Cavitation erosion wear behavior of ship propeller material: Analysis of surface roughness (Ra) using the taguchi method

In this research, different factors affecting the cavitation wear behaviors of Manganese Aluminum Bronze (MAB-CU4) material, which is preferred in ship propellers exposed to cavitation during operation, were investigated. The study focuses specifically on how these factors affect the change in surface roughness (R-a). The Taguchi experimental design is employed to analyze the data. Within this particular context, the cavitation erosion characteristics of the MAB-CU4 alloy have only been minimally investigated in existing literature. This study represents the first comprehensive examination of the impact of surface roughness, considering various parameters such as cavitation number, angle of attack, and distance. A high-pressure cavitation jet test rig was designed and produced for cavitation erosion experiments, following the specifications outlined in ASTM G134-95 standards. The experiments were carried out using the L9 orthogonal array design as recommended by the Taguchi method. The design and analysis of the system included certain parameters and levels, namely distance the nozzle and the specimen (S-off = 5, 10 and 15 mm), cavitation attack angle (30 degrees, 60 degrees and 90 degrees), and cavitation number (sigma = 0.006, 0.008 and 0.01). When the results are analyzed, it was observed that the surface roughness (R-a) of MAB-CU4 increases more than twice as much at a cavitation angle of attack of 30 degrees compared to 90 degrees. The most significant factor influencing this change in surface roughness (R-a) is the cavitation number, which has a value of 42.57%. Furthermore, the acquired 3D optical profilometry and SEM images demonstrated the variation in damage mechanisms based on the cavitation erosion parameters.