Advanced turbo-prop airplane interior noise reduction-source definition
Abstract
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.
- Publication:
-
Final Report Hamilton Standard
- Pub Date:
- October 1979
- Bibcode:
- 1979hast.rept.....M
- Keywords:
-
- Acoustic Measurement;
- Aircraft Noise;
- Noise Reduction;
- Sound Pressure;
- Turboprop Aircraft;
- Fuselages;
- Noise Intensity;
- Noise Prediction (Aircraft);
- Phase Shift;
- Wind Tunnel Tests;
- Acoustics