Nonintrusive, Acoustic Boundary Layer Profiler for Aerodynamic Tests

In both ground and flight tests, important information about aerospace vehicle performance can be derived from knowledge of the boundary layer profiles above the vehicle's surface. However, measuring these profiles is often difficult, since an instrument or instrument rake must be extended/swept normal to the surface to obtain them. Deployed sensors are by nature intrusive, and may corrupt flow quality locally, making accurate measurements over an area impossible on practical time scales. In tunnel tests such constraints frequently mean the measuring apparatus is completely separate from the model, an unworkable solution for flight tests. As an alternative, Nielsen Engineering and Research proposes to demonstrate the feasibility of a real-time, nonintrusive, boundary layer velocity profile measurement system based on acoustic refraction. This system employs a single-source/multiple-receiver configuration and will ultimately be fabricated in a small, possibly MEMS-based, wireless package. The system requires no mechanical deployment and has a temperature range appropriate for both subsonic and supersonic flight. Its small size makes it appropriate for wide area application both in aircraft tests and for airline operational use.