Computational Aeroacoustics for Analyzing Thermo-acoustic Instabilities in Afterburner Ducts

Ghulam, Mohamad M.; Gutmark, Ephraim

doi:10.2514/6.2018-4607

Cited by 1 publication

(1 citation statement)

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“…Blanchard et al simulated a bluff-body flame holder, and the proper orthogonal decomposition modes of the simulated results and experiments showed quantitative agreement [24]. Ghulam et al used COMSOL software to investigate the driving mechanism of combustion instabilities in a small rectangular combustion duct and obtained the pressure waves in the longitudinal and transverse directions [25]. On the research of the interaction of turbulence and combustion, numerical simulation has also shown its extraordinary ability [26].…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on the Route of Flame-Induced Thermoacoustic Instability in a Rijke Burner

2021

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The self-excited thermoacoustic instability in a two-dimensional Rijke-type burner with a center-stabilized premixed methane–air flame is numerically studied. The simulation considers the reacting flow, flame dynamics, and radiation model to investigate the important physical processes. A finite volume-based approach is used to simulate reacting flows under both laminar and turbulent flow conditions. Chemical reaction modeling is conducted via the finite-rate/eddy dissipation model with one-step reaction mechanisms, and the radiation heat flux and turbulent flow characteristics are determined by using the P-1 model and the standard k-ε model, respectively. The steady-state reacting flow is first simulated for model verification. Then, the dynamic pressure, velocity, and reaction heat evolutions are determined to show the onset and growth rate of self-excited instability in the burner. Using the fast Fourier transform (FFT) method, the frequency of the limit cycle oscillation is obtained, which agrees well with the theoretical prediction. The dynamic pressure and velocity along the tube axis provide the acoustic oscillation mode and amplitude, also agreeing well with the prediction. Finally, the unsteady flow field at different times in a limit cycle shows that flame-induced vortices occur inside the combustor, and the temperature distribution indicates that the back-and-forth velocity changes in the tube vary the distance between the flame and honeycomb in turn, forming a forward feedback loop in the tube. The results reveal the route of flame-induced thermoacoustic instability in the Rijke-type burner and indicate periodical vortex formation and breakdown in the Rijke burner, which should be considered turbulent flow under thermoacoustic instability.

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Section: Introductionmentioning

confidence: 99%