Micro-orifice single-phase liquid flow: Pressure drop measurements and prediction

The dimensionless pressure drop was measured for six micro-orifices with diameters of 150 micron, 300 micron and 600 micron, and thickness ratios between 1.87 and 6.93. The experiments were carried out with water for orifice Reynolds number between 6000 and 25,000, thus extending the range covered in previous researches in turbulent flow conditions. The dimensionless pressure drop was found to be a weak decreasing function of the Reynolds number, and was found to be unaffected by the micro-orifice diameter ratio or thickness ratio. The static pressure profiles measured immediately downstream of the microorifices were flat, indicating that the vena contracta is located within the micro-orifice. A new prediction method for the dimensionless pressure drop in micro-orifices at high Reynolds number was developed using available data.