The effect of front-to-rear propeller spacing on the interaction noise of a counterrotation propeller model was measured at cruise conditions. The data taken at an axial Mach number of 0.80 behaved as expected: interaction noise was reduced with increased spacing. The data taken at M=0.76 and M=0.72 did not behave as expected. At some of the test conditions the noise was unchanged; others even showed noise increases with increased spacing. A possible explanation, involving the amount of downstream blade area impacted by the tip vortex, is presented.
Effect of Front-to-Rear Propeller Spacing on the Interaction Noise of a Model Counterrotation Propeller at Cruise Conditions
1987
18 pages
Report
Keine Angabe
Englisch
Aircraft , Cruising flight , Propellers , Counter rotation , Models , Noise spectra , Spacing , Axial flow , Blade tips , Mach number , Vortices