CFD of Complex Three-Dimensional Multiphase Flowfields

摘要

In this Phase II SBIR effort, research multi-phase Navier-Stokes (NS) models were extended/formulated to provide the framework for analyzing post-hit C/B aerodynamic breakup scenarios with an emphasis on bulk liquid payloads. Our structured grid research (NS) model, CRAFT, also permits performing droplet cloud neutralization studies containing multi-phase combustion capabilities. A detailed flyout and aero-breakup study of a high speed blob is presented, showing the complex surface deformation characteristics and the droplet wake cloud structure behind the blob. The full dynamics from blob flyout to droplet wake cloud formation is described. We have examined the neutralization of droplet clouds by conventional chemical explosive mechanisms. The studies exhibit the marked sensitivities to the droplet sizes and to the timing of the explosion relative to the clouds trajectory. With sufficient energy and correct timing/charge locations, the possibility of neutralization countermeasures for lower altitude C/B threats appears viable. An engineering model, SDROP, is described which tracks a droplet, from high altitude to the ground, accounting for, shape deformation, variable internal temperature, and vaporization effects. The importance of including advanced models of these effects and their impact on droplet survivability are discussed. In the course of performing the work described, limitations in the ability of the CRAFT code to analyze varied aspects of the bulk liquid flyout/breakup problem with high accuracy were identified which would require: use of unstructured grid numerics with dynamic adapting features to highly resolve the gas/liquid interface; formulation of multi-phase numerics which can concurrently analyze incompressible, viscous (Newtonian or non-Newtonian) liquids and highly compressible gases over a broad range of speeds; and, cavitation capabilities.