抄録
The boundary layer formed on the wall in a microtube plays a role of wall of a converging and diverging nozzle. Then the flow at exit is supersonic and underexpaned flow. The Mach number at exit is also beyond unity even if the tube is straight. This phenomenon has not been widely kown yet. Therefore,experimental investigations on phenomenon of supersonic flow at the exit of straight microtubes whose diamerters were 320 and 530 μm were conducted. The successive incident and reflected shock wave on supersonic and underexpanded flow were visualized by Shadowgraph methods. The pressure and Mach number of underexpand flow was determined by the angle of the shock wave generated from the wedge. It is also cofirmed that Mach number at the exit of microtubes is beyond unity since the shock wave generates from the wedge.
