The Design and Testing of Airfoils for Application in Small Vertical Axis Wind Turbines

Abstract

In recent years more focus is put on the applications of wind turbines in the urban environment. One of the ways to do this is using a turbine with a vertical axis (a VAWT). This type of wind turbines is around for many centuries. The modern equivalent which is based on lift producing blades only exists for 30 years. In this period airfoils for this application have been developed, but still much work can be done in this held. During this project a design process is developed with the purpose of improving the NACA 0018 airfoil, which is commonly used in VAWT turbines. The aerodynamics involved in VAWT are investigated to find the design goals for the airfoil characteristics. Furthermore the currently used NACA 0018, which is used as the design reference, is investigated. The two main pillars of the design process are the RFOIL program and the VAWT simulation program. RFOIL is a panel method based program with boundary layer equations which can calculate the properties of 2D airfoils. RFOIL gives accurate enough results to be a powerful design tool in the Reynolds number range from 300,000 to 700,000. The VAWT simulation program, written in MATLAB, calculates the performance of a VAWT using 2D airfoil data. The final Matlab program allows to adjust the turbines geometry, to chose from multiple airfoils and to set a dynamic stall model on or off. As such 2D airfoil characteristic from RFOIL or wind tunnel tests can be inserted to view the turbines performance with this airfoil.