Transient Jet-Interaction Combustion Modeling

Interceptor missiles achieve high maneuverability in final phases of their mission via the use of divert/attitude control jets. Jet firings are of relatively short duration (10-40ms) and the aerodynamic interaction process is highly transient,characterized by large regions of jet-induced separation. The interactive process is strongly dependent on afterburning of jet exhaust constituents and on particulate interactions for heavily metalized DACS motors. Concerns of combustion productsreaching seeker windows and related particle obscuration/radiative heating issues also need to be addressed. Present abilities to support missile design are limited by computer resources with high-fidelity simulations for a fraction of the transient eventrequiring use of 64 or more processors and taking months to complete. This proposal addresses present limitations by advances in numerics and parallel code architecture, as well as in inclusion of pertinent physics and thermochemistry. Key elements ofwork proposed address: new zonal, multi-time step parallel architecture strategies to make the solution process more efficient, and, inclusion of advanced dynamic turbulent transitional models and pdf-based turbulent combustion models which have afirst-order effect on jet interactions at higher altitudes (h>30km). An optional task to examine use of unstructured numerics with specialized dynamic grid adaption is also proposed.The research proposed is of obvious benefit to the interceptor missilecommunity and we have supported both DoD and prime contractors (Lockheed, Raytheon, .) for many years in design-related issues pertinent to divert/attitude control jet interactions. This effort will clearly enhance our commercial relationships with bothDoD and prime contractors. In addition, transient jet interactions are of interest to the automotive and spray coating communities and we have been working with industry (Ford Motor Co., Sulzer Metco, .) in supporting advanced design work. Lastly,pulsatile spray injection is being investigated to enhance mixing in next generation airbreathing missile systems and this work has great relevance to the design of next generation combustors.