Wind tunnel tests on wind loads acting on micro-butterfly windbreak nets

Micro-butterfly windbreak nets are widely used in engineering applications, yet their wind load characteristics remain insufficiently understood. To determine these loads, in this study, high-frequency force balance wind tunnel tests were conducted on micro-butterfly nets with standard 35% and 45% porosity configurations. The results demonstrate that porosity is the key parameter governing the aerodynamic characteristics of micro-butterfly windbreak nets, while inflow wind speed has a negligible influence on drag coefficients. Windward area serves as the dominant factor determining the magnitude of drag coefficients, although it is not the sole determinant of lift coefficient peaks. The recommended drag coefficient values are 0.94 and 0.85 for 35% and 45% porosity nets, respectively. The reduced heights of wind loads fall within the 0.45∼0.6 range with 77% probability for both porosity configurations. Wind load estimations for supporting structures must account for the skewed wind load factor Kθ, for which this study provides validated reference values and fitting formulas. These experimental results establish essential references for the wind-resistant design of micro-butterfly windbreak net support systems.