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野村, 友和 ; 高橋, 易資 ; 武田, 親士 ; 石間, 経章 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Characteristics of the flow inside an engine cylinder model have been evaluated by a particle image velocimetry (PIV) and a laser Doppler anemometer (LDA). Verifications of the results by Partial
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Cells in Cartesian coordinate method numerical simulation have been also made by the experiment results. The model engine head that has two intake valves and transparent cylinder are used in the steady state flow condition. The tests are conducted by single- and dual- valve open condition with 8mm valve lift in-1470 Pa suction gauge pressure. The comparisons between the PIV and the LDA experiments show almost the same tendencies for mean velocities and turbulence intensities in the whole experimental regien qualitatively and also quantitatively. The differences in the valve open condition are clearly observed in the integral length and time scales that are estimated from the PIV and LDA data respectively. It is shown that the PIV results are useful for verification of numerical results, which agree reasonably with those of experiments.
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| 2.
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野村, 友和 ; 高橋, 易資 ; 石間, 経章 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Boundary layer flow over a multi-holed plate is analyzed in this paper. Two perforated plates which have different diameter of holes and a flat plate are tested in the rectangular duct. The
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diameters of holes are 20mm or 40mm in staggered arrangement and the all plates are 10mm in thickness. These studies are carried out by means of two-dimensional LDA (laser Doppler anemometer) and numerical simulation with Partial Cell method. The mean flow velocity and the relative turbulence intensity are 4.5m/s and 2% respectively in both the experiment and the calculation. Comparisons of flows over the three plates are made for the mean velocity, turbulence intensity and Reynolds stress. In addition, the difference in turbulence flow structure depending on the diameter of holes has been discussed by experimental results.
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| 3.
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野村, 友和 ; 石間, 経章 ; 小保方, 富夫
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application/pdf<br />Journal Article<br />Spatial correlation measurements of velocity fluctuations in turbulent flow over a rectangular cube are presented. Direct measurement of spatial correlation requires simultaneous measurement of
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velocities at two or multi-points in the flow. Therefore this study is carried out by means of a particle image velocimetry (PIV) or two LDAs (laser Doppler anemometer) composed by He-Ne and Ar^+ lasers. The cube is set on the floor of the wind tunnel. At the inlet, the mean flow velocity and the relative turbulence intensity are 4.0m/s and 1.5%, respectively in both experiments. Under this condition, the flow Reynolds number based on the rectangular cube height and the mean velocity is about 8800. Firstly, comparisons are made for longitudinal and transversal spatial correlation coefficients measured by LDA. Secondly, distributions of integral length scales distributions acquired by LDA and PIV have been discussed. In addition, the validities of integral length scale calculated by Taylor's hypothesis are evaluated in the flow.
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石間, 経章 ; 助名, 亮一 ; 小保方, 富夫 ; 河内, 勝義 ; 小林, 一光
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application/pdf<br />Journal Article<br />Characteristics of spray injected from the five types of swirl nozzle, which were the same design however differed in the static flow rates as 600, 700, 800, 900 and 1 000 cc/min respectively, have
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been evaluated by a phase Doppler anemometer (PDA) and a
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| 5.
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高橋, 易資 ; 野村, 友和 ; 石間, 経章 ; 小保方, 富夫
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application/pdf<br />Journal Article<br />The PCC (Partial Cells in Cartesian coordinate) method CFD code featured with
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less pre-processing time was used in this study to calculate the flow field around a rectangular cube. The turbulence model was consisted using a low Reynolds number κ-ε model and log law. To test the case of existence of many partial cells, the rectangular cube was set with 10 degrees of offset angle to the flow direction, and calculation mesh does not correspond to the cube surface. The mean flow velocity and turbulence intensity were set to 4.0 m/s and 1.5%, respectively in both experiment and calculation. The experiments were carried out by using two-dimensional laser Doppler anemometry (LDA) and particle image velocimetry (PIV). The numerical results were compared with the experimental results. Both results show good agreement between calculation and experiment in the mean velocity, turbulence intensity and Reynolds stress.
