POA * ONLINE SUBSCRIPTION ONLY

ESDU 82009 presents pressure loss and discharge coefficient data for subsonic compressible flow of gases through single, or multiple, sharp-edged orifices in thin or thick plates for flow rates up to choking. The mechanics of compressible flow through orifices are discussed briefly with particular attention to sonic flow conditions. The mass flow function, based on orifice entry conditions, that gives maximum mass flow rate is presented and pressure loss coefficients are then expressed as a function of the ratio of the actual mass flow function to that limiting value. All are functions also of porosity and thickness/diameter ratio of the orifice. The data cover a range of porosity between 0.001 and 0.95 and thickness/diameter up to seven. Discharge coefficients are presented for orifices of very small porosity, for maximum mass flow conditions and for conditions when the total-pressure loss coefficient exceeds unity. A flowchart guides the user through the calculations necessary to determine pressure loss or discharge coefficient and a worked example is included. A Fortran program is provided on disc in the software volume (ESDUpac A8209) both uncompiled and compiled within ESDUview, a user-friendly interface that runs under MS DOS and prompts on-screen for input data.