modelSuddenContraction
Extends from Interfaces.SISOFlow_nonConstArea.
Information
This component models a sudden pipe contraction. It computes the pressure loss of the fluid depending on the massflow rate or the massflow rate depending on a given pressure difference, some medium properties and the geometry of the contraction. The model is valid for both incompressible and compressible calculation up to at least Ma 0.3 at pipe outlet and one phase medium.
The pressure loss is calculated with the same functions used in the SuddenExpansion model. To obtain an inverse effect, the function is subjected to a virtual negative mass flow. The negative mass flow is compensated by a change of sign in the pressure drop. The mass flow through the base model is not affected by this.
The pipe bend component is using the partial model SISOFlow_nonConstArea implementing the common flow balances. For the calculation of pressure loss the function dp_suddenChange_DP by Modelica is implemented. The input records dp_suddenChange_IN_con & dp_suddenChange_IN_var are overwritten with the input parameters defining the geometry of the expansion 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 figure, a resistance coefficient chart representing the pressure loss model under common conditions is shown. (Currently not yet available)
[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) |
| Modelica.Fluid.Dissipation.PressureLoss.Orifice.dp_suddenChange_IN_con | In_con | Input record constants | |
| Geometry | |||
| SI.Length | d_1 | Inlet diameter | |
| SI.Length | d_2 | Outlet diameter | |
| Initialization › dp | |||
| ThermofluidStream.Utilities.Types.InitializationMethods | initdp | ThermofluidStream.Utilities.Types.InitializationMethods.none | Initialization method for pressure difference dp |
| SI.Pressure | dp_0 | 0 | Initial value for pressure difference dp |
| ThermofluidStream.Utilities.Units.MassFlowAcceleration | dp_acceleraton_0 | 0 | Initial value for der(dp) |
| Advanced | |||
| Medium.Density | rho_min | dropOfCommons.rho_min | Minimal density |
| StateSelect | dpStateSelect | StateSelect.default | State select for dp |
| ThermofluidStream.Utilities.Units.Inertance | L_value | dropOfCommons.L | Inertance |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.Density | rho | Mean density | |
| Medium.DynamicViscosity | mu | Mean dynamic viscosity | |
| Modelica.Fluid.Dissipation.PressureLoss.Orifice.dp_suddenChange_IN_var | In_var | Input record variables | |
| SI.ReynoldsNumber | Re | d_1*abs(m_flow)/A_1/mu | Reynoldsnumber |