Wind-tunnel tests on a model of a two-bladed horizontal-axis wind turbine and evaluation of an aerodynamic performance calculation method

Abstract

A two-bladed horizontal-axis wind turbine, with a diameter of 0.75 m and a solidity ratio of 0.0674, has been tested in the LST 3 x 2 of NLR. Most of the tests have been carried out at an almost constant Reynolds number of about 3.5 X 10/5. Comparison with a simple performance prediction method showed an acceptable agreement in qualitative respects (optimum blade shape and location of blade stall), but the quantitative agreement, especially concerning the value of Cp close to the optimum, was not acceptable. In the calculation method, the assumption has been made that the flow around the blade elements is two-dimensional, which assumption might be invalidated by centrifugal effects. For a better understanding of the differences between calculation and measurements and of the uncertainties due to wake-blockage effects, a more detailed investigation of the flow behind the rotor is proposed.