An Open-Source Virtual Wind Tunnel for Scale-Model Aerodynamics: Bridging Theory and Experimental Calibration

The integration of hands-on experimentation in wind energy education is often limited by the high cost of commercial wind tunnels. While low-cost, DIY wind tunnels provide an accessible alternative, small-scale models (under 10 cm) suffer from significant scale effects and mechanical friction, leading to a frustrating discrepancy between theoretical calculations and empirical measurements. To bridge this gap, this paper presents the development of an open-source, interactive virtual wind tunnel simulator designed to complement physical experimentation. The software, developed in Python using the Gradio and Trimesh libraries, processes the 3D geometry of 3D-printed rotor models (STL files) to estimate their aerodynamic efficiency. By calculating the geometric solidity of the blades, the system approximates the Tip Speed Ratio (TSR) based on Blade Element Momentum (BEM) principles. Through a web-based interface, students can predict the expected rotational speed (RPM) of their designs and calibrate a mechanical friction coefficient by comparing virtual predictions with real tachometer measurements from the physical tunnel. The current version serves as a preliminary approximation model. Future work will utilize experimental data from the physical wind tunnel to refine the algorithms, creating a data-driven feedback loop that will increase the simulator's accuracy, transition to non-linear friction models, and expand its educational scope. The source code and the interactive tool are openly available on GitHub for other educators to adapt.