Hot subsonic jet
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Introduction
This is an example flow simulation of a high-temperature subsonic nozzle with a temperature of 260$^o C$ and a Mach number of 0.376 at the nozzle throat.
The geometry and experimental conditions are provided by NASA Langley Research Center.
https://turbmodels.larc.nasa.gov/jetsubsonichot_val.html
Experimental results from NASA ARN2 (Acoustic Research Nozzle 2) with the following geometry and conditions
- Radius of the nozzle neck: 1 inch
- Pressure ratio, $p/p{ref}$ = 1.10203, $p{ref}$ = 14.3 psi
- Temperature ratio, $T/T{ref}$ = 1.81388, $T{ref}$ = 530 R
- Nozzle exit Mach number: 0.376
Along with the experimental results, we provide calculations from the $SST$ k-$omega$ model and the Spalart-Allmaras model from the NASA WIND code.
- solver : buoyantSimpleNFoam
- turbulence model : $standard$ $k-epsilon$
- density : Perfect Gas
- viscosity and thermal conductivity : Sutherland law
- nozzle inlet condition : 10059.65 Pa, 534.086 K
Start BaramFlow and load mesh
Run the program and select [New Case] from the launcher. In the launcher, select [Pressure-based] for [Solver Type] and [None] for [Multiphase Model].
Use the given polyMesh folder. In the top tab, click [File]-[Load Mesh]-[OpenFOAM] in that order and select the polyMesh folder.
General
Set Time as Steady, Gravity as (0 0 0).
Set Operating Pressure as 98595.03.
Models
For this example, we’ll use $Standard$ $k-epsilon$ model for turbulence.
Include Energy.
Materials
Material properties of air is as follows
- Density : Perfect Gas
- Specific heat : 1006
- Viscosity : Sutherland, As = 1.46e-6, Ts = 110.4
- Molecular Weight : 28.966
Boundary Conditions
Set the boundary type and values as shown below.
- inlet : Pressure Inlet
- Total Pressure : 10059.65
- Turbulence Specification Method : Intensity and Viscosity Ratio
- Turbulent Intensity : 1
- Viscosity ratio : 10
- Temperature : 534.086
- outlet : Pressure Outlet
- Pressure : 0
- Specify Backflow Properties : on
- Backflow Total Temperature : 294.4444
- Turbulence Specification Method : Intensity and Viscosity Ratio
- Turbulent Intensity : 1
- Viscosity ratio : 10
- farfield : Velocity Inlet
- Velocity Specification Method : Component (3.44 0 0)
- Turbulence Specification Method : Intensity and Viscosity Ratio
- Turbulent Intensity : 1
- Viscosity ratio : 10
- Temperature : 294.4444
- nozzle : Wall
- Velocity : No Slip
- Temperature : Adiabatic
- frontAndBackPlanes_pos, frontAndBackPlanes_neg : Wedge
Numerical Conditions
In this example, we’ll change the settings as shown below.
- Pressure-Velocity Coupling : SIMPLE
- Discretization Schemes
- Pressure : Momentum Weighted Reconstruct
- Momentum, Energy, Turbulence :Second Order Wpwind
- Under-Relaxation Factors
- Pressure : 0.1
- Momentum : 0.3
- Energy : 0.9
- Turbulence : 0.2
- Convergence Criteria
- Pressure : 0
- Momentum, Energy, Turbulence : 0.001
- Advanced
- Minimum Static Temperature : 100
- Maximum Static Temperature : 1000
- Turn on Include Viscous Dissipation Terms
Monitor
In this example, we will monitor the axial velocity of a point with x/D of 20 on the axis. Select [Add]-[Points].
Enter X-Velocity for Field and (1.016 0 0) for Coordinate.
Initialization
Enter the value and click the Initialize button at the bottom. Then click the [File]-[Save] menu to save the case file.
- Velocity : (3.44 0 0)
- Pressure : 0
- Temperature : 294.4444
- Scale of velocity : 100
- Turbulent Intensity : 1
- Turbulent Viscosity Ratio : 10
Run
Selct [Parallel]-[Environment] in menu. Set Number of Cores as you want and select [Local Machine] for [Parallel Type].
Change the values as shown below, and click [Start Calculation] button.
- Number of Iterations : 20000
- Save Interval : 1000
When the calculation is started, you can see the graphs of Residuals and point monitor as shown below.
Post-processing
Click the parview button in [External tools] to open the paraview.
Change the [Case Type] to [Decomposed Case].
Change [Coloring] to U.
