A New Miniature Wind Turbine for Wind Tunnel Experiments. Part I: Design and Performance

Abstract

Miniature wind turbines, employed in wind tunnel experiments to study the interaction of turbines with turbulent boundary layers, usually suffer from poor performance with respect to their large-scale counterparts in the field. Moreover, although wakes of wind turbines have been extensively examined in wind tunnel studies, the proper characterization of the performance of wind turbines has received relatively less attention. In this regard, the present study concerns the design and the performance analysis of a new three-bladed horizontal-axis miniature wind turbine with a rotor diameter of 15 cm. Due to its small size, this turbine, called WiRE-01, is particularly suitable for studies of wind farm flows and the interaction of the turbine with an incoming boundary-layer flow. Especial emphasis was placed on the accurate measurement of the mechanical power extracted by the miniature turbine from the incoming wind. In order to do so, a new setup was developed to directly measure the torque of the rotor shaft. Moreover, to provide a better understanding on the connection between the mechanical and electrical aspects of miniature wind turbines, the performance of three different direct-current (DC) generators was studied. It is found that electrical outputs of the tested generators can be used to provide a rather acceptable estimation of the mechanical input power. Force and power measurements showed that the thrust and power coefficients of the miniature turbine can reach 0.8 and 0.4, respectively, which are close to the ones of large-scale turbines in the field. In Part II of this study, the wake structure and dynamic flow characteristics are studied for the new miniature turbine immersed in a turbulent boundary-layer flow.

Wind farm power optimization via yaw angle control: A wind tunnel study

“…The model wind turbine employed in this wind tunnel study was developed in the previous studies of the authors. 29,30 It is a three-bladed horizontal-axis miniature wind turbine with a rotor diameter D of 15 cm and a hub height z h of 12.5 cm. Given its small size, this turbine is especially suitable for wind tunnel simulations of large wind farms.…”

“…A servo-electric controller (henceforth referred to as the RPM controller) is connected to each DC generator to simultaneously monitor and control the value of the rotational velocity X as well as the electrical current i generated by the DC machine. We then use torque calibration of the DC machine performed in the study by Bastankhah and Port e-Agel 29 to estimate the shaft torque T and consequently the mechanical power (i.e., P mech ¼ TÁX) based on the values of i and X. The bottom of each turbine tower is also attached to a DC motor.…”

Large-Eddy Simulation of Yawed Wind-Turbine Wakes: Comparisons with Wind Tunnel Measurements and Analytical Wake Models

“…The main characteristic quantities of the incoming boundary-layer flow measured in the wind tunnel are summarised in Table 1. The geometric parameters of the miniature wind turbine, WiRE-01 [38], used in the wind-tunnel experiments [19] are shown in Figure 2b. The number of the computational cells in the streamwise (x), spanwise (y) and vertical (z) directions for four cases with different mesh resolution are summarised in Table 2.…”

“…The sum of P e and P j is known as the converted power P conv and is computed by the product of the electrical current output I and the torque constant of the generator K [19]. Bastankhah and Porté-Agel [38] later found that, at the optimal tip speed ratio specified in this study (λ = 3.8), the ratio between P conv and P Mech equals 0.92 for this specific miniature wind turbine model, WiRE-01. The mechanical power extracted by the rotor using both the yawed ADMR parameterisation and the standard ADM without rotation is compared with the mechanical power obtained from the wind-tunnel experiments [19] in Figure 11b.…”

Actuator Disc Approach of Wind Turbine Wake Simulation Considering Balance of Turbulence Kinetic Energy

“…In the early stage of wake effect research, wind tunnel experiments and field measurements were used as the main experimental methods. An early wind tunnel experimental study was carried out at the National Aeronautical Research Institute (Swedish: Flygtekniska Försöksanstalten Abbreviated; FFA) and there were several more wind tunnel tests in recent years [2]. Some important onshore field measurements can be found in Tjaereborg [3], Nibe [4] and Sexbierum [5].…”