Plasma-Assisted Swirl Flame Dynamics: Imaging, Modal, and Acoustic Data

• The dataset provides combined optical, modal, spectral, and acoustic measurements of plasma-assisted swirl flames, enabling a comprehensive assessment of how sinusoidal plasma discharges affect flame structure, stability, and combustion dynamics. • High-speed CH* chemiluminescence images document the evolution of flame lift-off, attachment, reaction-zone position, and heat-release fluctuations across equivalence ratios from Φ = 1.0 to Φ = 0.45, under plasma-off and plasma-on conditions. • The data demonstrate that plasma actuation extends the stable operating range of the combustor: at Φ = 0.45, a self-sustained flame is observed only when plasma is applied, providing direct experimental evidence of plasma-enhanced lean flame stabilization. • POD and SPOD results quantify the redistribution of fluctuation energy among coherent flame structures, showing that plasma reduces the dominance of low-order modes and suppresses energetic high-frequency oscillations. • The simultaneous analysis of microphone signals and POD mode coefficients links acoustic pressure fluctuations to flame-structure dynamics, supporting the interpretation of plasma-induced stabilization through reduced unsteady heat release and improved flame anchoring. • The dataset can be used to validate reduced-order and high-fidelity models of plasma–flame interaction, including models of plasma-enhanced ignition, radical production, mixing, heat release, and thermoacoustic response. • The paired plasma-off and plasma-on measurements, acquired under identical imaging settings, provide a consistent benchmark for future experimental, numerical, and machine-learning-based studies of plasma-assisted combustion.