부산대학교 도서관

Past few decades have witnessed the growing importance of micro shock tube in various engineering applications like micro combustion, micro turbines, MEMS, particle delivery devices etc. Owing to its large surface area to volume ratio, micro shock tube exhibits different flow characteristics from the well established macro shock tube flows. One of the major changes involved in such kind of small scale flows is that the Knudsen Number becomes high enough to produce the molecular effects prominent. In these situations the operating pressure becomes a crucial factor in controlling the flow since a low operating pressure will induce rarefaction effects which makes the wall attached fluid slip and have a higher temperature than the wall value. Navier- Stokes equations becomes incompatible to predict such flows and depending on the Knudsen Number, N-S equations with slip wall conditions or molecular dynamics study are needed to be used to mathematically model the flow physics. In the present study, unsteady axi-symmetric CFD method has been applied to simulate the micro shock tube flow. Maxwell"s slip wall conditions were used to simulate the rarefaction effects produced by the large Knudsen Number. A comparative study on the unsteady behaviors of shock wave and contact discontinuity under different diameters and initial pressure conditions were, in detail, analyzed. The results obtained show much more attenuation of shock wave, compared with macro-shock tubes.