Cavitation wear prediction of propeller materials based on surface roughness measurement data

• Main Authors: Yevgeny O. Gorbachenko, Yury N. Tsvetkov
• Format: Article
• Language: English
• Published: Krylov State Research Centre 2019-12-01
• Series: Труды Крыловского государственного научного центра
• Subjects: cavitation wear; incubation period; propeller; propeller alloys; magnetorestrictive vibrator; surface irregularities; mean arithmetic deviation of profile
• Online Access: https://transactions-ksrc.ru/eng/archive/Cavitation-wear-prediction-of-propeller-materials-based-on-surface-roughness-measurement-data/

Object and purpose of research. This paper studies cavitation wear of propeller materials to predict its incubation period. Materials and methods. The experiments were performed with ultrasonic magnetostrictive vibrator UZDN-2Т in fresh water. Test samples were made of 25L, 08Kh14NDL and 08Kh15N4DML steels and BrА9Zh4N4L and BrА7MTs14Zh3N2TsL bronzes. Cavitation wear was estimated through regular weight checks of the samples by means of analytical scales, and irregularities of wear-exposed surface were identified by means of measuring mean arithmetic deviation of profile with MarSurf PS1 profile meter. Surface irregularities of worn areas on Al-bronze marine propellers (2765-mm four-blade propeller of a displacement ship and 710-mm five-blade propeller of a hydrofoil) were measured by means of dial-type depth gauge and MarSurf PS1 roughness meter respectively. Main results. This paper shows that mean arithmetic deviation of profile, Ra, during the incubation period is a linear time function, and Ra value corresponding to the end of the incubation period is a constant that does not depend on the intensity of cavitation for one and the same installation or one and the same equipment. The paper also suggests the methods for determination of Ra corresponding to the end of the incubation period for in-service propellers. Conclusion. The paper suggests a universal fast-track prediction procedure for incubation period predictions for both laboratory samples of alloys and final products (i.e. propeller blades) exposed to in-service cavitation wear. The procedure based on the changes in Ra value of surface profile makes it possible to considerably reduce the man-hours required for cavitation resistance tests of alloys and could also be helpful in the assessment of maintenance periods for in-service propellers.