Under-Expanded Gas Flow at a Straight Mini-Tube Exit

This paper focuses on under-expanded gas flow at a straight mini-tube exit. Pitot total pressure of gas flow (jet) in downstream region from a straight mini-tube exit was measured to give data for validation of numerical results. A mini-tube of 495μm in diameter & 56.3 mm in length and a pitot tube of 100 μm in outer diameter were used. The pitot total pressure was measured every 0.1 mm interval in the flow and radial directions. The measurement was done for the mass flow rates of 9.71×10⁻⁵ kg/s and 1.46×10⁻⁴ kg/s. The data were accumulated for validation of the numerical result to reveal the characteristics of the under-expanded gas flow at the exit of a mini-tube. Comparisons were conducted for sample computations and a slight discrepancy can be seen between numerical and experimentally measured pitot total pressures.