Development of Flow-Field Seeding for Large Wind Tunnels

The Air Force seeks a large production wind tunnel seeding system with full field steering capability. Additionally, the system must offer control of the particle size and density along with minimal maintenance and flow disturbance characteristics. These features will increase tunnel productivity, and compliment nonintrusive flow visualization techniques, such as Particle Image Velocimetry (PIV), Doppler Global Velocimetry (DGV), and more, without hindering other techniques like Pressure Sensitive Paint (PSP), and force/moment balance measurements among many. Advanced Projects Research, Incorporated (APRI) proposes a design satisfying these requirements using a translating injector array, capable of full field steering and individual injector flow control. A reversible gear pump will be installed for each individual injector delivering adjustable flow rates of propylene glycol to optimize particle number density in the test section. The injector delivers the seed fluid within a stream of regulated coflowing air to allow for desired dispersion of the particles into the tunnel. A central computer system interfaces between the user inputs and all the hardware subsystems