Training only. Do not use this for valve selection, operating decisions or safety assessments.
Flow lines: particles move through 5 solved OpenFOAM velocity fields (steady RANS, k-ω SST, half model, clean water at 1,800 m³/h) at 20, 30, 50, 75 and 100 % stem travel. In between, the fields are blended. Below 20 %, the 20 % pattern is steered through the real gap and is schematic. Speeds are slowed to about 1/4 and scale with flow rate.
Pressure loss: K comes from the same CFD: 73, 15.6, 2.3 and 0.43 at 20 to 75 %, with 0.15 at full open taken from typical published data. Coarser mesh checks gave 8 % higher K at 20 % and 3 % at 50 %. The 30 and 75 % cases used the coarser mesh only. Below 20 %, K is a scaled estimate.
Not validated. No test data or maker's Cv curve has been compared yet. The model leaves out the stem, bonnet dome and wedge guides. Dirty and sour services reuse the clean water pattern, scaled by density and flow. Limits for velocity and wear are teaching values. Flow is capped when the drop reaches 80 % of the available pressure.