Investigation on effect of anti-cavitation edge on performance and leakage vortex characteristics of tubular turbine for ocean power generation

Anti-cavitation edge directly affects turbine runner performance and clearance leakage flow. This paper takes a tubular turbine as the object of study and uses the numerical simulation method of SST-CC turbulence model based on rotation and curvature correction to study the effect of anti-cavitation edge thickness on the turbine internal flow patterns and the flow characteristics of tip leakage vortex under different conditions. The results show that the high-altitude bubble concentrated area on the blade suction surface is reduced after installing the anti-cavitation edges. Meanwhile, the leakage volume decreases by 13.28% under the optimal condition, and the maximum leakage decreases by 37.72% under the off-design condition. The raised structure of the anti-cavitation edge can effectively push the tip leakage vortex (TLV) away from the blade suction surface and destroy the original vortex structure; the strength of tip separation vortex (TSV) is obviously reduced. The energy loss increasingly reduces with the increase of anti-cavitation edge thickness, and the loss reduction value is greater in the off-design condition. The small negative helicity vortex at the draft tube wall surface disappears. The above research results provide a certain reference for the performance optimization of tubular turbine.