A supercavitating vehicle, a next-generation underwater vehicle
capable of changing the paradigm of modern marine warfare, exploits
supercavitation as a means to reduce drag and achieve extremely high
submerged speeds. In supercavitating flows, a low-density gaseous
cavity entirely envelops the vehicle and as a result the vehicle is
in contact with liquid water only at its nose and partially over the
afterbody. Hence, the vehicle experiences a substantially reduced
skin drag and can achieve much higher speed than conventional
vehicles. The development of a controllable and maneuvering
supercavitating vehicle has been confronted with various challenging
problems such as the potential instability of the vehicle, the
unsteady nature of cavity dynamics, the complex and non-linear
nature of the interaction between vehicle and cavity. Furthermore,
major questions still need to be resolved regarding the basic
configuration of the vehicle itself, including its control surfaces,
the control system, and the cavity dynamics. In order to answer
these fundamental questions, together with many similar ones, this
dissertation develops an integrated simulation-based design tool to
optimize the vehicle configuration subjected to operational design
requirements, while predicting the complex coupled behavior of the
vehicle for each design configuration. Particularly, this research
attempts to include maneuvering flight as well as various operating
trim conditions directly in the vehicle configurational
optimization. This integrated approach provides significant
improvement in performance in the preliminary design phase and
indicates that trade-offs between various performance indexes are
required due to their conflicting requirements. This dissertation
also investigates trim conditions and dynamic characteristics of
supercavitating vehicles through a full 6 DOF model. The influence
of operating conditions, and cavity models and their memory effects
on trim is analyzed and discussed. Unique characteristics are
identified, e.g. the cavity memory effects introduce a favorable
stabilizing effect by providing restoring fins and planing forces.
Furthermore, this research investigates the flight envelope of a
supercavitating vehicle, which is significantly different from that
of a conventional vehicle due to different hydrodynamic coefficients
as well as unique operational conditions.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/16237 |
| Date | 09 May 2007 |
| Creators | Ahn, Seong Sik |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Detected Language | English |
| Type | Dissertation |
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