| 摘要 |
A sealing arrangement is provided between relatively rotatable bodies of a machine in which, in operation, a relatively high pressure (P<SUB>1</SUB>) exists on one side of the sealing arrangement and a relatively low pressure (P<SUB>2</SUB>) exists on the other side, the pressure difference (P<SUB>1</SUB>-P<SUB>2</SUB>) being up to a predetermined maximum pressure difference (DeltaP<SUB>max</SUB>). The sealing arrangement includes a series of seals, the pressure dropping across each successive seal from the high pressure side of the sealing arrangement to the low pressure side. At least two of the seals are flexible seals, e.g. brush or leaf seals. Each flexible seal 14 is designed to function under a pressure drop (Deltap) up to a predetermined maximum pressure drop (Deltap<SUB>max</SUB>) across the flexible seal 14 and to provide a given resistance to fluid flow. Each flexible seal 14 is capable of recovering from an abnormal condition, due to normal operation of the machine, in which the resistance of the flexible seal to fluid flow decreases from a normal level to a substantially lower level. The series of seals are arranged in such a manner that the pressure drop across each flexible seal is less than the predetermined maximum pressure drop (Deltap<SUB>max</SUB>) when the pressure difference (P<SUB>1</SUB>-P<SUB>2</SUB>) between the high pressure side of the sealing arrangement and the low pressure side is equal to the said predetermined maximum pressure difference (DeltaP<SUB>max</SUB>) and another one of the flexible seals has suffered a recoverable decrease in its resistance to fluid flow. In one embodiment the flexible seal 14 is provided with a permanent by-pass path 16 communicating between its upstream and downstream sides.
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