Multiphysics Framework for Prediction of Dynamic Instability in Liquid Rocket Engines

Mitigation of dynamic combustion instability is one of the most difficult engineering challenges facing NASA and industry in the development of new continuous-flow combustion systems such as the combustion chambers in liquid-fueled rocket engines (LREs). Combustion instabilities are spontaneous, self-sustaining oscillations that tie the combustor acoustics to the combustion reaction itself. These oscillations can lead to a wide range of problems from off-design performance to catastrophic failure. Efforts to predict instabilities at design-time is hindered by the complex, multi-physics nature of the acoustics and chemistry, typically requiring multiple iterations of time and resource intensive system prototyping. The proposed Phase I STTR project aims to develop a simulation framework that will enable accurate, design-time prediction of instabilities. This framework will leverage the capabilities of Loci/CHEM for massively parallel, multi-physics flow simulations to generate low-order, independent models of combustion and acoustic response to perturbations. By solving for simultaneous solutions of these low-order perturbation models, it will be possible to numerically map the acoustic modes of the system to their stability characteristics, providing a means to predict instability. Phase I will develop critical additions to Loci/CHEM's combustion modeling capabilities, develop the appropriate acoustic models, develop a test plan for experimental validation of the combustion model, and conclude with a proof-of-concept demonstration of the full framework. In Phase II, an experimental campaign will be carried out to validate the combustion modeling tools developed in Phase I and augment the simulation framework with multi-phase modeling appropriate for full-scale LRE combustion chambers.