Circumferential Back-to-Back Seal Assembly with Bifurcated Flow

摘要

A circumferential seal assembly capable of separating a gas into two separate flow paths before communication between a rotatable runner and a pair of seal rings is presented. The seal assembly includes an annular seal housing, a pair of annular seal rings, a rotatable runner, and a plurality of groove structures. The seal housing is interposed between a pair of compartments. The seal rings are separately disposed within the seal housing and separately disposed around the rotatable runner. The groove structures are disposed along an outer annular surface of the rotatable runner. A gas is communicable onto the groove structures. Each groove structure includes at least two hydrodynamic grooves that separate and communicate the gas onto the seal rings. Each groove includes steps whereby the depth of at least one adjoining step decreases in the direction opposite to rotation with or without the depth of another adjoining steps increasing in the direction opposite to rotation.

主权项

1. A circumferential back-to-back seal assembly with bifurcated flow comprising:
(a) an annular seal housing disposed between a pair of compartments, said annular seal housing having at least one inlet; (b) a first annular seal ring; (c) a second annular seal ring, said first annular seal ring and said second annular seal ring separately disposed within said annular seal housing, a gas communicable between said first annular seal ring and said second annular seal ring via said at least one inlet; (d) a rotatable runner, said first annular seal ring and said second annular seal ring disposed around said rotatable runner; and (e) a plurality of groove structures disposed along an outer annular surface of said rotatable runner, said gas communicable onto said groove structures, each said groove structure separates said gas so that a first portion of said gas is directed onto said first annular seal ring to form a first thin-film layer between said rotatable runner and said first annular seal ring and a second portion of said gas is directed onto said second annular seal ring to form a second thin-film layer between said rotatable runner and said second annular seal ring, each said groove structure having at least two grooves, each said groove includes at least two adjoining steps wherein each said adjoining step has a base disposed at a depth (h), said depth (h) decreases from at least one said adjoining step to another said adjoining step in the direction opposite to rotation, a shoulder disposed between two said adjoining steps, said shoulder locally redirects said gas outward toward said first annular seal ring or said second annular seal ring so that flow of said gas is turbulent.