One technical difficulty is cavitation, where low pressure behind a turning blade causes air bubbles.
一个技术难题是气穴现象，一旦发生气穴现象，位于旋转螺旋桨叶后方的低压会产生气泡。
2
Propeller cavitation degrades propeller performance, erodes blade surfaces, produces noise, and causes vibration on the ship hull.
螺旋桨空泡会降低螺旋桨性能，产生空化剥蚀和噪声，从而导致船体振动。
3
To increase the head of bulb turbine, it is necessary to improve the runner blade design method and design high head bulb turbine with good energy and cavitation coefficient performance high.