Description: The tracking of critical flow features (CFFs) such as stagnation point, flow separation, shock, and transition in flight provides insight into actual aircraft performance/safety. Sensing of these CFFs across flight regimes involves numerous challenges such as a wide temperature/pressure range from subsonic to hypersonic flows. Tao Systems, Mesoscribe Technologies and Virginia Tech propose to develop a novel direct-write sensor architecture for the in-flight measurement of skin friction and heat flux that is survivable to temperatures exceeding 1000 deg. C while simultaneously providing fast response necessary for real-time signal processing to obtain CFFs. As a consequence, this technology will extend the utility of CFFs for aeroservoelastic control from subsonic to supersonic and hypersonic flows, as well as provide test information from experiments in flight.

Benefits: A potential non-aerospace commercial application of the IAPS relates to requirements where heat flux/skin friction would be usefu: e.g., for fire monitoring/control. Some examples of such applications are: safety of naval ships (to monitor the heat flux from weapons systems to adjoining areas and vice versa). A matrix of heat flux sensors covering an area will determine how much heat is penetrating/leaving a room, and the skin friction sensor can determine the level of air flow. These two parameters can provide much more information to determine if there is a fire and the rate at which it will expand. The potential customers range from weapons manufacturers to practically every large industry where fire hazard is a serious problem.

The primary target application of the proposed innovation and associated products and services (IAPS) is the current and next generation reusable launch vehicles, whose safety, reliability and efficiency are mission critical factors that involve informed trade-offs in a complex interaction between aerothermodynamics and aerostructures. The IAPS can be used to improve safety/reliability margins, obtain better estimates on performance predictions based on quantified flow characterization, e.g., location of boundary layer laminar-to-turbulent transition, with significant impact on the design of the thermal protection system. It has even been asserted that the uncertainty in transition location for some hypersonic vehicles can result in an uncertainty of 20\% in total vehicle weight, which is then compensated only by heavier thermal protection systems.