Induced Field-Point Pressures of a Ducted Propeller System.
NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD
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Total fluctuating pressures were measured on the internal surface of a 0-degree angle-of-attack duct of a ducted propeller system Kort nozzle type. The effects of blade loading in uniform flow and propeller blade cavitation in nonuniform flow on the harmonics of the blade-frequency propeller-induced pressure were determined. Also determined were the blade-frequency pressure-induced duct forces. Experimental results indicate that the blade-frequency pressures increase for an increase in blade loading with the second and third blade-frequency pressure being significant with respect to the blade-frequency pressure. Fluctuating blade-frequency vertical forces determined by integrating the pressure results from nonuniform inflow noncavitating conditions were approximately 1-percent of the mean thrust. In the experiments conducted at a given loading, cavitation on the propeller blades tended to increase the blade-frequency pressure downstream of the propeller by as much as a factor of three.
- Marine Engineering
- Fluid Mechanics