Abstract:

This Technical Note discusses the studies conducted by ESDU for the CFD validation of the predictions for pressure loss, discharge coefficient and flow characteristics in square-edged orifice plates. These studies used the validation data from the literature reviewed in ESDU TN 07007.

The purpose of this work was to generate validated CFD predictions for:

• square-edged and knife-edged orifice plates, free of burrs and other contaminants,
• circular, concentric orifices in circular pipes with identical upstream and downstream cross-sectional areas,
• fully-developed flow conditions upstream and downstream of the orifice,
• swirl-free, steady flow conditions with no cross-flow upstream or downstream of the orifice plate and flow normal to the orifice plate,
• laminar, transitional and turbulent flow regimes,
• single-phase, Newtonian liquids and gases in incompressible flow (Mach number ≤ 0.3 at the vena contracta plane).

The CFD validation studies covered the following geometrical configurations and pipe Reynolds numbers:

• orifice to pipe diameter ratios: 0.3 ≤ β ≤ 0.7; orifice thickness to diameter ratios: 0.01 ≤ t/d ≤ 5.0.
• pipe Reynolds number: 10 ≤ Re_D ≤ 10⁵.

Based on the comparisons of the ESDU CFD predictions with the experimental data in the literature, best practice guidelines are provided for the modelling of the flow characteristics and pressure loss in square-edge orifice plates.