Performance Study of Wind Turbines with Bend-Twist Coupled Blades at Underrated Wind Speeds

Atalay, Oğuz
Farsadi, Touraj
Kayran, Altan
Use of bend-twist coupled blades is one of the ways to alleviate fatigue loads in wind turbine systems. Load reduction is achieved by placing off-axis layers in the spar caps of composite wind turbine blades. Off-axis layers provide twisting of the blade in the feathering direction thereby decreasing the aerodynamic loads due to the reduced effective angle of attack. Reduction of fatigue loads in the wind turbine system is generally measured by the damage equivalent load. In the present study, performance of bend-twist coupled blades designed for a 5 MW wind turbine is investigated for the wind speeds ranging from the cut-in speed to the overrated wind speeds. The initial analysis of the wind turbine is done at the overrated speed of 15 m/s and it is shown that reduction in damage equivalent loads is achieved at almost no loss in the rated power compared to the reference wind turbine with the baseline blade. However, it is also demonstrated that at the underrated speeds; although reduction in damage equivalent loads can still be achieved with the bend-twist coupled blade, power loss occurs compared to the reference turbine. This study aims to make a performance study of wind turbine systems with bend-twist coupled blades in terms of load reduction achieved and power production and to propose modifications to simultaneously reduce the generator power losses and damage equivalent loads. As a preliminary design modification, it is shown that by reducing the pre-twist angle of the bend-twist coupled sections of the blades, it has been possible to eliminate the power loss disadvantage of wind turbines at the underrated wind speeds, while still achieving reduction in damage equivalent loads.


Structural Performance and Power Production of Wind Turbine Systems with Bend-Twist Coupled Blades in Underrated Wind Conditions
Şener, Özgün; Kayran, Altan (2018-01-12)
The implementation of bend-twist coupling effect on wind turbine blades on the structural performance and power production of wind turbine system exposed to underrated wind conditions are studied. The structural performance of wind turbine systems are evaluated by the decrease in damage equivalent loads in the whole wind turbine system and reduction in maximum fiber direction stresses in the blades with the exploitation of off-axis plies in the main spar caps of the wind turbine blades. Wind turbine models ...
Load Reduction in Wind Turbines with Bend-Twist CoupledBlades without Power Loss at Underrated Wind Speeds
Atalay, Oğuz; Kayran, Altan (null; 2018-01-01)
Usage of composite materials in wind turbine blades is a passive mechanism to alleviate fatigue loads besides the reduction in the mass of the wind turbine system. Off-axis plies in bend-twist coupled (BTC) blades account for the passive fatigue load reduction by reducing the effective angle of attack of blade sections. Reduction in fatigue loads is generally represented by damage equivalent load ratios. In the present study, multibody aeroelastic analyses are performed for wind turbine systems for the unde...
Classical Aeroelastic Stability Analysis of Large Composite Wind Turbine Blades
Farsadi, Touraj; Kayran, Altan (2016-01-04)
To achieve higher energy production bigger wind turbine systems with very long blades are increasingly used in the wind turbine industry. As the length of the wind turbine blades is increased, blades become more flexible in bending and torsion. Increased bending and torsional flexibility of long wind turbine blades may cause torsional divergence and flapwise bending-torsion flutter at high speeds. Therefore, it is important that aeroelastic stability characteristics of the blades be investigated to ensure t...
Aeroelastic Stability Evaluation of Bend Twist Coupled Composite Wind Turbine Blades Designed for Load Alleviation in Wind Turbine Systems
Farsadi, Touraj; Kayran, Altan (2016-01-04)
Wind turbine blades for turbines with large rotor diameter tend to be very flexible in order to remain weight and cost effective. Bending-twisting coupling induced in big composite wind turbine blades is one of the passive control mechanisms which is exploited to alleviate loads incurred due to the flexing of the blades. In the present study, aeroelastic stability characteristics of bend-twist coupled blades, designed for load alleviation in wind turbine systems, is investigated to check whether the bending...
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The atomization problem of high speed viscous jets has many applications in industrial processes and machines. In all these applications, it is required that the droplets have high surface area/volume ratio meaning that the droplets should be as small as possible. This can be achieved with high rates of turbulence and mixing of the flow. In order to constitute a foresight of geometry e ects on droplet size, experimental investigation and the determination of flow characteristics in near and far fields of a ...
Citation Formats
O. Atalay, T. Farsadi, and A. Kayran, “Performance Study of Wind Turbines with Bend-Twist Coupled Blades at Underrated Wind Speeds,” 2017, Accessed: 00, 2021. [Online]. Available: