Kimihiko Watanabe

Evaluation of the power output of a wind turbine with a brimmed diffuser shroud in fluctuating flows

Fossil fuels have been used extensively all over the world to satisfy energy demands. However, their availability is limited and their negative impact on the environment undeniable. Due to this, the need to develop alternative energy resources was recognized a few decades ago. Among different alternatives that have been developed, wind energy appears as a promising option to be implemented in many parts of the world. Nonetheless, its development and the cost per kW are still higher than that from fossil fuels. The intermittence of its capability to produce energy and the size of the wind power plant (as compared to a coal or nuclear power plant of the same energy output) have not made its implementation easier. In order to make wind energy more competitive and attractive to investors, new energy systems are desired. Specifically, it is desired to have a higher energy output. In this study a brimmed-diffuser shroud was incorporated into a 1 kW wind turbine. The turbine was then evaluated under fluctuating wind conditions. The experiments were conducted at the large boundary wind tunnel of Kyushu University. It is shown that power output increases for a fluctuating flow as opposed to a steady flow. The turbine power output is capable of following the changes in the wind speed accurately in the range of wind speed fluctuations tested. This is shown by correlation analysis and supported by the frequency spectrum. This study is part of a larger research work aimed at evaluating a novel wind turbine design. The current results are very encouraging. Possible wind sites of wind speed average lower than the current minimum accepted values can be exploited by using a turbine like the one evaluated in this work.© 2007 ASME