Weapons System Flow Separation

This proposal deals with the extension of physics in CFD codes to permit their more accurate and reliable analysis of transient missile jet/exhaust interactions. Such interactions include those associated with divert jet firings and with stage-separation, and their analysis is complicated by the significant role played by transitional turbulence effects, which impacts both the size and the oscillatory behavior of the separation region produced by the interaction, and thus impacts stability and control. The turbulent/transitional physics varies with flight regimes and the modeling required will be scoped-out via the performance of a substantive number of numerical studies. A detailed direct simulation (DNS) study will be performed for a divert jet firing on generic missile at 45 km and Mach 8 which will directly deal with the transitional physics. An AIT missile tested in the shock tunnel facilities at CUBRC with a DAC divert motor will also be analyzed for which detailed temporal data is available. Innovative techniques to minimize the size of the separated region and the oscillatory behavior will be examined employing pulsatile concepts with prescribed frequencies. Active control concepts which have been used for related problems will be discussed but the work deferred to Phase II.