DetailedPipeFlowDetailedPipeFlow: Detailed characteristic for laminar and turbulent flow |
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Information
This information is part of the Modelica Standard Library maintained by the Modelica Association.
This component defines the complete regime of wall friction. The details are described in the UsersGuide. The functional relationship of the friction loss factor λ is displayed in the next figure. Function massFlowRate_dp() defines the "red curve" ("Swamee and Jain"), where as function pressureLoss_m_flow() defines the "blue curve" ("Colebrook-White"). The two functions are inverses from each other and give slightly different results in the transition region between Re = 1500 .. 4000, in order to get explicit equations without solving a non-linear equation.
Additionally to wall friction, this component properly implements static head. With respect to the latter, two cases can be distinguished. In the case shown next, the change of elevation with the path from a to b has the opposite sign of the change of density.
In the case illustrated second, the change of elevation with the path from a to b has the same sign of the change of density.
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 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: 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: if system.use_eps_Re then system.m_flow_nominal else 1e2 * m_flow_small 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 |
Default Value: pathLengths 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)
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system |
Type: System Description: System properties |
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states |
Type: ThermodynamicState[n] Description: Thermodynamic states along design flow |
Extended by (4)
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Modelica.Fluid.Pipes.BaseClasses.PartialTwoPortFlow Wall friction, gravity, momentum flow |
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Modelica.Fluid.Pipes.BaseClasses.PartialStraightPipe Wall friction, gravity, momentum flow |
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Modelica.Fluid.Examples.HeatExchanger.BaseClasses.BasicHX Characteristic of wall friction |
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Modelica.Fluid.Examples.HeatExchanger.BaseClasses.BasicHX Characteristic of wall friction |