Thrust Characteristics and Nozzle Role of Water Jet Propulsion
Thrust Characteristics and Nozzle Role of Water Jet Propulsion
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DOI：
10.5293/ijfms.2017.10.1.047
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发表时间：
2017-03
影响因子：
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通讯作者：
Yongyan Ni;Weimin Liu;Zhanhao Shen;Pan Xiwei
中科院分区：
文献类型：
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作者：
Yongyan Ni;Weimin Liu;Zhanhao Shen;Pan Xiwei
用表面压力积分法和动量法分别计算了对旋轴流水射流推进的叶轮推力和系统推力，揭示了一个有趣的现象，即推力悖论。为了解释这一悖论，对叶轮推力和系统推力进行了物理和理论分析，结果表明，叶轮推力是头部相关的，由叶轮上下游的水力参数决定，而经典方程描述的动量法在最佳效率点下是有效的。由此推断，喷水推进喷嘴的作用主要是限制流经叶轮的流量，保证系统在产生动量差的同时，工作在最佳效率状态。相关数学公式表示，喷嘴直径是计算喷水推进工作条件的主导变量。因此，喷管直径可以由前一个表达式稳定地估计出来。最后给出了系统在不同转速下的推力定标特性。
Surface pressure integration and momentum method were respectively performed to evaluate the impeller thrust and the system thrust of a contra-rotating axial flow water jet propulsion, and an interesting phenomenon so-called thrust paradox was revealed. To explain the paradox, the impeller thrust and the system thrust were physically and theoretically analyzed, the results show that the impeller thrust is head involved and is determined by the hydraulic parameters upstream and downstream the impeller, while the momentum method depicted by a classic equation is valid simply under the best efficiency point. Consequently, the role of a water jet propulsion nozzle was deduced that the nozzle is mainly to limit the flow rate that crosses the impeller and to assure the system working under the best efficiency condition apart from its ability to produce momentum difference. Related mathematical formula expressed the nozzle diameter is the dominant variable used to calculate the working condition of the water jet propulsion. Therefore the nozzle diameter can be steadily estimated by the former expression. The system thrust scaling characteristics under various speeds were displayed lastly.