| 摘要 |
A steam turbine contains a housing, a rotor shaft which extends in the housing, and a shutter which is arranged between the housing and the rotor shaft. The shutter interacts with the housing and forms a flow duct in between, into which operating fluid is introduced. A cooling chamber is formed between an inner surface of the shutter, adjacent to the point at which the operating steam is introduced, and an outer circumferential surface of the rotor shaft. A cooling fluid is introduced into this cooling chamber at a temperature which is less than that of the operating steam. The shutter contains inner and outer rings, each of which is split into a pair of segments. The cooling fluid is introduced into a cavity which is constructed in at least one of the inner and outer rings. In consequence, at least one of the inner and outer rings is cooled, and the thermal expansion difference in the circumferential direction between the inner and the outer rings is minimised as a result of the temperature difference between the cooling fluid and the operating steam.
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