A Transient Enthalpy Probe for the Calibration of High Heat Flux Ablation Facilities.

The measurement of enthalpy in high energy ablation facilities is extremely difficult because of the high heat transfer rates which preclude the use of conventional steady state enthalpy probes. A transient enthalpy probe which can be swept through the flow and obtain the required enthalpy data in less than probe destruction time has been designed and tested at the Arnold Engineering Development Center (AEDC). This report presents the results of the development and testing of this probe. The probe has been tested in a 5-MW arc heated facility at probe stagnation pressures to 100 atm, measured enthalpy to 4000 Btu/lb, and heat fluxes in excess of 10,000 Btu/sq ft-sec. Results show that the transient enthalpy probe has evolved into a rugged calibration tool for use in such extreme environments.