Piston seal ring bypass

A machine comprising a rotor having:

• an inner member;
• an outer member encircling the inner member;
• a groove in one of the inner member and the outer member, the groove having a first side wall, a second side wall and a base;
• and
• a split ring seal accommodated in the groove and contacting a surface of the other of the inner member and the outer member,
• wherein:
• the first side wall has a plurality of open radial first channels;
• the second side wall has a plurality of open radial second channels;
• in an outward radial direction the second channels have an angular component opposite an angular component of the first channels;
• and
• viewed axially, the first channels and second channels are off radial by an angle θ of at least 5°.