Compressible Microchannel Flow

We present experiments on the isothermal gas flow at relatively high Mach numbers in microfabricated channels of small aspect ratios. The microchannels were fabricated by deep etching on silicon wafers, bonded to a Pyrex wafer to cover and seal them; the microchannels were 10 microns deep with a variety of widths. The accurate determination of the small flow rates was performed by measuring the displacement of a bead of mercury in a precision bore glass tube in a controlled environment. The experiment setup has been specially designed to account for inlet and outlet loss. The inferred friction coefficient at different values of Knudsen, Reynolds and Mach numbers shows that the flow inside the microchannel follows the classical laminar behavior over the range of experiments.