Effect of Transverse Surface Topography on Cavitation Erosion

Abstract

Experimental and numerical investigations on the effect of transverse surface topography on cavitation erosion were performed. Specimens made in 45 steel with different transverse surface topographies, which were finished by milling under different processing parameters respectively, were tested in the water-tunnel experimental devices. Scanning electronic microscope and photon microscope were adopted to analyze the cavitation erosion degree on the specimens’ surface after 120 minutes’ tests. Results showed that the degree of the cavitation erosion was affected by the distribution and shape of the surface topography, and the interval between the topography units, which represented the topographies’ distribution, played a more important role than the shape of the units. Numerical simulation results of the flow over flat surfaces with transverse topographies, which were triangle or trapezoid and proportional spacing, were obtained to explain the effect of the transverse surface topographies on cavitation erosion. The variation of the average pressure distribution in the vicinity of the surface and pressure fluctuation caused by the surface topographies both affect the collapse behavior of the cavities which usually exist in the flow. Experimental and numerical results indicate that the degree of cavitation erosion on the specimens in the water-tunnel can be reduced by proper topography design.