Evaluation of the Kort Nozzle Design for the United States Coast Guard 140 WYTM Cutter,
NAVAL ACADEMY ANNAPOLIS MD DIV OF ENGINEERING AND WEAPONS
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This report considers the shroud structure, the propeller hydrodynamics, the ice loading on the propeller blade, a possible ice deflection strut, and overall design of the kort nozzle. The shroud structure is considered first where it is found to be sufficiently strong. The next section, considers the propeller hydrodynamics, and the remaining topics. One serious problem with the present design is that there is no access to the propeller. Unless the port, starboard, or both sides of the nozzle is removable, the propeller would have to be installed and the shroud built around it. The screw would be inaccessible for repairs. Suggestions for how this problem could be solved are provided. The thrust and efficiency of the propeller together with the shroud meet requirements. However, the local velocity distributions are not hydrodynamically the best and results in cavitation on portions of the back and face of the blades. Slight modifications to the sections should alleviate this situation a very efficient subcavitating propeller should result. Details are supplied. Unless the propeller blades are to be steel, they are not strong enough to withstand extreme ice loading. Details of the ice loading are given. Supports for the nozzle are also discussed. These should be faired in to prevent adverse hydrodynamic drag, which reduces the total net thrust.
- Marine Engineering
- Fluid Mechanics