Flow Simulation around a Rotating Airfoil (VAWTs) : insight into Performance and Dynamics of Vertical Axis Wind Turbines

Details

Supervisors

Winckelmans, Grégoire ; Chatelain, Philippe

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil mécanicien, à finalité spécialisée

Abstract

This master’s thesis presents a comprehensive study on the aerodynamics of rotating airfoils within the context of Vertical Axis Wind Turbines (VAWTs). The study employs a novel methodology that combines Eulerian and Lagrangian techniques to analyze the dynamics of a moving airfoil. Adapted from Billuart et al.’s [1] work, this approach is tailored for individual moving bodies with predefined motions. The methodology integrates an Arbitrarily Lagrangian-Eulerian (ALE) formulation within the Finite Difference on Orthogonal Mesh (FDoom) solver, coupled with the Vortex Particle-Mesh (VPM) method that combines Lagrangian particles and an Eulerian grid for simulating incompressible flows. This coupling between the two computational domains, Eulerian and Lagrangian, enables a comprehensive advantages for the flow simulation in dynamic bodies. In this study of the aerodynamics of the rotating airfoil, various case studies and comparison among conducted, varying parameters such as Tip Speed Ratio (λ), Solidity (σ), and Radius to Chord Ratio (R/c) for Reynolds numbers of 200, 500, and 1000. The work is rooted in the longstanding study of vertical axis wind turbines (VAWTs), with references spanning both historical and contemporary sources. The primary objectives of the study encompass investigating flow patterns, understanding interactions, and validating results. The validation process involves detailed analysis of specific cases, particularly focusing on correlations between airfoil torque, power coefficients, and key factors including Angle of Attack (α), stall, lift, and drag coefficients. A comprehensive comparison across the range of case studies further contributes to the insights gained. Crucial dimensionless formulas are introduced to characterize various aspects of the system. These formulas include normalized time, solidity, torque, power, lift, and drag coefficients. They provide a concise framework for understanding and analyzing key parameters within the realm of airfoil aerodynamics. The study also investigates the impact of parameters such as Reynolds number and dynamic stall, leading to insights into the behaviour of vortex shielding and its effects on the airfoil’s performance. The results of the study highlight the complex flow dynamics around the rotating airfoil, with the visualization of significant changes in vortex formations among various cases. The interaction between the airfoil and these vortices is examined, shedding light on the implications for power coefficients and overall turbine performance. By dissecting the variations in lift, drag, and torque coefficients with changing parameters, a deeper understanding of the airfoil’s behavior is achieved. This research contributes to the existing knowledge in the field of VAWTs and provides valuable insights for the design and optimization of such systems.