Circumferential seal assembly with multi-axis stepped grooves

A circumferential seal assembly comprising:

• (a) an annular seal housing disposed between a pair of compartments;
• (b) a rotatable runner;
• (c) an annular seal ring disposed within said annular seal housing and disposed about said rotatable runner;
• and
• (d) a plurality of groove structures disposed along an outer annular surface of said rotatable runner, each said groove structure includes a groove, said annular seal ring disposed about said grooves, a source flow communicated into said groove to form a longitudinal flow therein;
• wherein:
• each said groove includes two adjoining steps whereby each said step defined by a base wall, said base walls arranged along said groove to decrease depthwise in direction opposite to rotation of said rotatable runner, said base walls disposed about a base shoulder, said base shoulder locally redirects said longitudinal flow to form an outward radial flow in direction of said annular seal ring;
• said base walls bounded by and intersecting a pair of side walls, each said side wall includes a side shoulder which narrows said groove widthwise and locally redirects said longitudinal flow away from one said side wall to form a lateral flow in direction of other said side wall;
• said side shoulders opposedly arranged whereby said side shoulders being aligned with each other and said base shoulder, said side shoulders extend into said rotatable runner so that each said side shoulder intersects one said base wall at a first depth from said outer annular surface and downstream from said base shoulder and each said side shoulder intersects other said base wall at a second depth from said outer annular surface and upstream from said base shoulder;
• said base wall upstream of said base shoulder being wider than said base wall downstream of said base shoulder
• said first depth being less than said second depth;
• said lateral flows intersect each other and each of said longitudinal flow and said outward radial flow within a plane containing said side shoulders and said base shoulder.