Initial Shakedown Testing of the Stanford High-Enthalpy Optical Tube/Tunnel

The Stanford High-enthalpy Optical Tube/Tunnel (SHOTT) is a newly-commissioned, dual-use impulse facility which can operate as either a reflected shock tube or reflected shock tunnel and is intended for the study of hypersonic flight-relevant phenomena. SHOTT is a pressure-driven facility rated to 15 MPa and is built around optical access to enable the development and deployment of advanced spectroscopic and imaging sensors. The facility is up to 15 meters long and has a 10.6-centimeter inner diameter. When operating as a reflected shock tube, SHOTT briefly generates stagnant test gases at temperatures which can exceed 10,000 K. When operating as a reflected shock tunnel with its current nozzle, SHOTT impulsively produces high-enthalpy, supersonic test gases at Mach 3, though additional nozzles may be deployed in the future to achieve different test-gas conditions. This work describes some of SHOTT’s design features and details initial characterization experiments of the facility in both operational configurations. In reflected shock tube mode, incident shock velocity is measured by a series of high-speed pressure transducers at a range of conditions, test times are measured, and experimental repeatability is characterized. Similar measurements are conducted in reflected shock tunnel mode, with the addition of a stagnation pressure probe mounted at the nozzle exit. Moving forward, SHOTT will be an integral part of hypersonics research at Stanford University, providing a testbed to investigate non-equilibrium thermochemistry and high-speed flow physics and acting as a proving ground for advanced optical diagnostic development.