Analysis of Multiple Stores Separation From Cavity

Abstract

Defense aviation is significantly concerned with predicting the trajectory of a store thrown from an aircraft. An ever-increasing range of stores must be carried by aircraft due to the growing need for them to perform diverse roles in a hostile environment. These include new, aerodynamically sophisticated stores with lifting bodies and old, long-stockpiled missiles and bombs.

This thesis study has been divided into three parts. First, the EGLIN test case’s valida- tion study using Chimera/Overset grid methodology is performed. Three-dimensional

Unsteady Reynolds’s Average Navier Stokes equations are solved with a Realizable k-ε turbulence model. The position, angular orientation, and surface pressure distribution of store results are compared with experimental data, and all the results are in good agreement. Second, multiple stores separation from the cavity was carried out, and the effects of passive flow control devices on the leading edge of the generic cavity were explored. The shear layer and the flow patterns outside the cavity were observed by the introduction of passive flow-control devices. The scenarios considered include a no-control device (NCD), rectangular flat-plate control device (RCD), and perforated flat-plate control device (PCD). Third, the efficacy of simulated passive flow control techniques on store separation trajectories is compared. Considering 0.95 Mach No, in terms of magnitude displacement, RCD stores drop 2.5m at maximum, in PCD stores drop at 3m, while NCD stores fall only 0.3m where shear layer pushes it back inside

the cavity. The results indicate that RCD and PCD effectively suppress the pitch- up tendency of the store during separation. It is observed that RCD faces high drag

and high-torque substantial hinge moment. When comparing the pitching and hinge moments of PCD and RCD, it is suggested that PCD is a reasonable middle ground.