Loss factor for mass flow rate from port_a to port_b (Idelchik 1994, diagram 4-14, p. 221):
zeta = [(1-A0/A1) + 0.707*(1-A0/A1)^0.375]^2*(A1/A0)^2 for Re(A0) ≥ 1e5, independent of alpha
Loss factor for mass flow rate from port_b to port_a (Idelchik 1994, diagram 4-13, p. 220, with A2=A1):
zeta = k*(1 - A0/A1)^0.75 + (1 - A0/A1)^2 + 2*sqrt(k*(1-A0/A1)^0.375) + (1- A0/A1) k = 0.13 + 0.34*10^(-(3.4*LD+88.4*LD^2.3)) (there is a typing error in the formula in diagram 4-13, the above equation corresponds to table (a) in diagram 4-12) LD = L/D0 for Re(A0) ≥ 1e4, 40 deg ≤ alpha ≤ 60 deg for other values of alpha, k is given as table in diagram 3-7 (this is not yet included in the function)
encapsulated function sharpEdgedOrifice import Modelica.Units.SI; import Modelica.Units.NonSI; import Modelica.Fluid.Fittings.BaseClasses.QuadraticTurbulent.LossFactorData; input SI.Diameter diameter "Inner diameter of pipe (= same at port_a and port_b)" annotation( Dialog); input SI.Diameter leastDiameter "Smallest diameter of orifice" annotation( Dialog); input SI.Diameter length "Length of orifice" annotation( Dialog); input NonSI.Angle_deg alpha "Angle of orifice" annotation( Dialog); output LossFactorData data "Pressure loss factors for both flow directions"; end sharpEdgedOrifice;