Measurement of Crashback Loads on a Blade of Propeller 4381 in an Open and Ducted Configuration in the 36-inch Water Tunnel

Abstract : Propeller 4381 was tested in crashback conditions in the 36-inch water tunnel at the Naval Surface Warfare Center, Carderock Division. The propeller was tested in both an open and ducted configuration to look at the differences in strain and derived bending moment loads at the root of a blade. Time history measurements were analyzed to determine unsteady strain levels at the root of the blade. The maximum unsteady strains were up to 2.5 times the mean strain on the blade for both configurations. The open and ducted configuration had similar maximum strain components, but the mean strain was lower for the ducted cases at advance coefficient values between -0.2 and -0.7.