Experimental investigation and theoretical analysis of effects of crosswind on flame lengths and tilting behaviors of pool fires with large ullage heights

• Experiments conducted for tank fires with varying fuel flow rates and crosswind speeds. • Down-reaching flame behaviour examined using a transparent fuel tray with a large ullage height. • Tilting and down-reaching flame phenomena under crosswind analysed in detail. • Effects of crosswind on internal pressure and flow fields investigated using CFD modelling. • Analytical models developed for predicting the tilting behaviour of upper and down-reaching flames. Pool fires with large ullage heights under crosswind are a common accidental fire scenario in tank farms, which can pose a serious threat to the safety of personnel and integrity of facility. This paper presents an experimental study of flame lengths and tilting behaviors of pool fires with a large ullage height and under various fuel supply rates and crosswind speeds. The geometric flame characteristics both inside and outside of the fuel tray were analyzed. Results indicated that, at the steady burning stage, the down-reaching flame depth and tilt degree and the upper flame tilt angle increased with crosswind speed. However, with an increase in the fuel supply rate, non-monotonic changes of these parameters were observed, highlighting its complex burning behavior. Based on experimental data and dimensionless analysis, correlations were developed to predict the down-reaching and tilting behavior of the internal flame. A modified dimensionless parameter was also introduced for the tilt angle of the upper flame under both crosswind and large ullage heights. The present results can deepen the understanding of the flame behaviors for tank fires under crosswind and provide practical guidance for safe storage of oil tanks and fire-fighting operation.