Theoretical Innovations in Combustion Stability Research: Integrated Analysis and Computation

Quantitative predictions of reactive flow dynamics from large-scale simulations of Liquid Rocket Engines (LRE) appear to be model dependent. Relationships and coupling among the dominant mechanisms most responsible for destabilization are obscured by the complexities of the model and subtle consequences of inherent ad hoc approximations not supported by mathematical rationale. The reliability of predictions is difficult to quantify. These uncertainties provide opportunities for novel theoretical (integrated analysis and computation) research aimed at reducing complexity and identifying primary drivers of instability (dominant coupling mechanisms). Phase I research will demonstrate that thermomechanical concepts and analysis can be employed to address stability processes in a LRE. Systematic asymptotic analysis is used to identify dominant physical processes occurring in an idealized supercritical LRE, and their inherent time and length scales. This form of analysis leads to model equations of reduced complexity, based on derived approximations with an a priori understanding of model limitations. Anticipated Phase II research will apply proven Phase I methodologies to very general equation systems capable of describing coupled chemico-physical phenomena in supercritical pressure, turbulent reacting flows, characteristic of an operational LRE. Computational solutions of the reduced equations will produce quantitative predictions of combustion stability, including concepts that will facilitate improved design practice BENEFIT: Simplified Liquid Rocket Engine computer codes with predictive reliability will; * facilitate LRE design practices based on first principles, * reduce the computational expense of design, * foster more cost-effective LRE design process, * enable the construction of stable LRE''s.