Blockage effect correction for a scaled wind turbine rotor by using wind tunnel test data

Abstract

a b s t r a c tThis paper discusses the procedure of a blockage effect correction method involving small-scale wind turbine rotor experimental data. To simulate the aerodynamic performance of full-scale rotors in the field, however, measured data from scaled model experiments need to be analyzed appropriately. One of the most important elements of such an analysis is a procedure to remove the blockage effect of the wind tunnel wall from the measured power data. In this paper, a correction algorithm proposed as part of Glauert's blockage effect correction method is used to process the data from a wind turbine rotor tested with three different wind tunnel sizes. Also, this study considered the modified blockage effect correction method, which has been used to process the rotor thrust data in closed-circuit wind tunnels and open-circuit wind tunnels. A small-scale rotor was tested under the same operating conditions, i.e., the same advance ratio, rotating speed, rotor torque and speed of the wind tunnel. The small-scale wind turbine rotor has a diameter of 1.408 m and a rotating speed according to the tip speed ratio. In each case, the effect of the blockage ratio and aerodynamic characteristics are determined using wind tunnel test results and with a simple analytical correction method. The results of the modified correction method show that the aerodynamic performance levels during a wind tunnel test are cleared by the blockage effect.

Wind tunnel study on power output and yaw moments for two yaw-controlled model wind turbines

“…The impact of the wind tunnel blockage on the wake expansion behind the same model turbine rotor has furthermore been investigated in a computational study by Sarlak et al (2016). For high blockage ratios, correction models (e.g., by Sørensen et al, 2006, or Ryi et al, 2015 for the power output are available. In this study, however, no correction models have been applied, in order not to add another dimension of modeling uncertainty to the results.…”

Assessment of blockage effects on the wake characteristics and power of wind turbines

“…Glauert's correction is derived from the momentum balance in terms of the velocity adjustment in the tunnel. The blockage correction has since been investigated theoretically, numerically, and experimentally in numerous studies (Akay et al, 2010;Chen and Liou, 2011;Ryi et al, 2015;Sørensen et al, 2006). Medici et al (2011) performed PIV measurements on a two-bladed and a three-bladed wind turbine model to investigate the blockage effects in the upstream region of the rotor and proved that the flow can be affected as far as 3 rotor diameters upstream the rotor plane, with a change in the turbine operation.…”

Wind tunnel experiments for innovative pitch regulated blade of horizontal axis wind turbine

“…Wind tunnel blockage correction was taken into account in current study. Blockage correction factor (f) was calculated using the algorithm from research by Ryi et al [23]. The corrected Cp and TSR were calculated using the following equations.…”