End-to-End Differentiable Model for Optimization of Rocket-Powered Vehicles Including Plume Radiant Emission

This paper proposes an end-to-end differentiable model for infrared radiant emission for low-altitude exhaust plumes. Considering plume radiant emission during the design phase is important for ensuring vehicle design constraints and objectives can be met while accounting for the coupling of plume radiant emission with other aspects of vehicle design. The model is suitable for computational frameworks using automatic differentiation or gradient-based optimizers—such as CasADi and AeroSandbox—which enable direct optimization of solid rocket-powered vehicle design with constraints on plume radiant emission. It consists of six submodels of different coupled physical phenomena: chamber thermodynamic equilibrium, motor internal ballistics, isentropic nozzle flow, plume flow field, afterburning kinetics, and radiative transfer. The combined model shows reasonable agreement for several different rocket-powered vehicles. The use of the model is demonstrated in an example case study for optimizing a low-thrust, transonic, rocket-powered aircraft concept.