Study of dynamic flow effects due to ship air wake and rotor downwash interaction on warship helo-decks

Helicopters have become an integral part as they provide extended capabilities in areas where land-based operations are not feasible. In order to facilitate helo operations, frontline warships are provided with a helo deck and a helo hangar. Hangar shapes which were traditionally designed with stowage volume and associated aviation systems availability are being additionally optimised for stealth aspects. However, the flow considerations on helo-deck are verified by Experimental Test Pilots (ETPs) performing high risk trials in later stages of warship construction. The non-availability of a design tool at initial design stage of a warship which can effectively optimize the dynamic flow conditions on the helo deck poses a significant challenge to the designer as well as the operator. Across the globe, combinations of warship forms and helicopter types are increasing and the task of qualifying multiple helo-decks is challenging for all Navies. This paper examines the effects of helicopter downwash interacting with ship airwake for a Simplified Frigate Ship (SFS2). The flow visualization studies, with simplified rotor downwash (SRD) and airwake measurements carried out in wind tunnel at IIT Delhi are presented. These studies give a valuable insight into the interaction of varying helicopter operations at different warship speed regimes. Further, they provide critical data for numerical model validation and parametric studies at initial design stages.