Abstract
Experimental investigations on nitrogen gas flow characteristics were conducted for a micro-tube. The micro-tube was fabricated in a stainless steel block by electrical discharge machining (EDM). The micro-tube was designed with a main flow tube and five pressure ports, which were led to the pressure transducers. The average diameter and the length of the main tube were of 373 μm and of 40 mm, respectively. The outlet of the tube faced to the atmosphere. The pressure of turbulent gas flow through a micro-tube falls steeply and Mach number increases near the outlet with increasing the inlet pressure due to flow acceleration. It is found that there exists a threshold of Mach number at which the local values of friction factor for the turbulent flow regime abruptly increase. In additional experiments, the flow at the micro-tube outlet was visualized by using a Schlieren method.
