FLAIR Tutorial 6: A fan mounted at the boundary of a cabinet

This case shows how to activate the "Fan Operating Point" option for a single fan mounted at the boundary of a cabinet as shown below.

Setting up the model

Start FLAIR with the default room

The FLAIR VR-Environment screen should appear, which shows the default domain with the dimensions 10mx10mx3m.

Set the cabinet size

Change the X size to 0.5m

Change the Y size to 0.5m

Change the Z size to 0.7m

Adding objects to the cabinet

a. add the top vent

X: 0.3 m

Y: 0.2 m

Z:0.0 m

X: 0.1 m

Y: 0.15 m

Z: tick 'at end'

b. add the fan object:

X:0.2 m

Y:0.0 m

Z:0.3 m

X: 0.15 m

Y: 0.0 m

Z: 0.2 m

c. add the first chip

X:0.05 m

Y:0.07 m

Z:0.02 m

X: 0.15 m

Y: 0.15 m

Z: 0.35 m

d. add the second chip by duplicating CHIP1

X: 0.3 m

Y: 0.15 m

Z: 0.35 m

e. add the PCB

X:0.3 m

Y:0.3 m

Z:0.01 m

X: 0.1 m

Y: 0.1 m

Z: 0.34 m

Now we have 5 objects listed in the 'Object management' dialog box as shown below

To activate the physical models

a. The Main Menu panel

To activate 'K-E' turbulence model

FLAIR always solves pressure and velocities. The temperature is also solved as the default setting.

The 'Models' page of the Main Menu.

to activate 'Fan operating point' option

0.  8.
25.  6. 
50.  4. 
75.  2.
100  0. 

To set the grid numbers and solver parameters

You can click on the 'Mesh toggle' button on the main control panel to view the grid distribution on the screen as shown below.

To set the probe location

The probe is used to monitor the progress of the calculations. We normally chose a location away from an inlet or fixed source, and in a region where things should stabilise. Here, we pick towards the opening.

I: 10

J: 3

K: 15

Running the Solver

To run the PHOENICS solver, Earth, click on 'Run', then 'Solver', then click 'OK' to confirm running Earth. These actions should result in the PHOENICS Earth monitoring screen.

As the Earth solver starts and the flow calculations commence, two graphs should appear on the screen. The left-hand graph shows the variation of solved variables at the monitoring point that was set during the model definition. The right-hand graph shows the variation of errors as the solution progresses.

To the end of the calculation, the monitoring display would be as shown below.

Viewing the results

Final result: Operating point data
Operating point data at sweep =   1000
 System mass flow rate:   3.0915E-02 kg/s  1.1130E+02 kg/h
 Fan Name: FAN              Fan Type: FAN1            
 FAN              mass flow rate:     3.0916E-02 kg/s   1.1130E+02 kg/h
 FAN              volume flow rate:   2.5671E-02 m^3/s  9.2414E+01 m^3/h
 FAN              velocity:           4.2784E-01 m/s
 FAN              pressure drop:      6.0686E-01 Pa 

Saving the case

Once a case has been completed, it can be saved to disk as a new Q1 file by 'File - Save working files'. The Q1 and associated output files can be saved more permanently by 'File - Save as a case'.