Counter-rotating turbine

A gas turbine engine, comprising:

• a compressor section;
• a combustion section;
• and
• a turbine section arranged in serial flow order,
• wherein the turbine section comprises a low-pressure (LP) turbine, the LP turbine comprising:
• an outer casing;
• an inner drum positioned inward of the outer casing in a radial direction, the outer casing and the inner drum defining an airflow path through the LP turbine;
• a first plurality of LP turbine blades, the first plurality of LP turbine blades comprising a first stage comprising first stage LP turbine blades that rotate in a first direction at a first speed, wherein the first plurality of LP turbine blades extend in the radial direction from an inner end coupled to the inner drum to an outer end isolated from the outer casing;
• a second plurality of LP turbine blades, the second plurality of LP turbine blades comprising a second stage comprising second stage LP turbine blades and a third stage comprising third stage LP turbine blades disposed downstream of the first stage LP turbine blades that rotate in a second direction opposite the first direction at a second speed, wherein the second plurality of LP turbine blades extend in the radial direction from an inner end coupled to the inner drum to an outer end isolated from the outer casing;
• first stationary guide vanes disposed upstream of the first stage LP turbine blades;
• second stationary guide vanes disposed between the second stage LP turbine blades and the third stage LP turbine blades;
• a first LP turbine spool connected to the first plurality of LP turbine blades on an inner side of the first plurality of LP turbine blades in a radial direction;
• and
• a second LP turbine spool connected to the second plurality of LP turbine blades on an inner side of the second plurality of LP turbine blades in the radial direction, and
• wherein the first speed is lower than the second speed.