Improving radiation estimation from circular pool fires through field-of-view angle analysis

Thermal radiation is the dominant mode of heat transfer in large-scale pool fires, making accurate prediction of radiative heat flux essential for fire safety assessment and hazard analysis. Traditional approaches often rely on simplified representations, such as point-source models or the solid-flame model, in which the target is assumed to view only the “half-flame” surface in view factor calculations. This study develops a mathematical framework to quantify the influence of the field-of-view (FOV) angle on view factor estimation between a differential target and a circular pool fire, considering both cylindrical and conical flame geometries. The view factor integrals are derived using contour formulations and solved numerically with high accuracy. Results show that neglecting the actual FOV systematically underestimates the view factor, with deviations dependent on sensor height, flame radius, and target separation. For cylindrical flames, deviations can exceed 5% at near-field distances and large radii, while conical flames exhibit smaller deviations that remain within acceptable accuracy limits. Time-resolved analyses further demonstrate that temporal variations in flame height have little effect on the resulting view factor. Overall, these findings emphasize the importance of incorporating realistic FOV effects in radiation modeling, while also identifying conditions under which simplified assumptions remain sufficiently accurate.