A blood flow assist system can include an impeller assembly including an impeller shaft and an impeller on the impeller shaft, a primary flow pathway disposed along an exterior surface of the impeller. The system can include a rotor assembly at a proximal portion of the impeller shaft. A secondary flow pathway can be disposed along a lumen of the impeller shaft. During operation of the blood flow assist system, blood can be pumped proximally along the primary flow pathway and the secondary flow pathway. The system can include a sleeve bearing distal the impeller. The system can include a drive unit having a distal end disposed distal a proximal end of the second impeller. The drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly.

A propeller for attachment to a rotatable output shaft of a submersible motor includes a hub having a first end, and an opposite second end, an outer curved surface, at least two blades extending radially outward from the outer curved surface and a central axial bore for receipt of the output shaft therethrough. The hub includes an arrangement of discharge channels extending between the first and second ends to allow waterflow and debris (e.g., grass, weeds and other stringy items) to pass through the hub and exit the second end without becoming entangled around the base of the motor output shaft.

A first opening, which passes through the blade surface part from a negative pressure side toward a positive pressure side, is provided between the first blade element and the second blade element on the blade surface part. A space between an outer edge of the first blade element extended from the side surface toward an outer edge side of the blade, and an outer edge of the second blade element extended from the side surface toward the outer edge side of the blade on the positive pressure surface side, is opened from the side surface in a radial direction of the blade surface part, so that an air current coming from the negative pressure side toward the positive pressure side through the first opening, flows from the first opening toward the outer edge side of the blade along the positive pressure surface.

The invention relates to a fluid pump device, in particular for the medical application, with a compressible pump housing and rotor, as well as with an actuation means which runs in the sleeve and on whose end the fluid pump is arranged. In order to utilize all possibilities of a space-saving arrangement of the respective pump housing of the rotor, which is compressible per se, and as the case may be, a bearing arrangement, the mentioned elements are displaceable to one another in the axial direction compared to an operation position. In particular these elements may be end-configured by way of an axial movement of the drive shaft after the assembly.

Apparatus and methods are described including a blood pump that includes an impeller that has proximal and distal bushings, and is configured to pump blood through a subject's body. A frame, which includes proximal and distal bearings, is disposed around the impeller. An axial shaft passes through the proximal and distal bearings of the frame and the proximal and distal bushings of the impeller. The axial shaft is coupled to at least one of the proximal and distal bushings of the impeller, such that the at least one bushing is held in an axially-fixed position with respect to the axial shaft, and is not held in an axially-fixed position with respect to the proximal and distal bearings. Other applications are also described.

A method for designing an impeller with a small hub-tip ratio includes the following steps: S1: obtaining an outer diameter D of the impeller with the small hub-tip ratio; S2: determining the number of blades and an airfoil of the blade of the impeller with the small hub-tip ratio; S3: obtaining a blade solidity s.sub.y at a rim of the impeller with the small hub-tip ratio and a blade solidity s.sub.g at a hub of the impeller with the small hub-tip ratio; S4: dividing the blades of the impeller with the small hub-tip ratio into m cylindrical sections in an equidistant manner, marking the cylindrical sections as 1-1, 2-2, . . . , m-m in sequence from the hub to the rim, and obtaining an airfoil setting angle β.sub.L of each of the cylindrical sections; and S5: performing a correction on the value of the airfoil setting angle β.sub.L in S4.

The present invention relates to a cavitation free rotary mechanical device with improved output and, in particular, to a rotary mechanical device (such as a hydro turbine, marine propeller, etc) including a rotatable shaft and associated blades (or cups or vanes), the rotary mechanical device configured to introduce air at one or more areas of extremely low pressure force on the surface of, or at least in the proximity of, the rotatable blades (or cups or vanes) during rotation and thereby prevent cavitation effects that would otherwise be caused by the extremely low pressure forces acting on such surfaces during operation.

A first opening, which passes through the blade surface part from a negative pressure side toward a positive pressure side, is provided between the first blade element and the second blade element on the blade surface part. A space between an outer edge of the first blade element extended from the side surface toward an outer edge side of the blade, and an outer edge of the second blade element extended from the side surface toward the outer edge side of the blade on the positive pressure surface side, is opened from the side surface in a radial direction of the blade surface part, so that an air current coming from the negative pressure side toward the positive pressure side through the first opening, flows from the first opening toward the outer edge side of the blade along the positive pressure surface.

On the blade surface part, a first opening passing through the blade surface part from a negative pressure side toward a positive pressure side is provided between the first blade element and the second blade element. A chord length of the first blade element along a direction connecting the apex A with the point B, is equal to or larger than a chord length of the second blade element along a direction connecting an apex C with a point D.

A rotor assembly includes a first rotor hub and a second rotor hub. The second rotor hub is coupled to the first rotor hub via a shaft fairing. The first rotor hub has a flat first surface coupled to the shaft fairing and a curved second surface opposite the flat first surface. The second rotor hub has a flat first surface on the lower side and a curved second surface opposite the flat first surface.