Develop Flow-Field Seeding for Large Tunnels

A seeding material is proposed that is effective for velocimetry measurements but is compatible with other optical instruments and does not interfere with wind tunnel operation. The identification of a clean seeding material and the development of a delivery system that would allow advanced velocimetry techniques to be deployed in several high value wind tunnels such at AEDC’s 16T and 4T and AFRL’s TGF is highly advantageous. A new form of clean seeding for PDV and PIV techniques that is based on the condensation of liquid Carbon Dioxide (CO2) into particles is proposed. The significance of this approach is the development of a non-intrusive seeding system that would allow particle based techniques to be universally applied to wind tunnels where contamination is a major drawback. The clean seeding technique not only minimizes contamination, it also lowers health risk concerns since the solid particles become a harmless gas that is not trapped in human lungs. Such an environmental friendly seeding system would revolutionize the way particle based diagnostic techniques are employed in large and small scale tunnels.