A Multiphase and Multiphysics CFD Technique for Fuel Spurt Prediction with Cavitation and Fluid-Structure Interaction

摘要

A ballistic projectile traveling through a dry bay and into a fuel tank can create a highly atomized transient fuel spray that can be ignited by the impact flash or incendiary mixture. Modeling and simulation of real-world physical events, such as internal aircraft fire initiation, is a must within the survivability community. The purpose of this study is to develop and to validate a physics-based tool that can quantify fuel spurts caused by impact and penetration of fuel tanks. Our first step is aimed at capturing and preserving critical physics of each hydrodynamic ram (HRAM) sub-model. The objectives were successfully accomplished by adapting an existing multiphysics and multiphase CFD code, CFD-ACE+, and by validating against available experimental data. The validation effort of the modified software showed very good agreements with experiments in terms of fundamental physics events that included: a) cavitation behind a moving cylinder; b) growth of cavitation zone as projectile travels inside tank; c) cavitation bubble collapse and associated high pressure; and d) fluid-structure interaction of HRAM with a flexible fuel tank wall. Fuel spurt predictions at different time instances have been compared to experimental images, and good agreement has been observed at various stages of the process, including the main spurt, secondary spurt, merging of the primary and secondary spurt, and highspeed spurt. Velocity comparison of main and secondary spurts between experiment and simulation showed good agreements.