Non-Repeatability of Store Separation Trajectories from Internal Weapon Bays Due to Unsteady Cavity Flow Effects - Lessons Learned from a 2D Investigation

Abstract

A 2D computational fluid dynamics (CFD) study was performed on one internal weapons bay release scenario to investigate subject of non-repeatable store separation trajectories from internal weapons bays due to unsteady cavity flow effects. This simplified problem provided an opportunity to thoroughly learn the OVERFLOW CFD code, and to identify potential issues and problems in my research plan. The empty weapons bay flow field was verified against the Arnold Engineering Development Center (AEDC) Weapons Internal Carriage and Separation (WICS) database. A generic 500-pound class air-to-ground weapon was released from an internal weapons bay at one specific release condition, but at varying times of the flow with respect to the unsteady flow. Following that, the same series of releases are performed with a 2,000-pound class air-to-ground store, showing that this same internal weapon bay and release condition combination can result in fully repeatable trajectories for a different weapon, and that the entire release scenario (weapon, weapons bay and flow field) must be considered when looking at this issue. Although the results do not match other 3D CFD results for similar release conditions, there were many lessons learned that will be applied to the primary 3D portion of my research.