A Framework for Gas-Surface Interaction Mechanism Correlation

ATA Engineering, Inc., (ATA) proposes to develop and demonstrate a framework for correlating finite-rate gas-surface interaction (GSI) mechanisms derived from low-cost experiments to flight conditions representative of hypersonic boost-glide vehicles. The developed framework will utilize our existing Multiphysics Engine which can model GSI with finite-rate chemistry by coupling state-of-the-art solvers for computational fluid dynamics and ablation response modeling. ATA will also use validated custom software tools for quantifying statistical distributions of unknown model parameters through calibration to experimental responses and adapt the tools to calibration of Multiphysics Engine GSI mechanism parameters and associated experimental data. In the proposed effort, the project team will conduct low-cost experiments to infer reaction rate parameters for air/carbon chemistry, use the adapted model correlation process to calibrate measured rate parameters to high-pressure experimental data from an arc jet test, and demonstrate the improvement of the proposed framework by comparing Multiphysics Engine simulation results using the developed GSI mechanism to those mechanisms commonly found in literature. The Phase I effort will focus on demonstrating a proof of concept for the proposed framework by developing a correlated GSI mechanism for POCO graphite. Inductively coupled plasma (ICP) torch experiments using oxygen/argon and air/argon mixtures will be conducted, with suitable diagnostic data collected to make spatially varying measurements of species mole fractions to compute surface reaction rate parameters. The ICP torch experimental data will result in a GSI mechanism with baseline rate parameters and uncertainties derived from relatively low-pressure measurements. To extend this mechanism to high-pressure conditions, the Multiphysics Engine and model correlation tools will be used to sample the parameter space defined by the uncertainties on each rate parameter through the simulation of an arc jet test at flight-relevant conditions. The improvement of the resulting correlated GSI mechanism over other mechanisms in the literature will be demonstrated by comparing their respective predictions for the arc jet test case. In Phase II, the project team will shift the focus to tactical materials and the demonstrated framework will be validated using previously completed ATA-led arc jet testing, at flight-relevant conditions, with relevant materials.