Parameter study of power production in wind farms - experimental investigation of interaction of two wind turbines in tandem array

The main goal of this experimental study was to find criteria for optimum total power productions of a tandem array of turbines in a "small" wind farm. Experiment included testing of two models of wind turbines (HAWT) in scale, each one with 0.9 m of rotor diameter. During tests turbine models were coaxial and were tested with 3 different relative distances, separating them denoted as 3D, 5D, and 9D, where D is rotor diameter. Working conditions also were varied by changing the Tip Speed Ratio (TSR) of both turbines and the turbulence intensity of the incoming wind. A hot wire probe was used to scan the velocity field between the model turbines in a defined positions to characterize velocity deficit and the level of the turbulence in disturbed flow

Analysis of the Flow Around the Wind Turbine Profile for Small Reynolds Number.

Celem pracy było wykonanie obliczeń dla opływu profilu aerodynamicznego NACA0018 stosowanego w turbinach wiatrowych małej mocy o pionowej osi obrotu. Do numerycznego modelowania przepływu został wykorzystany program ANSYS CFX. Wyniki obliczeń porównano z badaniami eksperymentalnymi dla określenia dokładności oraz przydatności przyjętej metody do modelowania zjawisk aerodynamicznych w zakresie małych liczb Reynoldsa. Rezultaty pracy mają określić przydatności programu ANSYS CFX do wyznaczenia pola przepływu wokół profilu i określenia jego charakterystyk dla pracy turbiny.The purpose of this study was to calculate of flow an aerofoil NACA0018 which is used in low-power wind turbines with a vertical axis of rotation. ANSYS CFX software was used for the numerical modeling of the flow. The results of calculations were compared with experimental studies to determine the accuracy and usefulness of the method for modeling aerodynamic phenomena. Results of the work may to be used for definition of the suitability of ANSYS CFX to determine the flow field around the airfoil and identify its performance characteristics for wind turbine

Ocena modeli wykonanych w technologii druku 3D przeznaczonych do badań w tunelu aerodynamicznym.

Preparation of an appropriate model to conduct experiments is a crucial aspect of every science investigation. Usually, apart from the requirement to achieve a desired level of a model quality, it is also very important to keep in mind the costs and time of its manufacturing. The following paper provides an overview of various 3D printing techniques. Four models of a standard NACA0018 aerofoil were manufactured in different 3D printing methods. Various parameters of the models have been included in the analysis: surface roughness, dimension tolerance, strength, details quality, surface imperfections and irregularities as well as thermal properties.Odpowiednie przygotowanie modelu do prowadzenia eksperymentów, jest kluczowym elementem każdego badania naukowego. Zazwyczaj, oprócz osiągnięcia wymaganego poziomu jakości, bardzo ważne jest, aby obniżyć koszty i czas jego wykonania. W artykule przedstawiono przegląd kilku technik druku 3D. Na potrzeby badań powstały cztery standardowe modele profili aerodynamicznych - NACA0018, wykonane różnymi metodami druku 3D. Zestawiono następujące parametry wykonanych modeli: chropowatość powierzchni, tolerancja wymiaru, wytrzymałość, jakość odwzorowania szczegółów, niedoskonałości i nieprawidłowości powierzchni, jak również właściwości termiczne

Experimental Investigation of the Cooperation of Wind Turbines

The article discusses the wind tunnel experimental investigation of two turbines (the downstream unit placed fully in the wake of the upstream one) at various turbulence intensity levels and wind turbine separation distances, at a Reynolds number of approximately 105. The velocity deficit due to the upstream turbine operation is reduced as the wake mixes with the undisturbed flow, which may be enhanced by increasing the turbulence intensity. In a natural environment, this may be provoked by natural wind gusts or changes in the wind inflow conditions. Increased levels of turbulence intensity enlarge the plateau of optimum wind turbine operation—this results in the turbine performance being less prone to variations of tip speed ratio. Another important set of results quantifies the influence of the upstream turbine operation at non-optimal tip speed ratio on the overall system performance, as the downstream machine gains more energy from the wake flow. Thus, all power output maximisation analyses of wind turbine layout in a cluster should encompass not only the locations and distances between the units, but also their operating parameters (TSR, but also pitch or yaw control of the upstream turbine(s))