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馬場, 泰一 ; 種市, 雄吾 ; 石間, 経章 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />To reduce friction loss in automotive reciprocating engine, it is required to
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know the lubricant oil film behavior. In the present study, a laser-induced fluorescence (LIF) and a particle image velocimetry (PIV) were applied to measure the oil film thickness and its velocity, independently. A model engine with a quartz glass cylinder was used. Using Rhodamine B, a linear relationship between oil film thickness and fluorescence intensity can be obtained in the range of 0 to 150μm. The LIF measurements were performed under the 300 rpm of mortaring condition. The range of oil film thickness was from 10 to 25 μm on the piston rings. The crank angle variation of oil film thickness was demonstrated successfully. The PIV measurements were also carried out under the motoring speed of 100 rpm. The velocity vector map was obtained in the slit of piston ring. The oil velocity was almost the same as the piston speed near the oil ring. Velocity profiles in the slit were visualized according to the crank angle positions. The results suggested the possibility to analyze the oil film behavior under the combination of the LIF and the PIV measurements.
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高橋, 易資 ; 野村, 友和 ; 石間, 経章 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />A computational fluid dynamics (CFD) code with partial cells in Cartesian coor
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dinate (PCC) method has been developed. The merit of this method is that input data preparation time is extremely short because computational mesh data are separated from geometry data. However, a general Cartesian coordinate method has a big subject in calculation accuracy. One of the factors is precision in geometry expression around the complicated shape, and another is a turbulence model near the wall because mesh is independent from the boundary and not fitted with it. Therefore, discretization equations were derived based on Finite Volumetric Method, and a combination of the wall function and a low Reynolds number k-ε turbulence model was proposed here. This paper describes implementation of this method and shows the results compared with experimental data by particle image velocimetry (PIV) at the steady flow in the cylinder of a 4-valves S.I. engine. The comparison results of velocity vector maps show good agreement between CFD and PIV.
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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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野村, 友和 ; 石間, 経章 ; 小保方, 富夫
概要:
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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高橋, 易資 ; 野村, 友和 ; 石間, 経章 ; 小保方, 富夫
概要:
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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