Computational Fluid Dynamics Study for Optimization of a Fin Design
Abstract
The three-dimensional, unsteady computations of an Unmanned Underwater vehicle with flapping fins were carried out. Several parametric studies were performed varying the amplitude and frequency of oscillation of the fin and the angle of attack of the fin at the root. The objective of these computations was to investigate the importance of these parameters on the fluid dynamics of force production in order to propel the vehicle at a constant speed of 3 kt. An unstructured grid-based unsteady Navier-Stokes solver with automatic adaptive remeshing was used to compute the flow about the vehicle through several complete cycles of fin oscillation for each of the cases studied. The computations show that the angle of attack of 20 of the root section of the fin is near optimum. The vehicle is capable of sustaining a 3 kt current and maintaining position with the fins flapping at a frequency of 2 Hz and an amplitude of 11 4%. As the frequency of oscillation is increased, the net thrust produced increases, but the vehicle will be subjected to large excursions in the normal force. As the fin is made rigid, there is a substantial penalty in lift during the upstroke.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 28, 2005
- Accession Number
- ADA441476
Entities
People
- Ravi Ramamurti
- William C. Sandberg
Organizations
- United States Naval Research Laboratory