Abstract
A large eddy simulation (LES) and combustion instability analysis are performed using OpenFOAM for the multiple shear-coaxial injector combustor DLR-BKD (in German Deutsches Zentrum für Luft–Brennkammer D, German Aerospace Center–Combustion Chamber D), which is a laboratory-scale combustor operating in a real-gas environment. The Redlich–Kwong–Peng–Robinson equation of state and steady-laminar flamelet model are adopted in the simulation to accurately capture the real-gas combustion effects. Moreover, the stable combustion under the LP4 condition is numerically analyzed, and the characteristics of the combustion flow field are investigated. In the numerical simulation of the combustion instability, the instability is generated by artificially superimposing the 1st transverse standing wave solution on the stable combustion solution. To decompose the combustion instability mode, the dynamic mode decomposition method is applied. Several combustion instability modes are qualitatively and quantitatively identified through contour plots and graphs, and the sustenance process of the limit cycle is investigated.
Highlights
When combustion instability occurs, the vibration generated during the combustion, disturbances in the propellant supply system, and acoustic fields affect the pressure, temperature, and flow rate in the combustion chamber, leading to the persistence of the unstable state
The combustion instability was investigated by conducting numerical analyses, and several authors used the large eddy simulation (LES) technique to extensively analyze the combustion instability mode generated in liquid rocket combustors or gas turbine engines [15,16,17,18]
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Summary
The vibration generated during the combustion, disturbances in the propellant supply system, and acoustic fields affect the pressure, temperature, and flow rate in the combustion chamber, leading to the persistence of the unstable state. This instability is characterized by large pressure fluctuations at a specific frequency or excessive heat transfer. In the case of high-frequency combustion instability, the energy perturbation emitted during the combustion process is combined with a specific acoustic mode in the combustion chamber, which rapidly amplifies the pressure fluctuation. The combustion instability was investigated by conducting numerical analyses, and several authors used the LES technique to extensively analyze the combustion instability mode generated in liquid rocket combustors or gas turbine engines [15,16,17,18]
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