Effect of Inlet Geometry on Fan Performance and Flow Field in a Half-Ducted Propeller Fan

In order to clarify the effect of rotor inlet geometry of half-ducted propeller fan on performance and velocity fields at rotor outlet, the experimental investigation was carried out using a hotwire anemometer. Three types of inlet geometry were tested. The first type is the one that the rotor blade tip is fully covered by a casing. The second is that the front one-third part of blade tip is opened and the rest is covered. The third is that the front two-thirds are opened and the rest is covered. Fan test and internal flow measurement at rotor outlet were conducted about three types of inlet geometry. At the internal flow measurement, a single slant hotwire probe was used and a periodical multisampling technique was adopted to obtain the three-dimensional velocity distributions. From the results of fan test, the pressure-rise characteristic drops at high flowrate region and the stall point shifts to high flowrate region, when the opened area of blade tip increases. From the results of velocity distributions at rotor outlet, the region with high axial velocity moves to radial inwards, the circumferential velocity near blade tip becomes high, and the flow field turns to radial outward, when the opened area increases

気流に伴われて流動する液膜への物質伝達に関する研究

第1章 序論 第2章 実験装置および方法 第3章 低気流速域での液膜の流動と流れ方向濃度変化の予測 第4章 高気流速域での液膜の流動と流れ方向濃度変化の予測 第5章 平均物質伝達係数の整理 第6章 結論Made available in DSpace on 2012-07-10T06:56:38Z (GMT). No. of bitstreams: 1 kinoue.pdf: 11823402 bytes, checksum: e25ad6fbbed45825d36a8f6eda9ebd13 (MD5) Previous issue date: 1995-03-27主1-参1工学_機械科

Design method for a bidirectional ducted tidal turbine based on conventional turbomachinery methods

Renewable energy sources include solar, wind, hydro, geothermal and biomass. Furthermore, ocean energy is being rapidly harnessed worldwide. In this study, to establish a suitable design method for various bidirectional ducted tidal turbines, instead of using blade element momentum theory and CFD, which have been used previously, the method used for turbomachinery was used for designing the turbines. A bidirectional turbine optimises the equipment design and reduces manufacturing and maintenance costs. Using the turbine power as the design condition, the difference in the tangential velocity between the front and rear of the turbine was calculated using Euler’s equation, and the blade stagger angle was determined based on the potential flow theory. To incorporate the effect of duct geometry into this design method in the future, the effect on the internal flow of the duct was experimentally investigated using three ducts with different maximum cross-sectional areas. Performance tests showed that the duct geometry had a negligible effect on the flow rate through the turbine. Therefore, the larger the maximum diameter of the duct, the greater the flow rate into the outside of the duct. The pressure difference between front and rear of the turbine and the inflow energy into the duct were different due to the energy conversion as the flow turned outside of the duct. To improve the accuracy of the design method, the effect of flow at the duct inlet and the energy conversion should be incorporated, and a review of the estimation method for the axial velocity ratio and the selection method for the design representative value should be conducted