hydrodynamics, soil characteristics, floating2. types of structures potentially applicable for...

Science & The Energy Challenge in Offshore Wind, 20th of May 2014 Science & The Energy Challenge in Offshore Wind, 20th of May 2014 Science & The Energy Challenge in Offshore Wind, 20th of May 2014

Prof. Andrei V. Metrikine

Hydrodynamics, Soil Characteristics, Floating

Science & The Energy Challenge in Offshore Wind, 20th of May 2014 Science & The Energy Challenge in Offshore Wind, 20th of May 2014

Content

1.  Offshore structures used in oil/gas industry 2.  Types of structures potentially applicable for Offshore Wind

3.  What is special about Offshore Wind structures 4.  Hydrodynamics

•  Monopile support

•  Jacket support •  Floating

5.  Soil-structure interaction


Types of offshore structures used in oil/gas industry


Potentially suitable for Offshore Wind apps structures

1.  Bottom founded – monopile; 2.  Bottom founded – jacket;

3.  Gravity based; 4.  Floating/bottom founded – mini TLP (tension leg platform)

5.  Floating+moored semisubmercible

6.  Floating+moored SPAR


What is special about OW structures?

1.  Coupled aero-hydro-soil-structure dynamic interaction with active control (sometimes complicated by ice).

2.  Relatively high for shallow water (in terms of offshore engineering) overturning moments.


Hydrodynamics: monopile support

1.  Simultaneous action of currents and waves 2.  Should not we stop using the Morison’s equation?

3.  How much is the hydroelastic interaction influenced by the aeroelastic interaction and control?

4.  Breaking waves, sloshing and ringing.


Hydrodynamics: jacket support

1.  We should stop using the Morison’s equation!

2.  Simultaneous action of currents and waves, local vorticity

3.  How much is the hydroelastic interaction influenced by the aeroelastic interaction and control?

4.  Breaking waves, sloshing.


Hydrodynamics: floating


Hydrodynamics: floating

1.  Simultaneous action of currents and waves in terms of potential occurrence of the VIV (Vortex Induced Vibration).

2.  Simultaneous hydro-aero-elastic modelling. 3.  Breaking waves and sloshing.

4.  Mooring lines (added damping, capacity, fixation to the seabed).

5.  Should we design for potential emergency disconnection?


Soil-structure interaction: challenges focused on monopiles

1.  Identification of the dynamic soil properties before and after the installation (stiffness and damping against the monopile motion).

2.  Long term stability under the specific and highly dynamic OWT loads.

3.  Extreme loads, post holing and self-healing. 4.  Pile driving: noise reduction in case of hydraulic driving,

improvement of the vibratory pile driving capacity.


Identification of the dynamic soil properties (to know the natural frequency and dissipation in soil-

structure interaction)


Identification of the dynamic soil properties (to know the natural frequency and dissipation in soil-

structure interaction)

1.  The identification seems to require the full wave inversion and special type of excitation.

2.  Can we in principle identify the dynamic soil properties before the installation?


Long term stability, extreme loading, post holing, self healing

1.  Not much seems to be known as yet for the offshore applications.

2.  PISA project may shed some light on the first item.


Pile driving by hammering: noise reduction

We need to be able to screen the noise


Pile driving by shakers: smart shaking with the aim to enable a deeper piling

Currently we can drive the piles till a certain depth only… after that the driving method is changed to the hammering.

Challenge: development of smart vibratory patterns.

hydrodynamics, soil characteristics, floating2. types of structures potentially applicable for...

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