Altitude Effects - Fluid Flow Transition and Continuum Breakdown

The innovation entails the extension of newly developed hypersonic transitional models and hybrid continuum/DSMC methodology to analyze plume and divert jet interactions at altitudes above 45km where present predictive capabilities are deficient due tocomplexities in the physics. In the altitude regime of 45-60 km, the separation zone generated by the interaction of the plume or divert jet with the missile aerodynamic flow is very large and laminar to turbulent transition occurs within this zone.Extensions of 3D PDE?s for kL (laminar fluctuations) and for G (intermittency), now used in the CRAFT CFD Navier-Stokes code for transitional hypersonic aerodynamic flows, will be formulated for plume-induced separated zone transition. For altitudes above60 km, continuum breakdown occurs and we will include slip regime boundary conditions into the CRAFT CFD continuum code as well as initiate formal one-way coupling of this code with the DAC DSMC code under assumptions of thermal equilibrium at the Birdbreakdown surface. Exploratory computational studies of generic missile/plume interactive flows will be performed encompassing the 45-80 km altitude regime with an optional task addressing non-continuum effects for a higher altitude divert jet problem.CRAFT Tech has played a leading role in supporting systems and developmental studies related to missile plume interactive flows in the lower endo regime. Overall support to date from both DoD and industry for such studies has been significant. Thiseffort will provide for the extension of such activities to the higher endo regime and the lower exo regime, permitting us to deal with a much broader array of problems. Particular areas where we see major commercialization potential include: (1) supportof MDA/MSIC Boost Phase Intercept studies for detection, discrimination and plume to hardbody handover; (2) Liquid and Solid threat simulant booster design (for target usage) where we have been supporting a number of industrial groups; and (3) Army effortsrelated to interceptor missile technology where divert jet effects at higher altitudes are of major concern.