modelDiffuser
Extends from Interfaces.SISOFlow_nonConstArea.
Information
This component models a diffuser. 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 diffuser. The component is valid for both incompressible and compressible calculation up to at least Ma 0.3 at pipe outlet and one phase medium.
The pipe bend component is using the partial model SISOFlow_nonConstArea implementing the common flow balances for components with non constant cross sectional areas. For the calculation of pressure loss the function dp_conicalDiffuserOverall_DP is used. It is based on the formulas and data provided in "Handbook of Hydraulic Resistance" by Idel'chik (1960). Be aware that there the book has been updated since then.
The function calculates and feeds back the pressure loss as well as total pressure loss coefficient and the partial pressure loss coefficientes due to diffuser enlargement and wall friction. For more information click here. The functions assumes pressure loss coefficient due to diffuser enlargement to be independent from Reynolds Number, constant wall fricition along diffuser length and uniform velocity profile at inlet.
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 pressure loss of the diffuser in the described in the figure is shown. (Currently not yet available)
[P. Jordan; HTWG Konstanz; 01/24]
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | assumeConstantDensity | true | = true, if incompressibility is assumed (use '= false' for Ma > 0.3) |
| SI.Angle | alpha | if not setLength then alpha_par else 2*atan((d_2 - d_1)/2/l_par) | Central divergence angle of diffuser walls |
| SI.Length | l_dif | if not setLength then (d_2 - d_1)/2/tan(alpha/2) else l_par | Diffuser length |
| SI.Length | ks_internal | if material == ThermofluidStream.Processes.Internal.Material.concrete then 5e-3 elseif material == ThermofluidStream.Processes.Internal.Material.wood then 0.5e-3 elseif material == ThermofluidStream.Processes.Internal.Material.castIron then 0.25e-3 elseif material == ThermofluidStream.Processes.Internal.Material.galvanizedIron then 0.15e-3 elseif material == ThermofluidStream.Processes.Internal.Material.steel then 0.059e-3 elseif material == ThermofluidStream.Processes.Internal.Material.drawnPipe then 0.0015e-3 else ks | Pipe roughness |
| Geometry | |||
| SI.Length | d_1 | Inlet diameter | |
| SI.Length | d_2 | Outlet diameter | |
| Boolean | setLength | true | = true, if diffusor length l_par is given (= false, if divergence angle alpha_par is given) |
| SI.Length | l_par | 0 | Diffusor length |
| SI.Angle | alpha_par | 0 | Central divergence angle of diffuser walls |
| Roughness | |||
| ThermofluidStream.Processes.Internal.Material | material | ThermofluidStream.Processes.Internal.Material.other | Material of pipe |
| SI.Length | ks | Pipe roughness | |
| Advanced | |||
| ThermofluidStream.Utilities.Units.Inertance | L_value | dropOfCommons.L | Inertance of pipe |
| Boolean | computeL | true | Compute L from r and l |
| Medium.Density | rho_min | dropOfCommons.rho_min | Minimal input density |
| StateSelect | dpStateSelect | StateSelect.default | State select for dp |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.Density | rho | Mean density | |
| Medium.DynamicViscosity | mu | Mean dynamic viscosity | |
| SI.ReynoldsNumber | Re | d_1*abs(m_flow)/A_1/mu | Reynolds Number |
| Internal.Types.PressureLossCoefficient | zeta_dif | Total pressure loss coefficient of diffuser | |
| Internal.Types.PressureLossCoefficient | zeta_exp | Pressure loss coefficient due to diffuser enlargement | |
| Internal.Types.PressureLossCoefficient | zeta_fr | Pressure loss coefficient of diffuser due to wall friction |