Comparison of simulations and wind tunnel measurements for the improvement of design tools for Vertical Axis Wind Turbines

Abstract

As wind turbines are getting larger and cost reductions through up-scaling are reaching a limit, there is increasing pressure to reduce their installation and operating costs, making the business case for Vertical Axis Wind Turbines (VAWTs) more interesting again. However, in order to properly assess the economic potential of large-scale VAWTs, improved design tools are required. As the research budget for VAWT projects is generally too small to carry out expensive large-scale wind tunnel tests and field measurements, alternative methods are required. In this work, the application of small-scale, lower budget methods for improving VAWT design tools is assessed. It is shown that (a) currently available tools for VAWT design have not been sufficiently validated, (b) lower budget, small-scale wind tunnel tests can be effective for examining VAWT performance in terms of average power coefficient vs. tip speed ratio as well as the dynamics of the torque, and (c) Detached Eddy Simulations on small-scale VAWTs can be effective for examining their performance in terms of average power coefficient vs. tip speed ratio as well as the forces on the blades. Based on these results, a process for the transfer of the results of lower budget, small-scale measurements and simulations into recommendations for improved design tools is being developed.