You are here: Tutorials > Propeller Acoustics > Simulation

11.16.5 Simulation

This section explain the settings to run the FWH source model. The steady result of Broadband model is used as an initial solution for the transient simulation using FWH model.

Create Monitoring Points

In the FWH model simulation, the sound pressure variation in the flow domain is of interest. Hence, monitoring points are created around the propeller to predict the sound pressure. The steps to create the monitoring points are as follows:

1. On the Geometric Entities Panel toolbar, click twice Create a Monitoring Point , to create Points Point 01 and Point 02.
2. Select each point in the Geometric Entities Panel and specify their Position values as shown in in the Geometry Tab of Properties Panel refer, Figure 11.380
3. Select Yes from the Acoustic receiver drop-down list in the Geometry Tab of Properties Panel. This outputs the sound pressure on the specified point.

Points	Position values
Point 01	-0.0225, 0.1, 0.2
Point 02	-0.0125, 0.05, 0.075

Table 11.15 - Monitoring points

Note: Monitoring points need to be created before running the simulation for recording data refer, Figure 11.381. The position of a Points may also be dragged to a new location using the Select in Toolbar and the Left Mouse Button.

 

Figure 11.380 - Create monitoring point

Figure 11.381 - Monitoring points

 

FWH Model (Transient) Simulation Settings

Select Fan in the Model Panel. Select Simulation Method to Transient (Moving Grid) in the Model Tab of Properties Panel. Click Simulation Panel. Enter Number of Revolutions as 2 and Time Steps Per Pocket as 60 (see, Figure 11.383). They determine the angular rotation each time-step. The Simulation Time (Duration) and the Number of Time Steps are automatically calculated based on the above settings. Define Result Saving Frequency as 80 in the Simulation Panel. Select Start from Solution and click Load Results to load the steady state result file (acoustics_propeller_model_steady.sres) to continue the simulation from the steady state results. After you save the project, click Start to run the simulation (see, Figure 11.383). The result files are saved as .sres in the working folder (Example: "acoustics_propeller_model_unsteady _080.sres"). The number of result files depend on the Result Saving Frequency.

Figure 11.382 - Transient Simulation modules

 

The residuals for the transient simulation are displayed under the Residual Tab in the Plot Panel as shown in Figure 11.384.

 

Figure 11.383 - Transient Simulation settings

Figure 11.384 - Residual - Transient case

 

Note: The Result Saving Frequency option in the Simulation Panel is set to a small value (say 5 or 10) before running the simulation to obtain better animations.