High-fidelity numerical investigations of a hydrogen rotating detonation combustor

The present work provides a contribution to the understanding of the rotating detonation and proposes simulation strategies, numerical methods and post-processing techniques for the study of the RDCs, that involve extremely fast transients and peculiar phenomena. In the first part, the numerical modelling of the hydrogen-air detonation is tackled, exploring different solutions to describe the explosion process without compromising the computational demand of a CFD analysis. The validation of the available detailed chemical schemes in the conditions relevant for a detonation provides a reference structure of the detonation front and thermodynamic states as well as the detonation speed. Building upon these descriptions, reduced chemistry models are proposed and verified in simplified cases of increasing complexity, ensuring the accuracy of the results and providing essential indications for the application of the model to realistic configurations, where the mesh requirements cannot overlook the computational costs. In the second part of the work, the non-premixed Rotating Detonation Combustor (RDC) installed at Technische Universität (TU) Berlin is studied by means of fully compressible, multispecies, reactive Navier Stokes equations. A stoichiometric, single wave test point is considered for the analysis and investigated both in cold and reactive conditions through Large Eddy Simulations with the AVBP code. For a cost-efficient modelling of the detonation process, the global single-step scheme with real species developed in the first part and calibrated for the conditions of interest is adopted. After an overall description of the wave stabilization process and global parameters, the analysis of the results focuses on the characterization of key features of the RDC flow field, such as the shocks structures, the gas state in refill region and the transient injectors operation subject to the periodic detonation passage. Finally, an advanced analysis technique for tracking the three-dimensional evolution of the detonation front and evaluating its propagation speed is developed, allowing a stochastic characterization of both the front speed and the refill region and highlighting their correlation. The present study demonstrates the importance of the complete resolution of the injection system to capture the interaction between the waves and the reactants injection, an essential aspect for the optimization of the RDC performances . In this context, this work represents a first step to characterize the main aspects related to the RDC operation and provides valuable insights for the future development of such devices.