Session: 13-03-05: General: Mechanics of Solids, Structures and Fluids V

Paper Number: 165323

Enhanced Blade Element Momentum Theory for Biplane Configuration 

The aerodynamic performance of wind turbine blades is crucial for optimizing energy capture and efficiency in renewable energy systems. This paper presents an advanced aerodynamic modeling approach for biplane wind turbine blades, focusing on the improved Blade Element Momentum (BEM) theory. Traditional BEM methods, while widely used, often struggle to accurately predict complex flow phenomena associated with wind turbine operations, such as dynamic stall, unsteady aerodynamics, and three-dimensional effects. To address these limitations, the improved BEM theory integrates advanced aerodynamic modeling techniques, including dynamic stall models and refined tip loss corrections, thereby enhancing predictive accuracy. The study begins with a comprehensive review of existing aerodynamic modeling methods, highlighting the strengths and weaknesses of classical BEM theory. The improved BEM theory is formulated to incorporate corrections for wake rotation, radial flow components, and dynamic stall effects, allowing for a more accurate representation of the aerodynamic forces acting on biplane configurations, which consist of two closely spaced airfoils. The interactions between the upper and lower blades introduce additional complexities that traditional models may overlook, making the improved BEM particularly suitable for analyzing biplane designs. Numerical investigations are conducted to evaluate the effects of key design parameters, including pitch angle, decalage angle, gap, and stagger ratios, on the aerodynamic performance of biplane wind turbine blades. Results demonstrate that optimizing these parameters can lead to significant improvements in lift-to-drag ratios and overall aerodynamic efficiency. Specifically, positive pitch angles applied to the upper airfoil yield the best performance, while negative pitch angles result in decreased efficiency due to increased drag and flow separation. Validation of the improved BEM theory is performed using experimental data obtained from wind tunnel tests on various biplane configurations. The comparison between theoretical predictions and empirical measurements shows that the enhanced BEM accurately captures the aerodynamic behavior of biplane blades, with reduced discrepancies in lift and drag coefficients across different operating conditions. The findings of this research underscore the potential of biplane configurations to enhance the aerodynamic performance of wind turbine blades. The improved BEM theory provides a comprehensive framework for accurately modeling the complex interactions inherent in biplane designs, facilitating the optimization of blade geometries for improved energy capture. Notably, the study reveals for biplane configuration, up to a 48% increase in aerodynamic efficiency and a 34% reduction in drag when optimal pitch and decalage angles are applied compared to thick monoplane inboard section. These results contribute significantly to advancements in wind energy technologies, highlighting the importance of refined aerodynamic modeling in the design and optimization of future wind turbine systems. The insights gained from this research pave the way for further exploration of biplane configurations in various wind energy applications.

Presenting Author: Cai Xia Yang University of North Dakota

Presenting Author Biography: Dr. Yang is an Associate Professor of Mechanical Engineering at the University of North Dakota where she conducts research in Nonlinear Dynamics, Data Analysis, Stability Analysis, Fault Detection and classification using vibration signals, estimation of center of mass and center of pressure using measured data, and posture stability analysis.

Authors:

Md Saifuddin Ahmed Atique University of North Dakota
Cai Xia Yang University of North Dakota