On the Propulsive Performance of Two Oscillating Fins in Series with heave-pitch coupled motions
Date Issued
2011
Date
2011
Author(s)
Chen, Bo-Yang
Abstract
In view of the fact that an underwater glider is lack of horizontal mobility, a concept design of biomimetic propulsor with two oscillating fins in series was proposed and investigated in the previous study to enhance the horizontal mobility without disturbing gliding. A test apparatus was established and a series of tank tests were carried out for clarifying its hydrodynamic characteristics. However, it was found that the propulsion performance of the proposed design is not as good as expected. Then the fixed intermediate plate was removed from the original design, and CFD calculation confirmed that the propulsion performance of the modified design has been improved. However, it was also concluded that the performance of two oscillating fins in series with simply pitch motion may have further improvement.
In the present study, CFD tool of FLUENT is applied to simulate the hydrodynamics of a single oscillating fin with heave-pitch coupled motions, and the results are compared with published experimental data. The validity of FLUENT is confirmed, and then it is applied to the proposed design of two oscillating fins in series with heave-pitch coupled motions.
A series of conditions of heave-pitch coupled motions are investigated. In addition, the effects of motion amplitude, phase angle and frequency to the propulsive performance are also clarified. The effects of the fore fin to improve the overall thrust and propulsion efficiency of two oscillating fins in series are confirmed, and the mechanism is clarified via the distribution of velocity and vorticity.
Subjects
Oscillating fin
Underwater glider
Biomimetics
CFD
Unsteady flow field
Type
thesis
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