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論文
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田部井, 勝稲 ; 白井, 紘行 ; 高草木, 文雄
概要:
application/pdf<br />Journal Article<br />Light emission properties of xenon-water cavitation in circular orifice flows
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were investigated experimentally and theoretically. The emission was enhanced by dissolving a small amount of Xe gas into water, and its spacial pattern was taken by a chilled CCD camera and an image intensifier. A spectrum of cavitation emission was measured by a spectrometer with a photon counter. Based upon the collisional and radiative theory for plasmas and a two-temperature model, synthetic spectra were calculated for emission of a collapsing xenon bubble at the minimum radius. It was found that the light emission pulsated and was intense around the flow axis a little downstream of the orifice, and the experimental spectrum was predominated by continuum and its intensity distribution was very similar to the theoretical ones with electron temperature of about 12000 K to 14000 K. Mean emission energy per unit pulse was estimated experimentally to be smaller than 5×10^<-9> μJ/nm・sr at the wavelength of 450 nm, which is consistent with the plasma conditions from the emission spectrum.
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| 2.
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論文
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田部井, 勝稲 ; 白井, 紘行
概要:
application/pdf<br />Journal Article<br />Properties of light emission from a cavitation generated by a circular orifice shear flow have been investigated experimentally. In order to enhance the weak emission from clear water
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cavitation, xenon gas and luminol were dissolved in the water. The emission intensity was directly measured by an optical system with a photon counter and a spectrometer. It was seen that the emission could be enhanced by more than 100 times, and that the measured spatial profile of emission and its spectrum for xenon-water cavitation were very similar to those for clear water. The spectrum for luminol-water cavitation was a simple superposition of the spectrum from clear water and that due to luminol. The color temperature of emission from xenon-water cavitation was as high as roughly 20 000K.
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論文
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田部井, 勝稲 ; 白井, 紘行 ; 高草木, 文雄
概要:
application/pdf<br />Journal Article<br />Emission experiments on cavitation bubbles in water were performed with circular orifice flows. The region emitting faint light due to the bubbles was visualized with the combined method of photon
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counting and computerized tomography. Emission data obtained from outer-side observation were inverted into internal intensity distributions by means of the modified Abel transformation in which the light-quenching effect by cavitation bubbles was taken into account. It was observed that, under the condition of large pressure difference before and behind the orifice, a large number of photons were emitted from the region downstream of the cavitation flows, and the emission intensity was strongly dependent upon the pressure difference. The effect of an addition of a small amount of luminol to water was examined to demonstrate the effectiveness of the present method.
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田部井, 勝稲 ; 白井, 紘行 ; 高草木, 文雄
概要:
application/pdf<br />Journal Article<br />By using the moire-schlieren method for symmetrical and asymmetrical flow fields, density distributions of underexpanded free jets of air from circular and square nozzles have been
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measured. Experimental moire image data of the flows, which show the integrated light deflection across the flow, were inverted to an internal density distribution by the numerical inverting method. The experiment was performed systematically by changing the pressure ratio across the nozzles from 4 to 13. It was found that the density profiles measured in the expanded free jets from a circular nozzle agreed with other experimental results on the whole, and that the results for a square nozzle showed complex flow configurations caused by the nozzle figure, nevertheless, the density distribution on the flow axis was very similar to that for a circular nozzle.
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藤沢, 延行 ; 小川, 芳弘 ; 白井, 紘行
概要:
application/pdf<br />Journal Article<br />Unsteady flow field inside a Savonius rotor at various overlap ratios has been investigated by flow visualization with a smoke-wire method. The experiment is performed for rotors with 4 different
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overlap ratios (OL=0-0.5) and for various rotor angles and
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藤沢, 延行 ; 白井, 紘行 ; 齋川, 雄司
概要:
application/pdf<br />Journal Article<br />Unsteady flow fields around a Savonius rotor and its power mechanism are studied by a flow visualization experiment for various rotor angles and tip-speed ratios. For small tip-speed ratios, the rotor
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receives a corotating torque mainly due to the difference of the drag on both the blades. As the tip-speed ratio increases, a Coanda-like flow pattern is formed on the convex side of an advancing blade, and the corotaing torque is expected by the induced lift, though the torque due to the difference of the drag decreases. The power performance of a Savonius rotor can be explained reasonably by the flow visualization results.
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