Patent attributes
A flow-propelled rotary knife system includes a housing, having an outlet end and walls defining a fluid passage, a rotatable blade holder, disposed at the outlet end and having a central aperture substantially aligned with the fluid passage, and at least one blade, extending diametrically across the central aperture of the blade holder. The blade holder is configured to rotate about a rotational axis passing through the central aperture, and the at least one blade has a twisted shape selected to rotationally propel the blade and the blade holder to rotate about the rotational axis when the blade is contacted by fluid flowing through the fluid passage and the central aperture in a flow direction, whereby objects propelled along the fluid flow path in the flow direction toward the outlet are helically cut by the rotating blade.