Typically the compressor and turbine sections have alternating ROTOR[rotating] and STATOR[stationary] blades.
Attempting to adjust the pitch of compressor or turbine blades turning at tens-of-thousands of RPMs would generate terrific forces and frictions... and confine the turning mechanisms within the shaft. This would be a monstrously complex Task for anything except giant slow-turning shafts. not to mention mindboggling balance/dynamics issues.
However IF blade pitch adjustments are required for optimized gas-path flow, then that typically occurs in the STATOR-blade rows. Each STATOR-row is linked-together so it will simultaneously adjust each blade in unison... which may be different for each stator row. This system of STATOR blade adjustment... outside of the compressor/turbine cases... optimizes thru-flow relative to conditions in/out-of conditions each ROTOR-blade stage.
Regards, Wil Taylor
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