ADVANCED TURBO-PROP AIRPLANE INTERIOR NOISE REDUCTION-SOURCE DEFINITION
Acoustic pressure amplitudes and phases were measured in model scale on the surface of a rigid semicylinder mounted in an acoustically treated wind tunnel near a prop-fan (an advanced turboprop with many swept blades) model. Operating conditions during the test simulated those of a prop-fan at 0.8 Mach number cruise. Acoustic pressure amplitude and phase contours were defined on the semicylinder surface. Measurements obtained without the semi-cylinder in place were used to establish the magnitude of pressure doubling for an aircraft fuselage located near a prop-fan. Pressure doubling effects were found to be 6dB at 90 deg incidence decreasing to no effect at grazing incidence. Comparisons of measurements with predictions made using a recently developed prop-fan noise prediction theory which includes linear and non-linear source terms showed good agreement in phase and in peak noise amplitude. Predictions of noise amplitude and phase contours, including pressure doubling effects derived from test, are included for a full scale prop-fan installation.
Hamilton StandardWindsor Locks, CT USA 06096
- Magliozzi, B
- Brooks, B M
- Publication Date: 1979-10
- Pagination: 90 p.
- TRT Terms: Accuracy; Acoustic measuring instruments; Acoustics; Aircraft noise; Effective sound pressure; Forecasting; Fuselages; Noise control; Phase shift (Electricity); Sound level; Turboprop aircraft; Wind tunnels
- Uncontrolled Terms: Interior; Noise reduction
- Old TRIS Terms: Acoustic measurement; Acoustic measurements; Noise intensity; Phase shift
- Subject Areas: Aviation; Vehicles and Equipment;
- Accession Number: 00312833
- Record Type: Publication
- Source Agency: National Technical Information Service
- Report/Paper Numbers: NASA-CR-159668 Final Rpt.
- Contract Numbers: NAS3-20614
- Files: TRIS
- Created Date: May 7 1980 12:00AM