Three eight bladed supersonic helical tip speed propellers were tested in the NASA Lewis Wind Tunnel at through flow Mach numbers of 0.6, 0.7, 0.75, 0.8, and 0.85. Such propellers are being considered as propulsors for a future energy conservative aircraft. The three propellers of equal performance, incorporate different plan forms and different amounts of sweep in order to investigate their noise generation, which could cause a cabin environment problem. The acoustically designed propeller SR-3 had 45 deg of tip sweep and was significantly quieter at Mach 0.8 cruise than the straight bladed propeller, SR-2. An intermediate 30 deg tip sweep propeller, SR-1m exhibited a noise level between the other two. Enhanced pressure-time traces indicated that SR-2 and SR-1m exhibited shock-like pressure traces at Mach-0.8 cruise while the SR-3 did not. Noise trends with varying helical tip Mach number and blade loading were also observed.
Tone noise of three supersonic helical tip speed propellers in a wind tunnel
Acoustical Society of America, Meeting ; 1979 ; Cambridge, MA
1979-06-01
Conference paper
No indication
English
Wind Tunnel Testing of High Speed Propellers
British Library Conference Proceedings | 1997
|Engineering Index Backfile | 1951
|High Supersonic Speed Wind Tunnel
Emerald Group Publishing | 1961