Supercavitating vehicles are characterized by substantially reduced hydrodynamic
drag with respect to fully wetted underwater vehicles. Drag is localized at the nose of the
vehicle, where a cavitator generates a cavity that completely envelops the body. This causes
the center of pressure to be always ahead of the center of mass, thus violating a fundamental
principle of hydrodynamic stability. This unique loading configuration, the complex and
non-linear nature of the interaction forces between vehicle and cavity, and the unsteady
behavior of the cavity itself make the control and maneuvering of supercavitating vehicles
particularly challenging. This study represents an effort towards the evaluation of optimal
trajectories for this class of underwater vehicles, which often need to operate in unsteady
regimes and near the boundaries of the flight envelope.
Flight trajectories and maneuvering strategies for supercavitating vehicles are here obtained
through the solution of an optimal control problem. Given a cost function and
general constraints and bounds on states and controls, the solution of the optimal control
problem yields the control time histories that maneuver the vehicle according to a desired
strategy, together with the associated flight path. The optimal control problem is solved using
the direct transcription method, which does not require the derivation of the equations
of optimal control and leads to the solution of a discrete parameter optimization problem.
Examples of maneuvers and resulting trajectories are given to demonstrate the effectiveness
of the proposed methodology and the generality of the formulation.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/4848 |
| Date | 07 December 2004 |
| Creators | Kamada, Rahul |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
| Format | 2910284 bytes, application/pdf |
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