Seal system for a gas turbine engine or the like

摘要

A dual labyrinth seal arrangement is provided for controlling the supply of sealing air to a bearing chamber of a gas turbine engine. The bearing chamber housing the bearing for a turbomachine shaft connecting a compressor stage with a gas generator turbine is surrounded by a second chamber. A first of the labyrinth seals is disposed between the shaft and the second chamber so as to reduce the pressure of a supply of high pressure sealing medium passing into the seal chamber. The second set of labyrinth seals are provided between the turbo shaft and the second chamber so as to reduce the pressure of sealing medium passing from the second chamber into the bearing chamber. In particularly preferred embodiments, a majority of the sealing medium is vented from the second chamber and supplied to the working cycle of the gas turbine engine, while the remaining smaller portion is supplied as sealing air into the bearing chamber via the second set of labyrinth seals.