噴流キャビテーション壊食に及ぼす衝突面貫通穴の影響

抄録

In hydraulic equipment, cavitation erosion is occurred on the surfaces at oil-jet impingement and the walls near the jet flow. Effects of a hole of a jet-impingement surface on erosion was investigated experimentally using hollow and solid cylindrical specimens. The stainless steel chamber with an inner diameter of 170 mm was utilized, including a long-orifice nozzle. The aluminum and acrylic specimens with a length of 20 mm, an outer diameter of 20 mm, and inner diameters of 0-5 mm were prepared. The test fluid was hydraulic oil with a viscosity grade of 32. The upstream and downstream absolute pressure were set at 10.1 MPa and 0.2 MPa, respectively. The standoff distance was set at 27.5 mm. The hole of the specimens contributed to reduce the erosion of the jet-impingement surfaces. However, the upstream-side inner wall of the flow passage was damaged for the small hole specimens and the downstream-side wall was damaged for the large hole specimens. The cavitating jet was visualized using a high speed video camera and the pictures were compared with the eroded specimens.