SUMMARY

Microchannel flows are of increasing importance. The characterization of fluid flow in microchannels by measuring the pressure drop through them or the associated friction factor is actively pursued research. Much of the previous work has focused on single phase fluid flow. However, for many applications both vapor and liquid may be present or desired, and it is important to characterize these flows. A particular interest that has been emphasized in the Thermal-Hydraulics Laboratory at Georgia Tech is mist flow since mist flows promise very high performance cooling. The proposed research will study two-phase mist flows in microchannels. In this study a two-phase air and water mixture will be generated using a unique ultrasonic apparatus. This apparatus should allow the independent variation of the droplet size and the liquid to gas ratio. This capability gives unique experimental flexibility. This two phase mixture will be passed through sub 100 micrometer channels to characterize the friction factor profile over a range of flow conditions and for different liquid to gas ratios. The results will be compared to analogous results in the single phase case, results from other studies, and theoretical results from a computational fluid dynamics (CFD) model. If the standard CFD model is inadequate, an improved model will be developed. The proposed research should advance the use of mist cooling in critical microchannel applications.