Investigation on parametrically excited motions of point absorbers in regular waves.
Citation:
Kevin Tarrant, Craig Meskell, Investigation on parametrically excited motions of point absorbers in regular waves., Ocean Engineering, 111, 2016, 67 - 81Download Item:
Abstract:
Free
floating objects such as a self
-
reacting wave energy converter (WEC), may experience a
condition known as parametric resonance. In this situation, at least two degrees of freedom
become coupl
ed when the incident wave has a frequency approximately twice the pitch or
roll natural frequency. This can result in very large amplitude motion in pitch and/or roll.
While classic linear theory has proven sufficient for describing small motions due to sm
all
amplitude waves, a point absorber WEC is often designed to operate in resonant conditions,
and therefore, exhibits significant nonlinear responses. In this paper, a time
-
domain
nonlinear numerical model is presented for describing the dynamic stability
of point
absorbers. The pressure of the incident wave is integrated over the instantaneous wetted
surface to obtain the nonlinear Froude
-
Krylov excitation force and the nonlinear hydrostatic
restoring forces, while first order diffraction
-
radiation forces
are computed by a linear
potential flow formulation.
A numerical benchmark study for the simulation of parametr
ic
resonance of a specific WEC
-
the Wavebob
-
has been implemented and validated against
experimental results. The implemented model has shown
good accuracy in reproducing
both the onset and steady state response of parametric resonance. Limits of stability were
numerically computed showing the instability regions in the roll and pitch modes
Sponsor
Grant Number
IRCSET (OK)
Author's Homepage:
http://people.tcd.ie/cmeskellDescription:
PUBLISHED
Author: MESKELL, CRAIG
Type of material:
Journal ArticleSeries/Report no:
Ocean Engineering;111;
Availability:
Full text availableDOI:
http://dx.doi.org/10.1016/j.oceaneng.2015.10.041Metadata
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