In this study, CFD analysis was performed for the complex turbulence flow in an unshrouded centrifugal impeller with the leakage flow through a blade tip clearance. CFD analysis is influenced by the analysis conditions such as geometry and the number of mesh or turbulence model etc. In this paper, therefore, the validity of CFD analysis was examined by comparing the results of CFD with those of the previous experiments. SSG turbulence model was adopted with the stationary condition for incompressible flow. The relative velocities, the static and total pressures, the Reynolds stresses and the circumferential component of absolute velocity etc. were compared along the impeller passage. The impeller passage flows showed the same tendency with experiment. The similar tendency appeared also in the impeller performances. Moreover, the effect of the tip leakage vortex induced from the passage inlet on the secondary flow was discussed.

A helical wind turbine has been analyzed experimentally and numerically and a novel design protocol has been proposed by means of blade element and momentum theory. The subject of the present analysis is to discuss the effect of low tip speed ratio and high one, respectively. In the low tip speed ratio, the turbine is driven by the torque generated from the flow turning radially after colliding with the runner. On the other hand, in the high tip speed ratio, the turbine is operated by the torque generated from the flow passing through axially the turbine. The present helical turbine has a maximum power coefficient as 40%, which is larger than that of conventional multi-blade wind turbine and is competitive with Darrieus wind turbine. Also, the turbine has a maximum torque coefficient of 48%, which is slightly lower than that of Savonius wind turbine.

Rotating shafts of turbomachinery such as pump, turbocharger and micro gas turbine are supported by journal bearings. However, oil whip occurs when the rotating shaft speed is increasing, so it is necessary to avoid this phenomenon. Authors focus on the journal bearing with two oil filler ports under starved lubrication. Also, studied the method of controlling the oil flow rate for the improvement of stability, maintaining performance of oil film and heat resistance. First, changing the angle of oil control valves were experimented. This has an influence on vibration, temperature and oil flow rate. Moreover, the control method based on the experimental results was presented. Finally, the characteristics of bearing with oil flow control and without oil flow control are compared. As a result, stability characteristics, maintaining performance of oil film and heat resistance of bearing are dramatically improved by using the oil flow control method.

In the mechanical design of a turbine blade for an automotive turbocharger, it is pointed out that the mistuning effect caused by the difference of casting condition should be considered. Namely, the difference of casting condition causes the small variation of Young's modulus of each blade on a turbine wheel. These small variations break the cyclic symmetry, and split the eigenvalue pairs. In the forced response of a mistuned system, the responses of all blades become different, and the response of a certain blade may become extremely large due to splitting of the duplicated eigenvalues and distortion of the vibration modes. In this study, as a reduction method for the resonant response of mistuned turbine wheels, asymmetric vane spacing is examined systematically using the reduced order model FMM and the Monte Carlo simulation. It is shown that asymmetric vane spacing is a practical method for reducing resonant responses.