不同喷嘴结构油罐旋转喷射搅拌器数值模拟

Numerical simulation of tank rotary jet mixers with different nozzle structure

原油罐清罐和油品调和时会应用油罐旋转喷射搅拌器,为了研究旋转喷射搅拌器喷嘴结构对搅拌效果的影响,对平喷嘴、拉法尔喷嘴和文丘里喷嘴进行了对比,使用ANSYS15.0实现直径16 m油罐的喷射搅拌全流场数值模拟,并以密度的标准差作为评价搅拌效果好坏的量化参考。在仿真计算的设置中,为了实现对喷嘴旋转的模拟,采用了滑移网格;黏性模型选择湍流的标准k-e模型;多相流模型选择混合模型。数值分析结果表明：出入口流速相等的情况下拉法尔喷嘴和文丘里喷嘴中的流速高于平喷嘴中的流速;在油罐旋转喷射搅伴器的搅拌作用下,密度标准差随时间推移逐渐减小;搅伴器配置拉法尔喷嘴和文丘里喷嘴后相比于平喷嘴搅拌效果更好,尤其是在搅拌20~30 min内,后者与前两者的差距最为明显。据此使用油罐旋转喷射搅拌器时,推荐配置拉法尔喷嘴或文丘里喷嘴。

Rotary jet mixers are widely used to purge gunk in crude oil tank and blended oil products. To identify impacts of nozzle structure on performances of mixtures, fl at nozzles, Laval nozzles and Venturi nozzles are compared. In addition, ANSYS15.0 is used to simulate the whole fl uid fi eld with jetting and blending in oil tank with diameter of 16 m. Moreover, the standard deviation of densities serves as a quantitative index in assessments for performances of the mixture. During simulation, sliding grid is adopted to simulate nozzles＇ rotating. Standard k-ε model with turbulent fl ow is adopted as the viscosity model, and mixed model is deployed as the multi-phase fl ow model. Results of numerical simulation show that both current velocities in Laval and Venturi nozzles are higher than that in fl at nozzles under the same fl ow rate of inlet and outlet, whereas the standard deviation of densities decreases with time. Rotary jet mixers with Laval and Venturi nozzles have mixing performances better than that of those with fl at nozzles. The difference is especially high within mixing time of 20-30 min. Laval and Venturi nozzles are good choices for rotary jet mixers deployed in oil tanks.