Global aeroheating wind-tunnel measurements using improved two-color phosphor thermography method

Detailed aeroheating information is critical to the successful design of a thermal protection system (TPS) for an aerospace vehicle. NASA Langley Research Center's (LaRC) phosphor thermography method is described. Development of theory is provided for a new weighted two color relative-intensity fluorescence theory for quantitatively determining surface temperatures on hypersonic wind-tunnel models and an improved application of the one-dimensional conduction theory for use in determining global heating mappings. The phosphor methodology at LaRC is presented including descriptions of phosphor model fabrication, test facilities, and phosphor video acquisition systems. A discussion of the calibration procedures, data reduction, and data analysis is given. Estimates of the total uncertainties (with a 95% confidence level) associated with the phosphor technique are shown to be approximately 7-10% in LaRC's 31-Inch Mach 10 Tunnel and 8-10% in the 20-Inch Mach 6 Tunnel. A comparison with thin-film measurements using 5.08-cm-radius hemispheres shows the phosphor data to be within 7% of thin-film measurements and to agree even better with predictions via a LATCH computational fluid dynamics (CFD) solution. Good agreement between phosphor data and LAURA CFD computations on the forebody of a vertical takeoff/vertical lander configuration at four angles of attack is also shown. In addition, a comparison is given between Mach 6 phosphor data and laminar and turbulent solutions generated using the LAURA, GASP, and LATCH CFD codes on the X-34 configuration. The phosphor process outlined is believed to provide the aerothermodynamic community with a valuable capability for rapidly obtaining (three to four weeks) detailed heating information needed in TPS design.