CFD-based optimization and experimental validation of supersonic separator design with angular injection swirler for efficient gas dehydration

The supersonic separator (SS) offers a compact, energy-efficient approach for gas dehydration, yet its separation mechanism remains poorly understood due to the coupled effects of supersonic flow, rapid phase change, and strong centrifugal acceleration. In this study, computational fluid dynamics (CFD) was employed to systematically optimize the nozzle wall geometry and swirler configuration. Structural optimization was performed in three steps: (i) wall profile refinement, (ii) evaluation of convergent and divergent lengths, and (iii) diffuser outlet diameter and profile selection. Among tested geometries, the Witoszynski convergent profile, combined with a 200 mm convergent length and linear diffuser, achieved superior cooling performance (CP), lowering minimum gas temperatures below 214 K. Despite effective cooling, an SS without swirler achieved only 9-10% collection efficiency (CE). To address this, both vane-based and angular injection swirlers were designed and optimized. CFD results revealed that the angular injection design reached a maximum efficiency of 83%, outperforming the vane swirler (79%). Based on the optimized geometries, a laboratory-scale prototype incorporating the angular injection swirler was fabricated and experimentally tested under saturated and supersaturated air conditions. The experimental setup confirmed CFD predictions, demonstrating high CE and effective CP. Wall temperature measurements via laser thermometry closely matched CFD-predicted thermal fields, further validating the model. These findings establish that optimized SS geometry coupled with a passive angular-injection swirler enables efficient condensation and moisture separation at practical operating scales, paving the way for industrial implementation in related applications.