Aiming to address the challenge that traditional oil-immersed UHV transformers struggle to defend against high-energy arc faults

where pressure surges induced by faults can cause structural damage of tanks and combustion/explosion accidents

this paper investigates explosion-proof transformer tank design and its protective mechanisms. The transformer tank with internal aluminum foam is firstly designed based on the pressure development and structural failure characteristics during the arc events. Simultaneously

a transient fluid-solid coupling simulation model is built

and influence of aluminum foam on the structural failure of transformers is analyzed. Simulation results show that aluminum foam can absorb a part of arc energy through plastic deformation

which is positively related to the quantity of aluminum foam. The aluminum foam attenuates and delays the impluse pressure on tank walls

reducing deformation in covered areas while increasing deformation in uncovered regions. It improves strain and stress conditions at sidewall welds

lowering their failure risk

whereas worsens bolt stress states and increases bolt strain. Protective effect of the aluminum foam exhibits locality and nonlinearity. The foam quantity and layout should match the arc energy and position while reinforcing tank connection structures. This study provides guidance to design of the explosion-proof transformer tanks.