轴向间隙对对旋式喷水推进泵水力特性的影响

Effects of Axial Clearance on Hydraulic Characteristicsof Counter-Rotating Water-Jet Pump

关键词:  对旋式轴流泵  喷水推进  轴向间隙系数  外特性  内部流动

Key words:  Contra-rotating axial flow pump  Water jet propulsion  Axial clearance coefficient  External characteristic  Internal flow

摘要:

为研究对旋式喷水推进泵叶轮轴向间隙对泵水力性能及推力的影响，基于RNG k - ε湍流模型和SIMPLEC算法，参考导叶与叶轮间的轴向间隙范围，对五组不同间隙系数的喷水推进泵模型进行了数值模拟。定义了对旋叶轮首次级间隙系数δ，分析了不同轴向间隙系数下泵外特性、内部流动能量转化以及推力特性的变化规律。通过推进泵性能实验结果与数值模拟结果的比较，验证了数值计算方法的可靠性。研究表明：在研究的间隙范围内，对旋叶轮轴向间隙的增加可以改善首级叶轮的低压区；当0.13<δ<0.17时不利于次级叶轮回收首级叶轮的流体能量；在轴向间隙系数0.09<δ<0.13的范围内可以明显提高推进泵的效率，δ=0.09时效率最高，达到85%；当轴向间隙系数δ>0.17时，推力有较明显的下降趋势。因此，通过内部流动分析和外特性以及推力特性的研究，共同验证了首次级叶轮间的轴向间隙是影响对旋式喷水推进泵水力特性的重要因素。

Abstract:

The axial clearance coefficient δ between first and secondary stage impeller is defined to investigate the effects of axial clearance on hydraulic performance and thrust characteristic of the contra-rotating water-jet pump. Refering to the range of axial clearance between guide vane and impeller, 5 water-jet pump models with different axial clearance coefficient were designed. Based on the RNG k-ε turbulence model and SIMPLEC algorithm, the numerical simulation of five groups water-jet pump models with different clearance coefficient were carried out. The pump external characteristics, internal flow characteristics and thrust characteristics are analyzed with different axial clearance coefficients. Numerical results agree well with the experience results, which verify the effectiveness of numerical simulation method. With the increase of δ within the scope of the study, the low pressure area of the front impeller can be improved effectively. The energy from the front impeller is difficult to be absorbed by the rear impeller with 0.13<δ<0.17. The efficiency of the water-jet pump can be promoted as the axial clearance coefficient range from 0.09 to 0.13, the efficiency can be up to 85% as δ=0.09. When the axial clearance coefficient is greater than 0.17, the value of thrust displays a significant downtrend. As a result，the axial clearance coefficient δ has been proved as a significan factor to hydraulic characteristics of counter-rotating water-jet pump through the analysis of internal flow, external characteristics and thrust characteristics.