Design Tools for Combustion Stability

The combination of complex physics and extremely severe combustor environments presents a formidable challenge to engineers who must ensure that high-pressure, high-performance rocket engines are stable from combustion instabilities.  We propose here an improved methodology for predicting the combustion stability of oxidizer-rich staged-combustion engines.   The methodology integrates high-fidelity CFD, state-of-the-art engineering analysis, and subscale experiment and test.  Our emphasis in this proposal is on velocity-coupling, specifically on the unsteady mixing of asymmetric injector elements due to an oscillating velocity field.  The desired outcomes of the Phase I are feasibility demonstrations of modeling the physics unsteady mixing due to an oscillating velocity field, derivation of a combustion response function that captures the modeled physics, and a test chamber that can be used to obtain validation data and insight into the problem.  A set of detailed requirements for a potential Phase II effort will also be defined. BENEFITS: The anticipated benefits of the proposed research include gaining significant physical insight into the dynamic interactions between acoustic waves and the injector flow field, methods for reducing high fidelity simulations into simpler combustion response functions, a mechanistic basis for the velocity-coupling correlation for predicting stability, and methods for generating transverse waves in high pressure environments so that the flow field response can be measured.  These benefits will be of considerable use to the development of a hydrocarbon boost engine.  As such, the potential commercial applications include enhancing the IN Space-Purdue Generalized Instability Model (GIM) engineering design tool to include additional physics-based modeling and broaden the design space the GIM tool can support.