Near-Field Combustion-Noise Source Dynamics in a Reacting Supersonic Temporal Mixing Layer

Sriram P. Kalathoor; Joseph C. Oefelein

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arXiv · 2606.15626

Near-Field Combustion-Noise Source Dynamics in a Reacting Supersonic Temporal Mixing Layer

Sriram P. Kalathoor·Joseph C. Oefelein

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Abstract

Compressibility and chemical reactions in reacting flows provide source mechanisms for pressure fluctuations whose signatures depend on the flow, source distribution, and acoustic environment. Bounded flows can sustain strong feedback and narrowband tones, whereas boundary-free flows more often exhibit broadband source activity distributed across frequency. Near-field combustion-noise source dynamics are examined in a supersonic reacting hydrogen-air temporal mixing layer using high-fidelity time-resolved direct numerical simulation data. Pressure, heat-release, and dilatation fields are used to identify how localized reacting structures, compressive disturbances, broadband spectral content, and burst-driven temporal organization interact. The results show weak pressure--heat-release coherence concentrated within selected low-frequency bands, with no collapse onto a single dominant mode. Combustion intermittency modulates the near-field pressure response within these bands and is accompanied by burst-driven amplitude modulation and transient trajectory sensitivity, while the overall dynamics remain broadband and bounded. A planar source-radiation-potential projection further shows moderate low-frequency angular bias associated with the heat-release source distribution. Information-theoretic measures indicate that pressure fluctuations share more statistical structure with heat release than with dilatation. The analysis characterizes source-side organization and near-field pressure response in the sampled DNS of a reacting shear layer, providing a basis for subsequent observer-based or acoustic-analogy radiation calculations.

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Sriram P. Kalathoor, Joseph C. Oefelein. 2026-06-14. Near-Field Combustion-Noise Source Dynamics in a Reacting Supersonic Temporal Mixing Layer. https://arxiv.org/abs/2606.15626

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