PIV measurement of internal flow in mini centrifugal pump

The diameter of the ventricular assist pump and cooling pump for electrical devices like servers is about a dozen millimetres and these kinds of pumps belong to the mini pump. The internal flow condition of the mini centrifugal pump has to be clarified because there are so many types of mini pumps according to special specifications and shapes. Therefore, in this research, an open impeller was adopted as a mini centrifugal pump with 55mm impeller diameter in consideration of reduction in impeller manufacturing cost and its internal flow was investigated. Since the outlet angle of the test impeller is large, the maximum efficiency flow rate moves to a large flow rate and the relatively high head and efficiency were obtained in large flow rate region. In the present paper, the velocity and vorticity distribution near the volute tongue are shown and the internal flow in the mini centrifugal pump is clarified based on the PIV measurement results

Internal Flow of Contra-Rotating Small Hydroturbine at Off- Design Flow Rates

Small hydropower generation is one of important alternative energy, and enormous potential lie in the small hydropower. However, efficiency of small hydroturbines is lower than that of large one. Then, there are demands for small hydroturbines to keep high performance in wide flow rate range. Therefore, we adopted contra-rotating rotors, which can be expected to achieve high performance. In this research, performance of the contra-rotating small hydroturbine with 60mm casing diameter was investigated by an experiment and numerical analysis. Efficiency of the contra-rotating small hydroturbine was high in pico-hydroturbine and high efficiency could be kept in wide flow rate range, however the performance of a rear rotor decreased significantly in partial flow rates. Then, internal flow condition, which was difficult to measure experimentally, was investigated by the numerical flow analysis. Then, a relation between the performance and internal flow condition was considered by the numerical analysis result