A study on the numerical cavitation tunnel

螺旋桨空泡引起的船体表面压力脉动的估算是船舶设计过程中的重要内容。本研究针对此船体表面压力脉动，采用空泡模型进行数值模拟，并对船体与螺旋桨组合系统进行模拟，以更准确地模拟船体与螺旋桨之间的相互作用。在无空化条件下，计算结果与实验结果吻合较好。对于空化情况，也获得了良好的定性一致性。然而，定量一致性不如非空化条件。在叶片频率处的压力脉动预测值约为实验测量值的60%，而在模拟中预测的更高频率分量远小于实验测量值。这些高频波动是由群腔塌陷或叶尖涡空泡破裂等复杂现象引起的。由于这些现象在本空化中没有被模拟，因此在模拟中没有再现高频波动。尽管如此，这是第一次尝试直接通过CFD预测船体表面压力波动，并对相关研究界产生了影响。

Estimation of the hull surface pressure fluctuation due to propeller cavitation is important in the design procedure of a ship. In this research project, we aim at predicting this hull surface pressure fluctuation through numerical simulation using a cavitation model.We have carried out simulation for a combined system of a ship hull and propeller in order to model the interaction between the hull and propeller more accurately. A good quantitative agreement with the experiment was obtained for non-cavitating condition. Also for cavitating cases a good qualitative agreement was obtained. However, the quantitative agreement was not as good as for the non-cavitating condition. The predicted magnitude of the pressure fluctuation at the blade frequency was about 60% of the measured value in the experiment, while higher frequency components predicted in the simulation were much smaller than that. Those high frequency fluctuation is induced by complex phenomena such as collapse of crowd cavity or bursting of tip vortex cavitation. Because those phenomena are not modeled in the present cavitation, high frequency fluctuation was not reproduced in the simulation. Nevertheless, this was the first attempt to predict the hull surface pressure fluctuation directly by CFD, and has an impact on the related research community.