Enhancing energy efficiency in cavitation processes by optimized flow confinement: A novel vortex diode reactor design

Vortex cavitation generators provide superior cavitational yield, lower inception pressure, and reduced erosion risk compared to conventional reactors, but their efficacy in wastewater treatment presents opportunities for improvement. This study employs a comprehensive CFD-driven approach to systematically optimize key geometric parameters of vortex cavitation reactors. Results demonstrate that a 120° convergent wall angle redistributes cavitation from the vortex core to the shear layer, while a 25 mm chamber height maximizes vapor generation by stabilizing the low-pressure zone. Incorporating a Venturi-type outlet (13° diffusion angle) delays pressure recovery, and dual 30° inlets enhance throat velocities by 66.7%. The underlying principle is identified as a shift in the governing cavitation mechanism towards a synergistic coexistence of vortex-core and shear-layer cavitation, driven by the altered velocity profile. Experimental validation confirms the optimized reactor achieves 56.4% tetracycline degradation efficiency with substantial thermal effects (81.2°C bulk temperature) and a high cavitational yield of 1.95×10 −5 mg/J at 0.8 MPa, significantly outperforming conventional vortex diodes. Radical scavenging experiments identify 1 O 2 and ·O 2 − as the primary reactive oxygen species, with the residual degradation attributed to mechanical and thermal effects inherent to cavitation collapse. This work provides both an optimized reactor configuration and fundamental design principles for developing high-efficiency vortex-based HC systems in wastewater treatment applications.