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A honeycomb labyrinth seal includes a downstream-most row of honeycomb cells which extends beyond the exit edge of a base portion, so that a portion of each cell of the downstream-most row of honeycomb cells overhangs the base portion by an amount approximately equal to one half the width of the dra

A honeycomb labyrinth seal includes a downstream-most row of honeycomb cells which extends beyond the exit edge of a base portion, so that a portion of each cell of the downstream-most row of honeycomb cells overhangs the base portion by an amount approximately equal to one half the width of the drainage passages formed in the base portion.

대표청구항 ▼

1. A honeycomb labyrinth seal cooperatively associated with rotatable steam turbine blades, the honeycomb seal comprising: a base portion having an inlet edge corresponding to the upstream portion of the seal and an exit edge corresponding to the downstream portion of the seal and being mounted o

1. A honeycomb labyrinth seal cooperatively associated with rotatable steam turbine blades, the honeycomb seal comprising: a base portion having an inlet edge corresponding to the upstream portion of the seal and an exit edge corresponding to the downstream portion of the seal and being mounted on a seal support ring having a radial surface; a plurality of rows of honeycomb cells extending radially inwardly from the base portion so that each cell is open adjacent the blade; a plurality of passages so disposed that each cell is connected to at least one passage and at least one passage is open upstream of the rows of the honeycomb cells and at least one passage is open downstream of the rows of the honeycomb cells, thereby permitting steam to flow through the passages and cells from the upstream side to the downstream side of the honeycomb; and a moisture removal/extraction slot opening disposed in a radial direction between the seal support ring and a downstream row of stationary blades; wherein a portion of a downstream-most row of honeycomb cells extends axially downstream beyond the exit edge of the base portion and the radial surface of the support ring, and wherein each rotating blade has an exit edge which extends axially downstream beyond the downstream-most row of honeycomb cells so that a radial drainage flow is induced by centrifugal force at the downstream-most row of honeycomb cells. 2. A honeycomb labyrinth seal as recited in claim 1 wherein the passages extend circumferentially adjacent the base portion. 3. A honeycomb labyrinth seal as recited in claim 1, wherein the passages are grooves disposed in the base portion. 4. A honeycomb labyrinth seal as recited in claim 1, wherein the cells are hexagonally shaped. 5. A honeycomb labyrinth seal as recited in claim 1, wherein the downstream-most row of honeycomb cells is centered over a strip of the base portion formed between the exit edge and the downstream-most passage, so that a portion of each cell in the downstream-most row of honeycomb cells overhangs, the, base portion. 6. A honeycomb labyrinth seal as claimed in claim 5, wherein the overhanging portion of each cell of the downstream-most row of honeycomb cells is substantially equal to one half the width of the passages. 7. A honeycomb labyrinth seal as recited in claim 1, wherein the downstream-most row of honeycomb cells extends beyond the exit edge of the base portion by about one half of a groove width. 8. A honeycomb labyrinth seal as recited in claim 1, wherein the exit edge of the backing plate is substantially in line with a downstream radial surface of a seal support ring. 9. A honeycomb labyrinth seal as recited in claim 1, wherein the rotatable blades are un-shrouded.