Please enable JavaScript.
Coggle requires JavaScript to display documents.
Constructional Details (2/2) - Coggle Diagram
Constructional Details (2/2)
Pitch Ratio
0,6
Highly Loaded Propellers - Tugboats
High diameter
2,0
High-speed boats
High pitch, small diameter
Radial Distribution of Pitch
Twin Screws
Usually constant
Single Screws
Pitch reduced close to Hub
Due to
Greater wake variation over disk
Pitch reduced close to Tip
High loaded propellers
Delay onset or reduce severity
Tip-Vortex cavitation
Decrease thrust loading
Usually Rake Aft
Increases clearance
Increases Efficiency
reduces prediodic forces
Developed Blade-area Ratio
0,35
Smaller area of blades related to disk
1,0
High speed ships
Same area as Disk
Thickness
Higher
Worse for Hydro Efficiency
Higher strength
Good for delay certain types of cavitation
Materials
Requirements
Light
Smooth surface
High resistance to erosion
Usual
Cast Iron
Cheap
Little tensile strength
Thicker
Cast Steel
Much thicker
Manganese Bronze
Good
Manganese-nickel-aluminum Alloy
Good
