Axial flow steam turbines

摘要

A drum-type rotor carries an annular row of moving blades having root portions held within a slot in the periphery of the rotor. A turbine casing surrounds the rotor and carries a static blade assembly with an annular row of static blades which, together with the annular row of moving blades, constitutes an impulse turbine stage. The static blade assembly has a radially inner static ring confronting a periphery of the rotor with a seal acting therebetween. The static blade assembly has an outer static ring which has a substantially greater thermal inertia and stiffness then the inner static ring and is capable of sufficient radial sliding relative to the casing so as to accommodate relative thermal expansion and contraction of the outer static ring and the turbine casing.