Numerical Analysis of Influencing Factors and Capability for Thermal Wave NDT in Liquid Propellant Tank Corrosion Damage Detection

Due to the disadvantages of traditional NDT methods for liquid propellant tank corrosion detection, Thermal Wave Nondestructive Testing (ITWNDT) technology was applied. The heat exchange process of thermal wave in corrosion tank was simulated by the numerical method. Parameters of TWNDT as the best detection time (t_best), the maximum surface temperature difference (ΔT_max), and the temperature difference holding time (τ_ΔT>0.1) were discussed as the targets. Based on these parameters, factors influencing the detection results of tank materials, dressed liquid (also considered as the corrosion product), pit characters (depth and size), heat flux and thermal excitation time length (pulsed width), environmental conditions and other factors were analyzed. Simulation results show that ITWNDT can identify the defect depth, size and position rapidly and effectively. Material properties of the tank were influencing the t_best, ΔT_max and τ_ΔT>0.1, while the dressed liquid, thermal excitation parameters and the conditions of environment do not influence the t_best. Pit characters of the depth and size have close relationship with t_best and ΔT_max, therefore, for a tank with certain material and certain liquid dressed in, the pit corrosion damage can be accurately evaluated.