A quantitative description of flow and mixing in bioreactors is necessary to assess the exposure of the microorganisms to suboptimal conditions, which may negatively impact key performance parameters of a process, such as yield and productivity. The traditional approach of quantifying mixing, by means of a terminal mixing time, is inadequate because it rests on the assumption that a homogeneous state is reached, and it provides little information on the mixing process itself. In this study, it has been demonstrated how flow-following sensor devices can be used to obtain detailed knowledge on macroscopic flow in stirred bioreactors under turbulent flow conditions. The flow generated by common impeller types; the Rushton disc turbine and the pitched blade turbine, has been examined in terms of the axial flow features and circulation times under various levels of agitation. It was demonstrated that useful features to characterize the flow in the vessel, such as the axial distribution and axial velocity profile of the sensor devices could be obtained for the examined conditions. Based on these features it was observed that the flow following behavior of the sensor devices were negatively affected at higher impeller speeds. This finding was corroborated by CFD simulations of the vessel. The mean circulation times determined by the sensor devices were found to be highly correlated to the mixing times determined from homogenization of a chemical tracer (t_m = 2.2–2.6 t¯_c), which demonstrates that flow-following sensor devices can be used to quantify macromixing in bioreactors. Furthermore, the underlying circulation time distributions could be derived, which were found to be well described by the lognormal probability distribution.

必须对生物反应器中的流动和混合进行定量描述，以评估微生物在次优条件下的暴露情况，这可能会对过程的关键性能参数（例如产量和生产率）产生负面影响。通过最终混合时间量化混合的传统方法是不够的，因为它基于达到均匀状态的假设，并且它提供的关于混合过程本身的信息很少。在这项研究中，已经证明了如何使用流动跟随传感器设备来获得关于湍流条件下搅拌生物反应器中宏观流动的详细知识。常见叶轮类型产生的流量；拉什顿圆盘涡轮机和斜叶涡轮机，已经根据不同搅拌水平下的轴流特征和循环时间进行了检查。结果表明，对于所检查的条件，可以获得表征容器中流动的有用特征，例如传感器装置的轴向分布和轴向速度分布。基于这些特征，观察到传感器装置的流动跟随行为在较高的叶轮速度下受到负面影响。这一发现得到了船舶 CFD 模拟的证实。发现由传感器设备确定的平均循环时间与由化学示踪剂的均质化确定的混合时间高度相关（例如，可以针对所检查的条件获得传感器装置的轴向分布和轴向速度分布。基于这些特征，观察到传感器装置的流动跟随行为在较高的叶轮速度下受到负面影响。这一发现得到了船舶 CFD 模拟的证实。发现由传感器设备确定的平均循环时间与由化学示踪剂的均质化确定的混合时间高度相关（例如，可以针对所检查的条件获得传感器装置的轴向分布和轴向速度分布。基于这些特征，观察到传感器装置的流动跟随行为在较高的叶轮速度下受到负面影响。这一发现得到了船舶 CFD 模拟的证实。发现由传感器设备确定的平均循环时间与由化学示踪剂的均质化确定的混合时间高度相关（t _m  = 2.2–2.6 t¯ _c )，这表明流动跟踪传感器装置可用于量化生物反应器中的宏观混合。此外，还可以推导出基本的循环时间分布，发现它可以用对数正态概率分布很好地描述。