In order to improve the reliability of the refrigerant compressor, the phenomena of refrigerant foaming in lubricating oil have been examined. The nucleation conditions of refrigerant HCFC-22 are examined experimentally in 2 kinds of oils, such as alkyl-benzene oil and polyol-ester oil, which have the different molecular structure. From these experiments, it is found that there exists a critical value of the bubble growth work under which the refrigerant foaming occurs, and this value is a universal one regardless of the kind of lubricating oil, temperature and refrigerant mole solubility. On the base of the experimental results, a new empirical formula of the pressure drop for the refrigerant foaming is suggested. From this formula, it becomes possible to calculate the bubbles generating condition in arbitrary temperature and refrigerant solubility.

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In recent years, the studies about blood pumps with small size which can be inserted easily and rapidly have received considerably attention. Smaller blood pumps can correspond to the case of emergency for percutanuous assisted circulation. In this work, a micro blood pump of axial flow type with 10.5mm in diameter is developed. The test of hydraulic performance of this pump is carried out. Consequently, the performance of the flow rate Q=4-5L/min and head H≥90mmHg are obtained at the pump rotational speed N=20000min^-1. The results are adequate as blood pump for human heart. Cavitation occurrence in human body becomes an important subject, because cavitation bubbles are attributable to hemolysis and bubble embolism. An inception of cavitation is confirmed at the conditions of N=23500min^-1, H=120mmHg and Q=5L/min. Cavitation phenomena around this blood pump are examined.

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This paper describes newly developed last stage steam turbine blades and its verification test results. The last stage blades of a steam turbine are essential to improve turbine efficiency. To keep it at high level, a fully three-dimensional computational fluid analysis was applied to the profile design. In order to enhance its reliability, the centrifugal stress was precisely optimized using a boundary element method as well as a finite element method. The natural frequencies at the operational speed were also computed not to lie close to the exciting frequencies. The characteristics of vibration were verified by spin tests with full-scale blades.

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To analyze the complex three-dimensional flow structure of an axial flow fan and determine the validity of its application, PIV is used to provide detailed space and time resolved experimental data for understanding and control of flow field. The high resolution stereoscopic PIV system was successfully employed in this study for the investigation of flow structure around the axial flow fan. Using the once-per-revolution signal from the rotor, image fields were captured at a fixed position of the blades and hence provides the ability to do phase-averaging. The three-dimensional instantaneous velocity fields, phase-averaged velocity fields, instantaneous and mean vorticity distributions of the stereoscopic PIV measurement results were represented at typical planes of the flow field. Phase-averaged velocity fields were calculated based on 200 frames of the instantaneous stereoscopic PIV measurement results. From the velocity distribution, the vorticity and turbulent intensity distribution, which are known to be major factors of fan noise, were calculated and its diffusion was discussed as they travel downstream. From the reconstructed three-dimensional velocity iso-surface at 8 cross planes of the outlet flow fields, the three-dimensional features can be seen clearly.

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The experiments conducted by the authors have showed that the power output of a diffuser-shrouded wind turbine is enhanced significantly by coupling a brim to the diffuser exit plane. This paper presents a simple theory to estimate the power augmentation effect of the brimmed diffuser. The augmentation ratio of inlet velocity and the power coefficient are the functions of the base-pressure coefficient of brim, the pressure recovery coefficient of diffuser and the loading coefficient of turbine. The loading coefficient to provide the maximum power coefficient is linked to the aerodynamic performance of the turbine blade based on the present theory.

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For wind turbines under operation, blades will get dirty due to various materials brought by the wind. Though clean blades are always favorable, there is no good means for keeping them clean up to now. In this technical note, we have applied super-hydrophilic coating with the photocatalyst to the blades of a small wind turbine having rotor diameter of 910 mm and studied the effectiveness as a means to clean the blade surface with a rainfall. From the test for nearly a year, we see that the super-hydrophilic coating is sufficiently usable for self-cleaning wind-turbine blades.

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