径向剖分双吸式工业液力透平的内部流动损失特性分析

Flow loss characteristics of radial split double-suction pump as turbines

针对双吸式离心泵反转作液力透平运行区间狭窄、效率低等问题,对实际工程应用中的一台径向剖分双吸式离心泵反转作工业液力透平的内部流动损失特性进行了研究。首先,采用了数值模拟方法预测了液力透平在泵和透平典型工况下的水力性能,对比了透平在泵工况下的实验结果,验证了数值模拟的准确性和可靠性;然后,结合熵产理论,定量分析了透平工况下各过流部件对于总能量损失的权重以及熵产成分比重的分布情况;最后,结合局部流动特征进一步揭示了主要过流部件内流动损失的发生位置和产生原因。研究结果表明:壁面熵产是导致径向剖分双吸式工业液力透平内部流动损失的主要原因,在0.8Q_(b)、Q_(b)、1.2Q_(b)工况下,壁面熵产分别占总熵产的55.3%、69%、67.4%;导出室是透平内熵产占比最大的水力部件,局部回流、流动冲击等不良流动特征是导致湍流熵产增加的主要原因。该研究结果对离心泵反转作工业液力透平的优化设计、运行调控和推广应用有一定的借鉴意义。

The double-suction centrifugal pump has the disadvantage of a narrow operating range and low efficiency under the pump as turbines(PATs) operation conditions.The flow loss characteristics of radial split double-suction PATs was investigated in this manuscript based on the background of practical engineering applications.Firstly,the hydraulic performance of pump and turbine in typical operation conditions of PATs was predicted by the numerical simulation method.The accuracy and reliability of the numerical simulation method applied was verified by comparing the experiment results under the pump condition.Then,the entropy generation theory was adopted to obtain the quantitative analysis of the weight of the various flow components for the loss of the PATs system and the proportional distribution of the fluid components.Finally,the internal fluid characteristics were analyzed under the typical operation conditions to reveal the location and cause of fluid loss in the main flow components.The research results illustrate that the wall entropy production is the main cause of internal flow loss in radial split double-suction PATs.Under the operating conditions of 0.8Q_b,Q_b,and 1.2Q_b,the wall entropy production respectively accounts for 55.3%,69%,and 67.4% of the total entropy production.The export chamber is the hydraulic component with the highest proportion of entropy production inside the PATs.The main reasons for the increase in turbulent entropy production are adverse flow characteristics such as local backflow and flow shock.The research results have certain reference significance for optimizing design,regulating operation,and promoting industrial hydraulic turbines.