Pressure generated by partially water-repellent flat thrust bearing with weak water-repellent part

Abstract

The generation state of the pressure for partial water-repellent (slip) type flat thrust bearings with high/low slip parts was examined with experiments and infinite width bearing approximation. In this bearing, water-repellent (WR: high slip), weak water-repellent (WWR: low slip) and hydrophilic (HP: non-slip) regions were alternately arranged in the slip direction, and the pressure to support the load was generated by discontinuity of shear flow rate in each region. The measured pressure in slip direction increased in the water repellent side (static contact angle of water droplet θ≒110 °) and weak water repellent part (θ ≒80 °), and it decreased in the hydrophilic side (θ≒10 °). And this pressure distribution in circumferential direction was close to quadrangle and it increased almost in proportion to the load. The pressure distribution differed greatly depending on the slip length in low slip part (e.g. WWR), it became a quadrangle having a maximum pressure at the boundary of the non-slip part (e.g. PH). For example, the pressure distribution became close to a triangle when the slip length in low slip part was long close to the slip length in high slip part (e.g. WR). Whereas, it became a quadrangle close to a trapezoid when low slip part had the short slip length. For the bearing with large angle φWWR in low slip part, the generated pressure and the difference in generated pressure at each load was lower. Especially, generated pressure decreased when φWWR approached the maximum angle (60° in this experiment) because high slip and non-slip areas became extremely narrow. Incidentally, the effect of slip length in high slip part on the load capacity was remarkable, but the influence of slip length in low slip part was hardly observed.

Keywords

• slip flow
• water-repellent
• thrust bearing
• pressure distribution
• water lubrication