In this master thesis project the initial steps for the design of a new wind tunnel
for aeroacoustic measurements are made. Well-documented sizing methods for
different wind tunnel parts were found in a literature study and were used
together with 2D CFD simulations to create a new wind tunnel design. Thick
corner vanes were used in this design with the purpose of using them as baffle
mufflers to create a better environment for aeroacoustic measurements inside the test section. The performance of the wind tunnel was evaluated thereafter by 3D CFD simulations. The 3D simulations provide an idea of the flow velocities, the flow uniformity, turbulence intensities, pressure losses and noise sources inside the wind tunnel. Since an existing wind tunnel fan and 42 kW motor was to be reused, noise measurements were done to find the noise characteristics of the fan-motor combination and to have an idea of how noise would propogate in
the environment were the new wind tunnel would be placed. After the noise
measurements, predictions of the transmission loss through the corner vanes
were made by using finite element analyses.

Material bend-twist coupling has been widely studied in the research community as a passive control mechanism for a wind turbine. However, there is a lack of research in incorporating it in the rotor design process, with little research being conducted for its application to small wind turbines. The present study focuses on this issue by including bend-twist coupling in the design of a 500W wind turbine by using a combination of parametric studies and a multidisciplinary constrained optimisation approach. By doing so, it aims to establish the effectiveness of bend-twist coupling as a tool for passive load alleviation in small wind turbines. The effectiveness is tested through obtaining a significant decrease in the flapwise blade root bending moment accompanied by only a marginal decrease in the AEP, when compared with the baseline uncoupled turbine. The reference blade is designed under limitations imposed by the rules of the Small Wind Turbine Design Contest. Bend-twist coupling is introduced in the blades with a fixed aerodynamic design. The rotor performance is analysed inHAWCStab2. The internal structure of the blade is created with the intention of producing flexible blades with a single composite material used throughout the blade. Carbon-epoxy and glass-epoxy FRPs are considered as the material to be chosen in the unidirectional laminae. The cross-sectional stiffness analysis is conducted using BECAS for a range of fibre layup angles in both carbon-fibre and glass-fibre blades. Carbon outperformed glass for all fibre angles with regard to the amount of coupling seen in the crosssections. Apart from flapwise bend-twist coupling, other secondary torsion couplings are also present. A load response study is carried out for varying positive fibre layup angles in both carbon-fibre and glass-fibre blades, under steady wind conditions for the operational wind speed range. An increase in the flapwise blade tip displacement and a reduction in the flapwise bending loads with increasing fibrelayup angles is observed for both glass-fibre and carbon-fibre blades. The HAWTOpt2 aero-structural design tool using OpenMDAO as its core is utilised to implement the optimisation. The spanwise fibre layup angle and laminate thickness distribution are the only design variables that were allowed to be manipulated by the optimiser. The objective function is comprised of two different individual objective functions weighed according to the situation. The optimisation cases failed due to inaccurate gradients of the objective function and constraints. Due to time constraints the manufacturing of the blade and, static load and wind tunnel testing were not carried out.

Given the prime importance of wind tunnel setup when it comes to aero-elastic study, the main intent of this project is to devise a mechanism for supporting system of 2D aero-elasticity experiment in the Red Wind Tunnel Facility at DTU that allows three-degree-of-freedom motion of the rigid model. This project work is mainly inspired by the fact that deep stall aero-elastic
Characteristics of wind turbines, which govern the design of stall-regulated wind turbines at high wind speed, have been barely investigated in literatures so far. So in redesigning the test section of the wind tunnel facility the following sub-tasks are included: (1) Literature survey on test section design/construction for 2D aero-elastics testing of aerofoils. (2) Panel code simulation of wing/tunnel interaction. (3) Adapted design of new test section to the Red wind tunnel facility. (4) To some extent building and testing the new test section. The implementation and actual design may be too time demanding to be fulfilled within the given time slot, however a specific design for the Red tunnel facility is documented through flow analysis and drawings at the end of the project. Among which the first and third item have been addressed and the fourth item partially as well, but the second item is still to be done with the flow solver Q3UIC which was developed by Néstor in DTU. Since the aerodynamic code of this tool is only for pitching motion, extending this tool for this thesis work happened to be out of scope.