As a high specific speed pump, the contra-rotating axial flow pump with two rotors rotating reversely has been proved with higher hydraulic and cavitation performance, while in our previous researches, the potential interaction between two rows was distinctly observed for our prototype rotors designed with equal rotational speed for both front and rear rotors. Based on the theoretical and experimental evidences, a rotational speed optimization methodology was proposed and applied in the design of a new combination of contra-rotating rotors, primarily in expectation of the optimized pressure distributions as well as pertinently improved hydraulic performances including cavitation performance. In the present study, given one stationary and two rotating frames in the contra-rotating rotors case, a pressure measurement concept taking account of the revolutions of both front and rear rotors simultaneously was adopted. The casing wall pressure data sampled in time domain was successfully transferred into space domain, by which the ensemble averaged -to- pressure distributions at the tip of two contra-rotating rotors under different operation conditions were studied. It could be seen that the rotor pair with the optimized rotational speed combination as well as work division, shows more reasonable -to- pressure distribution and well weakened potential interaction. Moreover, combining the loading curves estimated by the measured casing wall pressure, the cavitation performance of the rotor pairs with new rotational speed combination were proved to be superior to those of the prototype pairs.

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As a major component of a power plant, a turbine generator must have sufficient reliability. Longer blades have lower natural frequency, thereby requiring that the design of the shaft and takes into account the coupling of the vibration mode, nodal diameter k=0 and k=1 with vibration of the shaft.
The present work analyzes the coupling of the translation motion of the shaft with in-plane vibration of the blades with k=1 modes. At a rotational speed Ω₁=|ω_s-ω_b|, the resonance of the blades has a relatively large amplitude. A violent coupled resonance was observed at a rotational speed Ω₂=ω_s+ω_b. Resonance in vibration at Ω₁=|ω_s-ω_b| was experimentally confirmed.

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Flow fields in 2- and 4- half-ducted propeller fans for the outdoor units of air-conditioners were calculated with large eddy simulation based on finite element method with the aim of investigating the influence of number on aerodynamic noise. We confirmed that the tip vortex had a great influence on aerodynamic noise in half-ducted propeller fans. The length of the tip vortex trajectory and the pitch for the 2- propeller fan were longer than those for the 4- propeller fan. These were suppressed the interaction between the tip vortex and the adjacent in the 2- propeller fan. The 2- propeller fan was therefore more silent than the 4- propeller fan.

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As centrifugal pumps with a single can secure large passed particle size, they are widely used as sewage pumps transporting liquid containing foreign bodies. Not only dos the internal flow of centrifugal pumps with a single vary significantly according to the flow rate, but it also varies significantly according to the rotation of the impeller, and therefore it is extremely complex. Elucidation of this complex and unsteady internal flow is extremely important for enhancing efficiency by reducing loss and realizing high reliability by reducing the fluid force. This research has involved a structural survey of flow in the casing of closed-type centrifugal pump with a single through PIV measurement and CFD analysis. The study has showed that various vortexes were produced inside the casing by maximum efficiency point flow rate, and that a large scale vortex structure which varies significantly along with rotation of the impeller is formed. This suggests that increase or decrease of mixing loss inside the casing produced by rotation of the impeller does not depend on increase or decrease of vortex area inside the casing, but is rather produced by increase or decrease of vortexes produced near the tongue part and the beginning of the volute winding.

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The Savonius wind turbine has a lower performance than other types of wind turbines which may attract more study focus on this turbine. This study aimed to improve wind turbine performance by combining a conventional with an elliptical into a combined rotor. The analysis was performed on three models in computational fluid dynamics (CFD) using ANSYS_Fluent Release 14.5. Then the results were verified experimentally using an open wind tunnel system. The results of the numerical simulation were similar to the experimental and showed that the combined rotor has better dragging flow and overlap flow than the conventional and elliptical . Experimental verification showed that the combined was to increase the maximum coefficient of power (Cpmax.) by 11% of the conventional and to 5.5% of the elliptical .

