ViAcoustics has developed the Automated Fan Test Plenum for use in conducting acoustic and aerodynamic testing of small air moving devices in general accordance with ISO 10302 and ANSI S12.11.

The need for a fixture to test air moving devices was recognized many years ago in the Information Technology industry. In the early 1960’s, George Maling and his associates at IBM developed a plenum for the testing of such devices. The plenum consisted

of a polyester film-covered framework that was constructed of 5 cm by 5 cm wood. The polyester film provided an airtight yet acoustically transparent surface for the plenum. An adjustable exit port assembly allows control of pressure drop across and flow rate through the plenum, allowing cooling fans and other air moving devices to be mounted to the plenum and exposed to the actual aerodynamic conditions under which they would be operated. Air moving devices are then operated in the plenum, and the sound power emissions of the device are determined.

While the manual plenum proved to be a valuable tool for the acoustic characterization of air moving devices, using the plenum for high volume production level testing of fans was very labor intensive and tedious. The need to constantly adjust operating conditions and read transducers meant numerous entries into the test chamber. Full characterization of a specific air moving device over its entire range of operating conditions required many hours of laboratory and test technician time.

ViAcoustics has improved on the initial plenum design by constructing an aluminum framed plenum with removable polyester film panels and mounting points for the automation hardware. The result is a robust fixture for conducting fan acoustic and aerodynamic measurements.

The Automated Fan Test Plenum from ViAcoustics allows for rapid and accurate characterization of fans and other air moving devices. By using linear motion control mechanisms and remote readout transducers, the plenum can be operated entirely from the acoustic test chamber control room.

The LabView based control software allows the test operator to control the position of the slider based on one of three control regimes:

1. Go To a Specified Position

2. Go To a Specified Operating Point (pressure drop and flow volume)

3. Bump by a set Increment

The plenum is equipped with a piezometric ring and low pressure transducer, which allows the control software to pressure drop across the plenum in the laboratory control room.

The slider system has been aerodynamically calibrated, allowing the flow volume through the chamber to be estimated from the pressure drop and the slider position. The calculated flow rate is displayed on the control panel for the software.

A tachometer with a remote optical sensor is also included on the plenum, allowing for monitoring of fan RPM with the control room.

The control software also control a DC power supply, allowing the input voltage to the fan to be varied from within the control room. The software also monitors the current being supplied to the fan.

The Automated Fan Test Plenum is supplied with all transducers, automation hardware, sensors, data acquisition boards and I/O controllers needed to operate the system. The LabView based software has been developed by Nelson Acoustics and is supplied with the plenum. Full system integration and training services are available from ViAcoustics.

For more information please contact us at info@viacoustics.com