Research

Dr. Amrit Verma, Dr. Andrew Goupee, and Dr. Yifeng Zhu have been awarded a $300k NSF EAGER grant to study the root causes of intricate oscillation orbits in the nacelle of bottom-fixed offshore wind turbines during installation. Their project will include a unique model-scale experiment in a wave tank and the development of a digital twin using Generative Artificial Intelligence (AI) to predict real-time orbital motions during installation. Additionally, the project will involve collaboration with Bangor High School to provide research internships to high school students, as well as partnerships with the National Renewable Energy Lab (NREL), Equinor - a global leader in offshore wind farm development), and Kartorium - an Alaska-based digital twin company.

Experimental Basin Scale Tow Testing

• Barge-type FOWT tow testing in two different towing orientations.

• Measure towline tensions, 6DOF motions, video camera feed, and wave height.

• Determine drag coefficient of foundation shape, calculate added resistance in waves, analyze wake profiles observe FOWT motion behavior over a range of tow speeds.

Towing Prediction Calculations

• Predict towline tensions, bollard pull, and dynamic tensions in the presence of waves.

• Validate the numerical model using past towing operations i.e., VolturnUS 1:8 2013.

• Perform parametric studies to inform future towing operations and predict required vessels and towline configurations.

A wake is defined as the region of disturbed flow behind an object. This region is characterized by reduced velocity and increased turbulence. As the flow progress downstream the wake becomes wider, and the velocity recovers slowly. In wind farms, downstream wind turbines are often operating in upstream turbines’ wakes leading to overall power losses and increased fatigue on blades. In addition, wakes dynamics are affected by the surrounding environmental conditions. If atmospheric stability has been found to influence strongly the wake recovery of a wind turbine, fewer studies have investigated the effect of meteorological conditions such as rain on the wake characteristics. Studies on particle-laden flows have indicated that inertial particles could either enhance or reduce the turbulence by interacting with the carrier flow. The aim of this project is to perform wind tunnel experiments to study water droplets influence on the velocity deficit recovery and turbulence features of the wake.

As wind turbine blades become larger, the impact of edgewise gravity loads becomes increasingly critical, leading to several issues. One significant problem is breathing, which refers to the cyclic out-of-plane motion of the trailing edge panels caused by edgewise gravity loads on wind turbine blades during blade rotation and results in increased peel stresses in the adhesive joint at the trailing edge, resulting in fatigue failure and, in severe cases, trailing edge splitting. 

This research aims to investigate the effect of wind turbine blade breathing on trailing edge life prediction using an aerospace-motivated Durability and Damage Tolerance Analysis (DADTA) approach. Durability analysis uses a structural fatigue approach to predict structural life without defects during the initial design phase.  On the other hand, damage tolerance analysis uses a fracture mechanics approach and a damage growth method to update the structural life prediction to address manufacturing defects and damage incurred during system operation. Though the DADTA approach is mandated in the aerospace community to determine structural life, it has yet to be widely adopted within the wind turbine blade industry.  

Non-crimp fabric (NCF) composites are a popular choice for applications in aerospace and wind energy due to their high in-plane strength and stiffness. Despite these advantages, NCF composite are susceptible to damages from transverse impact loads, compromising their structural integrity. Addressing this challenge, fiber hybridization has been identified as a promising method to enhance the damage tolerance of these materials. This project specifically explores the effect of interlayer hybrid fiber composites, employing alternating layers of glass and carbon, to improve the mechanical properties, impact behavior, and post-impact loading of NCF composites.