NominalTurbulentPipeFlowNominalTurbulentPipeFlow: Quadratic turbulent flow in circular tubes for given nominal values 
This information is part of the Modelica Standard Library maintained by the Modelica Association.
This model defines the pressure loss assuming turbulent flow for
specified dp_nominal
and m_flow_nominal
.
It takes into account the fluid density of each flow segment and
obtains appropriate pathLengths_nominal
values
for an inverse parameterization of the
TurbulentPipeFlow
model. Per default the upstream and downstream densities are averaged with the setting useUpstreamScheme = false
,
in order to avoid discontinuous pathLengths_nominal
values in the case of flow reversal.
The geometry parameters crossAreas
, diameters
and roughnesses
do
not effect simulation results of this nominal pressure loss model.
As the geometry is specified however, the optionally calculated Reynolds number as well as
m_flows_turbulent
and dps_fg_turbulent
become meaningful
and can be related to m_flow_small
and dp_small
.
Optional Variables if show_Res
Type  Name  Description 

ReynoldsNumber  Res[n]  Reynolds numbers of pipe flow per flow segment 
MassFlowRate  m_flows_turbulent[n1]  mass flow rates at start of turbulent region for Re_turbulent=4000 
AbsolutePressure  dps_fg_turbulent[n1]  pressure losses due to friction and gravity corresponding to m_flows_turbulent 
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 to allow flow reversal, false restricts 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: false 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) 
m_flow_turbulent 
Value: if system.use_eps_Re then 0.1 * m_flow_nominal else system.m_flow_small Type: MassFlowRate (kg/s) Description: Turbulent flow starting from m_flows > m_flow_turbulent (may be wider for large discontinuities in static head) 
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:n1]) 
pathLengths_internal 
Default Value: pathLengths_nominal Type: Length[n  1] (m) Description: pathLengths used internally; to be defined by extending class 
Res_turbulent_internal 
Default Value: Res_turbulent_nominal Type: ReynoldsNumber[n  1] Description: Re_turbulent used internally; to be defined by extending class 
system 
Type: System Description: System properties 


states 
Type: ThermodynamicState[n] Description: Thermodynamic states along design flow 