Surface Heat Flux Measurements Based on the Non-Integer System Identification Method Using Surface Temperature Data

AbstractThis paper presents an experimental approach to inversely determine surface heat flux from surface temperature data for an arbitrary body. The relation between heat flux and temperature is calibrated using the non-integer system identification method. The surface temperature is measured using an infrared camera. The approach is applied using a well-established plasma wind tunnel condition so that the results are comparable to a reference measurement with a water calorimeter. The maximum deviation between the reference and the novel heat flux measurement was 6.3% and 14.3% for two separately generated impulse responses, respectively. In conclusion, this new method allows in future applications an additional heat flux determination based on surface temperature data. Since surface temperature data is a standard measurement, only an additional calibration step is needed to standardize this heat flux measurement method. Disclosure statementNo potential competing interest was reported by the authors.Additional informationNotes on contributorsChristian DuernhoferChristian Duernhofer is a PhD student with the High Enthalpy Flow Diagnostics Group (HEFDiG) at the Institute of Space Systems of the University of Stuttgart, Germany. He has completed his Bachelor and Master studies of Aerospace Engineering at the University of Stuttgart in 2019. His research focuses on the application of inverse methods for heat flux measurements in high enthalpy flows. Currently, he develops a new sensor design for the measurement of the heat flux distribution on a surface from sparse in-depth temperature data. He has published 3 conference papers.Fabian HufgardFabian Hufgard is a PhD student with the High Enthalpy Flow Diagnostics Group (HEFDiG) at the Institute of Space Systems of the University of Stuttgart, Germany. He has completed his Bachelor and Master studies of Aerospace Engineering at the University of Stuttgart in 2017. His research focuses on the application of inverse methods for heat flux measurements in high enthalpy flows with particular emphasis on transpiration cooling. He recently developed a new method to measure the surface heat flux on transpiration cooled walls. This approach uses the pressure information behind the cooled wall to solve the inverse heat conduction problem. He is author of about 30 publications in international journals, conference proceedings and book chapters mainly on the topic of heat and mass diffusion in homogeneous and porous media.Stefan LoehleStefan Loehle is heading the plasma wind tunnel laboratory at the Institute of Space Systems of the University of Stuttgart and leads the High Enthalpy Flow Diagnostics Group (HEFDiG). He has over 15 years of experience in teaching and research on high enthalpy flow diagnostics specializing in reentry thermophysics and optical diagnostics. He developed and applied diagnostics for several airborne observations of reentry events, as for example ATV1, Hayabusa, and CYGNUS. He has published over 130 conference proceedings and 72 journal paper and 6 book contributions. Since 2018 he is an AIAA Technical Committee Member for Plasma Dynamics and Lasers and since 2022 he is on the editorial board of Nature Scientific Reports.Stefanos FasoulasStefanos Fasoulas is a Professor for Space Transportation Technology and Managing Director of the Institute of Space Systems of the University of Stuttgart, Germany. He received his PhD in 1995 in aerospace engineering at the University of Stuttgart, Germany. He has over 30 years of experience in research and teaching. He also served as Professor for Space Systems and Utilization and Director of the Institute for Aerospace engineering at the TU Dresden, Germany. He is author or coauthor of more than 300 peer-reviewed or conference publications and reviewer for various journals related to space transportation, electrical propulsion, and space systems. In 2021 he was appointed as Dean of Faculty of Aerospace Engineering and Geodesy at the University of Stuttgart.