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.

A marine propeller includes a plurality of blades attached to a hub, with a disk area ratio of approximately 50%, a blade area ratio of approximately 61%, a blade rake angle of approximately 26.5 degrees, a blade skew angle of approximately 0 degrees, and wherein the angle between the chord line at any given radius r on said blades with a line that is parallel to the propeller axis of rotation and intersects the chord line, is equal to tan.sup.−1(2πNr/Vo)−α, where N is the rotational speed of the propeller at a selected design condition, Vo is the speed of the water entering the propeller (i.e. the speed of the vessel) at the design condition, and α is the angle of attack at the radius r at said design condition, and where a is generally constant across most or all of the span of the blades at the design condition, and where the value of α may be selected to be lower near the hub than for the remainder of blade, and where additional camber is provided in the leading edge region, such that leading edge camber line angle of attack is reduced relative to the chord line angle of attack for the overall blade section.

A marine propeller includes a plurality of blades attached to a hub, with a disk area ratio of approximately 50%, a blade area ratio of approximately 61%, a blade rake angle of approximately 26.5 degrees, a blade skew angle of approximately 0 degrees, and wherein the angle between the chord line at any given radius r on said blades with a line that is parallel to the propeller axis of rotation and intersects the chord line, is equal to tan.sup.−1(2πNr/Vo)−α, where N is the rotational speed of the propeller at a selected design condition, Vo is the speed of the water entering the propeller (i.e. the speed of the vessel) at the design condition, and α is the angle of attack at the radius r at said design condition, and where a is generally constant across most or all of the span of the blades at the design condition, and where the value of α may be selected to be lower near the hub than for the remainder of blade, and where additional camber is provided in the leading edge region, such that leading edge camber line angle of attack is reduced relative to the chord line angle of attack for the overall blade section.

The invention relates to a rotor for a pump, having at least one blade, the rotor being able to be actuated to rotate about an axis of rotation in order to convey a fluid in the axial or radial direction, the rotor being able to be deformed reversibly elastically in the radial direction between a first, radially compressed state and a second, radially expanded state which the rotor adopts without the effect of external forces, and a third state of the rotor being provided in which, in pumping operation under fluid loading, the rotor is deformed from the first state to beyond the second state.

A propeller having a means for creating fluid flow in a non-axial direction and redirecting it in an axial direction.

A blade is provided for the cycloidal marine propellers or cycloidal aerial rotors. Said blade is provided with the capabilities, in response to the control system commands to dynamically and in real time; flex itself along its chord in any required way, vary its relative pivot point position, change its planform by extending or retracting a trailing edge extension, differentially if needed on the right and left, turn the flap along the trailing edge in either direction or allow it to be turned by the flows. Said blade is also optionally provided with one or more elastic trailing edges whose stiffness is dynamically, and possibly differentially along the blade span, variable by the control system. For the reversal of the leading and trailing edges for operation in reverse airflow and other conditions the blades are provided with edges that can be made rigid when functioning as the leading edge and flexible if needed when functioning as the trailing edge. Also the blades are provided with the capability of varying their cross-sectional profile thickness and reshaping it. Finally the blades are given on command flow permeability along much of their surface. These capabilities will enable each control system controlled blade to continually optimally adjust to and make the best use of its immediate operating environment as it travels along its trajectory within each revolution.

A marine vessel propeller to convert engine rotational power into propulsive thrust is of a built-up propeller (BUP) type having a circular array of propeller blades, wherein each propeller blade is a single piece including a blade part and a base part. The base part has a generally circular inner surface with a number of radially extending cylindrical indents provided with planar end wall and fastening holes arranged through the base part at a location of the indents. A cylindrical insert is provided with a hole parallel to a longitudinal axis of the insert and arranged to fit into the indent, such that the propeller blades are attachable to a propeller shaft using exemplary fastening bolts through the fastening holes and inserts. A propeller blade and method for installing a marine vessel propeller are also disclosed.

A propeller for a water vehicle is provided, comprising a hub and at least two blades, said blades extending outwards from the hub in the radial direction, and the propeller having a uniform blade distribution. The problem addressed by the invention is to provide a propeller for a water vehicle which allows unwanted generation of noise to be efficiently reduced or avoided. According to the invention, the angular distance between the blade tips of two consecutive blades of the propeller varies in relation to the angular distance between the blade tips of two other consecutive blades.

A propeller for a water vehicle is provided, comprising a hub and at least two blades, said blades extending outwards from the hub in the radial direction, and the propeller having a uniform blade distribution. The problem addressed by the invention is to provide a propeller for a water vehicle which allows unwanted generation of noise to be efficiently reduced or avoided. According to the invention, the angular distance between the blade tips of two consecutive blades of the propeller varies in relation to the angular distance between the blade tips of two other consecutive blades.

To provide a propeller for a boat propulsion apparatus, which propeller is excellent in maintainability including easy assembly and easy disassembly and reliably reduces the impact force caused by colliding with an obstacle and transmitted to the hub and the output shaft of the boat propulsion apparatus. The propeller includes: a shaft sleeve insertably and removably fixed to an output shaft of the boat propulsion apparatus; a plurality of blade components that are individually supported by the shaft sleeve and are arranged at intervals in a rotation direction of the output shaft; and a plurality of dampers disposed in such a manner that each of the plurality of dampers is disposed between adjacent two of the plurality of blade components.