Design of a steady-state heat flux probe for measurements in an induction-heated plasma flow [wind tunnels]

The design of a steady-state heat flux probe for high-enthalpy plasma flows was performed using empirical and numerical methods. A commercial code has been used to assess the local heat transfer inside the probe, at the stagnation point. The study led to the optimization of the cooling circuit geometry and to the quantification of the convective heat transfer coefficient. A minimal mass flow rate was thus defined to avoid local boiling. Classical uncertainty theory has been used to derive the maximum mass flow rate leading to the state-of-the-art uncertainty of 10%. It is shown that with the proposed geometry it is possible to obtain an uncertainty of 5% or less in the heat flux range (350 kW/m², 1200 kW/m²). A method is proposed by which the operational chart of the probe can be drawn for any change in the design parameters. The chart is given for the present design