A Hydrofoil Instrument Platform for Obtaining Profiles of Ocean Properties.
Abstract
Results are reported of a feasibility study of a hydrofoil instrument platform to obtain profiles of ocean properties for long deployment periods. The platform uses a low-Reynolds-number, controlled, hydrodynamic lift device to 'fly' the instrument package up and down the water column along a taut cable. Because local currents will drive the platform vertically, power requirements will be low and long deployments will be possible. Because only a single set of sensors will be required to cover the vertical range desired, the system will be low-cost and, for most applications, expendable. Additionally, the system will provide greater vertical resolution that could be provided by a series of fixed multiple sensors. Aspects of the concept studied include: platform neutral buoyancy, water density variations, minimum operating current versus platform size, direction reversal mechanisms, tethering methods, electrical power requirements, and data transmission links. A delta wing configuration was selected for the hydrofoil due to its high lift at low current speeds and its overall compact shape. Tow tank model tests demonstrated operation at low Reynolds numbers and operation of a passive mechanism for direction reversal. The lift characteristics of the model agreed with theory and the passive mechanism successfully changed the direction of the model at the top and bottom of the tank. It was concluded that the concept is feasible. A design for a system to be used in ice-covered Arctic seas is proposed. It would operate in currents as low as 3 cm/s and gather data over a vertical range of 300 m for periods of up to one year.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1986
- Accession Number
- ADA168625
Entities
People
- D. C. Echert
- D. J. Hanzlick
- E. W. Geller
- James Morison