转速及倾角对组合桨功率和微观混合性能影响研究

Influence of impeller geometry and rotational speed on the power and micro-mixing performance of the stirred tank equipped with multiple impeller

为了研究多层搅拌桨片倾斜角度以及转速对反应器功率和微观混合性能的影响规律,对装配不同多层搅拌桨的搅拌反应器内的流体流动和微观混合性能进行了实验和数值模拟研究,在反应器内引入碘化物-碘酸盐平行竞争反应体系来评估搅拌釜内的微观混合性能。此外,提出了表征反应器微观混合性能的离集指数(X_(S))和流场湍流特性之间的关联式,结果表明,模拟值与实验值吻合程度较高。当叶片倾角较小(φ≤30°)时,叶片倾角对釜内微观混合性能影响较小;而当叶片倾角较大(φ≥45°)时,釜内微观混合性能随叶片倾角的增加而显著减小。X_(S)与log(ε)之间基本呈线性关系。

In order to systematically investigate the impact of inclined angles and rotational speeds of multiple impeller on the power consumption and micro-mixing performance in a stirred tank,experimental and numerical simulation approaches are employed to investigate the hydrodynamics and micro-mixing process in the stirred tank equipped with different multiple impellers where iodide-iodate parallel competitive reaction system is introduced to evaluate the micro-mixing performance of the fluid flow in the reactor.Meanwhile,correlation between the segregation index(XS)and turbulent characteristic parameters is also obtained.The results show that the numerical model conducted can well predict the power consumption and micro-mixing performance of the stirred tank equipped with different multiple impellers.When the inclined angle of the blade is smaller than 30°,little influence of inclined angle on the micro-mixing performance is observed.However,the micro-mixing performance is significantly decreased with an increase in the inclined angle of the impeller blade when the inclined angle is larger than 45°.It is also found that Xs is linearly proportional to log(ε),whereεindicates the turbulent dissipation rate.