Effects of droplet ratio and void fraction on the attenuation of radiative heat flux in water curtain

Abstract

The attenuation effects of radiative heat flux in water curtain are theoretically and experimentally investigated along the vertical direction from the nozzle. Based on the boundary conditions of water curtain, the general form of the attenuation efficiency of radiative heat flux is introduced as a function of droplet ratio and void fraction using the vertical 180 nozzle. The droplet ratio is applied to a 50% cumulative distributions (d50) for droplet mean diameters and a 99% that (d99) for the maximum diameters. In addition, the ratio of d50/D (hydraulic diameter of the injection nozzle) is correlated with the −0.39 index of Webber number to estimate the decrease tendency of the measurement values. The void fractions are well curve-fitted by flow rate and distance within±3% error along the vertical direction for the vertical 180 nozzle. The radiative heat fluxes are obtained by considering the convective term in energy equation. To verify the reliability of the present equation, the attenuation efficiencies of radiative heat flux are obtained from the vertical 60 nozzle. The results show that the predictions and experiments are in good agreement within a±10% error as flow rate increases in the fully break-up region.