Method for Heat Flux Determination of a Transpiration-Cooled Wall from Pressure Data

An approach to measure heat flux in transpiration-cooled environments from plenum pressure gauges is presented. The inverse problem of determining the net surface heat flux from an in-depth temperature measurement is replaced by the measurement of the pressure change in the gas reservoir at the rear side of the porous structure. The measurement is based on an in situ calibration using noninteger system identification. The pressure data are directly related to the net surface heat flux. In comparison with temperature readings at different depths and by analyzing different coolant gas mass flows, the hypothesis is that the main pressure increase is evolving over the thickness of the sample due to the heat flux at the surface. Consequently, the measurement of plenum pressure changes at constant outflow pressure conditions to analyze surface heat flux is considered a valuable tool for future heat flux measurements in transpiration-cooled environments.