University of Twente Student Theses


A novel construction of wind tunnel models for wind energy applications

Valk, Y.A. de (2019) A novel construction of wind tunnel models for wind energy applications.

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Abstract:Transition from fossil-fuels as the prominent form of energy to renewable sources has led to the revival of wind turbines for large scale power production. Efficiency at which wind turbines convert the kinetic energy of the wind into electric power highly depends on the design of the turbine rotor blades. The process of designing rotor blades nowadays relies heavily upon numerical simulations using both panel codes (XFOIL) and Navier-Stokes solvers. Predictions using these numerical methods, within the re- gion of their applicability, are in fair agreement with experimental data. However in regimes beyond aerodynamic stall and for very thick airfoils their predictions start to deviate significantly. As such, in these cases, no reliable data is available for further rotor blade design. Therefore the need to verify two- dimensional characteristics of airfoils outside the applicability of numerical methods using experimental techniques remains. The wind tunnel of the Engineering Fluid Dynamics (EFD) group at the University of Twente (UT) is an open-jet closed-circuit wind tunnel. Airfoil models with a chord length up to 0.3 m which, together with a maximum jet velocity of 60 m/s at free stream turbulence intensities below 0.08%, enable chord based Reynolds numbers around 1 million to be reached in this tunnel. To further enhance the capabilities for aerodynamic research and education on (wind turbine) aerodynamics an instrumented airfoil model was desired. An instrumented DU97-W-300 airfoil model representative for wind turbine applications is designed and manufactured at the UT. An experimental campaign measuring the aerodynamic characteristics such as lift, drag and moment is executed in the EFD wind tunnel facility. For deriving the aerodynamic lift force, surface pressures are measured using an array of pressure taps around the model perimeter. Wake velocities downstream the model are measured to determine the aerodynamic drag. The obtained data matches that available in literature such that the model is suitable for publishable research. Moreover, model manufacturing was accomplished completely at the UT presenting the aerodynamic experimental capabilities within the EFD group. Besides this work a two-dimensional numerical analysis is performed on the corresponding airfoil shape to asses the predictive accuracy of Navier-Stokes solvers with respect to panel codes and experimental data.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
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