AN ADDITIVELY MANUFACTURED SMALL FOOTPRINT WIND TUNNEL FOR WALL JET AND PARTICLE SCAVENGING STUDIES

Subsonic wind tunnels are essential for flow performance quantification and visualization in academic and industrial research. Depending on the application requirements, wind tunnels vary widely in cost and size. In our laboratory, a small footprint wind tunnel was needed for low-speed wall-jet particle scavenging research. We required a test section size of approximately 12in x 12in x 3ft in length, a test section mean velocity of approximately 4-5 m/s, turbulence levels of less than 2%, a re-configurable inlet, and a variable height test-section bottom table to enable wall-jet testing. An open circuit suction tunnel was additively manufactured at very low cost with a plastic 3D printer. The particular inlet design for our application has a co-flow configuration that includes a separate flow inlet through a blower, enabling the generation of a plane wall jet through a rectangular slot. Additionally, the tunnel is equipped with easily and inexpensively reconfigurable components, inducing an adjustable height build plate, an adjustable angle inlet flow guide plate, a variable speed axial fan, and a diffuser with an embedded filter to remove scavenged metal powder and provide pressure drop. The design incorporates a conventional contraction section with a bell mouth and honeycomb to minimize free stream turbulence and improve flow uniformity in the test section. The total cost of the tunnel was under $1000. The design detail of each wind tunnel part and its construction is presented in this work. Additively manufactured components enable an easily reconfigurable facility. It is hoped that our success with this effort may inspire others to design and build such test facilities using inexpensive commercial 3D printers.