Response of Propulsors to Turbulence 



MEASURED RESPONSE DUE 

 TO TURBULENCE GENERATED 

 BY A 4-INCH MESH GRID 



40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 

 FREQUENCY (Hz) 



Fig. 12 - Power spectral density of the response of a ten- 

 bladed, 8 -inch -diameter propeller to turbulence (Test 5531, 

 Run Z: distance between the grid and the propeller = 20M = 

 80 inches; measured water-tunnel turbulence level without 

 the grid u = 0.00 llU; turbulence level at the propeller due 

 to the grid u = 0.03U; tunnel velocity U = 15.4 ft/sec; pro- 

 peller advance ratio J = 1.22) 



309 



