Description: As a continuation of the Interdisciplinary Consulting Corporation's (IC2's) current Phase II effort development of dual-axis shear stress sensors that are applicable in ground test facilities covering a large range of flow speeds, IC2 proposes to develop a prototype dual-axis wall shear stress sensor with a protective coating, a dual-axis sensor with integrated temperature compensation, and a sensor calibration method based on a known magnetic field. These advances will help the dual-axis shear stress measurement system address a critically unmet measurement need in NASA’s technology portfolio, specifically the ability to make time-resolved, continuous, direct, two-dimensional measurements of mean and fluctuating wall shear stress in wall-bounded turbulent and transitional flows in subsonic and transonic facilities. The realization of this capability not only benefits advanced air vehicle development but also impacts fundamental compressible boundary layer physics research areas such as transition to turbulence in three-dimensional flows, extending the current capabilities of NASA’s ground test facilities. Inclusion of a sensor coating and temperature compensation will improve the robustness of the sensors, minimizing calibration errors and enabling their use in a larger variety of flow environments. The handheld magnetic calibrator will provide a method for in situ calibration of the sensors after installation a wind tunnel or model surface, providing further confidence in acquired experimental data.

Benefits: The proposed technology enables dual-axis wall shear stress measurement in a wide range of subsonic to transonic test facilities including: NASA Langley Research Center's 14' by 22' Subsonic Wind Tunnel, Basic Aerodynamics Research Tunnel (BART), and 16' Transonic Dynamic Tunnel; the 9' x 15' Low-Speed Wind Tunnel at NASA Glenn Research Center; and the 11' x 11' Transonic Unitary Plan Wind Tunnel at NASA Ames Research Center.

Customers seeking or currently designing next-generation civilian or defense aircraft have a similar measurement need. Furthermore, active flow control requires compact, accurate measurements of fluid parameters such as wall shear stress. Non-NASA applications include: Government agencies such as Army and Air Force University wind tunnels Industry manufacturers such as Boeing, Airbus, GM, and Ford