Fundamental Issues and Canonical Flows

Measurement and Observation of Jet Thrust for Water Flow Through Micro-Orifice

[+] Author and Article Information
Akiomi Ushida1

Center for Fostering Innovative Leadership,  Niigata University, Niigata-shi 950-2181, Japanakiomiushida@nagoya-u.jp

Tomiichi Hasegawa

Faculty of Engineering,  Niigata University, Niigata-shi 950-2181, Japan

Takehiro Hoshina, Shouta Kudou, Hiroshige Uchiyama

Graduate School of Science and Technology,  Niigata University, Niigata-shi 950-2181, Japan

Takatsune Narumi

Faculty of Engineering,  Niigata University, Niigata-shi 950-2181, Japan


Corresponding author.

J. Fluids Eng 134(8), 081201 (Jul 27, 2012) (7 pages) doi:10.1115/1.4007014 History: Received July 25, 2011; Revised June 21, 2012; Published July 27, 2012; Online July 27, 2012

Owing to the many potential industrial and biological applications of microfluid mechanics, it has recently become an attractive research topic. However, researchers have mainly concentrated on microchannel flows and studies investigating micro-orifice flows are rare cases. In the present study, the results from experiments conducted on flows through micro-orifices with diameters of 100 μm, 50 μm, and 25 μm are presented. In these experiments, the thrust and diameter of observed outflow jets are measured. The resultant thrust and diameter of the jets for the 100 μm orifice flow agree with the numerical predictions obtained via the Navier–Stokes equations. Conversely, for an orifice with a diameter of 50 μm or less, it is found that the thrust is lower than that predicted and the existence of jet swell becomes apparent. With the estimated elastic stress proportional to squared mean velocity, a change in the elasticity of the water as it flows through a micro-orifice is strongly suggested.

Copyright © 2012 by American Society of Mechanical Engineers
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Figure 1

Electron microscope image of micro-orifice: (a) front and (b) back views

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Figure 2

Experimental apparatus for measuring jet thrust

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Figure 3

Method for measuring jet thrust

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Figure 4

Calibration of jet thrust method by using capillary

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Figure 5

Experimental apparatus for measuring jet diameter

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Figure 6

Schematic image of issued jet out of micro-orifice

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Figure 7

Numerical regions and boundary conditions

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Figure 8

Velocity profiles calculated at the exit of orifice having L/D=0.20

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Figure 9

Numerical results for jet thrust when: (a) L/D=0.20, (b) L/D=0.40, and (c) L/D=0.80

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Figure 10

Experimental results of Tm /ρQV plotted against Re for micro-orifice with (a) D=100 μm, (b) D=50 μm, and (c) D=25 μm

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Figure 11

Example of jet observation

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Figure 12

Dj /D versus z/D when: (a) D=100 μm, (b) D=50 μm, and (c) D=25 μm

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Figure 13

Schematic image of estimation of ESswell

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Figure 14

Elastic stress ESthrust and ESswell plotted against mean velocity V



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