초록 ▼

A low-aspect ratio propeller system is provided with a multiple ring structure formed with a plurality of circular or non-circular, annular, narrow equivalent air foil rings which are held by rails in a predetermined relationship with the propeller blades. The upstream ring is located downstream fro

A low-aspect ratio propeller system is provided with a multiple ring structure formed with a plurality of circular or non-circular, annular, narrow equivalent air foil rings which are held by rails in a predetermined relationship with the propeller blades. The upstream ring is located downstream from the tip vortex of the propeller within the axial span of the propeller. One or more additional downstream-located rings are used so as to provide at least one annular multiple ring-defined pump aperture through which peripheral vortices generated by the propeller blades or fan blades may enhance the mass flow. In one propeller system, a low-aspect-ratio propeller is employed with high blade angles of attack and non-stall capability to generate strong vortices which enhance the beneficial effect of the multiple ring structure. These vortices increase thrust because their induction action on the rings increase beneficial ring flow circulation. Augmented ring flow reduces the velocities in the expanding wake by increasing the mass flow. The destruction of tip and root vortices reduces noise. The multiple ring structure also serves as a guard to protect people and animals against the rotating propeller. A plurality of embodiments are shown and described.

대표청구항 ▼

In a boat engine driving a rotating shaft for moving the boat through water comprising: an axial flow propeller for rotation about an axis and having a plurality of radially-extending blades; said blades being oriented with an axial span selected to move water in a downstream direction along the axi

In a boat engine driving a rotating shaft for moving the boat through water comprising: an axial flow propeller for rotation about an axis and having a plurality of radially-extending blades; said blades being oriented with an axial span selected to move water in a downstream direction along the axis during propeller rotation; a ring cage structure formed of a plurality of axially-spaced water flow enhancing rings located around the axis, with a plurality of said water flow enhancing rings being axially-located around the blades within their axial spans; said propeller blades having tips which generate tip vortices during rotation with the shape of the blades being selected to strengthen the tip vortices; the blade tips and the radially-inner edge of said water flow enhancing rings being in sufficiently close proximity and with dimension of said axial water flow enhancing rings and their axial spacings being selected to form apertures through which tip vortices from the blades augment the water flow in said downstream direction; whereby tip vortices can be converted to useful water flow for enhanced performance of the engine.