Radial flow seals for rotating shafts which deliberately induce turbulent flow along the seal gap

A hydrostatic face seal assembly used to restrict the flow of fluid from a relatively higher pressure region in a housing to a relatively lower pressure region in the housing at a juncture of a stationary housing member and a rotating shaft member rotating about its axis, said shaft having a radially extending annular seal runner having a radially extending sealing surface thereon, said runner mounted for rotation therewith, said assembly comprising:

• (a) a face seal ring member mounted around said shaft and having a radially extending primary annular sealing face surface positioned for movement axially relative to said shaft and toward and away from said seal runner surface and forming a seal gap therebetween to break down the pressure radially across the seal ring member, said seal ring member sealing face surface having an inner and an outer edge thereon, one of said inner and outer edges of said sealing face surface being exposed to the higher pressure region in said housing and the other of said inner and outer edges of said sealing face surface being exposed to the lower pressure region,
• (b) said sealing face surface being formed to converge toward said seal runner surface along the gap in the direction from said one edge of said sealing face surface toward said other edge thereof to provide a converging flow path in said seal gap in the radial direction from said one edge toward said other edge, and forming only a single sealing dam in said seal gap, said sealing face surface being intentionally formed with a geometry that converges sufficiently to deliberately create turbulent fluid flow and to have a Reynolds number in excess of 1800 within and along said seal gap, whereby a larger clearance between said sealing face surface and said seal runner surface is thus created than would exist for laminar flow along said seal gap.

A fluid seal assembly comprising a rotatable shaft having a radially extending runner with a radially extending runner surface thereon, a housing receiving said shaft and having walls thereon defining a pressure chamber therein, a seal ring having a pair of opposed radial surfaces thereon, said ring receiving said shaft in the opening thereof and mounted in said housing in axial floating relationship with said runner surface, one of said seal ring radial surfaces being exposed during operation of said assembly to the pressure in said chamber, the other of said seal ring radial surfaces confronting said runner surface and being spaced therefrom when said chamber is pressurized to form a seal gap therebetween, said other of said seal ring surfaces having one extremity thereof exposed to said pressure chamber and the other extremity exposed to a relatively low pressure region in said housing, said other seal ring surface being shaped to provide radial convergence of said seal gap in the radial direction from said one extremity toward said other extremity and forming only a single sealing dam therein adjacent said other extremity, said other seal ring surface being shaped to provide said convergence of at least 1 milli-inch in height toward said runner surface with the widest portion of said seal gap being adjacent said one extremity to deliberately create turbulent flow of fluid in said seal gap, and, when said chamber is pressurized, the spacing at the narrowest height of said seal gap is deliberately greater than the spacing that would exist for laminar flow along said seal gap, and additional sealing means interacting between said seal ring and said housing to prevent flow from said pressure chamber to said low pressure region except along said seal gap.