The Study of Short-Circuit Flow in Gas Cyclones Based on Numerical Simulation

Short-circuit flow severely degrades cyclone separation, yet its influence zone has not been clearly defined. In this work, the Reynolds stress model (RSM) was adopted to perform numerical simulations for a 300 mm PV-type cyclone separator, and the simulation results were validated against published tangential-velocity experimental data. The radial velocity along the extension lines of the vortex finder’s inner wall was analyzed to define the short-circuit flow influence zone, and a sector-resolved intensity index was proposed to quantify its circumferential non-uniformity. The results show that the lower boundary of the influence zone is a circumferentially varying curved surface rather than a horizontal plane. Among the four sectors, the 180–270° sector exhibits the greatest penetration depth (55 mm) and the highest inward radial velocity (−15.45 m/s). The proposed index indicates that Sector III contributes 38.7% of the total short-circuit flow intensity, and the dimensionless index is 0.127 for the present case. Within the influence zone, the inward radial velocity peaks at Z = 12 mm and approaches zero by Z = 53 mm, while the tangential velocity increases from 4.22 to 57.13 m/s, indicating Rankine vortex development. The short-circuit flow is governed by the coupled effects of inlet jet squeezing, vortex-core displacement, and the interaction between upward and downward flows. The proposed influence-zone definition and intensity index provide a quantitative framework for describing short-circuit flow and may be useful for evaluating cyclone design and short-circuit-flow suppression strategies.