小孔を通過する流れに関する研究 : 第2報,速度場に関する実験

概要

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The velocity field of an inlet and outlet flow through small orifices was experimentally examined. The velocity along the center line near the orifices was measured with a laser doppler anemometer, stream lines in the whole flow region were photographed, and the following points were clarified : (1) The center line velocities of liquid paraffin agree with the theoretical value of Stokes flow in the region of Reynolds numbers below 10. (2) With distilled water, a diverging angle of the issuing flow from a larger orifice is smaller than that of the issuing flow from a smaller orifice. Furthermore, a characteristic isolated vortex is generated on the downstream side of the orifice at the Reynolds number of from 10 to 30. (3) With ethanol used as a test liquid, the diverging angle of the issuing flow is small even for the Reynolds number of less than 10, and the flow resembles a jet. (4) The magnitude of the diverging angle of the issuing flow have a decisive effect on the value of the excess pressure drop at the same Reynolds number ; the larger the diverging angles is, the smaller the excess pressure drop is. (5) The dimension of the isolated vortex generated with the outlet flow of water is, when non-dimensionalized with the orifice diameter, correlated with a dimensionless number V(λ/ν)^<1/2>, where V is the mean orifice velocity, λ is a time proper to water and ν is the kinematic viscosity.
一般社団法人日本機械学会の論文
1987-12-25