Study on the acoustic characteristics of a heavy-duty gas turbine combustor

The acoustic characteristics of combustor are an important theoretical basis for determining whether a gas turbine will undergo thermoacoustic coupled oscillatory combustion. In this paper, the acoustic numerical model of a heavy-duty gas turbine combustor is established and its acoustic characteristics are studied using ANSYS simulation software. The results show that: 1) the acoustic pressure oscillation in the chamber primarily appears as the longitudinal mode below 705 Hz, while above 870 Hz, the transverse mode appears. 2) the effect of temperature on the acoustic natural frequency of the chamber enhances with the order of the acoustic mode. 3) the acoustic frequency of each order of the combustor varies considerably at low load conditions, and no longer varies when the gas turbine load is higher than 80 % rated power. 4) the variation of acoustic frequency with gas turbine load can be fitted by a third-order polynomial, and the acoustic frequency is proportional to the first and third orders.