Under Expanded Gaseous Flow at a Straight Micro Tube Exit

Abstract

This paper focuses on underexpanded gaseous flow at a straight microtube exit. The pitot total pressure of gas flow (jet) in the downstream region from a straight microtube exit was measured by a total pressure pitot tube to accumulate data for validation of numerical results. A microtube of 495خ¼m in diameter and 56.3 mm in length and a total pressure pitot tube of 100 خ¼m in outer diameter were used. The pitot total pressure was measured at intervals of 0.1 mm in both the flow and radial directions. The measurement was done for the mass flow rates of 9.71 أ— 10−5 kg/s and 1.46 أ— 10−4 kg/s. The data were accumulated for validation of the numerical results to reveal the characteristics of the underexpanded gas flow at the exit of a microtube. Comparisons were conducted for numerical results of corresponding cases and a slight discrepancy can be seen between numerical and experimentally measured pitot total pressures.