An Experimental Investigation of Gaseous Flow Characteristics in Microchannels

Gaseous flow characteristics in fused silica microtubes and square microchannels are studied experimentally. The existing works in the literature on experimental gaseous flow are analyzed. The data in fused silica micro circular tubes with diameters ranging from 50 μm to 201 μm and the data in fused silica micro square channels with hydraulic diameter ranging from 52 μm to 100 μm show that the flow friction factors are in good agreement with the theoretical prediction for conventional tubes and no distinguishable deviation is observed. The transition Reynolds number is around 2000 and a slight early transition from laminar to turbulent is observed due to the compressibility effect. For the helium flow in fused silica microtubes with inner diameters ranging from 10 μm to 20 μm, the decrease in friction factor is observed. In addition, factors including roughness, compressibility and rarefaction that may have significant effects on flow characteristics in microchannels are discussed.