Effects of Flow Tube Structural Parameters on Flow Characteristics near a Blowout Well

Flow tubes are key rescue devices used to respond to explosions and fires caused by blowouts. Improperly designed flow tubes can cause buckling failures, which can result in injuries or fatalities, particularly during high-speed blowouts, so optimizing the design based on the mechanism of high-speed blowout flow near the flow tube can improve rescue efficiency and reduce risk. This study investigated the flow control mechanism and analyzed the lift force of variable-diameter flow tubes. Simultaneously, the suction effect generated by the flow tubes was also quantified. The effect of flow tube structure and posture parameters on the flow field near a blowout well was numerically investigated using Fluent CDF software 2020R2, and the realizable k-ε turbulent model was used to account for turbulence. The inlet velocity was set to 300 m/s in order to simulate a high-speed blowout flow. The diameter ratio of the upper and lower parts of the flow tube changed from 1:1 to 1:2.4, and the ratio of the lower part to the total length changed from 1:10 to 3:10. The effects of the diameter ratio and length ratio on the distribution of the velocity and pressure in the flow tube were investigated. A strong negative pressure profile was observed in the equal-diameter flow tube. As the diameter ratio increased from 1:1.6 to 1:2.4, the negative pressure decreased from −1094 Pa to −214 Pa. In addition, the risk of personal suction due to negative pressure at the bottom of the flow tube was evaluated, and the effectiveness of drainage and the capability of flow control were analyzed. When the diameter ratio was increased by approximately 12.5%, the flow rate of entrainment decreased by 4% compared to the equal-diameter tube. Furthermore, the flow tube was subjected to significant upward lift forces during the snapping process, thereby increasing the risk of dislodgment. The effect of the changes in height and angle on the lift forces on the flow tube during buckling-up-installation was examined. It was found that the lift force decreases with height and is sensitive to the angle of inclination. Overall, it was concluded that the diameter ratio of the flow tube and the length of the lower section are key parameters for flow tube design.