Burble Effect: Superstructure and Flight Deck Effects on Carrier Air Wake

摘要

The purpose of the present work was to qualitatively and quantitatively model the air wake created by an aircraft carrier flight deck and superstructure in order to understand how it affects aircraft on approach and landing. The 'burble effect' is the name given by navy pilots to the velocity deficit and downwash field immediately aft of an aircraft carrier. This turbulent region of air has adverse effects on landing aircraft and can cause pilots to bolter, missing the arresting wires and requiring another landing attempt. The experimental approach involved using a five-hole Pitot probe rake system for mapping of the air wake of a 6 ft aircraft carrier model. Wind tunnel tests were performed at Reynolds numbers of 11,000,000 and wake maps of 288 point measurements each were generated for configurations with and without the superstructure. The experiment showed that the superstructure created a region of extremely low flow velocity and downward flow angle. While the hull/deck configuration produced velocity deficits as low as 17%, the presence of the superstructure increased this to almost 30%. Furthermore, the addition of the superstructure decreased the downwash angle at the deck edge from -5 to -8 deg. Under these conditions, an aircraft on approach will experience an increased descent rate as it passes through the burble region. The presence of strong downwash compounds this adverse effect, making it more severe closer to the flight deck. Results also show that the superstructure geometry affects the severity of the burble effect.