Title page for ETD etd-05092005-165137


Type of Document Master's Thesis
Author Shafer, Daniel Manfred
Author's Email Address dmshafer@vt.edu
URN etd-05092005-165137
Title Active and Passive Flow Control over the Flight Deck of Small Naval Vessels
Degree Master of Science
Department Aerospace and Ocean Engineering
Advisory Committee
Advisor Name Title
Mason, William H. Committee Chair
Devenport, William J. Committee Member
Findlay, David B. Committee Member
Keywords
  • backward facing step
  • frigate ship airwake
  • flow control
  • helicopter/ship operations
  • airwake
Date of Defense 2005-04-27
Availability unrestricted
Abstract
Helicopter operations in the vicinity of small naval surface vessels often require excessive pilot workload. Because of the unsteady flow field and large mean velocity gradients, the envelope for flight operations is limited. This experimental investigation uses a 1:144 scale model of the U.S. Navy destroyer DDG-81 to explore the problem. Both active and passive flow control techniques were used to improve the flow field in the helicopter’s final decent onto the flight deck. Wind tunnel data was collected at a set of grid points over the ship’s flight deck using a single component hotwire. Results show that the use of porous surfaces decreases the unsteadiness of the flow field. Further improvements are found by injecting air through these porous surfaces, causing a reduction in unsteadiness in the landing region of 6.6% at 0 degrees wind-over-deck (WOD) and 8.3% at 20 degrees WOD. Other passive configurations tested include fences placed around the hangar deck edges which move the unsteady shear layer away from the flight deck. Although these devices cause an increase in unsteadiness downstream of the edge of the fence when compared to the baseline, the reticulated foam fence caused an overall decrease in unsteadiness in the landing region of 12.1% at 20 degrees WOD.

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