Phase Transition Characteristics of Natural Ester During Streamer Propagation Under Impulse Voltage

The influence of insulating oil phase transition on streamer formation and propagation remains unclear. This paper establishes a multi-branch streamer discharge model incorporating phase transition considerations. The improved model effectively captures the morphology and propagation characteristics of polarities of optical discharges. Simulations reveal distinct structural patterns: dendritic positive streamers versus bush-like negative streamers, in agreement with experimental observations. Positive streamers exhibit more numerous and densely distributed bubbles compared to their negative counterparts, while demonstrating higher branch electric fields in bubble regions. This intensified electric field distortion within positive streamer channels leads to enhanced ionization processes. Due to bubble-induced ionization amplification in the channels, streamer growth demonstrates nonlinear dynamic characteristics. This study provides new insights for refining streamer discharge models and offers valuable references for understanding formation mechanisms of streamer discharges in insulating oil.