Intershaft seal system for minimizing pressure induced twist

A method for minimizing twist within an intershaft seal system disposed between an inner shaft and an outer shaft comprising the steps of:

• (a) communicating a fluid from a high pressure region to a low pressure region separated by a piston ring disposed between a forward mating ring and an aft mating ring, said piston ring includes a plurality of substantially vertical channels, each said substantially vertical channel directly communicates at one end with an outer diameter face when said outer diameter face includes at least one outer groove directly contacting a dam or an inner diameter face along said piston ring when said forward mating ring includes at least one port which communicates said fluid to said inner diameter face and directly communicates at another end with a substantially horizontal channel;
• (b) directing said fluid onto a plurality of divergent flow grooves disposed along said aft mating ring, each said divergent flow groove includes a pair of grooves which intersect at an apex, each said substantially horizontally channel also communicates with at least one said apex, said fluid enters each said substantially vertical channel and passes into said substantially horizontal channel exiting onto said apex as said piston ring rotates with respect to said divergent flow grooves, said pair of grooves being substantially symmetric about said apex, said fluid impinges said apexes so that said fluid flows into said pairs of grooves, said forward mating ring includes a plurality of hydrodynamic grooves;
• and
• (c) producing a first fluid pressure force along said piston ring via said divergent flow grooves, said first fluid pressure force being substantially symmetric across a radial width of said piston ring with respect to said apexes.