Study on the CO₂ Spontaneous Condensation Characteristics of H₂–CO₂ Binary Gas in 3D Swirling Convergent–Divergent Nozzle

In this study, a 3D numerical model for swirling condensation of H 2 –CO 2 binary gas is established based on the Eulerian–Eulerian model and condensation kinetics theory. This model reveals the dynamic process of spontaneous CO 2 condensation in the swirling‐supersonic coupled field. The focus is on investigating the regulatory mechanisms of swirl symmetry and blade twist angle on the CO 2 condensation behavior in hydrogen‐rich gas. The research findings indicate that the tangential velocity generates by the swirling flow reaches up to 110.6 m/s, driving the peak Mach number radially migrating toward the near‐wall region and reconfiguring the spatial distribution of condensation. Under the influence of a double‐stage swirl generator, the peak nucleation rate along the nozzle center axis decreases to 1.83 × 1021 m −3 ·s −1 , representing a 42.1% reduction compared to the nonswirling condition. Additionally, the nucleation region shifts from the flow field center to a wall‐annular zone. Swirl symmetry determines the morphology of the liquid‐phase distribution, while a blade twist angle within the range of 180° to 270° can synergistically optimize both the phase mass exchange efficiency and the degree of droplet refinement. This study provides theoretical support for the development of efficient carbon capture technologies.