In order to clarify the effect of tip clearance (TC) size on fan performance and the flow field at rotor outlet in asmall semi-open axial fan, the experimental investigation was carried out. The tip diameter of test f...In order to clarify the effect of tip clearance (TC) size on fan performance and the flow field at rotor outlet in asmall semi-open axial fan, the experimental investigation was carried out. The tip diameter of test fan rotor was180mm and test TC sizes were lmm (TC=1mm) and 4mm (TC=4mm). Fan characteristics tests were carried outfor two cases of TC size and three-dimensional velocity fields at rotor outlet were measured using a single slanthot-wire probe at four flow-rate conditions. As a result, it was found that the pressure - flow-rate characteristicscurves for two cases showed almost the same tendency. However, the ensemble averaged velocity profiles alongradial measurement stations of TC=4mm largely changed compared with that of TC=lmm in cases of smallflow-rate condition. From the phase-locked averaging results, it was also found that the vortex existed in the rotoroutlet flow field of high flow-rate condition for each TC case. Compared with the vortices for TC=1mm andTC=4mm, the vortex for TC=4mm was stronger than that for TC=1mm.展开更多
The Wells turbine for a wave power generator is a self-rectifying air turbine that is available for an energy conversion in an oscillating water-air column without any rectifying valve. The objective of this paper is ...The Wells turbine for a wave power generator is a self-rectifying air turbine that is available for an energy conversion in an oscillating water-air column without any rectifying valve. The objective of this paper is to compare the performances of the Wells turbines in which the profile of blade are NACA0020, NACA0015, CA9 and HSIM15-262123-1576 in the small-scale model testing. The running characteristics in the steady flow, the start and running characteristics in the sinusoidal flow and the hysteretic characteristics in the sinusoidal flow were investigated for four kinds of turbine. As a conclusion, the turbine in which the profile of blade is NACA0020 has the best performances among 4 turbines for the running and starting characteristics in the small-scale model testing.展开更多
An experimental apparatus was developed to study the three dimensional separated flow with spiral-foci.The internal decelerating flow was generated by the air suction from a side wall to produce the separation on an o...An experimental apparatus was developed to study the three dimensional separated flow with spiral-foci.The internal decelerating flow was generated by the air suction from a side wall to produce the separation on an opposite-side wall.The relation between the upstream boundary layer and the generation of spiral-foci in the separation region was observed by a tuft method.As a result,it was clarified that the spiral-focus type separaton could be produced on the side wall and its behavior was closely related to the vortices supplied into the separation region from the boundary layer developing along top wall or bottom one.展开更多
文摘In order to clarify the effect of tip clearance (TC) size on fan performance and the flow field at rotor outlet in asmall semi-open axial fan, the experimental investigation was carried out. The tip diameter of test fan rotor was180mm and test TC sizes were lmm (TC=1mm) and 4mm (TC=4mm). Fan characteristics tests were carried outfor two cases of TC size and three-dimensional velocity fields at rotor outlet were measured using a single slanthot-wire probe at four flow-rate conditions. As a result, it was found that the pressure - flow-rate characteristicscurves for two cases showed almost the same tendency. However, the ensemble averaged velocity profiles alongradial measurement stations of TC=4mm largely changed compared with that of TC=lmm in cases of smallflow-rate condition. From the phase-locked averaging results, it was also found that the vortex existed in the rotoroutlet flow field of high flow-rate condition for each TC case. Compared with the vortices for TC=1mm andTC=4mm, the vortex for TC=4mm was stronger than that for TC=1mm.
文摘The Wells turbine for a wave power generator is a self-rectifying air turbine that is available for an energy conversion in an oscillating water-air column without any rectifying valve. The objective of this paper is to compare the performances of the Wells turbines in which the profile of blade are NACA0020, NACA0015, CA9 and HSIM15-262123-1576 in the small-scale model testing. The running characteristics in the steady flow, the start and running characteristics in the sinusoidal flow and the hysteretic characteristics in the sinusoidal flow were investigated for four kinds of turbine. As a conclusion, the turbine in which the profile of blade is NACA0020 has the best performances among 4 turbines for the running and starting characteristics in the small-scale model testing.
文摘An experimental apparatus was developed to study the three dimensional separated flow with spiral-foci.The internal decelerating flow was generated by the air suction from a side wall to produce the separation on an opposite-side wall.The relation between the upstream boundary layer and the generation of spiral-foci in the separation region was observed by a tuft method.As a result,it was clarified that the spiral-focus type separaton could be produced on the side wall and its behavior was closely related to the vortices supplied into the separation region from the boundary layer developing along top wall or bottom one.
