Effects of Perforated Liners on Controlling Combustion Instabilities in Annular Combustors
Guangyu Zhang, Xiaoyu Wang, Lei Li, Xiaofeng Sun
Abstract
This paper investigates the effects of two perforated liners on controlling combustion instabilities in a simplified annular combustor using a three-dimensional modeling approach. With this approach, the effects of radial modal coupling caused by the impedance jump across the connection interface between the rigid wall and perforated liner in the combustor are studied. The eigenfrequencies of the first longitudinal mode, the second longitudinal mode, and the first azimuthal mode are examined. The results show that the radial modal coupling is crucial to the prediction of the stability. It is also found that the absorption of the perforated liners is directly determined by the integrated effect of the local fluctuating pressure differences across the perforated plates. The integrated effect is influenced by both the position and length of the perforated liners. Effective control is achieved when the liners are placed at the pressure antinode of the combustion chamber, whereas ineffective control is achieved when they are placed at the pressure node of the combustion chamber. Also compared is the effectiveness of the outer and inner liners, and it is found that it is essential to consider the coupled system of the two liners when checking the overall control effects.