Predictive Gas Dynamic Computations for New Test Conditions for the High Enthalpy Shock Tunnel Göttingen

Abstract

The High Enthalpy Shock Tunnel in Göttingen (HEG) is the only hypersonic test facility in Europe capable of recreating high-enthalpy flows encountered in spacecraft re-entry. The HEG is a free-piston shock tunnel, meaning it relies on a piston to compress the driver gas. Once a high enough pressure is reached, a steel diaphragm ruptures, releasing a shock wave into the shock tube, which ultimately creates the entry conditions for a hypersonic nozzle. The gas passes through the nozzle, through the test section, and into a dump tank. Depending on the condition, the piston can be up to 850 kg, and reaches velocities upwards of 300 m/s. This could cause a great amount of damage to the shock tunnel. To avoid any risk of damage, new conditions are developed using a quasi-one-dimensional Lagrangian simulation tool, named L1d. In this report, the process of creating a new condition is described. Initially, existing conditions were simulated, to create a set of simulation parameters able to reliably recreate experimental measurements. Then, a new set of operating parameters were developed that could possibly work as a new test condition. In addition to this, the effect of the piston mass on test times, as well as the relationship between diaphragm thickness and burst pressure was investigated.