Simulation of Combustion Instability in Premixed Gas Turbine Engines

This paper describes an investigation of combustion instability mechanism in premixed gas turbines. First, the preliminary concept of combustion instability is reviewed and then all types of frequency modes of combustion instability are studied. The results show that combustion instability is excited at first longitudinal mode; therefore the first mode or probably the second mode of longitudinal wave are the most important modes. Consequently, in this investigation only first longitudinal mode is considered. This simulation is based on equivalence ratio oscillations, which is an important mechanism for gas turbine combustion instability. The results are validated according to previons analytical and experimental results and show good agreements.