Mapping the Airwake of a Model DD-963 Along Specific Helicopter Flight Paths

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Mapping the Airwake of a Model DD-963 Along Specific Helicopter Flight Paths

G. A. Anderson

This study is a continuation of flow visualization studies done in the NPS low-speed environmental wind tunnel. The long term goal is to map the airwake around a ship model and scale to full size for the purpose of determining safe operating envelopes on non-aviation ships. This project used hot wire and hot film anemometry to establish a data base for helicopter approach paths at 0 deg, 30 deg port, and 30 deg starboard ship yaw angles. Calibration of the wind tunnel revealed that some turbulence generators, used in two previous studies, created excessive turbulence intensity levels and were subsequently removed. Analysis along the flight paths was done with and without the model in place. The comparison showed that turbulence intensity levels of up to 50% were experienced in the proximity of the flight deck. These levels fell by 40 to 50% within 1/4 ship length along all approach paths. The starboard yaw approach path contained the greatest turbulence magnitudes and the 0 deg yaw contained the least. Keywords: Turbulence intensity; Bluff body aerodynamics; Spectrum/autocorrelation; Airborne wake; Operating envelopes; Destroyers; Theses. (EDC)