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Recently, the demand of highly loaded centrifugal compressors is increasing due to environmental and economic reasons. In a compressor aerodynamic design, including the matching of an impeller and a diffuser, it is very important to predict the impeller flow field precisely using low calculation cost Computational Fluid Dynamics (CFD). However it becomes difficult to predict a compressor performance with enough accuracy because a large flow separation and a strong clearance leakage flow occur due to its high loading. Therefore, in order to validate the prediction accuracy of low calculation cost CFD to the highly loaded compressor, flow measurements at the impeller exit were conducted by using 3 holes yaw meter and hot wire anemometry, and high fidelity CFD was calculated by using Large Eddy Simulation (LES).

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In a wave energy converter with oscillating water column (OWC), an OWC due to the sea wave motion is used to drive an air column in the air chamber, and that results in a bi-directional airflow. An air turbine for this bi-directional airflow is used to convert the pneumatic energy into the mechanical energy. A counter-rotating impulse turbine for wave energy conversion has been proposed by M. E. McCormick in 1978. In a previous study, authors investigated the effect of geometry on the performance of counter-rotating impulse turbine, and clarified that the efficiency of this turbine is higher than the single rotor impulse turbine in a range of high flow coefficients. In this study, the middle vanes were installed between the two rotors in order to achieve further improvement in the performance, and its effect on the turbine performance was investigated by using the computation fluid dynamic (CFD) analysis.

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