Acoustic Investigation of Aerodynamic Appendages for Wind Turbine Blades: Fluid-dynamic Tests

Abstract

Received: 30 January 2019 Accepted: 18 April 2019 The fluid-dynamic characterization of aerodynamic devices called trailing-edge serrations aimed at reducing wind turbine blades noise emissions is here presented. Nowadays, the development of aerodynamic noise mitigation solutions is a hot topic. However, a detailed fluid-dynamic analysis of such devices cannot be found in literature. The present work will discuss the results of an experimental test campaign carried out at the Environmental Wind Tunnel of the “Università Politecnica delle Marche” intended to study the induced effects of these devices when applied on a wing with NACA 642 014A airfoil operating in various conditions. Tests were based on both global measurements, performed with load balance, and local pressure measurements. In addition, frequency analysis of the balance signal and flow visualization tests were also performed. Global measurements showed that serrated edges are capable of countering trailing-edge separation in a not well-understood manner. On the other hand, local observations revealed that flow is accelerated along serration extension. Lastly, flow visualization tests pointed out a sort of flow deviation towards the skewed edge of the serration on the pressure side of the airfoil.