Design and Characterization of Supersonic Indraft Wind Tunnel

A small supersonic indraft tunnel was designed to grow experimental capabilities at the New Mexico State University Mechanical and Aerospace Engineering Department. Indraft tunnels provide constant stagnation conditions and they are safe and inexpensive to operate. They are also well suited for dry climates such as New Mexico. Square nozzle contours for test section Mach numbers of 2.3, 3, 4, and 5 are found with a method of characteristics computer program with boundary layer correction. A fifth-order polynomial is utilized too for shaping the subsonic part of the nozzle. The Mach 2.3 nozzle is compared to the nozzle of a similar indraft tunnel at the University of Arizona. Two- and three-dimensional simulations provide information about the boundary layer displacement effect and the flow uniformity in the test section. Assuming isentropic flow, the run time of the tunnel is analyzed based on tank size. Finally, detailed computer-aided design drawings of the entire indraft tunnel are presented.