Performance Evaluation of a Hybrid Water Curtain Nozzle for Exposure Fire Mitigation in Factory Buildings

Factory buildings in industrial complexes are often densely arranged with insufficient separation distances, increasing the risk of rapid fire spread to adjacent structures. Although defensive water streams are used during firefighting operations to prevent fire extension, their effectiveness is limited by spatial constraints and the dispersion of firefighting resources. In this study, a water curtain system installed on factory exterior walls was proposed to provide defensive water application through a direct connection to a fire engine pump. To enable long-duration operation under limited water-supply conditions, a hybrid water curtain nozzle was developed and compared with a conventional drencher nozzle. Performance was evaluated using radiant heat flux, panel core temperature, and water consumption. Heat flux sensors were installed through panel penetrations to avoid direct water contact, and thermocouples were embedded within the panel core to minimize interference from the water film. The results showed that the hybrid nozzle (Hollow + Flat, 45°) reduced water consumption by approximately 84% while maintaining effective radiant heat shielding and temperature reduction, enabling longer operation of the water curtain system with the same available water supply.