基于CFD的潜液式液化天然气泵导叶设计

Design of liquefied natural gas submerged pump guide vane based on CFD

潜液式液化天然气(liquefied natural gas,LNG)泵工作时,屏蔽电机和泵体全部浸没在低温液体中.为减小泵的径向和轴向尺寸,潜液式LNG泵采用了一种特殊结构的导叶.在分析潜液式LNG泵导叶结构特点的基础上,研究导叶进口喉部宽度和折转角对泵设计工况水力性能的影响.首先,设计不同几何参数的导叶,并分别与同一叶轮进行匹配;再通过ANSYS CFX软件,采用标准k-ε湍流模型对各导叶分别进行全流场数值计算.计算结果表明:进口喉部宽度是潜液式LNG泵导叶的关键尺寸,设计时需重点考虑;进口喉部宽度存在最优值,且最优值大于经验值;进口折转角对泵扬程和效率影响较小.因此,设计导叶时可优先确定其他关键尺寸,再通过调节进口折转角改善导叶的结构.

Liquefied natural gas （LNG） submerged pump is designed to immerse its canned motor and pump body into cryogenic liquid. To reduce radial and axial sizes, special guide vanes with different structures from popular ones are used. By analyzing the LNG pump structure, two key geometric parameters, inlet width and turning angle, were investigated to see how they affect pump hydraulic performance in the design. LNG pump guide vanes with different inlet widths and turning angles were designed to assemble the same impeller. Three-dimensional turbulent flows of different models were then numerically simulated using a standard k-~ turbulence model with ANSYS CFX. The comparative study revealed that optimum value of inlet width exited, and was larger than experience-based values. Inlet width had great influence on the pump performance, while turning angle was much less important. Therefore, designing an LNG pump guide vane, inlet width should be given high priority, and turning angle should be adjustable for structural design.