Study on Flow Characteristics of Cryogenic Hybrid Journal Bearings

Abstract

In the present study, a flow visualization experiment in the clearance between a clear floating-ring and a rotating journal was carried out in order to clarify the effect of the sweepback angle (θs) of the leading edge of the recess on the flow characteristics. Four types of the floating-rings with different recess geometries, i. e., the Young Leaf Mark, the square and the non-recessed geometries, were operated at a rotational speed of up to 45,000 rpm using liquid nitrogen as the working fluid to observe the interaction between source flow from the recess and rotating flow induced by the journal rotation in the clearance. The cavitation cloud inside the clearance was induced by viscous frictional heating and the pressure drop. The influence of the θs value on the flow characteristics was investigated by comparing flow coefficient (Cf) and the cavitation cloud area ratio (Ac) obtained from the visual image. Based on the experimental results, the dependence of the flow characteristics on the rotational speed was confirmed to be affected by the sweepback angle of the leading edge of the recess.

Keywords

• journal bearing
• cryogenic turbopump
• flow visualization
• recess sweepback angle
• cavitating flow
• liquid nitrogen