船舶喷水推进器进水流道效率的数值计算

Numerical calculation of inlet duct efficiency of marine waterjet propulsion

根据第21届、23届及24届ITTC关于喷水推进器能量公式的不同定义分别推导了进水流道效率的3种计算公式。在保持总流量不变的条件下,用满足最小偏差量的半椭圆来拟合进流面的形状,以CFD为工具对进水流道效率进行数值计算。对比分析7个不同进流面位置的计算结果,证明了进流面选在进口前1倍叶轮直径处是实用而合理的。研究结果表明,包含动能、压能、势能的进水流道效率公式最为合理,包含动能和压能的公式在CFD计算时可以作为流道效率的简化公式;重力对流道效率的计算值没有影响;由简化公式得到的计算方法可以大大减少计算量。

According to different energy definitions from the 21 st,23 rd and 24 th ITTC,three different kinds of inlet duct efficiency formulas are derived.On the consistent condition of total flow mass,the shape of capture area is fit by a semi-elliptical,and then inlet duct efficiency is calculated by CFD.Seven results on different locations of capture area are compared,which shows that it is practical and rational to choose capture area at one-impeller length before the inlet duct.The research result indicates that the formula including kinetic、pressure and potential energies is most reasonable,and the formula including kinetic and pressure energies can be used as the simplified efficiency formula in the calculation of CFD.The gravity has no effect on the value of inlet duct efficiency,and the amount of calculation can be greatly reduced by the simplified method derived from the simplified efficiency formula.