An apparatus and system for a marine propeller assembly are provided. An aft retention member that may be used with the marine propeller assembly includes a base, an opposing nose and a conic body extending therebetween along a centerline normal to the base. The aft retention member also includes at least one protuberance extending radially away from a surface of the conic body. The protuberance extends axially along a surface of the aft retention member from the base arcuately convergent to a predetermined point between the base and a tip of the nose.

This impeller is equipped with: an impeller body formed from a resin and shaped as a disk with an axis as the center thereof, and having a boss hole section formed therein which a rotating shaft for rotating around the axis engages; compressor blades provided on the front-surface side of the impeller body; and a ring-shaped reinforcing ring provided inside the impeller body in the circumferential direction of the impeller body.

An aerofoil having a leading edge and a trailing edge, the leading edge including a plurality of slits extending toward the trailing edge, such that the leading edge is defined by alternating peaks and troughs. Each peak extends in a generally spanwise direction and defines a peak width, each peak being separated from an adjacent peak in the spanwise direction by a trough. Each trough extends in the generally spanwise direction and is spaced in a chordwise direction from the peak, each trough defining a trough width. A ratio of the peak width to the trough width is between 4:1 and 10:1.

An aerofoil having a leading edge and a trailing edge, the leading edge including a plurality of slits extending toward the trailing edge, such that the leading edge is defined by alternating peaks and troughs. Each peak extends in a generally spanwise direction and defines a peak width, each peak being separated from an adjacent peak in the spanwise direction by a trough. Each trough extends in the generally spanwise direction and is spaced in a chordwise direction from the peak, each trough defining a trough width. A ratio of the peak width to the trough width is between 4:1 and 10:1.

A blade made of layered material, such as composite material, configured for exposure to a fluid flow, comprises skins (1, 2) defined between a leading edge (3) and a trailing edge (4) which skins in cross-section form a flow profile. The layered material may consist of several layers of fiber material (5, 5, . . . ) impregnated with a matrix material, wherein layers of fiber material each comprise a respective body portion (6, 6, . . . , 13) between and transverse to the skins and each at least a respective skin portion (7, 7, . . . ; 8, 8, . . . ) that forms part of the skins. The said skin portions all extend from the related body portion in the direction of the trailing edge. Of said skin portions at least two consecutive skin portions of the one skin overlap and/or two consecutive skin portions of the other skin overlap each other.

This disclosure relates to a system for reducing cavitation at a surface that moves relatively with respect to a first fluid. The system comprises a degasser configured to at least partially degas a second fluid. The system also comprises a reservoir in communication with the degasser and configured to house the at least partially degassed second fluid, the reservoir having an outlet that is arranged for directing the second fluid towards the surface. The system is configured such that the directing of the at least partially degassed second fluid towards the surface forms a boundary layer at the surface. The boundary layer is adapted to at least partially increase the negative pressure required to initiate cavitation at the surface so as to reduce the occurrence of cavitation during such relative movement.

Disclosed is a propeller having at least first and second blade assemblies located one above the other. Each of the blade assemblies has a plurality of blades that extend radially outward from a shaft. The shaft can be coupled to a suitable land, sea or air vehicle (e.g., a ship). The blades of the first blade assembly lie above and alternate out of phase with the blades of the second blade assembly. Each of the blades of the first and second blade assemblies slopes downwardly relative to the shaft such that the leading sides thereof are located lower along the shaft than the opposite trailing sides. The blades of the first blade assembly are aligned with respective ones of the blades of the second blade assembly to establish substantially continuous and long downwardly sloping surface areas capable of maximizing the propulsion force generated by the propeller.

Disclosed is a propeller having at least first and second blade assemblies located one above the other. Each of the blade assemblies has a plurality of blades that extend radially outward from a shaft. The shaft can be coupled to a suitable land, sea or air vehicle (e.g., a ship). The blades of the first blade assembly lie above and alternate out of phase with the blades of the second blade assembly. Each of the blades of the first and second blade assemblies slopes downwardly relative to the shaft such that the leading sides thereof are located lower along the shaft than the opposite trailing sides. The blades of the first blade assembly are aligned with respective ones of the blades of the second blade assembly to establish substantially continuous and long downwardly sloping surface areas capable of maximizing the propulsion force generated by the propeller.

A propeller blade includes a body configured to extend radially from the hub of a propeller. The body can include a front surface, a back surface, a leading edge, and a trailing edge. The top of the body can form a tippet that generally transitions the front and back surfaces from extending in a generally radial direction to a generally axial direction. The tippet can reduce radial flow and force losses, redirect the radial flow in an axial direction, reduce the exit flow area of the propeller, and increase the inlet flow area of the propeller. The front surface of the blade can have a planar configuration that prevents or reduces the creation of low or negative pressure across the front surface of the blade and associated cavitation.

A propeller blade includes a body configured to extend radially from the hub of a propeller. The body can include a front surface, a back surface, a leading edge, and a trailing edge. The top of the body can form a tippet that generally transitions the front and back surfaces from extending in a generally radial direction to a generally axial direction. The tippet can reduce radial flow and force losses, redirect the radial flow in an axial direction, reduce the exit flow area of the propeller, and increase the inlet flow area of the propeller. The front surface of the blade can have a planar configuration that prevents or reduces the creation of low or negative pressure across the front surface of the blade and associated cavitation.