Experimental Plasmatron Heat Flux Measuring Techniques Study

A presentation in the Undergraduate Research Kaleidoscope: Library East Commons Performance Space, November 9, 2009.Ground testing for hypersonic re-entry vehicles is an invaluable methodology to vehicle conception. The Von Karman Institute plasmatron is a facility that can duplicate the localized aerothermodynamic properties and conditions experienced on atmospheric reentry. Because of its relevance to design oriented testing activities, accurate heat flux measurements are crucial. Therefore this study addressed the heat flux measuring capabilities of two different temperature sensors. Experimentally, two calorimeters, (one with type K thermocouple only and the other with both thermocouple and PT100), were tested under a range of typical Plasmatron operating conditions. An inversion of the calorimeters was also performed for comparison and cross checking within the facility. Namely increased air mass flow had a thinning effect on the error differences between the two sensors. Further, there were no systematic differences between the two calorimeters (i.e. thermocouple heat flux from calorimeter A compared to calorimeter B). For the main experiment, thermocouple heat flux measurements were always higher than PT100. The inversion of the two calorimeters, however, showed a reversal of heat flux ordering as a result of aggravated the inlet thermocouple sensor readings. A case study was performed to test for grounding effects on sensor behavior, concluding that direct sensor grounding is not a source of increased temperature reading