摘要 |
A corrugation has a radially inner wall circumferentially surrounding an axis. The inner wall defines an inner cavity configured to conduct a liquid axially through the inner cavity. A radially outer wall of the corrugation overlies the inner wall. The outer wall adjoins the inner wall so as to form a closed outer cavity bounded by the inner and outer walls and separated from the inner cavity by the inner wall. The inner wall has at least one opening providing fluid communication between the inner and outer cavities for the corrugation to serve as a reservoir for the liquid.
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