液氧涡轮泵新型螺旋阻尼密封泄漏特性研究

Investigation on the Leakage Characteristics of a Novel Helical Damper Seal for the Liquid Oxygen Turbopump

针对某液氧涡轮泵离心轮前凸肩密封,提出了一种新型螺旋阻尼密封结构(静子面孔腔和转子面螺旋槽)。为研究离心轮凸肩密封进口高预旋影响,提出了能够同时模拟动密封进口压力场和速度场的“双进口边界”数值模型。采用液体(水工质)孔型阻尼密封和螺旋密封的泄漏量实验结果,验证了基于三维定常Navier-Stokes(RANS)方程的动密封稳态泄漏流动数值预测方法的有效性和准确性。对比研究了迷宫密封、孔型阻尼密封、双螺旋密封等3种传统动密封结构和新型螺旋阻尼密封在某液氧涡轮泵6种变负载运行工况(负载率φ为23%、31%、54%、77%、100%、108%)、2种进口预旋比(λ为0、0.75)下的泄漏特性。结果表明:相比于3种传统动密封结构,新型螺旋阻尼密封在全工况下均具有最佳的封严性能(泄漏量减小10%~50%),尤其在高负载工况(更高转速、更大压差);新型螺旋阻尼密封的泄漏量对进口预旋、压差和转速等运行条件的变化敏感性最低(在23%~108%变载荷运行、无预旋时,新型螺旋阻尼密封的泄漏变化量相对于迷宫、孔型和双螺旋密封减小了45%、40%、29%),具有优良的变工况适应能力,能够满足液氧涡轮泵深度变推力的工作需求,是一种理想的液氧涡轮泵离心轮凸肩密封结构。

For the liquid oxygen turbopump with a front shoulder seal,a novel helical damper seal with cavities on the stator side and helical grooves on the rotor side is proposed.To study the influence of high inlet preswirl on the impeller shoulder seal performance,a“double inlet boundary”numerical model is proposed to simulate the pressure field and the velocity field at the rotating seal inlet.The reliability and accuracy of the present steady-state numerical method based on three-dimensional steady Navier-Stokes(RANS)equations are demonstrated for the prediction of the leakage flow in rotating seals,using the experiment data of an experimental hole-pattern damper seal and an experimental helical-groove seal with liquid(water)working fluid.The leakage characteristics of four types of rotating seals are investigated and compared,including the labyrinth seal,the hole-pattern damper seal,the double helical-groove seal and the novel helical damper seal,under six variable load conditions(load rate φ=23%,31%,54%,77%,100%,108%)and two inlet pre-swirl ratios(λ=0,0.75).The results are as follows:compared with the three traditional rotating seals,the present novel helical damper seal possesses the best sealing performance(a reduction in leakage by 10%-50%)under all working conditions,especially under high load rates(higher rotational speed and larger pressure difference).Moreover,the novel helical damper seal is least sensitive to the change of operating conditions including the inlet preswirl,the pressure difference and the rotational speed.Compared with the labyrinth seal,the hole-pattern seal and the double-helical-groove seal,the novel helical damper seal realizes leakage reduction by 45%,40% and 29%,respectively under variable loads from 23% to 108% without preswirl,showing the best adaptability to variable working conditions.Therefore,the novel helical damper seal is a desirable impeller shoulder seal for the liquid oxygen turbopump to allow the deep variable thrust operation of engine.