Operational Prediction of Arcjet Model Preheating Within Expansion Tube Facility

Effective integration between the expansion tube and arcjet plasma generator relies on a carefully sequenced interaction between each component of the system to simulate ablating models exposed to hypervelocity flow. Owing to the unique operational characteristics of each stage, it is essential to understand how these differences are reflected in the testing procedures and the analysis of results from an integrated testing apparatus. This study explores a numerical reproduction of the Arcjet Preheating within Expansion tube (APEx) facility at the University of Oxford. The OPG2 arcjet operation is simulated using a KATS-FD flow solver to match the measured heat flux and pressures, which serves as inflow conditions for simulating the ablation process using the KATS-MR solver before the model traverses to the CXT expansion tube. The expansion tube flow is initially modelled using L1d4 program, with gas fill conditions specified in the driver, shock tube, and acceleration tube. These conditions are later used to account for shock deceleration and nonequilibrium phenomena with LASTA 2.0 program. The transient flow around the test model in the expansion tube is modelled by KATS-FD flow solver with Adaptive Shock Alignment methodology. Building on these operational parameters, this work aims to investigate the effects of elevated surface temperature variations during the operation, as well as the related timescales of boundary layer diffusion within the quasi-steady test duration of the expansion tube.