| 摘要 |
A twin spool rotor shaft having an inner rotor shaft and an outer rotor shaft concentric to the inner rotor shaft, an outer shaft seal assembly formed between the outer rotor shaft and a stationary casing, and an inner shaft seal assembly formed between the outer shaft and the inner shaft. The two seal assemblies include a purge cavity and two drain cavities formed on the sides of the purge cavity. A purge fluid is supplied to the outer purge cavity, and drain passages in the stationary housing drain the two outer drain cavities without mixing the two fluids. The outer purge cavity is fluidly connected to the inner purge cavity through a radial passage in the outer rotor shaft in one embodiment, or through a bore tube passing within the inner rotor shaft in a second embodiment. The inner drain cavities are connected to the outer drain cavities through similar connections, either through radial passages in the outer rotor shaft in the first embodiment or through additional bore tubes in the inner rotor shaft in the second embodiment.
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