Investigation on Effects of Water Mist Characteristics According to Axial Position on Thermal Radiation Attenuation Performance

Abstract

In this study, the effects of water mist characteristics according to the axial position on thermal radiation attenuation performance were experimentally investigated using the single-fluid nozzle. Under the water flow rate conditions of 200∼350 g/min, the thermal radiation attenuation performance was measured at the axial position (i.e., downstream direction of water mist from nozzle exit) of 200∼1000 mm. In addition, during the discharge of water mist, the water supply pressure and droplet size of water mist were measured and the water mist was visualized. As a result, with an increase in the water flow rate, the thermal radiation attenuation performance was improved. Overall, the attenuation rate was measured to be 12.4∼30.1%. In the axial position of 200∼400 mm, with an increase in the axial distance from the nozzle exit, the thermal radiation attenuation performance was improved. This may be because the effect of improvement of the thermal radiation attenuation performance by an increase in the spray width is predominant over the effect of reduction in it by an increase in the droplet size. In addition, in the axial position of 400∼1000 mm, with an increase in the axial distance from the nozzle exit, the thermal radiation attenuation performance was reduced. This is because the droplet size of water mist increases and spray width is narrowed. Based on this study, it was confirmed that the water mist characteristics according to the axial position and thermal radiation attenuation performance are closely correlated.