Diaphragm#
Copyright © EDF 2002 - 2026#
ThermoSysPro Version 4.2#
This component model is documented in Sect. 13.7 of the ThermoSysPro book.
Diaphragm#
A diaphragm measures pressure losses to compute mass flow rates.
For water/steam, the flow regime can be single-phase or homogeneous two-phase flow. This model accounts for friction pressure losses only.
Following assumptions are made:
the diaphragm aperture relies on sharp ridges.
The friction pressure loss coefficient is calculated using the geometry of the diaphragm. The diaphragm component thus completes the singular pressure loss, in which the pressure loss coefficient is a single parameter.
Modelica component model#
The equations mentioned below are implemented in the component Diaphragm, located in the WaterSteam.PressureLosses sub-library.
This component has 2 connectors:
C1: fluid inlet,
C2: fluid outlet.
Nomenclature#
Symbol |
Description |
Unit |
Definition |
Modelica name |
|---|---|---|---|---|
\(D\) |
Diaphragm diameter |
\(\mathrm{m}\) |
D |
|
\(h\) |
Fluid specific enthalpy |
\(\mathrm{J} / \mathrm{kg}\) |
h |
|
\(m\) |
Fluid mass flow rate |
\(\mathrm{kg} / \mathrm{s}\) |
Q |
|
\(P_{\mathrm{i}}\) |
Fluid pressure at the inlet |
\(\mathrm{Pa}\) |
C1.P |
|
\(P_{\mathrm{o}}\) |
Fluid pressure at the outlet |
\(\mathrm{Pa}\) |
\(-\) |
C2.P |
\(Re\) |
Reynolds number |
\(\frac{4 \cdot \lvert \dot{m} \rvert}{\pi \cdot D \cdot \mu \cdot \Omega}\) |
Re |
|
\(Re_{\lim }\) |
Limiting Reynolds number |
\(-\) |
\(10^{5}\) |
Relim |
\(\zeta_{\zeta}\) |
Fluid pressure loss |
\(\mathrm{Pa}\) |
\(P_{\mathrm{i}}-P_{\mathrm{o}}\) |
deltaP |
\(\mu\) |
Friction pressure loss coefficient |
\(-\) |
khi |
|
\(\rho\) |
Fluid dynamic viscosity |
\(\mathrm{Pa} \mathrm{s}\) |
mu |
|
\(\Omega\) |
Fluid density |
\(\mathrm{kg} / \mathrm{m}^{3}\) |
rho |
Governing equations#
Static momentum balance equation#
Validity domain:
\(\forall \dot{m}\)
Mathematical formulation:
Comments:
Friction pressure loss coefficient#
Validity domain:
\(\forall \dot{m}\) with \(Re>Re_{lim}\) and \(\Omega>0\)
Mathematical formulation:
Comments:
References#
El Hefni, Baligh and Bouskela, Daniel (2019). Modeling and Simulation of Thermal Power Plants with ThermoSysPro, sect. 13.7. Springer Nature Switzerland AG.