Radiative Heating Uncertainty for Hyperbolic Earth Entry, Part 3: Comparisons with Electric Arc Shock-Tube Measurements

The computational technique and uncertainty analysis presented in Part 1 (Johnston et al., Assessment of Radiative Heating Uncertainty for Hyperbolic Earth Entry Part 1: Flight Simulation Modeling and Uncertainty, Journal of Spacecraft and Rockets, Vol. 50, No. 1, 2013) for Mars-return radiative heating simulations are applied to Electric Arc Shock-Tube cases. These experimental cases contain wavelength-dependent intensity measurements in a wavelength range that covers 60% of the radiative intensity for the 11 km/s, 5 m radius flight case studied in Part 1. Comparisons between the predictions and Electric Arc Shock-Tube measurements are made for a range of experiments. The uncertainty analysis presented in Part 1 is applied to each prediction, and comparisons are made using the metrics defined in Part 2 (Johnston et al., Assessment of Radiative Heating Uncertainty for Hyperbolic Earth Entry Part 2: Comparison with 1960s-Era Shock-Tube Measurements, Journal of Spacecraft and Rockets, Vol. 50, No. 1, 2013). The agreement between predictions and measurements is excellent for velocities greater than 10.5 km/s. Both the wavelength-dependent and wavelength-integrated intensities agree within 30% for nearly all cases considered. This agreement provides confidence in the computational technique and uncertainty analysis presented in Part 1, and provides further evidence that this approach is adequate for Mars-return simulations. Existing experimental data that include the influence of massive ablation on radiative heating are reviewed. It is concluded that existing data are not sufficient for the present uncertainty analysis. Experiments to capture the influence of massive ablation on radiation are suggested as future work, along with further studies of the radiative precursor and improvements in the radiation properties of ablation products.