Fan(MRF)

Download mesh
Download simulation

Introduction

Mesh and velocity

This is a steady-state incompressible flow analysis example. The problem is to predict the flow using multiple reference frames (MRFs) as the impeller rotates inside a fan.

The computational conditions are as follows

  • solver : buoyantSimpleNFoam
  • turbulence model : $Standard$ $k-epsilon$ model
  • density : 1.225 $kg/m^3$
  • viscosity : 1.79e-5 $kg/ms$
  • Rotation velocity : 1,000 RPM
  • flow condition : 10 $m/s$ at inelt

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

For this example, we’ll use default conditions.

Models

For this example, we’ll use default conditions.

Materials

For this example, we will use the properties of air.

Cell zone Conditions

Cell Zone Conditions allow you to set MRF, Sliding Mesh, Source, and more. In this example, we are using a Multiple Reference Frame, MRF condition for the ‘rotating’ Cell Zone.

Select Multiple Reference Frame, MRF and set values as follows

  • Multiple Reference Frame, MRF
    • Rotating Speed : 1000(RPM)
    • Rotation-Axis Origin : (0 0 0)
    • Rotation-Axis Direction : (0 0 1)
    • Static Boundary : casing

Boundary Conditions

Each boundary condition is set as follows

  • blade, casing
    • Velocity Condition : No Slip

  • inlet : Velocity Inlet
    • Velocity Specification Method : Magnitudde, Normal to Boundary
    • Profile Type : Constant
    • Velocity Magnitude : 10 (m/s)
    • Turbulent Intensity : 1 (%)
    • Turbulent Viscosity Ratio : 10

  • outlet : Pressure Outlet
    • Total Pressure : 0 (Pa)

Numerical Conditions

In this example, we’ll change the settings as shown below.

  • Pressure-Velocity Coupling Scheme : SIMPLE
  • Discretization Scheme
    • Pressure : Linear
    • Momentum : Second Order Upwind
    • Turbulence : Second Order Upwind
  • Under-Relaxation Factors
    • Pressure : 0.3
    • Momentum : 0.5
    • Turbulence : 0.7
  • Convergence Criteria
    • Pressure : 0.001
    • Momentum : 0.001
    • Turbulence : 0.001

Initialization

Use default vaues.

Enter the value and click the Initialize button at the bottom. Then click the [File]-[Save] menu to save the case file.

Run

Change the values as shown below, and click [Start Calculation] button.

  • Number of Iterations : 1000
  • Save Interval : 100
  • Retain Only the Most Recent Files, 1
  • Data Write Format : Binary
  • Selct [Parallel]-[Environment] in menu. Set Number of Cores as you want and select [Local Machine] for [Parallel Type].

When the calculation is started, you’ll see a graph of Residuals and Force monitor as shown below.

|residual{:target=”_blank”}|

Post-processing

Draw the pressure distribution in the fan.

Click the parview button in [External tools] to open the paraview.

Change the [Case Type] to [Decomposed Case].

Use the [Slice] function to cut a cross-section inside the domain.

Click the Z-normal button and enter 0.01 for the z value in Origin.