modelCurvedBend
Extends from Interfaces.SISOFlowBend.
Information
This curved pipe bend model computes the pressure loss of the fluid depending on the massflow or the massflow depending on a given pressure difference, some medium properties and the geometry of the pipe bend.
Note that the results may differ from actual values. Due to complex flow behavior in pipe bends, widely applicable formulas are approximations only. If the pressure drop coefficient of a real component is known, it is recommended to calibrate the model to this value using the roughness parameter.
The model is usable for both incompressible and compressible calculation up to at least Ma 0.3 at pipe outlet and one phase medium. The best performance is achieved when using steady state or slowly changing boundary conditions. Numerical stability is best by given mass flow rate and one given pressure boundary. When using two pressure boundaries deviations due to inertia have to be accepted. The Model is not valid for hydraulic shock calculation (sudden change of pressure or mass flow rate).
This component is an adaptation of CurvedBend by Modelica to make it compatible with ThermofludiStream library.
The pipe bend component is using the partial model SISOFlowBend implementing the common flow balances. For the calculation of pressure loss the function dp_curvedOverall_DP by Modelica is implemented. The input records dp_curvedOverall_IN_con & dp_curvedOverall_IN_var are overwritten with the input parameters defining the pipe bend geometry and fluid properties. For more information on the underlying pressure loss function, click here. To improve the accuracy when compressible media are used, center state fluid properties (mean dynamic viscosity & mean density) are defined and refered to in the pressure loss function.
The following 3 figures, resistance coefficient charts representing the pressure loss model under common conditions are shown. (Currently not yet availble)
[P. Jordan; HTWG Konstanz; 10/23]
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | assumeConstantMaterialProperties | true | = true, if constant density and dynamic viscosity is assumed (use '= false' e.g. for Ma > 0.3) |
| Geometry | |||
| SI.Length | d | Diameter | |
| SI.Angle | delta | Bending angle (5° - 180°) | |
| SI.Length | R | Radius of curvature | |
| Roughness | |||
| ThermofluidStream.Processes.Internal.Material | material | ThermofluidStream.Processes.Internal.Material.other | Material of pipe |
| SI.Length | ks | Roughness of pipe | |
| Advanced | |||
| StateSelect | dpStateSelect | StateSelect.default | State select for dp |
| ThermofluidStream.Utilities.Units.Inertance | L_value | dropOfCommons.L | Inertance |
| Boolean | computeL | true | Compute L from r and l |
| Medium.Density | rho_min | dropOfCommons.rho_min | Minimal density |
| Initialization › dp | |||
| ThermofluidStream.Utilities.Types.InitializationMethods | initdp | ThermofluidStream.Utilities.Types.InitializationMethods.none | Initialization method for dp |
| Initialization › Pressure difference | |||
| SI.Pressure | dp_0 | 0 | Initial value for dp |
| ThermofluidStream.Utilities.Units.MassFlowAcceleration | dp_acceleraton_0 | 0 | Initial value for der(dp) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.Density | rho | Mean density | |
| Medium.DynamicViscosity | mu | Mean dynamic viscosity |