modelSuddenContraction
Extends from Interfaces.SISOFlow_nonConstArea (SISOFlow considering dynamic effects due to different inlet/outlet cross sectional areas).
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 |
|---|---|---|---|
| String | instanceName (from DropOfCommonsPlus) | getInstanceName() | Instance name |
| 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 | |
| Layout | |||
| Boolean | displayInstanceName (from DropOfCommonsPlus) | dropOfCommons.displayInstanceNames | = true, if instance name is displayed |
| Boolean | displayParameters (from DropOfCommonsPlus) | dropOfCommons.displayParameters | = true, if displaying parameters is enabled |
| Advanced | |||
| ThermofluidStream.Utilities.Units.Inertance | L (from SISOFlow_nonConstArea) | dropOfCommons.L | Inertance of the flow |
| StateSelect | m_flowStateSelect (from SISOFlow_nonConstArea) | StateSelect.default | State select for m_flow |
| Boolean | clip_p_out (from SISOFlow_nonConstArea) | If false, set dr_corr to zero | |
| Medium.AbsolutePressure | p_min (from SISOFlow_nonConstArea) | dropOfCommons.p_min | Minimal steady-state output pressure |
| 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 |
| Initialization › Mass flow | |||
| InitializationMethods | initM_flow (from SISOFlow_nonConstArea) | ThermofluidStream.Utilities.Types.InitializationMethods.none | Initialization method for m_flow |
| SI.MassFlowRate | m_flow_0 (from SISOFlow_nonConstArea) | 0 | Initial value for m_flow |
| ThermofluidStream.Utilities.Units.MassFlowAcceleration | m_acceleraton_0 (from SISOFlow_nonConstArea) | 0 | Initial value for der(m_flow) |
| 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) |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| ThermofluidStream.Interfaces.Inlet | inlet (from SISOFlow_nonConstArea) | ||
| ThermofluidStream.Interfaces.Outlet | outlet (from SISOFlow_nonConstArea) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| SI.MassFlowRate | m_flow (from SISOFlow_nonConstArea) | inlet.m_flow | mass flow through component |
| SI.Velocity | c_in (from SISOFlow_nonConstArea) | Inlet velocity | |
| SI.Velocity | c_out (from SISOFlow_nonConstArea) | Outlet velocity | |
| SI.Pressure | dr_corr (from SISOFlow_nonConstArea) | ||
| SI.Pressure | dp (from SISOFlow_nonConstArea) | Static pressure difference dp = p_out - p_in | |
| SI.Pressure | dq (from SISOFlow_nonConstArea) | Dynamic pressure difference dq = q_out - q_in | |
| 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 |