Rapid prototyping for hypervelocity impulse facility test models

Abstract

The X2 expansion tube facility at The University of Queensland is capable of simulating entry into most of the planetary bodies in our solar system, producing test conditions with stagnation enthalpies in excess of 100 MJ/kg. Models used in X2 are typically made from steel and, consequently, manufacture is often constrained to conventional methods, with associated long lead times, and high cost. Through an experimental campaign, the survivability and applicability of Rapid Prototype models was investigated. Three prototyping methods were investigated; Selective Laser Sintering, Stereolithography, and Fused Deposition Modelling, and these were compared to a steel baseline. A computational stress analysis was used to design an internally hollow test model geometry. All models survived the experimental test-time, one was destroyed by the post-experiment flow. It was thought that test-models might ablate during the experimental test time and this was investigated by using filtered imaging to capture Cyanogen radiation occurring in the model's boundary layer. Ablation was seen in all Rapid Prototype models, most strongly observed in the Selective Laser Sintered and Acrilonitrile Butadiene Styrene models. These models may be suitable for the study of non-equilibrium radiative emission just behind the shock wave, or ablation phenomena in a model's boundary layer.