Boeing Technology Services -- Quiet Air Facility

We test a variety of environmental control systems in the Quiet Air facility.

The Quiet Air Facility (QAF) is a hemi-anechoic test chamber that has two muffled air supplies and controls. Typical tests done in this facility include testing aircraft air conditioning systems and components which are subject to airflow noise problems.

We use this facility for developing and testing the design of environmental control systems and components; calibrating instruments; and developing and verifying small to medium-sized mechanical and electrical components and systems such as fans, motors, pumps, gearboxes, and power supplies.

The QAF test chamber is approximately 32 x 32 feet with a 10 foot ceiling. The wedges are of polyurethane foam with a low frequency cutoff of about 200 Hz. Wedges can be placed on the floor to create a fully anechoic test environment.

Quiet Air Facility
  • Hemi- or fully-anechoic
  • Double wall acoustic construction
  • 400 Hz Power: 208 v, 3 phase
  • Computer control of airflow and data acquisition
  • Muffled air supplies
  • Flows of 2.3 and 7 lbm/sec.
  • Pressures to 50 psi

The QAF is a versatile general-purpose hemi-anechoic chamber with two air supply lines, a primary and secondary. The air supply lines provide a platform to perform acoustic tests on equipment and systems which require airflow. Aircraft environmental control systems (ECS) and related components can be simulated in the facility for measurements of noise radiated by or transmitted through the system. A 400 Hz power source is available for operating aircraft AC electrical equipment. Other acoustic tests, such as sound power measurements, can be performed in the facility utilizing the hemi-anechoic properties of the chamber with or without airflow.

The QAF measures 392 X 404 X 129 inches. It has a raised metal, acoustically hard floor and perforated, acoustically absorptive panels on the walls and ceiling. The walls and ceiling also utilize 12 inch foam wedges to increase the low frequency absorption. The facility with the wedges is anechoic down to 250 Hz . Spare acoustic wedges are available to place on the floor of the facility to obtain a complete anechoic facility down to 250 Hz.

The primary air line provides up to 5.7 lbs/sec or 4560 cfm of airflow . The secondary air line provides up to 2.3 lbs/sec or 1840 cfm of airflow. Each air supply is regulated by its own digital valve which can be controlled manually or automatically using the QAF's data acquisition program "QT". Currently, using the "QT" program, air can be set by flow in lbs/sec, cfm, or ft/min given the cross sectional area of the test hardware. The program can also be modified to control the airflow by Mach Number or other parameters where they can be determined by an equation from measured quantities. Each air line is supplied from Plant II central air with 300 psi. A regulator is installed in the line to lower the supply pressure for better control of the actual pressure. The regulator can be set up to 150 psi.

Quiet Air Facility

The QAF data system consists of three major components which may be operated somewhat independently. The host computer, currently MTC, could be any computer with an available GPIB interface within reach of the bus extender and on the lab network for the X-terminal operation. The aero/thermal data acquisition instrumentation allows up to 60 Scanned DC Channels (HP 3497A) plus a 48-channel Scanivalve which requires one of the sixty scanned channels.

400 Hz, 208 V, 3 phase power is supplied by a motor-generator located on the north side of the 2-80 building in a small room east of Bay A-7 (near door N-17). The control console is located outside the QAF facility doors with a startup procedure located on the side of the unit. The QAF houses three outlets inside the chamber, one at the center of each wall, except the west wall where the air supply lines come into the chamber. 60 Hz, 110 V grounded outlets are located next to the 400 Hz outlets inside the chamber. 480 V, 60 amp outlet is available and is next to the 400 Hz control console outside of the chamber doors.

Two instrumentation patch panels are located on the west and south inside walls of the chamber. Each panel has 10 pressure transducer lines, 5 temperature sensor lines, 5 microphone lines, and 5 coaxial cable lines. These panels are wired to the QAF control console and transducer racks for monitoring and data acquisition by the "QT" program.

To join the many companies using testing resources available at The Boeing Company, contact the Boeing Technology Services Marketing Manager at 206-662-1478, request a quote online, or e-mail us for more information about our test capabilities.