高压大流量来流对泵作透平启动过程非定常流动特性的影响

In some industries such as petrochemical, oil refining, and seawater desalination, a large number of fluid with high pressure is reduced to the low pressure through the relief valve or is directly discharged. If so, that will cause a huge waste of energy. Using existing inverted centrifugal pump as a hydraulic turbine is a very important method to realize the recycling of the liquid’s high pressure. However, in the process of suddenly starting, the response of the nonlinear system under mutational working conditions usually becomes uncontrollable. The root reason for this is the unsteady flow inside the pump as turbine. However, the relevant researches are inadequate both at home and abroad. Some key scientific problems have not been effectively solved, such as the suitable turbulent mathematical model that is able to accurately calculate the unsteady flow, the influence mechanism of the internal flow on the external performance, etc..In this project, theoretical analysis, numerical simulation, the internal and external characteristic experiments would be employed to deeply and systematically study the starting process of pump as turbine. The large eddy simulation method for weak compressible fluid would be established according to the dynamic subgrid stress model with the Helicity constraints. The effect of the coming flow parameters such as pressure and flowrate magnitude and the key geometric parameters on transient hydraulic performance would be obtained. Combining the results of the internal flow field characteristics and external hydraulic performance, the internal relationship between them could be established. Meanwhile, the lower limit values of the pressure and flowrate magnitude that could accomplish the starting process could be determined. As such, the capturing energy mechanism of pump as turbine during startup period would better revealed, which provides the theoretical support for the safe startup of pump as turbine.

在石油化工、炼油、海水淡化等行业中存在大量高压流体通过减压阀减至低压或者直接排放的现象，若不进行回收利用将造成极大的能源浪费。利用现有离心泵反转作为液力透平是实现液体压力能回收利用十分重要的手段。但是在突然启动过程中，非线性系统在突变条件下的响应变得不可控。根本原因是内部的非定常流动所致。但目前国内外研究不够充分，适合非定常流动精确数值计算的湍流数学模型、内部流动对外特性的影响机制等关键科学问题未能有效解决。.本项目拟从理论推导、数值模拟、内外特性实验三方面对泵作透平启动过程进行系统深入的研究。建立带螺旋度约束动态亚格子模式的弱可压流动大涡模拟方法，明确压力和流量来流特征参数、过流部件关键几何参数对其瞬态水力性能的影响规律，建立内部流动特征与瞬态性能参数之间的内在关联，确定来流压力和流量完成泵作透平启动过程的下限值，揭示泵作透平启动过程的获能机理，为泵作透平安全运行提供理论支撑。

在石油化工、炼油、海水淡化等行业中存在大量高压流体通过减压阀减至低压或者直接排放的现象，若不进行回收利用将造成极大的能源浪费。利用现有离心泵反转作为液力透平是实现液体压力能回收利用十分重要的手段。但是在突然启动过程中，非线性系统在突变条件下的响应变得不可控。根本原因是内部的非定常流动所致。本项目旨在系统掌握泵作透平在启动过程中的瞬态特性。理论推导了确定离心泵最优叶片数的两种理论计算方法，设计了多个具有不同叶轮几何特征的常规闭式叶轮和复合叶轮离心泵并进行了性能实验。实验研究了根据最优叶片数方法设计的原型离心泵的启动特性，对其在不同启动加速度和不同阀门开度情形下的启动过程进行了瞬态水力性能试验。建立了适用于非稳定工况情形的泵作透平广义欧拉方程式，据此计算出在非典型性启动过程中的附加理论扬程。系统实验研究了泵作透平非典型性启动过程中稳定转速和阀门开度对瞬态水力性能和特性的影响。系统研究了泵作透平循环管路系统不同启动加速情形下的内部三维粘性非定常流动特性。在泵作透平非典型性启动过程中，叶轮加速导致理论扬程减小，流量增加导致理论扬程减小。旋转加速扬程与流动惯性扬程均呈现先上升后下降的演化趋势。与旋转加速扬程相比，流体惯性扬程较小。非典型性启动过程中的无量纲扬程系数和无量纲流量系数与转速和流量有关，而无量纲功率与转速和流量基本无关。泵作透平通过的流量与出口静压曲线到达稳定值的时间相对于转速均具有滞后性；泵作透平流域内熵产与涡量主要分布在叶片之间。泵的相似定律并不适用于在泵作透平瞬时启动过程中的性能预测。掌握了泵作透平在能量回收启动过程中的瞬态特性，为泵作透平安全运行提供理论支撑。. 通过研究共发表论文20篇，其中SCI检索论文16篇，EI检索论文2篇，其他论文2篇。出版学术专著1部，授权发明专利2件。培养毕业硕士研究生2名，晋升正高职称1人，副高职称3名。