Objective

To visualize sound field and diagnose the noise sources on a compressor.

Test Procedure

1. The compressor was mounted on a test rig.
2. Two patches of 60-microphone array was used to capture acoustic pressure data conformal to the compressor surface.
3. Data was captured for 6 seconds.
4. Acoustic pressure, normal acoustic intensity and surface velocity were reconstructed on the compressor surface to identify the noise sources.

Results

The following screenshot shows the A-Weighted Sound Pressure Level spectrum. The spectrum shows harmonics of the motor rotation frequency as well as a clear peak at 1320 Hz.

Acoustic Pressure Distribution

The sound pressure distribution the compressor assembly surface shows loud area over the motor in the center.

Acoustic Intensity Distribution

Intensity distribution confirms positive acoutic energy flow from the motor surface.

ODS (Operational Deflection Shape)

The screenshots on left and below show the normal surface velocity, which depicts the operational deflection shapes of the motor surface. They clearely shows the vibration modes of the motor surface at the corresponding structural vibration frequencies.

1320 Hz

655 Hz

1055 Hz