Lifetime-based phosphor thermometry for global heat flux measurement in a hypersonic rarefied tunnel under strong background radiation

Abstract

Lifetime-based phosphor thermometry using Mg4FGeO6:Mn is successfully implemented on a standard hypervelocity ballistic model 2 (HB-2 model) and an HB-2 model modified with tail fin in a hypersonic rarefied tunnel at a Mach number of 10. A novel Reynolds decomposition correction method is proposed to remove the heating device-induced strong background radiation, which is characterized by complex spatial and temporal distributions. Three methods are compared for heat flux calculation: an insitu calibration method, the Cook–Felderman method, and a double-layer numerical method. The in situ calibration method exhibits the least relative error (9.47 %), outperforming the other two methods. The global heat flux distribution at a high spatial resolution (0.25 mm/pixel) reveals the fine flow features of the models. Particularly, the modified HB-2 model exhibits a complex flow, related to the shock-boundary layer interaction, shock–shock interaction, and significant 3D effects. The presented measurement technique and data processing method can enable long-duration advanced aerothermal testing in hypersonic tunnels involving a large temperature rise.