Brimmed-diffuser augmented wind turbines can significantly increase the power of the rotor. Multi-rotor systems (MRSs) have a lot of merits such as significant saving mass and overall cost of the wind turbine system. A MRS is defined as a wind turbine consists of more than one rotor in a single structure. In this research, a MRS consists of brimmed-diffuser augmented wind turbines are studied. In wind tunnel experiments, the power output and aerodynamics of two and three brimmed-diffuser augmented wind turbines placed in vicinity have been investigated as the MRS. Results show a significant increase of up to 12% in total power output of the MRS with brimmed-diffuser augmented wind turbines compared to the sum of the stand-alone same turbines. The increase is due to the accelerated gap flows and low pressure areas around the gaps.

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Wind power is one of the fastest growing sources of power production in the world today and there is a constant need to increase the power production. Blades are important main component affecting the amount of power production. In addition, there are some sites that the environmental conditions under which wind turbines are operated in Japan are more severe than those in other countries. Therefore there are some blade repair records in spite of wind turbine size. The quantitative power production analysis of before and after blade repairs in Japanese sites are not reported in the literature. This paper shows the analysis results about the comparison of each power curve and annual energy production (AEP) of before and after blade repairs. Uplift in AEP of about 1% is possible through the blade repair. So blades maintenance such as blades repair has proven to be very important.

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An aero-elastic simulation model named AIST-RAM (AIST-Real time Aero-elastic simulation Model) was constructed and evaluated through the comparison between the experimental data and the results of the simulation, according to the two-bladed horizontal axis model turbine with teetered hub as well as the three-bladed small sized horizontal axis wind turbine. Applying the technology named HILS (Hardware In the Loop System), the accuracy of the calculation as to the teetering in the wind tunnel test of the teetered hub system, and the accuracy of the loads as to the three-bladed rigid hub system under the open-air operation of inter-connection to the grid were investigated. As a result, feasibility of the simulation model as to the speed and accuracy of the calculation was clearly recognized.

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