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Lightning protection measures for wind turbines are becoming important as the use of wind turbines is increasing rapidly along with its capacity and height. In order to understand the manner of lightning attachment to wind turbine blades, experiments with various types of samples were conducted. Experimental studies revealed following issues. Regarding a non-conductive sample, the 50% flashover voltage of polluted sample was reduced by 10% as compared to a non-pulluted sample. Creeping discharges on the polluted samples occurred more frequently, and penetrated through the surface, damaging the sample. The sample with a receptor system showed lower protection performance than the covered with a conducting cap.

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This paper describes the results of the experiments of wind turbine blades with rocket triggered lightning. A number of wind power stations have been projected and planted. Lightning damage to wind turbines has been an increasing problem recently. So development on protection of wind power plants from lightning is necessary to be fully run for the future.
In the experiments, the 1.8m long was struck by the lightning discharge triggered by rocket. For the kept dry inside, the very strong discharge of positive peak current 28kV, total charge 520 Coulombs, was triggered, but the breakdown did not occur through the into inside. Another polluted by salty wet inside was struck by the lightning discharge of negative peak current of 4kA with 0.5 Coulombs. The lightning was small, nevertheless, the was broken at the upper edge and the was disconnected by crack. For the protection of , the surface was covered with stainless steel plate. The itself was safe when the big positive lightning discharged, while most part of stainless steel cover was burned out. Supplement breakdown tests of wind turbine were carried out with lightning impulse voltage in laboratory.
As a result, it became clear that the kept dry inside was an effective lightning protection of wind turbine blades.

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In the present study, we surveyed the performance of closed-type centrifugal pump with a single and its fluctuations through an experiment and a CFD analysis, and comparatively verified the outlet flow, with the objective of elucidating the internal flow structure and loss generation mechanism of the pump. Furthermore, we quantitatively evaluated each hydraulic loss on the pump and examined the relationship with the vortex structure in an impeller. The result showed that fluctuations in the impeller loss were notable at any flow rate with the maximum value at a phase angle of 133° when the best efficiency point flow rate. It suggests an impact of the vortex generated on the shroud side near the end of the outlet winding. While the impeller loss indicates similar behavior to the best efficiency point flow rate at a high flow rate, but its fluctuation was extremely large, and we found that such fluctuations are the behavior at a low flow rate was opposite to other flow rates.

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We are aiming to analyze Inverse tapered that produced by inverting the chord length at tip and root and Taper based on CLARK-Y airfoil; by running test in wind tunnel at 13 m/s wind speed. Simulate both of them with ANSYS Fluent software with different Reynold’s numbers relatively with different angle of attacks started with (-15) degrees and ended up with (20) degrees. Finally, using the simulation results in Q- software with the Element Methods (BEM) to produce Cp - λ curves. The other aim is to understand the physics of the inversed tapered .

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MT type

configuration, which is exclusively designed for vertical axis wind turbine, has been proposed by authors. It has been discovered that performance of this MT is better than those of conventional blades such as Savonius turbine or NACA0018 airfoil. In this paper it is attempted to improve the performance of the MT by changing its configuration. To this end, genetic algorithm is employed. By changing configuration, it is attempted to increase lift force of the MT . Two-dimensional panel method, numerical analysis of inviscid potential flow, is employed to evaluate the lift force. Obtained improved new MT are provided for experiments to confirm its lift force. This experiment is conducted in Hele-Shaw cell. In this Hele-Shaw cell streamlines of potential flow around a are visualized. The lift force of the new MT is calculated from streamline intervals visualized in the Hele-Shaw cell. Results of the experiments show that the lift force of the new MT has similar trend to that predicted by two-dimensional panel method. Lift and drag forces of the blades in viscous flow condition are also measured by wind tunnel experiments. From the results obtained by these inviscid and viscid investigation it is suggested that the new MT may increase the performance of actual VAWT.

