The Interdisciplinary Consulting Corporation (IC2) proposes to develop an ultra-low-profile, ultra-smooth-surface, robust, real-time wall shear stress sensing system using microelectromechanical systems (MEMS) technology that can provide quantitative skin friction measurements during flight tests. The goal of this research is to advance IC2’s current capacitive wall shear stress sensor technology that is capable of making quantifiable mean and fluctuating skin friction measurements in controlled wind tunnels, and allow them to be used in harsh, subsonic flight-test environments. Such a transducer would be the first of its kind and will provide information that characterizes complex flow fields, leading to a better understanding of the fluidic phenomena in real-world applications as well as providing a way of validating computational fluid dynamics simulations. The newly designed sensor will feature more robust geometries, sensor bump stops to minimize debris-impact damage, and a protective film coating that prevents moisture, debris collection, and structural damage. Improved electronics will digitize the device signal in the sensor head, replacing the bulky and expensive multi-conductor analog cabling currently used with inexpensive micro-digital cabling - this eliminates the remote signal-conditioning electronics, which will decrease the effort and cost of sensor installation on a flight-test aircraft. The new electronics will also measure and compensate for changes in temperature and vibrations encountered during flight and will provide its calibration data to the user digitally through a TEDS (Transducer Electronic Data Sheet) interface.
The proposed instrumentation technology has the potential to be usable in multiple NASA flight-test facilities, as well as implemented across government-owned, industry, and academic institution test facilities. The target market is real-time shear stress measurement instrumentation for flight test within test facilities, including the Armstrong Flight Research Center and the Edwards Flight Test Range Complex.
Real-time quantitative measurement of mean and fluctuating wall shear stress is not currently possible with existing technologies. Government agencies (DoD, DARPA) and industry manufacturers (e.g., Boeing, Lockheed, GE) have similar needs to NASA and are limited by the lack of accurate wall shear stress measurement capabilities in flight-test environments.