Features of the Upgraded Imaging for Hypersonic Experimental Aeroheating Testing (IHEAT) Software

Abstract

The Imaging for Hypersonic Experimental Aeroheating Testing (IHEAT) software is used at the NASA Langley Research Center to analyze global aeroheating data on wind tunnel models tested in the Langley Aerothermodynamics Laboratory. One-dimensional, semi-infinite heating data derived from IHEAT are used in the design of thermal protection systems for hypersonic vehicles that are exposed to severe aeroheating loads, such as reentry vehicles during descent and landing procedures. This software program originally was written in the PV-WAVE ® programming language to analyze phosphor thermography data from the two-color, relative-intensity system developed at Langley. To increase the efficiency, functionality, and reliability of IHEAT, the program was migrated to MATLAB ® syntax and compiled as a stand-alone executable file labeled version 4.0. New features of IHEAT 4.0 include the options to perform diagnostic checks of the accuracy of the acquired data during a wind tunnel test, to extract data along a specified multi-segment line following a feature such as a leading edge or a streamline, and to batch process all of the temporal frame data from a wind tunnel run. Results from IHEAT 4.0 were compared on a pixel level to the output images from the legacy software to validate the program. The absolute differences between the heat transfer data output from the two programs were on the order of 10 -5 to 10 -7 . IHEAT 4.0 replaces the PV-WAVE ® version as the production software for aeroheating experiments conducted in the hypersonic facilities at NASA Langley. Nomenclature β = thermal product, = ! (Btu/ft 2 -°R-s 1/2 ) C = sub-expression from step function equation, ! ℎ ! ! c h = convective heat transfer coefficient (lb/ft 2 -s) c P = specific heat capacity at constant pressure (Btu/lb-°F) D = sub-expression from step function equation, ℎ !" ! ℎ ! − !"!# h = enthalpy (Btu/lb) k = thermal conductivity (Btu/hr-ft-°F) κ = thermal diffusivity (ft 2 /s) L = characteristic length of model in axial direction (in.) = sub-expression from step function equation, P = pressure (psi or psia) = rate of heat transfer (Btu/hr-ft 2 ) ρ = density (slug/ft 3 ) t = time (s) T = temperature (°F or °R) θ = temperature difference (°F or °R) x = axial dimension on the model (in.) y = longitudinal dimension on the model (in.) y ref = characteristic length of model in longitudinal direction (in.)2 Subscripts: aw = adiabatic wall conv = convection F-R = Fay-Riddell init = initial tw = tunnel wall w = wall (surface of model) Acronyms: IHEAT = Imaging for Hypersonic Experimental Aeroheating Testing IR = infrared LAL = Langley Aerothermodynamics Laboratory 1D = one-dimensional 2D = two-dimensional 3D = three-dimensional