Flow characteristics on helodeck of a generic frigate ship model through experiment and CFD

Abstract

In light of modern Naval warfare strategy demanding high degree of stealth in design, the external geometry of frontline warships has undergone a paradigm shift. These changes in geometry have led to a modified aerodynamic environment around the ships, which has detrimentally affected helicopter operations from frontline warships such as Frigates and Destroyers. Accordingly, studies are in progress across several nations, to understand the helo operating environment on such ship forms, using modern experimental and numerical techniques with an aim towards creation of accurate virtual models in CFD and arrive at novel solutions for improving the helodeck design without compromising on stealth. Working in this direction, investigations have been undertaken on Internationally accepted Simplified Frigate Ship SFS2 which is currently being used for research purposes by many advanced countries, with minor simplifications to the representative form. The airwake on the helodeck for the ship model is experimentally mapped through a grid of over 1500 points in wind tunnel, over seven planes, using a five-hole pitot probe. The results in terms of contour and vector plots have been analysed in line with the findings of literature survey. On the numerical front, the environment of the experiments has been modelled in ANSYS FLUENT for the modified SFS2 model and a validation study is undertaken through use of a large databank generated through the wind tunnel experiments. Transition SST turbulence model is identified as the most suitable model for the analysis of this class of flows.