基于CFD的对旋轴流式喷水推进泵转速控制方法

为了研究不同转速比下对旋轴流式喷水推进泵的外特性,应用计算流体动力学的方法对不同工况下的喷水推进泵进行数值模拟,分析了推进泵外特性与转速比的关系以及不同转速比下对旋泵的内部流动结构与能量耗散的特征.计算结果表明：不同转速比下喷水推进泵的外特性变化较大;通过比较,得到了不同流量下效率最高点的最优转速比;当流量小于1.0Qd时,控制首级叶轮的转速可以获得最优转速比;流量大于1.0Qd时,控制次级叶轮的转速获得最优转速比;通过对0.9Qd时速度三角形和内部流场的分析,发现降低转速可以减小首级叶轮进口冲角,改善内部流场,减小水力损失.通过以上分析验证了转速控制方法的有效性.

CFD-based rotational speed control method for contra-rotating axial-flow waterjet pump

To study the performance of two-stage contra-rotating axial waterjet propulsion pump under different rotational speed ratios, the fluid flows in a waterjet pump are simulated under different working conditions by using computational fluid dynamics （CFD） method, and the relationship between the performance and speed ratio is established, further the flow structure and turbulent energy dissipation rate are analyzed. The results show that the performance of the pump depends largely on rotational speed ratio. Through comparison, the optimum speed ratio for the best efficiency is obtained at different flow rates. When a flow rate is less than 1.0Qa, the optimum speed ratio can be realized by controlling the front impeller speed. When a flow rate is higher than 1.0Qa, however, the optimum speed ratio can be achieved by altering the rear impeller speed. Through an analysis of the velocity triangle and internal flow field at 0.9Qd, it is identified that the reduction of the front impeller speed is helpful to low angle of attack experienced by the front impeller, causing improved internal flow field and decreased hydraulic losses. These results confirm the method of speed control for the contra-rotating axial-flow waterjet pump is feasible.