Modelica.Fluid.Pipes.BaseClasses.WallFriction

Different variants for pressure drops due to pipe wall friction

Information

This package provides functions to compute pressure losses due to wall friction in a pipe. Every correlation is defined by a package that is derived by inheritance from the package WallFriction.PartialWallFriction. The details of the underlying pipe wall friction model are described in the UsersGuide. Basically, different variants of the equation

   dp = λ(Re,D)*(L/D)*ρ*v*|v|/2

are used, where the friction loss factor λ is shown in the next figure:

PipeFriction1.png

Extends from Modelica.Icons.Package (Icon for standard packages).

Package Content

Name Description
Modelica.Fluid.Pipes.BaseClasses.WallFriction.PartialWallFriction PartialWallFriction Partial wall friction characteristic (base package of all wall friction characteristics)
Modelica.Fluid.Pipes.BaseClasses.WallFriction.NoFriction NoFriction No pipe wall friction, no static head
Modelica.Fluid.Pipes.BaseClasses.WallFriction.Laminar Laminar Pipe wall friction for laminar flow in circular tubes (linear correlation)
Modelica.Fluid.Pipes.BaseClasses.WallFriction.QuadraticTurbulent QuadraticTurbulent Pipe wall friction for turbulent flow in circular tubes (simple characteristic, mu not used)
Modelica.Fluid.Pipes.BaseClasses.WallFriction.LaminarAndQuadraticTurbulent LaminarAndQuadraticTurbulent Pipe wall friction for laminar and turbulent flow in circular tubes (simple characteristic)
Modelica.Fluid.Pipes.BaseClasses.WallFriction.Detailed Detailed Pipe wall friction for laminar and turbulent flow (detailed characteristic)
Modelica.Fluid.Pipes.BaseClasses.WallFriction.TestWallFrictionAndGravity TestWallFrictionAndGravity Pressure loss in pipe due to wall friction and gravity (only for test purposes; if needed use Pipes.StaticPipe instead)

Modelica.Fluid.Pipes.BaseClasses.WallFriction.TestWallFrictionAndGravity Modelica.Fluid.Pipes.BaseClasses.WallFriction.TestWallFrictionAndGravity

Pressure loss in pipe due to wall friction and gravity (only for test purposes; if needed use Pipes.StaticPipe instead)

Information

This model describes pressure losses due to wall friction in a pipe and due to gravity. It is assumed that no mass or energy is stored in the pipe. Correlations of different complexity and validity can be selected via the replaceable package WallFriction (see parameter menu below). The details of the pipe wall friction model are described in the UsersGuide. Basically, different variants of the equation

   dp = λ(Re,D)*(L/D)*ρ*v*|v|/2

are used, where the friction loss factor λ is shown in the next figure:

PipeFriction1.png

By default, the correlations are computed with media data at the actual time instant. In order to reduce non-linear equation systems, parameter use_nominal provides the option to compute the correlations with constant media values at the desired operating point. This might speed-up the simulation and/or might give a more robust simulation.

Extends from Modelica.Fluid.Interfaces.PartialTwoPortTransport (Partial element transporting fluid between two ports without storage of mass or energy).

Parameters

NameDescription
replaceable package MediumMedium in the component
replaceable package WallFrictionCharacteristic of wall friction
lengthLength of pipe [m]
diameterInner (hydraulic) diameter of pipe [m]
crossAreaInner cross section area [m2]
height_abHeight(port_b) - Height(port_a) [m]
roughnessAbsolute roughness of pipe (default = smooth steel pipe) [m]
use_nominal= true, if mu_nominal and rho_nominal are used, otherwise computed from medium
mu_nominalNominal dynamic viscosity (e.g., mu_liquidWater = 1e-3, mu_air = 1.8e-5) [Pa.s]
rho_nominalNominal density (e.g., rho_liquidWater = 995, rho_air = 1.2) [kg/m3]
Nominal operating point
m_flow_nominalNominal mass flow rate [kg/s]
Assumptions
allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
dp_startGuess value of dp = port_a.p - port_b.p [Pa]
m_flow_startGuess value of m_flow = port_a.m_flow [kg/s]
m_flow_smallSmall mass flow rate for regularization of zero flow [kg/s]
show_Re= true, if Reynolds number is included for plotting
from_dp= true, use m_flow = f(dp), otherwise dp = f(m_flow)
Diagnostics
show_T= true, if temperatures at port_a and port_b are computed
show_V_flow= true, if volume flow rate at inflowing port is computed

Connectors

NameDescription
port_aFluid connector a (positive design flow direction is from port_a to port_b)
port_bFluid connector b (positive design flow direction is from port_a to port_b)
replaceable package WallFrictionCharacteristic of wall friction
Automatically generated Thu Dec 19 17:20:10 2019.