Lab Affiliation(s):
Laboratory for ship and platform flow
Advisor:
Paul Sclavounos
Areas of Expertise:
  • Computational hydrodynamics
  • Wave structure interaction
  • Offshore wind energy
Expected date of graduation:
September 1, 2017

Yu Zhang

  • PhD

Department: 

  • Mechanical Engineering

Lab Affiliation(s): 

Laboratory for ship and platform flow

Advisor: 

Paul Sclavounos

Top 3 Areas of Expertise: 

Computational hydrodynamics
Wave structure interaction
Offshore wind energy

Expected date of graduation: 

September 1, 2017

CV: 

Thesis Title: 

Nonlinear Wave Loads on Offshore Wind Turbines and Fatigue Analysis

Thesis Abstract: 

Wind energy is one of the more viable sources of renewable energy and offshore wind

turbines represent a promising technology for the cost effective harvesting of this

abundant source of energy. To capture wind energy offshore, horizontal-axis wind

turbines can be installed on offshore platforms and the study of hydrodynamic loads

on these offshore platforms becomes a critical issue for the design of offshore wind

turbine systems.

A versatile and efficient hydrodynamics module was developed to evaluate the

linear and nonlinear loads on floating wind turbines using a new fluid-impulse formulation

— the Fluid Impulse Theory(FIT). The new formulation allows linear and

nonlinear loads on floating bodies to be computed in the time domain, and avoids

the computationally intensive evaluation of temporal and spatial gradients of the velocity

potential in the Bernoulli equation and the discretization of the nonlinear free

surface. The module computes linear and nonlinear loads — including hydrostatic,

Froude-Krylov, radiation and diffraction, as well as nonlinear effects known to cause

ringing, springing and slow-drift loads — directly in the time domain and a stochastic

seastate. The accurate evaluation of nonlinear loads by FIT provides an excellent alternative

to existing methods for the safe and cost-effective design of offshore floating

wind turbines.

The time-domain Green function is used to solve the linear and nonlinear freesurface

problems and efficient methods are derived for its computation. The body

instantaneous wetted surface is approximated by a panel mesh and the discretization

of the free surface is circumvented by using the Green function. The evaluation of the

nonlinear loads is based on explicit expressions derived by the fluid-impulse theory,

which can be computed efficiently.

Contact Information:
77 MASSACHUSETTS AVENUE
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Cambridge
Massachusetts
02139
6173351334