Ph.D. Dissertation Defense by Michael Kohl
Wednesday, April 7, 2004
( Dr. Said Abdel-Khalik, Chair)
"An Experimental Investigation of Microchannel Flow With Internal Pressure Measurements"
Microchannel flow and convection has become an important design aspect in the creation of many of today's microdevices. Unfortunately, experimental data for microchannel flow and convection are highly inconsistent. The scatter in the data may be due to several factors including the difficulty in properly instrumenting a micrometer scale experiment and possible effects associated with microscale geometry.
In order to obtain a better understanding of microchannel flows, experiments have been conducted that address some of the most likely issues that could be causing large inconsistencies in published data. Using microfabrication technologies, straight channel test sections that allow internal pressure measurements were fabricated. The test-sections were created in silicon wafers with integrated tap lines and pressure sensors. The pressure sensors employ a novel, off-chip optical measurement scheme. Experiments have been conducted with both compressible and incompressible fluids, spanning laminar, transitional and turbulent flow regimes.
The results indicate that friction factor data for microchannels in the range
of 25 to 100 microns can be accurately determined from data for standard large
channels. The large inconsistencies in previously published data are probably
due to instrumentation errors and improper accounting for compressibility effects.