无轴式喷水推进泵的水动力特性

Hydrodynamic characteristics of shaft-less waterjet pump

为提高现有SDPM-450型喷水推进泵的水动力特性,提出了无轴式喷水推进泵的理念.采用齿轮轮缘驱动结构代替原有的皮带轮——驱动轴传动结构,避免了驱动轴对泵进流场的扰动作用.应用商业CFD软件分别对无轴式喷水推进泵和原模型进行三维建模和数值计算,围绕理论、内部流动和推进性能3个方面进行水动力特性研究.对比分析表明：驱动轴的摒弃降低了进水流道的损失系数和伴流系数,减小了不均匀进流对喷水推进泵速度场的扰动,进而加强了喷水推进泵的过流能力和做功能力;无轴式结构增强了喷水推进器的推进性能,在高航速区间内尤为明显,推力增大了20%,推进效率提高了15%;高效区间向高航速方向延伸,船舶的航行范围得以拓宽,平均增幅为3~5节.因此,无轴式喷水推进器结构上具有可行性,水动力特性上具有优越性,该研究为喷水推进装置的未来发展提供了一个方向.

A design concept of shaft-less waterjet propulsion pump is put forward to improve the hydrodynamic performance of existing SDPM -450 waterjet pump. In such a design, a gear transmission system replaces the conventional beh-shaft transmission to drive the pump impeller. Since the upstream shaft has been removed, its disturbance on the flow field in the inlet conduct is awfided. The hydrodynamic performances of the shaft-less waterjet pump and the conventional one are predicted by using CFD code under ship high speed conditions. The hydrodynamic characteristics are clarified based on theoretical analysis, internal flow field and propulsion performance. A theoretical analysis shows that the flow rate discharged by the pump and the capability of doing work of the pump are improved. As a result, the shaft-less pump is subject to 20% more thrust and 15% more efficiency compared with the conventional pump. Based on flow field analysis, the shaft-less pump presents a shrunk wake am/a reduced inflow loss. The propulsion performance analysis reveals that the shaft-less pump can work more efficiently at a high speed, causing a 3 -5 knot increment in the sip speed in average.