Violent thermal interactions resulting from the sudden contact of a cold vaporizable liquid and a hot liquid may cause high-pressure explosions. The effects of water jet injection into a pool of molten Aluminum, Bismuth and Tin was experimentally investigated. The results of water injection into hot liquid metal varied with the dynamic jet properties from mild boiling to immediate explosion accompanied by a shock wave. In general knowledge of fuel coolant interaction at the moment of contact between high temperature melt and water, the two liquids separated by a stable layer of vapor, then the vapor film locally collapsed due to melt temperature decrease, allowing a direct contact of the two liquids which may generates the high explosive vapor expansion. In the coolant injection the cold liquid temperature continues to rise with the jet penetration, in general, that should stabilize the vapor layer, but hydrodynamic instabilities affect the vapor layer stability allowing direct contact. Experiments results indicate that the jet dynamic properties affect the: feasibility of steam explosion to occur, the maximum pulse pressure and the delay time of the explosion. In this study enhanced hydrodynamic instabilities introduced to the system in the form of two adjacent parallel water jets. These experiments produce higher pressure pulses and shorter pre mixing time then a single water jet, suggesting a significant influence of the jet breakup behavior while penetrating the melt, on steam explosion feasibility. Injection of water into Aluminum did not produce steam explosion at all. Large voids in the Aluminum ingot were found, suggesting that liquid water were presence at the time of solidification. Smooth void surfaces suggest that stable film boiling allow the melt to solidify with no direct contact with water. Further experiments with external pressure pulse may reveal the energy threshold to trigger aluminum steam explosion.