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A comparative investigation of leakage flow and film-cooling characteristics on different squealer tips is conducted under the conditions of stationary and moving casing. Firstly, the numerical method used in the calculations has been verified. Then, the influences of film-hole arrangement, squealer height and blowing ratio are studied in detail. Three different film-hole configurations are taken into consideration. For type-A and type-B, the film holes are arranged in one row, but located on the middle-camber line and near the suction side squealer, respectively. Type-C places two rows of 7 film holes at the leading edge and one row of 6 film holes at the middle chord region. The results show that the relative motion of the casing leads to the formation of a scraping vortex near the casing, which not only compresses the cavity vortex, but also acts as a pair of labyrinths with the cavity vortex to the leakage flow. The effect of the moving casing on the film-cooling effectiveness of squealer tip varies with the film-hole arrangements. When the casing is moving, the tip leakage loss increases with the decrease of the rim height because the blockage effect of the vortexes in the cavity decreases. Nevertheless, type-C obtains the best tip cooling performance in both cases of stationary and moving casing.

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The effects of the inlet position of on the performance of a centrifugal impeller are numerically investigated. The inlet position of the can be determined by the outer diameter, the leaning angle of the inlet, the shroud and hub angular momentums specified at the inlet. It is found that the flow fields of the optimal impeller are obviously superior to those of the impeller whose leading edge was installed at impeller eye. The range analyses reveal that angular momentum specified at the inlet hub is the least important factor in affecting the efficiency of impeller, while the outer diameter of leading edge plays the most important role in determining the pressure ratio.

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Three-dimensional numerical simulations are carried out to investigate the effects of film-hole arrangement and blowing ratio on the squealer tip leakage flow field and tip film-cooling performance. Six film-hole arrangements with 13 holes are designed in the current study for comparison. In type-A and type-B, the film-cooling holes are arranged in a single row, located at the middle camber line or close to the suction-side squealer. The four modified film-hole arrangements are realized by placing two rows of total 7 film-cooling holes at the leading edge (type-C, type-D, type-E and type-F) and remaining the rest film-cooling holes in a row at the middle chord zone. The results show that the leakage flow entering the tip gap from the leading edge of suction side, the leading edge of pressure side and the middle chord and trailing edge of pressure side behaves different flow feature inside the tip cavity, inducing complicated swirling flow filed. The modified film-hole arrangements yield more reasonable film coverage on the tip surface by comparing with the single row film-hole arrangement under relatively high blowing ratios. In addition, the modified film-hole arrangements also show different rules on the film-cooling effectiveness distributions over some specific surfaces, such as tip cavity bottom surface and squealer top surface, as well as PS squealer inner surface and SS squealer inner surface. Among the presented four modified film-hole arrangements, type-D and type-F gain the most favorable film-cooling improvement.

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Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields; automobile radiator pump, ventricular assist pump, cooling pump for electric devices and so on. Further, the needs for mini centrifugal pumps would become larger with the increase of the application of it for electrical machines. It is desirable that the mini centrifugal pump design be as simple as possible as precise manufacturing is required. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, we started research on the mini centrifugal pump for the purpose of development of high performance mini centrifugal pumps with simple structure. Three types of rotors with different outlet angles are prepared for an experiment. The performance tests are conducted with these rotors in order to investigate the effect of the outlet angle on performance and internal flow condition of mini centrifugal pumps. In addition to that, the thickness is changed because blockage effect in the mini centrifugal pump becomes relatively larger than that of conventional pumps. On the other hand, a three dimensional steady numerical flow analysis is conducted with the commercial code (ANSYS-Fluent) to investigate the internal flow condition. It is clarified from the experimental results that head of the mini centrifugal pump increases according to the increase of the outlet angle and the decrease of the thickness. In the present paper, the performance of the mini centrifugal pump is shown and the internal flow condition is clarified with the results of the experiment and the numerical flow analysis. Furthermore, the effects of the outlet angle and the thickness on the performance are investigated and the internal flow of each type of rotor is clarified by the numerical analysis results.

