Network simulation of the rapid temperature changes in the composite nozzle wall of an experimental rocket engine during a ground firing test

This paper introduces a robust computational technique named the network simulation method (NSM) that is exemplary for the numerical prediction of spatio-temporal temperatures in multi-layered composite walls in regular coordinate systems. The problem that was analyzed here deals with a composite nozzle wall of an experimental rocket engine that is fabricated with two dissimilar materials: a metallic substrate and a ceramic coating. The model involving two coupled, unidirectional nonlinear heat conduction equations in a two-material wall (ceramic coating and metallic substrate) and a convective–radiative boundary condition has been solved numerically with the NSM. NSM has its genesis in the resistance–capacitance analogy that exists between unsteady, unidirectional conduction of heat and unsteady flow of electric current. The network-simulated estimates for the temperature–time history inside the composite nozzle were performed with the code PSPICE easily, quickly, and accurately. The rapid temperature raise of the ceramic coating/metallic substrate interface from room temperature is the determining factor in this study. The time lapse to reach the melting temperature of the metallic substrate dictates the approximate duration of the ground firing test and evidently constitutes the primary design constraint.