An investigation of flow dynamics in a novel arrow-shaped confined impinging jet reactor

This study presents a comprehensive investigation into the flow dynamics of a novel arrow-shaped confined impinging jet reactor (CIJR), with a focus on understanding the influence of inlet angles on mixing behavior and flow stability. CIJRs are widely recognized for their rapid and energy-efficient mixing performance, particularly valuable in chemical and pharmaceutical applications. However, the geometric design, especially the inlet angle between inlet streams, remains an underexplored factor in optimizing reactor performance. Using a combination of numerical simulations and micro-PIV (Particle Image Velocimetry) experiments, this study analyzes flow regimes, vortex structures, pressure fluctuations, and turbulent kinetic energy distributions across various inlet angles and Reynolds numbers. The results show that the arrow-shaped geometry alters the formation and oscillation behavior of the impingement plane compared to traditional CIJRs. Larger inlet angles enhance flow stability and reduce asymmetry, contributing to a more stable stagnation point location and overall improved flow uniformity. Increasing the inlet angle reduces stagnation point offset and minimizes dead zone, enhancing mixing stability and performance. However, when the inlet angle becomes too large, it disrupts the development of the vortex structure, preventing the formation of smaller vortices. This inhibition of vortex development can negatively impact the mixing efficiency of the CIJR. Under the experimental conditions, CIJR_20° configuration reduces the mixing time and oscillation amplitude by 22.82% and 63.19%, respectively, and provides an optimal balance between turbulence-driven mixing and structural stability. These findings offer critical insights into the rational design and operation of CIJRs, enabling controllable mixing performance tailored to specific processing needs.