Methodology for Performance Validation of Load Cells in Wind Tunnel - A Case Study of a Low-subsonic Wind Tunnel

Wind Tunnel is often used to estimate the aerodynamic performance of designed airplane configurations, such as lift (L) and drag (D). Unlike computational approaches, such as computational fluid dynamics (CFD) using ANSYS Fluent, which often require substantial computational time and resources, Wind Tunnels can provide results instantaneously. However, extensive setup and preparation for experiments are inevitable. Various operational aspects must be considered to validate the design and performance of a full-scale aircraft in a confined subscale space. Among them, dynamic or geometric scaling in Wind Tunnel testing is crucial for fully representing actual flight conditions within the limited section areas, wind speeds, and control parameters. Many research efforts using Wind Tunnels primarily focus on these or are used only for cross-checking the performance trend validations. However, measurement errors — often referred to as offsets, data scaling factors, biases, and calibration-related sensor and data-acquisition issues — are not thoroughly investigated in most Wind Tunnel experiments before they are conducted. This paper aims to develop a rigorous methodology to validate the performance of a Wind Tunnel as a case study, housed in the College of Engineering at Tennessee Tech University (TTU), specifically the low-speed subsonic Wind Tunnel, which operates at a maximum wind speed of 11.5 m/s—the Tunnel measures 6-degrees-of-freedom (DOF) forces and torques via a ground-mounted load cell sensor. The authors of this paper present the validation methodology by conducting a series of static and dynamic Wind Tunnel tests on sample objects known for their D characteristics. 3D printers were used to create several samples, enhancing the completeness and rigor of testing procedures. The results show that the comparison of Wind Tunnel testing and analytical results yields a 12.6% error, indicating that the results are valid and can be used to obtain true-to-life aerodynamic characteristics of articles tested in this facility.