Plasma-driven shock wave dynamics in transformer oil: Spatiotemporal source distribution and acoustic impedance effects

Shock waves generated by streamer discharges in transformer oil are a critical factor leading to mechanical damage and explosion incidents in oil-immersed transformers. To clarify the mechanisms of shock wave generation and propagation, this study developed an experimental platform for streamer-induced shock waves and constructed a streamer model based on electrohydrodynamic drift-diffusion, along with a shock wave propagation model driven by volumetric pressure source density. According to the comparison between the simulation and experimental results, the accuracy of the streamer model and the shock wave propagation model was validated. The results show that the high electric field at the streamer tip induces localized ionization, forming plasma clusters. Moreover, plasma clusters generate concentrated volume pressure sources via electron energy absorption, with the source intensity sharply rising to 1.09 × 1020 s−2 upon streamer completion. Subsequently, under high-energy volume pressure sources, the shock wave exhibits typical spherical longitudinal wave characteristics: specifically, a pulse duration of 2.35 μs, a stable central frequency of 417 kHz, and amplitude decay following a power-law model. Finally, the study demonstrates that material interface acoustic impedances significantly alter shock wave behavior. Specifically, the oil–acrylic–air interface generates multi-peak oscillatory waveforms due to multipath interference, while the oil–acrylic interface amplifies wall pressure peaks by 42.1% through constructive interference. This study provides a theoretical foundation for understanding the mechanisms of shock wave generation and propagation induced by streamer discharge in oil.