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To investigate the influence of profiles on cavitation behavior in impeller of centrifugal pump, a centrifugal pump with five different profiles impellers are studied numerically. The impellers with five different profiles (single arc, double arcs, triple arcs, logarithmic spiral and linear -variable angle spiral) were designed by the in-house hydraulic design code using geometric parameters of IS 150-125-125 centrifugal pump. The experiments of the centrifugal pump have been conducted to verify numerical simulation model. The numerical results show that the profile lines has a weak effect on cavitation inception near inlet edge position, however it has the key effect on the development of sheet cavitation in impeller, and also influences the distribution of sheet cavitation in impeller channels. A slight changing of setting angle will induce significant difference of cavitation in impeller. The sharp changing of impeller setting angle causes obvious cavitation region separation near the impeller inlet close to suction surface and much more flow loss. The centrifugal pump with profile of setting angle gently changing (logarithmic spiral) has the super cavitation performance, which means smaller critical cavitation number and lower vapor cavity volume fraction at the same conditions.

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Since large-scale commercial wind turbine generator systems such as MW-class wind turbines are becoming widely operated, the vibration and distortion of the are becoming larger and larger. Therefore the soft structure design instead of the solid-design is one of the important concepts to reduce the structural load and the cost of the wind turbine rotors. The objectives of the study are development of the fluid-structure coupled analysis code and evaluation of soft rotor- design to reduce the unsteady structural load. In this paper, fluid-structure coupled analysis for the HAWT rotor is performed by free wake panel method coupled with hinge-spring model for the flapwise motion. In the model, the continuous deflection of the rotor is represented by flapping angle of the hinge with one degree of freedom. The calculation results are evaluated by comparison with the database of the NREL unsteady aerodynamic experiment. In the analysis the unsteady flapwise moments in yawed inflow conditions are compared for the blades with different flapwise eigen frequencies.

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In order to study the flow law of shunt vane type aviation fuel pump under the condition of gas-liquid mixture transportation, based on the RNG K-ε turbulence model and the Euler-Euler non-uniformity model, using the ANSYS CFX software to calculate an aviation fuel pump under different gas content conditions, and analyzing the flow of the fuel pump and the pressure law of the pressure. The research shows that the gas phase is mainly distributed in the front section of the long suction surface and the back section of the short pressure surface. The increased gas content will result in increased liquid velocity in the pump, which makes the gas phase gradually develop towards the suction surface of long and short blades and diffuse to the impeller flow path. The gas content mainly affects the pressure surface load of the fuel pump blades. The pressure load curve fluctuates at the relative position of the short (0.5-0.6) and long (0.3-0.6) as well as at the end of the and decreases with the increase in gas content. The change of pressure fluctuation of the is mainly reflected at the junction of long and short blades, and the pressure fluctuation amplitude of the front section of the short and middle section of the long fluctuates greatly. With the increase in gas content, the pressure fluctuation amplitude at each monitoring point reduces. The research results can provide some reference for the design of aviation fuel pumps.

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現在，複合材料が各方面で多く用いられ，その中でも炭素繊維強化プラスチック積層板（CFRP）は航空機用部材等として数多く使用されるようになってきている．一方，CFRPは成形加工後において切断や穿孔等の各種機械加工が施されることが多く，特に切断加工には外周刃切断方式が用いられる傾向にある．しかしながら，CFRPの切断加工では，それに含まれる強靱な炭素繊維の影響によって工具摩耗が著しいという問題点を有する．そこで，本研究ではCFRPに代表される複合材料の切断方式として振動外周刃切断方式の適用性を検討するものであり，本論文では切断精度や工具寿命等について実験的に検討した結果を述べる．

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