Investigation of the Formation Mechanism and the Magnitude of Systematic Error of Thermocouple Measurements in High-Temperature Heat Shield Aerospace Materials
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The main factors influencing the systematic error of contact temperature sensors in a nonstationary thermal experiment have been determined, and its formation mechanisms have been analyzed. By comparison of the experimental data and the results of simulation, it has been established that, in highly porous heat-resistant materials, errors in thermocouple readings are determined by two differently directed mechanisms — advanced heating of the thermocouple by the radiant heat flux and the decrease in the conductive heat flux due to the additional heat resistance in the region of its contact with the sample. These mechanisms provide correction of the error and difference between the radiant and conductive heat fluxes. From the results of the analysis, certain features of the error formation process at various distances from the heated surface of the sample have been established and quantitative relations for error magnitudes have been obtained.
Keywordshighly porous materials thermal field nonstationary experiment mathematical modeling error formation mechanism comparative analysis approximation
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