The Liner Technology Facility (LTF) is used to measure the impedance of acoustic liners for application to the engines and airframe of aircraft.
Facility Characteristics
- Small Flow Duct Acoustics – Grazing Flow Impedance Tube (GFIT)
- Duct Size 2.0” w x 2.5” h
- Frequency Range 0.4 – 3.0 kHz
- Sound Pressure Levels up to 150 dB
- Flow Mach 0 – 0.6
- Large Flow Duct Acoustics – Curved Duct Test Rig (CDTR)
- Duct Size 6” w • 15” h
- Frequency Range 0.4 to 2.4 kHz
- Sound Pressure Levels up to 140 dB
- Flow Mach 0 to 0.5
Types of Testing
- Grazing Flow Impedance Tube (GFIT)
- Measure acoustic liner impedance
- Evaluate flow profile effects
- Curved Duct Test Rig (CDTR)
- Generate selected higher-order modes
- Evaluate duct curvature effects
- GFIT & CDTR
- Evaluate inlet and aft-duct configurations
Other Facility Features
- Raylometer: automated test rig for evaluation of DC flow resistance
- Normal Incidence Tube: no-flow test rig for measurement of liner acoustic impedance
- Waveguide Calibrator: test rig for calibration of sensors at frequencies up to 90 kHz
Contact
Michael G. Jones (michael.g.jones@nasa.gov)