The Aerospace Shock Tube (AST) was acquired from The Aerospace Corporation in El Segundo, California. The facility was designed and implemented specifically for chemical kinetics measurements. To accomplish this, several key features were integrated into the facility. First are the driver and driven section lengths that allow test times up to 2.5 milliseconds when helium is used as a driver gas. Also, to minimize boundary-layer effects, the facility has a 16.2-cm inner diameter and a surface finish with a 1-μm or better roughness. When making measurements within the reflected-shock region in a shock tube, it is important to take measurements close to the endwall; this facility has diagnostic access 1.6 cm away from the endwall.
The facility offers many features allowing for the operator to generate an ideal experiment with constant temperature and pressure within 1% of the desired conditions. The Aerospace Shock Tube has a diverging flow setup. This means the driver section has a smaller inner diameter (7.62 cm) than the driven section (16.2 cm) with a diverging nozzle directly after the diaphragm section. The driver section is 3.25 m long and the driven section is 7.88 m long. A four foot mixing tank is used to make high-purity mixtures for testing. To achieve high purity for chemical kinetics experiments, a vacuum system utilizing a rotary vane pump and turbomolecular pump is used to achieve pressures of 10-5 Torr in the driven section and mixing tank before introducing the test gas. A specially designed gas handling manifold is used with 0-10 and 0-100 Torr Baratron gauges to create test mixtures and fill the driven section. The driver section utilizes a rotary vane pump and a simple gas handling manifold with driver gas tailoring capabilities.
Diagnostic capabilities of this facility include pressure transducers, thermocouples, and tunable diode laser systems. Five PCB pressure transducers are used to measure shock velocity, and a PCB and a Kistler are used to measure sidewall (1.6 cm from endwall) and endwall pressure, respectively. Currently this facility has a laser diagnostic tuned for absorption measurements of H2O. Further details on this facility and its previous functions at The Aerospace Corporation can be found in Vivanco’s Master’s Thesis (2014) and in Petersen (2015).
Image of the Aerospace Shock Tube at Texas A&M.