In order to investigate fundamental characteristics of three-dimensional separations of decelerating cascade flow, a channel flow around a NACA65 blade in a decelerating flow by turning was examined. Effect of attack angles of 31deg. and 35deg. on the channel flow was focused on. Five-hole probe survey showed that the location of accumulation of the low-energy fluid was at 0.2 and 0.75 of the height ratio for 31deg. whereas around midspan for 35deg. PIV measurement showed that various focus-type separations were seen in the flow for 35deg., and the three-dimensional vortex structure was considered by using a vortex filament.

The lubrication analysis is an effective method for the condition monitoring and diagnosis of power plants. The method is still in a trial stage in pumps for irrigation and drainage. The lubricating oil were sampled and analyzed annually from 2011 to 2014 from two gearboxes for drainage pumps in operation for 18 years. The viscosity was abnormally low and the particle number concentration in oil, C_Np was high in 2012. The Fe concentration, C_M(Fe), and the C_Np of large particles increased significantly in 2013. A gear tooth failure was discovered in 2014, when a particle that is characteristic to fatigue wear was found in the oil.

For failure diagnosis, the criteria for C_Np and C_M(Fe) are necessary and the observation of wear particles is helpful. For the early-stage detection of abnormal symptom, it is useful to monitor the increase rate of C_Np in each particle size range.

Tip injection, fluid injection upstream from a compressor airfoil tip, to a low-speed centrifugal compressor was investigated experimentally to visualize flow fields using PIV. PIV measurements reveal flow fields at the tip and mid-span of circular cascade channel with and without tip injection. With or without tip injection, tip injection does not affect the flow field at mid-span region under both design point and near-stall point of compressor operation condition. With tip injection, the jet controls the flow around the tip region by changing the flow direction from circumferential to radial as an airfoil passes the injector, and rotating stall is suppressed completely for the entire flow passage of the compressor.

In this study, the effects of vane clearance position in VGS (variable geometry system) nozzle on the flow field at the inlet of turbine impeller of turbocharger were investigated experimentally at two nozzle opening conditions by using 5-hole Pitot tube. The effect of the existence of clearance pin was also examined. The experimental results clarified that the influence of leakage flow through the clearance obviously appeared in the case that vane clearance is arranged only at hub side by closing nozzle opening condition, and consequently the associated loss generation was increased and eventually the uniformity of the circumferential distributions of loss and flow angle at the downstream of nozzle was deteriorated. On the other hand, the influence of clearance pin became remarkable by opening nozzle opening condition.

Cavitation inception of a bubble nucleus including both vapor and non-condensable gas in a liquid under a constant tension is theoretically investigated based on bubble dynamics. The liquid is exposed to the tension during a finite time and, after that, restores to the atmospheric pressure. A model equation suitable for dealing with cavitation inception is derived on the basis of Rayleigh-Plesset equation and confirmed to be valid by comparison with numerical solutions of Rayleigh-Plesset equation for liquid hydrogen, liquid oxygen, water, olive oil and glycerol. Simple formulas obtained are found to be able to predict well a bubble radius during the tension being imposed on the bubble and, after that, a maximum radius attained under the subsequent atmospheric pressure. The growth behaviors of bubble are classified into three cases depending upon three parameters on the tension-viscosity, the initial gas pressure-viscosity, and the surface tension-viscosity.