泵喷推进器间隙流动控制技术试验研究

Experimental study of controlling tip clearance flow in a pump-jet propulsor

[目的]旨在抑制转子叶梢间隙流动,解决其给泵喷推进器水动力性能和非定常激振力带来的问题。[方法]以某型前置定子式泵喷推进器为对象,采用环状柔性密封结构与转子端环配合的方法,研究其抑制转子叶梢的间隙流动的有效性。通过保持导管结构近似刚性固定,测得推进器转子的推力和扭矩,给出转子的敞水效率,在高功率频闪仪的辅助下,观察记录各设计工况下的空化初生点,计算绘制出推进器的空化初生特性曲线。针对有/无间隙的推进器模型,在空化/非空化状态下通过试验测得转子轴的振动加速度,以此评估间隙消除对轴系振动的影响。[结果]结果显示:带有柔性密封结构的泵喷推进器,其转子的推力和扭矩显著提升,也使得转子敞水效率在中低进速系数下得到显著提升,且在设计点附近基本保持不变,在较高进速系数下略有下降;在设计点附近一段很宽的进速系数(0.85<J<1.40)下,无间隙泵喷推进器的空化性能更优;与有间隙泵喷推进器相比,装有无间隙泵喷推进器的轴系,其轴向振动加速度幅值在大多数特征频率处都显著降低。[结论]研究结果表明,采用柔性密封结构来抑制叶顶间隙流动,对于提高中低进速系数下的转子敞水效率、优化设计点处的空化性能以及抑制推进器的轴系振动等具有积极作用。

[Objective]This paper aims to suppress the adverse effects of tip clearance flow on the hydrodynamic performance and unsteady excitation force of a pump-jet propulsor.[Method]As for the pre-swirl stator pump-jet propulsor,an annular flexible seal structure closely matched with a rotor tip ring is used to study the validity of suppressing the clearance flow on the rotor tip.The rotor thrust and torque of the propulsor are measured by keeping the shroud approximately rigidly fixed,enabling the rotor open water efficiency to be obtained.In addition,the point of cavitation inception at each design condition is observed and recorded carefully with the help of a high-power stroboscope,and the cavitation inception curves of the propulsor with/without tip clearance are obtained through calculation.Finally,tests of shaft vibration acceleration on the pump-jet propulsor with/without tip clearance are conducted under conditions of cavitation and non-cavitation in order to evaluate the effects of diminishing tip clearance.[Results]The results show that the thrust and torque of the rotor of the pump-jet propulsor with a flexible seal structure are significantly increased,which in turn renders open water efficiency significantly increased at low and medium advance coefficients,unchanged near the design point and slightly decreased at the high advance coefficient.Moreover,the cavitation performance of the pump-jet propulsor without clearance is better at a wide range of advance coefficient,0.85<J<1.40,near the design point.In addition,compared with a pump-jet propulsor with clearance,the amplitude of axial vibration acceleration of the shaft equipped with a pump-jet propulsor without tip clearance is significantly reduced at most characteristic frequencies.[Conclusion]The results of this study demonstrate that using a flexible seal structure to suppress tip clearance flow has a positive effect on improving open water efficiency at low and medium advance coefficients,optimizing cavitation performance at the design point and suppressing the shafting vibration of the propulsor.