Base heat flux measurement techniques in impulse hypersonic test facilities

Abstract

Safe and efficient hypersonic missions require exhaustive testing to capture the surface heat flux used in optimizing thermal protection systems. Though low, base heat transfer rates are still relevant and their estimation is of the utmost importance. Impulse hypersonic test facilities like the shock tunnel are commonly used for such estimation tests. The present paper compares contemporary heat flux measurement techniques, namely, E‐type coaxial thermocouples, Pt‐thin films, and atomic layer thermopiles in a hypersonic shock tunnel at the base of a scaled‐down re‐entry capsule. Base flow establishment is ensured using pressure measurements. The measurements indicated that the base‐stagnation point heat flux was approximately 2% to 3% of the forebody stagnation heat flux and it stabilized at an approximate nondimensional establishment time of 43.2 ± 2.4.

Stagnation heat flux estimation in spherically blunt axisymmetric hypersonic models

“…The models are experimented in a conventional hypersonic shock tunnel, IITB-ST, 12 and the test gas used is air ( γ = 1.4). The test gas is doubly heated and pressurized through shock waves and further expanded to a hypersonic freestream of Mach 8.8 ± 2.5% at the test section.…”