Design, prototyping and testing of a supersonic shock tunnel

The shock tube facility at the University of Kansas is to be converted into a Reflected Shock Tunnel facility. The conversion will require the design of a test section for a Mach number of 1.73. The open end of the shock tube was closed with a burst disk made of a 0.016 in 2024 T3 Aluminum sheet (With 4 scoring lines to control the breaking lines for a clean burst). The disk bursts after the incident normal shock reflects from the end wall producing a stagnation pressure of 75.32 psia downstream of the shock tube. The exploding flow goes through a convergent transition duct from a circular inlet shape to a square throat. The geometry of this transition duct was designed based on computational methods that helped minimize pressure losses and the creation of vortices around the corners. The transition duct is connected to a divergent shock-free expanding nozzle designed using the 2-D Method of Characteristics for minimum length. Both transition duct and expanding nozzle were constructed from ABS plastic using rapid prototyping. The instrumentation used in this research is based on two high frequency response pressure transducers. One is a KISTLER 211B4 pressure sensor installed along the wall of the shock tube upstream of the transition duct; while the other is a PCB 137A22 pressure pencil probe that records the exit flow total pressure in the convergent-divergent nozzle. The preliminary measurements confirmed our design goals in the transition duct and nozzle, test duration and test section Mach number.