A Real-Time Combustion Instability Simulation with Comprehensive Thermo-Acoustic Dynamic Model

Abstract

The thermo-acoustic instability in the combustion process of a gas turbine is caused by the interaction of the heat release mechanism and the pressure perturbation. These acoustic vibrations cause fatigue failure of the combustor and decrease the combustion efficiency. This study aims to develop a segmented dynamic thermo-acoustic model to understand combustion instability of a gas turbine. Then, the combustion instability was designed using the acoustic heat release model, and the designed instability model was segmented using the finite difference method, to evaluate the characteristics of flame propagation at each node. The combustion instability model was validated using experimental data to verify the instability amplitude. Also, the optimal node number was determined using the adiabatic flame temperature response. 10 nodes were selected in this study. A sensitivity analysis showed the predicted instability amplitude decreased when the nodes increased until node 4, due to heat generation. However, above 4 nodes the amplitude decreased, since the combustion outlet was directly connected to the ambient. As a result, the segmented combustion instability model was able to evaluate the flame propagation characteristics more accurately and found the largest area of instability was near the flame area.

A Bee Colony Neuro-Fuzzy Controller to Improve Well Premixed Combustion

“…Then, the result of a chemical reaction is characterized in a balance case using the specifications of the mass fraction. Based on the equation of species conservation, we found the dynamical equation of fuel, oxidizer, and products in equation ( 4) [20].…”

“…The flame propagates, increasing the pressure perturbation cross the axis x when the boundary condition will reduce their amplitudes. The Cantera algorithm and data from the representative chemical species were ©2023 SjF STU Bratislava 29 used to create the chemical composition table [20].The part inside the single quotes specifies that the species, kinetics, and thermodynamics are calculated according to the GRI 3.0 mechanism for methane.…”

Thermoacoustic combustion instability of propane‐oxy‐combustion with CO2dilution: Experimental analysis

“…3 Combustion instability is among the most critical operational challenges encountered in combustion systems of gas turbines, industrial boilers, furnaces, etc. 11 Heat release oscillations in combustion systems mostly arise from mass flux fluctuation in combustion reactants (that can cause equivalence ratio perturbations) and/or flame-vortex interaction in a swirl or bluff-body stabilized flames. 4,5 The onset of thermoacoustic instability was first postulated by Rayleigh 4 in 1878 for a mass of air vibrating in a cylinder bounded by a piston as follows: "If heat be given to the air at the moment of greatest condensation or to be taken from it at the moment of greatest rarefaction, the vibration is encouraged."…”

“…10 Moreover, acoustic vibrations resulting from thermoacoustic instability are linked to combustors failure as a result of fatigue and reduced combustion efficiency. 11 Heat release oscillations in combustion systems mostly arise from mass flux fluctuation in combustion reactants (that can cause equivalence ratio perturbations) and/or flame-vortex interaction in a swirl or bluff-body stabilized flames. 12 To analyze and understand a linear flame response to a disturbance, the development of a flame transfer function (FTF), which relates the heat release and the acoustics is essential.…”