Abstract:

In order to study the acoustic oscillation characteristics and provide the reference for the design and later experiment of air heater, the acoustic oscillation of an air heater is numerically investigated. The simulations are conducted with different fixed injector locations, focusing on the analysis of instability features of various point probes and instantaneous evolutions in the combustor. Typical features of combustion instability, such as starting, very rapid linear growth and the development of a highly non-linear limit cycle are observed. The instantaneous flow field shows that the second order transverse acoustic mode may be easily formed when the injector is located in the center of the faceplate, and it moves from the faceplate to the entrance of the nozzle. While the first order transverse acoustic mode is formed easily when the injector is located 53.6mm from the faceplate center, and its movement is not observed obviously.

Key words: Combustion instability, Transverse acoustic oscillation, Numerical simulation, Air heater