Influences of Journal Rotating Direction on Cryogenic Hybrid Journal Bearings

Abstract

In the present study, two types of nine-recess hybrid journal bearings (HJBs) with different recess geometries, i.e., the Young Leaf Mark and the square, were operated at a rotational speed of up to 67,000 rpm using the cryogenic journal bearing test apparatus at JAXA to clarify influences of the journal rotating direction on the cryogenic HJB. Liquid nitrogen was supplied to the test bearings with a pressure of up to 4 MPa. The test bearings were 60 mm in diameter and 25 mm in width, with a 0.055 mm clearance and a recess area ratio of 0.186. Based on the experimental results the dependence of the rotor vibration on the rotational speed was confirmed to be affected by the journal rotating direction. The test HJBs with the positive sweepback angle of the recess leading edge showed the smallest rotor vibration in the high-rotational-speed operation where the hydrodynamic effect was predominant.

Keywords

• journal bearing
• cryogenic turbopump
• recess sweepback angle
• rotordynamic performance
• liquid nitrogen