Shrouded axial flow turbo machine utilizing multiple labrinth seals

Abstract

A turbo machine includes a plurality of rotor wheels mounted on and extending radially outward from a shaft to a radially outermost periphery. A shroud band for each rotor wheel has an inner and outer radial surface, with the inner radial surface secured to the radially outermost periphery of a plurality of buckets on each of the rotor wheels. The outer radial surface has a central portion displaced radially outward from upstream and downstream portions of the radial outward surface. A plurality of diaphragms are axially spaced from the rotor wheels and are configured to direct fluid against and effect rotation of the rotor wheel. An axial extension from each diaphragm surrounds and is spaced from the outer radial surface of the shroud band. First and second seal teeth extend radially inward from the axial extensions of each diaphragm and terminate at tips adjacent to the upstream and downstream portions, respectively. The tips of the first and second seal teeth extend radially inward of and are axially spaced from the central portion to form first and second non-contact axial seals, respectively. Each shroud band includes a pair of opposing sides between the inner and outer radial surfaces and may have at least one non-radial cut extending through the opposing sides, where the sides of the cut remain in contact during thermal expansion or contraction.