Research on the Flow Characteristics of the Airflow Field in an Open Fan Array

Small aerial vehicles operating at low altitude are frequently exposed to wind fields with strong spatial gradients and rapid temporal variations. Although conventional closed-section wind tunnels provide well-controlled test conditions, they are generally unable to reproduce the large-scale non-uniformity typical of urban low-altitude environments. Open multi-fan arrays provide a promising alternative because they can generate programmable inflow conditions over a relatively large test area. In this study, a 9 × 9 open fan array is investigated using the momentum-source method to reproduce representative inflow conditions, including uniform flow and shear flow. The numerical results reveal a persistent edge-dissipation effect: velocity decays more rapidly and turbulent kinetic energy is higher near the outer fans than near the array center. In the uniform-flow case, a relatively stable low-turbulence corridor develops downstream of the array. In the shear-flow case, the imposed asymmetry is preserved, while edge-induced losses become more pronounced near the perimeter. These results clarify the main flow structures generated by open multi-fan arrays and provide a physical basis for future wind-environment testing of aerial vehicles.