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State-of-Art Comprehensive Aeromechanics Analysis and Disruptive Technologies in Wind Turbines

Principal Investigator(s): 

Abstract: 

The Alfred Gessow Rotorcraft Center (AGRC) at the University of Maryland has been at the forefront of rotor technology since its founding in 1982. The Center carries out multidisciplinary research involving aerodynamics, dynamics, stability, CFD, acoustics, composite structures, transmission and drive trains, design, and smart structures. The research program at the Center is very vibrant, and over the years, there has been a phenomenal production of research publications and graduate engineers related to the rotary-wing systems. Many of our students are now playing a leading role in wind energy, and some of our faculty members are called upon frequently in an advisory role.

 
Comprehensive Analysis Methodology: Over the years, we have developed a finite-element/multibody based comprehensive rotor analysis that covers state-of-the-art aerodynamics, nonlinear dynamics and composite modeling, and is widely used by rotorcraft industry. Each blade is modeled as an elastic beam undergoing large flap and lag bending, elastic twist and axial deformation. It has the capability to consistently couple the CFD analysis with structural dynamic analysis, and can model a range of hub configurations with redundant load paths. Recently, there have some attempts to upgrade this methodology for wind turbines. The goal of the proposed research is to upgrade this comprehensive aeromechanics analysis capability for modern wind turbines by systematically including gravity, tower shadow, earth boundary layer and drive-train effects and validate it systematically with available test data for a wide range of wind turbines.
 
Revolutionary Vertical Axis Turbine: Most of the current research activities in wind turbines are focused on horizontal axis turbines. However, there have been some selected attempts in vertical axis wind turbines, called as Darrieus turbines. Recently at AGRC, we have developed a revolutionary cyclocopter system that has enormous potential for its transition into a vertical axis wind turbine. Using a passive cyclic pitch control, it has been demonstrated that the wind energy can be efficiently harvested. We have carried out systematic testing of a range of cycloidal configurations in the wind tunnel and the detailed loads and flow measurements were successfully validated with multibody dynamics analysis. Using this comprehensive design methodology, we propose to develop revolutionary wind turbines, especially for an urban setting.
 
Composite Tailored Couplings: Because of superior fatigue characteristics with composite materials, rotor blades are now routinely built as a laminated structure. Unbalanced ply lay-up in a laminated blade section can introduce structural couplings such as bending-torsion and extension-torsion, which can have an enormous impact on the aeromechanics of a rotor blade. Recently at AGRC, scaled rotor model tests in wind tunnel demonstrated that tailored composite couplings could significantly increase rotor performance, reduce vibratory loads, and increase blade stability. The objective of the proposed research is to examine this disruptive technology in wind turbines to improve the rotor performance and operating life of blades.