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石間, 経章 ; ヨゼフ, イスマイル M ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Particle laden water jet have been analyzed by means of a laser Doppler anemom
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eter (LDA). Glass spheres of 389μm in mean diameter were loaded into the injection water by a particle mixer and after then injected into still water bath. The particle/water jet injectors were made by brass pipes of which diameters were 5 and 8 mm. The mean velocities of the center of the jet were set as 1.8 and 1.5 m/s for 5 and 8 mm pipes, respectively. The initial volume fraction was set as 0.087% in all experiments. The results of vertical relative velocity between particle and water indicate that the particles have same velocity as water at the outlet of the jet however particle velocities are larger than that of water at the expanded jet in downstream. From the results of the transverse relative velocity, it is considered that the particle can get larger velocity than water at a certain downstream from the outlet. These features are well explained by using local Stokes number defined by local time scale of the turbulence and particle time constant as well as Saffman's lift force.
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TAKEDA, Chikashi ; OHTA, Yuji ; ISHIMA, Tsuneaki ; ISHII, Kiyoshi ; OBOKATA, Tomio
概要:
application/pdf<br />Journal Article<br />In order to measure flow velocity in the swirl and radial directions of a cylinder of an engine in practical use by means of a laser Doppler anemometer(LDA)through a small measuring window on the
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cylinder head, a back scattering fringe mode LDA is used. This LDA, however, can not be used to measure the velocity component in the axial direction of the cylinder. A single incidence-beam reference-mode LDA is developed to measure the velocity component along the optical axis of the LDA and is applied to measure the fluctuating flow velocity in the axial direction of the cylinder. Ensemble-averaged mean velocity and fluctuation intensity of the velocity as measured using the LDA show good agreement with those measured using the conventional fringe-mode LDA. Based on these results, it can be concluded that the reference-mode LDA is applicable to measurements of the flow velocity in the axial direction of the cylinder through the amall window on the cylinder head.
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| 8.
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武田, 親士 ; 太田, 祐司 ; 石間, 経章 ; 石井, 清 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />In order to measure flow velocity in the swirl and radial directions of a cylinder of an engine in practical use by means of a laser Doppler anemometer (LDA) through a small measuring window on
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the cylinder head, a back-scattering fringe mode LDA is used. It, however, could not measure the velocity component in the axial direction of the cylinder. The single incidence-beam reference-mode LDA is developed to measure the velocity component along the optical axis of the LDA and applied to measure the fluctuating flow velocity in the axial direction of the cylinder. Ensemble-averaged mean velocity and fluctuation intensity of the velocity as measured by the LDA show good agreement with those measured by the conventional fringe-mode LDA. Based on these results, it can be concluded the reference-mode LDA is applicable to measurements of the flow velocity in the axial direction of the cylinder through the small window on the cylinder head.
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| 9.
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細谷, 肇 ; 小保方, 富夫
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application/pdf<br />Journal Article<br />There have been many experiments to characterize Diesel fuel spray under steady-state conditions. However, the appropriate number of holes and the hole position on the sac to be used in the
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experiment are not clear. To address this subject, we investigate Diesel type spray flows using a laser Doppler anemometer (LDA) and a phase Doppler anemometer (PDA). Spray flow characteristics such as mean and fluctuating two-component velocities, two-dimensional distribution of particle diameter and the variation of three parameters at the log-hyperbolic fitting for particle size distribution are given from measured data. Spray jets from four varieties of Diesel nozzle are compared with each other to clarity the differences in spray characteristics between them. The results show that the spray from the single-hole nozzle on top of the sac is distinct from the others.
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| 10.
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小保方, 富夫 ; 橋本, 徹 ; 五十木, 慎一 ; 柄沢, 隆夫 ; 志賀, 聖一 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />The swirl and axial components of gas velocity in the disk-type combustion cha
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mber of a firing engine were measured by an LDA. The engine was operated under the conditions of a speed of 1500rpm, η_υ=0.5, φ=1.4 and ignition timing of 30°BTDC. The gas velocities at 9 points on a diameter at midheight of the combustion chamber were analyzed by the cycle-resolved method. The bulk (mean) velocity was determined by the frequency discrimination method with the cut-off frequency of 667Hz. The flame propagation pattern was detected by ionization probes set at 17 points on the piston. It has been observed that, in the case of fired operation, the turbulence intensity is higher, the integral length and micro length scales are longer and the swirl flow is weaker and is eccentrically shifted compared with the case of motored operation. These results show that it should be noted that there are remarkable differences in the gas flow between motored operation and fired opeation.
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