Time dependent full-core multiphysics analysis of nuclear thermal propulsion reactors

Abstract

Nuclear thermal propulsion is the high thrust, high specific impulse rocket engine technology for future crewed missions to Mars and beyond. This paper presents a full-core multiphysics analysis approach that accounts for thermal–hydraulic and thermo-mechanical feedback while adjusting control drum position during operation. This time-dependent coupled multiphysics approach is then compared to previously adopted decoupled analysis. The results demonstrate that neglecting multiphysics feedback and control drum rotation introduces significant errors into the spatial power distributions, which subsequently cause significant errors in the prediction of thermal and mechanical safety margins during engine operation. Finally, the multiphysics approach is applied to design the fuel orificing pattern for an engine that can provide a specific impulse of 900 s while maintaining acceptable maximum fuel temperatures throughout a 60-minute main-stage burn. The analysis presented in this paper conclusively demonstrates the benefits of adopting a multiphysics approach to design high specific impulse nuclear thermal propulsion reactors.