Simultaneous PSP and TSP measurements of transient flow in a long-duration hypersonic tunnel

The current work presents simultaneous measurements of transient flow using fast-responding pressure- and temperature-sensitive paints in a long-duration hypersonic tunnel; the pressure, temperature and heat flux fields were obtained on a standard model (HB-2) at Ma = 5. Fast PSP and TSP were applied symmetrically on the model with low thermal conductivity. Both coatings were illuminated by a UV-LED, and unsteady pressure and temperature data were recorded at 500 Hz using a high-speed camera. Time-dependent temperature correction was applied on the PSP data based on the TSP results, while the heat flux was calculated from the time-resolved temperature fields using a 1D semi-finite heat conduction model. The temperature-induced errors in PSP data were effectively removed by the current compensation method. The pressure and heat flux results showed good agreement with the reference data from previous studies. The key events throughout the hypersonic tunnel run were captured by the unsteady PSP/TSP data, including the tunnel start-up, the flow build-up, the steady flow period and the tunnel shutdown. The differences caused by the change of attack angle were also clearly recognized. The current PSP/TSP system has shown great potential for unsteady flow diagnostics in hypersonic flows.