ビスコシールのガス巻込み現象 : 巻込まれたガスの挙動(流体工学,流体機械)

概要

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The gas ingestion phenomena of a viscoseal, which is a type of noncontact seal, are described. A screw shaft, 40mm in diameter and 145mm in length, is horizontally set in the casing, which is 40.4mm in inner diameter. Sealant, which fills the 0.2mm radial clearance between the screw shaft and the housing, is pressurized by the screw-pump effect. Flow visualization and pressure measurements are performed in the viscoseal. Changes in the gas-liquid interface are found to be different from the ingested gas motion depending on the rotating angle of the screw shaft. Most of the ingested gas bubbles are observed in the screw groove when the screw shaft is rotating in the direction of the gravitational force. In contrast, the ingested gas bubbles are observed both in the screw groove and on the screw land when the screw is rotating in the opposite direction to gravity. Also, the ingested gas bubbles are subdivided with increasing pressure in the sealant along the screw axis. Both the formation of the air-liquid interface and the ingested gas motion are influenced by the circumferential pressure differences in the sealant, which are both experimentally and theoretically observed. As a result, it is confirmed that the ingested gas deformation is affected by both the direction and the force of the pressure in the sealant.
2010-09-25