射流式离心泵非设计工况下内部流动研究

Internal Flow of Flow-ejecting Centrifugal Pump under Off-design Conditions

为了研究射流式离心泵在非设计工况下的内部流动特性,选取JETST-100型射流式离心泵作为研究对象,运用CFX软件提供的RNG k-ε湍流模型,对模型泵内部流动情况进行了三维非定常数值模拟,得到各过流部件内部的速度场和压力场分布等流动信息,比较了在不同运行流量下,射流器进口和喉管处质量流量的变化情况,并将模拟结果与试验进行对比。结果表明:射流器内部压力最高区域在喷嘴进口处,低压区域在喉管附近,喷嘴附近速度最大,抽送液体的进流口速度最小;叶轮中流出的液体大部分回流至射流器进口,随着泵运行流量的减小,回流所占射流器喉管处质量流的比例增加;对叶轮内的流动分析显示,叶片吸力面的速度普遍高于压力面的速度,进一步影响了该型泵的运行效率。

In order ejecting centrifugal to study the internal flow characteristics in the flow passage components of flow- pump under off-design conditions, the type JETST - 100 self-priming pump was selected. It consists of seven parts ： the inlet pipeline, jet aerator, wear ring, elbow, impeller, outlet pipeline and pump chamber. The transient numerical simulation for internal flow situation of computational model was carried out based on RNG k-6 turbulence model by using CFX software. The flowing information of velocity and pressure in flow passage components of centrifugal pump were obtained. Comparison of flow change between inlet and throat of jet aerator under different operating conditions was performed and the simulation results were compared with the test results. The results showed that the highest pressure area of jet aerator was located at the inlet of nozzle, low pressure area was located at the vicinity of throat, and the maximum velocity occurred at the area of the vicinity of nozzle, the minimum velocity generated at the inflow part of suction liquid. With the flow rate decreased, mass flow rate of reverse flow in throat of jet aerator was increased ; effluent liquid from the impeller was mostly reversed to the inlet of jet aerator. The flowing analysis of impeller showed that the blade suction surface velocity was generally higher than the blade pressure surface velocity, which further affected the operating efficiency of the pump. The study results will supply a theoretical reference for hydraulic optimization .design of the internal flow status of flow-ejecting centrifugal pump under off-design conditions.