Local Mass-Specific Enthalpy Measurements with a New Mass Injection Probe

The results of local measurements of the mass-specific enthalpy in a high-enthalpy oxygen plasma flow are presented. The sensor measures enthalpy based on stagnation point heat flux measurements and its reduction by mass addition into the boundary layer. The efficiency of this boundary-layer cooling depends on the freestream enthalpy. Thus, an analysis of this heat flux reduction is a measure for enthalpy. The enthalpy probe is described and theoretically analyzed, and measured data are compared to locally resolved enthalpy measurements from optical diagnostic measurements. For the pure oxygen plasma flow, a simplified theoretical model neglecting chemical reactions and diffusion fits comparably well to the measurements based on optical diagnostics. The mass-specific enthalpy at the corresponding plasma condition applying optical diagnostics is , and the probe measures .