Material Testing Using Preheating in the Sandia Hypersonic Shock Tunnel

Preheating of carbon-based materials for testing in Sandia’s Hypersonic Shock Tunnel (HST) is discussed. The technique replicates material surface temperatures experienced during hypersonic flight by using electrical resistance. This method is inspired by pioneering work at the University of Queensland. The design of the heating method and test sample is presented. An imaging pyrometry method to characterize the surface temperature of the model is also presented. Utilizing a high-speed color camera, the pyrometer employs a two-color band ratio technique with an estimated uncertainty of less than 5%, which is comparable to other pyrometry devices presented in the literature. Benchtop demonstration of the heating method and surface temperature characterization are shown, along with initial high-speed imaging results from a study of the heated model in the HST. Stagnation enthalpy (H0), stagnation pressure (P0) and free-stream Mach numbers (Ma) used in this study were H0=4.0 MJ/kg, P0=27.5 MPa, Ma=9.2, and H0=8.8 MJ/kg, P0=16.6 MPa, Ma=7.3 respectively.