Aerodynamic Characteristics of Ducted Propulsion Fan Using Secondary Air Intake

Ducted propulsion fans are widely recognized for their ability to enhance aerodynamic efficiency and operational safety by utilizing a surrounding shroud to contain the flow and mitigate blade tip losses. However, maximizing thrust and optimizing internal flow dynamics remain critical challenges in further improving their aerodynamic performance. This study investigates the aerodynamic characteristics of a ducted propulsion fan configured with a secondary air intake channel designed to enhance mass flow ingestion. Utilizing Reynolds-Averaged Navier–Stokes (RANS) simulations coupled with the Shear Stress Transport (SST) k-omega turbulence model, the internal flow dynamics and aerodynamic efficiency of configurations both with and without the secondary air intake channel are examined. The secondary air intake, strategically located adjacent to the rotor blade tip, increases the mass flow rate and, consequently, enhances thrust. Physically, this configuration successfully reinjects bypass flow to mitigate tip leakage vortices, significantly reducing the low-velocity wake regions adjacent to the rotor tip. Several configurations were evaluated by systematically varying the intake channel’s position, curvature, and the dimensions of its inlet and outlet ports under static conditions at 6000 rpm. Numerical results demonstrate that the optimal design improves thrust by an additional 2.2% compared to the baseline ducted fan without the auxiliary intake port due to the mitigated tip vortices and stabilized flow field.