The impact of single-disk and multi-disk theories on wind turbine design

Aerodynamics is an experimental science, and outstanding design results are achieved through trial and error. This article primarily discusses the bottlenecks encountered in innovative wind power development, pointing out the shortcomings of the Betz limit as applied to new wind power theories and the long-standing misconceptions caused by the conclusions of the “Betz limit” in guiding aerodynamic design for novel wind turbines. It argues that the Betz limit is applicable only under the conditions of traditional single-disc horizontal-axis wind turbines and is not suitable for vertical-axis wind turbines. Instead, vertical-axis wind turbines should be explained using a new framework—the multi-disc theory—along with practical examples of its application.