Dynamic Coupling in a Model Rocket Combustor

Fuller, Tristan

doi:10.25394/pgs.8281850.v1

Cited by 1 publication

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“…Compared with experimental results, the unstable combustion frequency is usually overestimated by ≥ 15% (Smith et al, 2010c;Srinivasan et al, 2015), and the amplitude of pressure oscillations is underestimated by up to 40% (Garby et al, 2013). Comparative study of 2D axisymmetric and full 3D numerical simulation of CVRC was conducted by Garby et al (Fuller, 2019) using dynamic thickened flame and LES models. It was reported that the numerical results of full 3D configuration simulation were more consistent with that of experiments.…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Numerical Analysis of Longitudinal Thermoacoustic Instability in a Single-Element Rocket Combustor

Guo

Ren

et al. 2022

Front. Energy Res.

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This study numerically investigated the thermoacoustic combustion instability characteristics of a scaled rocket combustor based on a hybrid of the Reynolds-averaged Navier–Stokes and large–eddy simulation method. The turbulence–combustion interactions were treated using flamelet generated manifold approach. An unstable case was simulated with detailed reaction mechanisms (GRI-Mech 3.0). The obtained results agree well with experiment data from Purdue University, in terms of pressure oscillations frequency and power spectral density spectrum. The combustion instability mode was identified to be coupled with the first longitudinal acoustic mode of the combustion chamber by dynamic model decomposition method. According to Rayleigh index analysis, the unstable driving source was found to be located near the combustor step, which was further confirmed by time-averaged flow fields. Detailed three-dimensional vortex ring shedding evolutions at the combustor step were tracked with fine time resolution. Results indicate that the combustion instability arises from periodic vortex ring shedding at the combustor step and interacting with the chamber wall. The unburnt reactants were rolled up by the shedding vortex ring, which would not break up until impact with the chamber wall. Therefore, the mixing performance was significantly enhanced, leading to sudden heat release. Consequently, the thermal energy is added to the acoustic field, and the first longitudinal mode is thus reinforced, giving rise to large amplitude axial velocity oscillations which prompt the generation of the new vortex ring. The results of the present investigation will support the design and development of high-performance rocket engines.

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Section: Introductionmentioning

confidence: 99%