the combustion is also damped when a stable acoustic mode is achieved with the acoustic liner. The flame dynamic, the hydrodynamic, and the acoustic phenomena can all be considered when using the LNSEs. This indicates that the LNSEs may allow us to consider a more complex mechanism that can affect the thermoacoustic inability in the combustor system and help us to design better dampers to control.