TONE NOISE OF THREE SUPERSONIC HELICAL TIP SPEED PROPELLERS IN A WIND TUNNEL
Three supersonic helical tip speed propellers were tested in the NASA Lewis 8- by 6-foot wind tunnel. This is a perforated-wall wind tunnel but it does not have acoustic damping material on its walls. The propellers were tested at tunnel through flow Mach numbers of 0.6, 0.7, 0.75, 0.8, and 0.85 with different rotational speeds and blade setting angles. The three propellers, which had approximately the same aerodynamic performance, incorporated different plan forms and different amounts of sweep and yielded different near field noise levels. The acoustically designed propeller had 45 deg of tip sweep and was significantly quieter at M = 0.8 cruise than the straight bladed propeller. The intermediate 30 deg tip sweep propeller, which was swept for aerodynamic purposes, exhibited noise that was between the other two propellers. Noise trends with varying helical tip Mach number and blade loading were also observed.
- Presented at 97th Meeting of the Acoustical Society of AM., Cambridge, Mass., 11-15 Jun. 1979.
Department of the NavyThe Pentagon
Washington, DC United States 20350
- DITTMAR, J H
- Jeracki, R J
- Blaha, B J
- Publication Date: 1979
- Pagination: 66 p.
- TRT Terms: Acoustic measuring instruments; Acoustics; Aerodynamics; Aircraft noise; Harmonics; Noise control; Performance; Propeller blades; Propeller driven aircraft; Propellers; Sound level; Supersonic flow; Supersonic speed; Wind tunnels
- Uncontrolled Terms: Noise reduction
- Old TRIS Terms: Acoustic measurement; Blade tips; Helical flow; Noise intensity; Sweep effect
- Subject Areas: Aviation; Vehicles and Equipment;
- Accession Number: 00198894
- Record Type: Publication
- Source Agency: National Technical Information Service
- Report/Paper Numbers: NASA-TM-79167 Conf Paper
- Files: TRIS
- Created Date: Oct 17 1980 12:00AM