Published online by Cambridge University Press: 04 July 2016
Discharge coefficients for annular orifices formed between pistons and a cylindrical bore are reported for twelve pistons having orifice length to gap ratios in the range 12 to 50. Square-edged, radiused and tapered orifices are examined at high fluid pressure differentials with Reynolds number varying in the range 500-4000. The radial gaps were determined by examining the flow for each piston geometry at low Reynolds numbers.