Mixing of Complex Fluids with Confined Impinging Jets

受限撞击射流（CIJ）已被证明是高效的连续混合器，为更传统和效率较低的工业混合技术（如机械搅拌容器）提供了强有力的替代方案。在这些装置中，两个或更多个液体流通过相对的射流注入到受限空间中。在适当的条件下，撞击流的快速减速会促进流体动力学不稳定性，从而可以快速实现混合，而无需移动机械部件。与搅拌容器相比，CIJ可以通过在流动中提供更高和更均匀分布的能量耗散率来提供更有效的混合能量利用。 CIJ混合器可以证明是一个合适的解决方案，以加强连续工艺，需要快速均匀的流。然而，非牛顿流体的复杂流变特性对混合性能的影响尚未完全了解。因此，为处理复杂流体提供更强大和强化的CIJ混合器操作的额外研究仍然至关重要。 本计画将针对剪切稀化流体与黏弹性流体在CIJ中的流动与混合特性进行计算与实验研究。将使用计算流体动力学（CFD）获得流动的数值模拟。先进的实验技术，如平面激光诱导荧光（PLIF）和粒子图像测速（PIV），也将用于流动和混合的表征。

Confined Impinging Jets (CIJs) have been shown to be highly efficient continuous mixers, offering a strong alternative to more traditional and less efficient industrial mixing technologies such as mechanically stirred vessels. In these devices, two or more liquid streams are injected into a confined space by opposed jets. Under appropriate conditions, a hydrodynamic instability promoted by the rapid deceleration of the impinging streams allows for mixing to be achieved rapidly and without moving mechanical parts. When compared to stirred vessels, CIJs can offer a more efficient utilisation of energy for mixing by providing higher and more uniformly distributed energy dissipation rates in the flow. CIJs mixers can prove to be a suitable solution to intensify continuous processes that require a rapid homogenization of streams. Nonetheless, the impact that the complex rheological properties of non-Newtonian fluids can have on the mixing performance is not yet fully understood. Additional studies to offer a more robust and intensified operation of CIJs mixers for processing complex fluids are, thus, still crucial. This project will focus on the computational and experimental study of the flow dynamics and mixing performance of shear-thinning and viscoelastic fluids in CIJs. Numerical simulations of the flow will be obtained with Computational Fluids Dynamics (CFD). Advanced experimental techniques, such as Planar Laser Induced Fluorescence (PLIF) and Particle Image Velocimetry (PIV), will be also used for the characterization of the flow and mixing.