Fundamental Investigation on an Oil Damper : 5th Report, Effects of Eccentricity Between the Centers of Cylinder and Piston

Abstract

In a series of the work, we study on a simply constructed oil damper ; it has an annular cross-sectional clearance between the cylinder and the piston as a flow channel of oil. This report describes an analytical and experimental study of eccentric effects on the drag of the piston placed eccentrically within the cylinder. Assuming a laminar and unsteady flow, we analyze the oil stream through the eccentric annular channel, and derive an added mass and a damping coefficient of the oil damper. These values are compared with experimental results, and the following results are obtained : The eccentricity increases the added mass and decreases the damping coefficient of the oil damper. An increase in frequency of reciprocating motion of the piston reduces the eccentric effects.