Theoretical Innovations in Combining Analytical, Experimental, and Computational Combustion Stability Analysis

Combustion stability is an important consideration in the design of liquid rocket engines. While fundamental modes of unstable operation in simple geometries are easily identified using analytical methods, recent times have seen these methods greatly expand in scope, applied in semi-numerical format to increasingly complex geometries and flow situations. Much remains to be explored in understanding the role of chemistry and turbulence interaction, nonlinear effects and coupled unstable modes and such others. While analytical models and CFD have largely been kept apart by convention, some recent advances have begun to pave the way for their effective integration. The generalized use of the Galerkin approach to complex physics has enabled a straightforward usage of eigen-functions to preempt numerical solutions such that each solution yields greater physical insight into the problem. We propose here a series of advancements to make combustion stability analysis more efficient by a natural coupling between analysis, CFD and experiments. Among others, these methods will include: the use of reduced basis methods, the ability to model uncertainty in flow calculations, high order accurate and efficient calculations of flows in complex geometries. This research will be performed jointly by HyPerComp Inc. and the Computational Combustion Laboratory at Georgia Tech. BENEFIT: Work proposed here has a broad appeal to manufacturers of solid and liquid propellant rocket motors as well as gas turbine engines. These are significant markets and will be able to sustain a niche software suite to be developed. An effective modeling strategy and an integrated simulation environment can result in tremendous cost savings in trial and error testing. Specifically, the combustion stability application will serve as a front runner to promote HyPerComp Inc.’s upcoming product line of very high order accurate simulation software for multiphysics, a first in the industry. Allied technologies such as uncertainty modeling and reduced basis methods will bring new energy into an otherwise routine set of modeling applications currently in vogue.