Regenerative Cooling System Investigation and Calorimetric Design for Heat-Transfer Characterisation in a Hydrogen–Oxygen Rotating Detonation Combustor

Abstract

Rotating Detonation Engines (RDEs) offer a pressure-gain combustion cycle capable of increasing rocket engine efficiency within compact geometries. While theoretical analyses predict meaningful performance advantages, experimental validation at high pressure remains limited. To support this transition from short-duration to sustained operation, the German Aerospace Center (DLR) developed a hydrogen–oxygen Rotating Detonation Combustor (RDC) and performed several test campaigns. As these evolve towards long-duration firings, active cooling becomes essential. The main challenge lies in achieving reliable heat removal and accurate calorimetric measurement while maintaining structural integrity and manufacturability. This thesis addresses that challenge through two complementary developments at different levels of maturity. The first focuses on the long-term path towards flight-relevant configurations: a regenerative cooling analysis tool was created to assess the feasibility of actively cooled RDE liners at larger scales. The model predicts wall heat fluxes, coolant-side temperature evolution, and material temperature margins under representative operating conditions. After benchmarking against published datasets, it was applied to both single- and dual-coolant architectures to explore geometric and operational trade-offs, ultimately defining a feasible regenerative design concept suitable for DLR test benches. In parallel, a near-term experimental design was developed to characterise wall heat fluxes on small-scale, water-cooled hardware. A calorimetric inner body was conceived to enable spatially resolved measurements under relevant boundary conditions. The proposed hybrid concept combines additively manufactured internal routing with conventionally machined copper interfaces, balancing cost, manufacturability, and diagnostic access. Conjugate heat-transfer simulations defined the thermal envelope, while cold-flow testing quantified hydraulic losses and verified flow uniformity ahead of hot-fire application. Together, the regenerative cooling study and the calorimetric hardware form a coherent methodology for RDE thermal characterisation: a rapid predictive framework for design exploration, anchored by experimental measurement capability. This combination strengthens the foundation for the progressive development of regeneratively cooled, flight-relevant rotating detonation engines.