Numerical investigation of discharge-induced pressure waves in insulation oil via sequential Keller-Miksis method

Discharge-induced pressure shock critically affects the fault progression and explosion-proof safety of oil-immersed transformers, being tightly coupled to bubble pulsation dynamics. To address the inability of conventional bubble dynamics models to account for transient energy dissipation during the collapse-rebound process, a sequential Keller-Miksis model is proposed. It divides the pulsation into sequential evolutionary stages and integrates an ambient pressure correction mechanism. By deriving an equivalent pressure excitation from the dynamics model as the input, a coupled pressure acoustics-solid mechanics model is established to simulate the generation, propagation, and interfacial reflection of discharge-induced pressure waves in oil. Results show that the proposed model accurately predicts the bubble radius, pulsation period, and collapse timing while quantifying transient energy losses. The mean relative errors for the maximum bubble radius and pulsation period are 3.12% and 4.65%, respectively. The simulated pressure waveforms are in agreement with the experimental measurements. Specifically, The established coupled model reveals that the interfacial reflection and superposition of pressure waves, excited by the discharge shock and the first collapse-rebound process, shape the impulsive oscillatory characteristics of the measured signals, with liquid-surface reflections serving as a significant contributing factor. This model and simulation approach precisely capture bubble dynamics and pressure characteristics, providing a theoretical foundation for pressure-based fault warning and explosion-proof research.