Design Tools for Combustion Stability

ABSTRACT: When using the current state-of-the-art in spatial discretization, numerical flux functions and temporal integration techniques, the amount of effort required for simulations in general geometries is prohibitively large for most unsteady simulations in multi-element rocket engines. In addition, current numerical techniques, while effective for stationary flows, have a potential for spurious reflections at interfaces, where grid sizes change abruptly. These limitations render present day approaches less than successful for unsteady flows. Following an exhaustive search for an efficient method to push rocket engine flow simulations to the next level, both in terms of fidelity and turnaround time, Metacomp Technologies proposes to employ an innovative application of high resolution methodologies in the CFD++ framework. In Phase II, the innovative methodology will be applied to gas-gas, gas-liquid and liquid-liquid problem classes. BENEFIT: The proposed technology will result in a dramatic reduction in computational effort to achieve a desirable level of fidelity in the simulation of unsteady flow in rocket engines. It will lead to a modern high-fidelity rocket engine flow simulation capability that can predict the onset of instability as well as transient response of the flow in the combustion chamber to disturbances. The proposed research will complement other developments at Metacomp sponsored by the Air Force. CFD++ will become a useful tool for AFRL to explore new designs for high performance rocket engines. Concurrently, rocket engines are increasingly used in the commercial, non-military, market. Examples are the various Earth-to-Space rocket-powered payload carriers, some of which are government-sponsored, others privately owned. Recent years have seen the birth of commercial space travel. While still in its infancy, increased activity in this area indicates a potentially big market in the near future. Since all these vehicles must be able to travel in vacuum, most of them will resort to chemically fueled rocket engines, which will encounter the same transient problems associated with military rocket motors. Consequently, the current proposal has potential for a diverse usage, benefitting both military and commercial sectors.