Xuemin Wang

Computational fluid dynamics (CFD) plays a crucial role in optimizing micro-centrifugal pump geometries; however, conventional workflows often suffer from fragmentation, manual intervention, and poor interoperability among software tools. In this study, an integrated CFD-based simulation–optimization platform was developed to establish a closed-loop workflow covering parametric modeling, automated meshing, steady CFD analysis, and multi-objective optimization. Using a micro-centrifugal pump as a case study, optimal Latin hypercube sampling, a Kriging surrogate model, and a multi-objective genetic algorithm were combined to quantify the relationships between key structural parameters and hydraulic performance and to identify Pareto-optimal designs. Sensitivity analysis showed that blade count and volute throat height were the dominant factors affecting pump head and efficiency. Compared with the baseline design, the optimized schemes achieved average improvements of 40.36% in head and 22.89% in hydraulic efficiency, with Scheme 1 showing the best overall balance. Experimental validation using hydraulic performance testing and particle image velocimetry showed that the deviation between predicted and measured heads was within 10%, and the measured flow-field trends agreed well with the CFD results. The proposed framework provides a reproducible method for the design optimization of micro-centrifugal pumps and other small-scale turbomachinery.

Stirred bioreactor has been widely used in biopharmaceutical field, and it is particularly important to understand the culture environment of animal cells in stirred bioreactor. This study, utilizing Computational Fluid Dynamics (CFD) in conjunction with the Population Balance Model (PBM), explores the effect of various operational conditions and impeller combinations (downward-pumping elephant ear impeller (EED) combined with a concave disc turbine impeller (CBDT), dual downward-pumping elephant ear impellers (EED-EED), and a combination of downward-pumping (EED) and upward-pumping (EEU) elephant ear impellers) on bioreactor performance, with the goal of developing a stirred bioreactor suited for animal cell culture. The findings reveal that increasing the stirring rate significantly enhances fluid circulation within the bioreactor, leading to an increase in gas holdup. Enhanced stirring rate and aeration not only facilitate bubble dispersion but also result in a significantly higher gas holdup in the lower part of the bioreactor compared to the upper part. Moreover, higher stirring rate also lead to larger bubble diameters. At the highest stirring rate, the maximum hydrodynamic stress in the bioreactor reaches 16 Pa, while the Kolmogorov length scale is smaller at high stirring rate. The EED-EEU demonstrates effective gas dispersion with uniform bubble distribution and minimal hydrodynamic stress; the EED-EED combination, while offering the best bubble dispersion, is associated with larger bubble diameters and higher hydrodynamic stress.