WOLFRAM SYSTEM MODELER

PartialGenericPipeFlow

GenericPipeFlow: Pipe flow pressure loss and gravity with replaceable WallFriction package

Wolfram Language

In[1]:=
SystemModel["Modelica.Fluid.Pipes.BaseClasses.FlowModels.PartialGenericPipeFlow"]
Out[1]:=

Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

This model describes pressure losses due to wall friction in a pipe and due to gravity. 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,Δ)*(L/D)*ρ*v*|v|/2.

By default, the correlations are computed with media data at the actual time instant. In order to reduce non-linear equation systems, the parameters use_mu_nominal and use_rho_nominal provide 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.

Parameters (17)

m

Value: n - 1

Type: Integer

Description: Number of flow segments

n

Value: 2

Type: Integer

Description: Number of discrete flow volumes

nParallel

Value:

Type: Real

Description: Number of identical parallel flow devices

g

Value: system.g

Type: Acceleration (m/s²)

Description: Constant gravity acceleration

allowFlowReversal

Value: system.allowFlowReversal

Type: Boolean

Description: = true, if flow reversal is enabled, otherwise restrict flow to design direction (states[1] -> states[n+1])

momentumDynamics

Value: system.momentumDynamics

Type: Dynamics

Description: Formulation of momentum balance

m_flow_start

Value: system.m_flow_start

Type: MassFlowRate (kg/s)

Description: Start value of mass flow rates

p_a_start

Value:

Type: AbsolutePressure (Pa)

Description: Start value for p[1] at design inflow

p_b_start

Value:

Type: AbsolutePressure (Pa)

Description: Start value for p[n+1] at design outflow

useUpstreamScheme

Value: true

Type: Boolean

Description: = false to average upstream and downstream properties across flow segments

use_Ib_flows

Value: momentumDynamics <> Types.Dynamics.SteadyState

Type: Boolean

Description: = true to consider differences in flow of momentum through boundaries

Re_turbulent

Value: 4000

Type: ReynoldsNumber

Description: Start of turbulent regime, depending on type of flow device

show_Res

Value: false

Type: Boolean

Description: = true, if Reynolds numbers are included for plotting

from_dp

Value: momentumDynamics >= Types.Dynamics.SteadyStateInitial

Type: Boolean

Description: = true, use m_flow = f(dp), otherwise dp = f(m_flow)

dp_nominal

Value:

Type: AbsolutePressure (Pa)

Description: Nominal pressure loss (only for nominal models)

m_flow_nominal

Value:

Type: MassFlowRate (kg/s)

Description: Nominal mass flow rate

m_flow_small

Value: if system.use_eps_Re then system.eps_m_flow * m_flow_nominal else system.m_flow_small

Type: MassFlowRate (kg/s)

Description: Within regularization if |m_flows| < m_flow_small (may be wider for large discontinuities in static head)

Inputs (9)

pathLengths

Type: Length[m] (m)

Description: Lengths along flow path

states

Type: ThermodynamicState[n]

Description: Thermodynamic states along design flow

vs

Type: Velocity[n] (m/s)

Description: Mean velocities of fluid flow

crossAreas

Type: Area[n] (m²)

Description: Cross flow areas at segment boundaries

dimensions

Type: Length[n] (m)

Description: Characteristic dimensions for fluid flow (diameters for pipe flow)

roughnesses

Type: Roughness[n] (m)

Description: Average height of surface asperities

dheights

Type: Length[n - 1] (m)

Description: Height(states[2:n]) - Height(states[1:n-1])

pathLengths_internal

Type: Length[n - 1] (m)

Description: pathLengths used internally; to be defined by extending class

Res_turbulent_internal

Default Value: Re_turbulent * ones(n - 1)

Type: ReynoldsNumber[n - 1]

Description: Re_turbulent used internally; to be defined by extending class

Components (2)

system

Type: System

Description: System properties

states

Type: ThermodynamicState[n]

Description: Thermodynamic states along design flow

Extended by (3)

DetailedPipeFlow

Modelica.Fluid.Pipes.BaseClasses.FlowModels

DetailedPipeFlow: Detailed characteristic for laminar and turbulent flow

TurbulentPipeFlow

Modelica.Fluid.Pipes.BaseClasses.FlowModels

TurbulentPipeFlow: Quadratic turbulent flow in circular tubes (using mu to regularize laminar region)

NominalTurbulentPipeFlow

Modelica.Fluid.Pipes.BaseClasses.FlowModels

NominalTurbulentPipeFlow: Quadratic turbulent flow in circular tubes for given nominal values