TY  - EJOU
AU  - Esposito, Antonio 
AU  - Lappa, Marcello 
AU  - Pagliara, Rocco 
AU  - Spada, Gennaro 

TI  - A Mixed Radiative-Convective Technique for the Calibration of Heat Flux Sensors in Hypersonic Flow
T2  - Fluid Dynamics \& Materials Processing

PY  - 2022
VL  - 18
IS  - 2
SN  - 1555-2578

AB  - The ability to measure the very high heat fluxes that typically occur during the hypersonic re-entry phase of space vehicles is generally considered a subject of great importance in the aerospace field. Most of the sensors used for these measurements need to be checked periodically and re-calibrated accordingly. Another bottleneck relates to the need to procure thermal sources that are able to generate reliable reference heat fluxes in the range between 100 and 1000 kW/m<sup>2</sup> (as order of magnitude). In the present study, a method is presented by which, starting from a calibration system with a capacity of approximately 500 kW/m<sup>2</sup> only, heat fluxes in the range of interest for hypersonic applications are generated. The related procedure takes advantage of established standards for the characterization of a radiative heat flux. It also builds on the hybrid radiative-convective nature of typical hypersonic heat fluxes and the yet poorly explored possibility to use convective sources of heat to produce high-intensity fluxes. The reliability of such a strategy has been tested using a high enthalpy supersonic flow facility relying on an electric arc-heater and pure Nitrogen as work gas. Stagnation-point heat fluxes have been successfully measured (with reasonable accuracy) in the range between 600 and 1500 kW/m<sup>2</sup> for values of the centerline enthalpy spanning the interval from to 6 to 24 MJ/kg.
KW  - Photometry; heat flux sensor; calibration facility; radiative source; convective source

DO  - 10.32604/fdmp.2022.019605