后置灯泡贯流装置灯泡体形式的数值模拟

Numerical simulation of optimal bulb of tubular pump

为了深入研究灯泡体形式对装置流动特性及水力性能的影响,采用RNGk-ε紊流模型和SIMPLEC算法,基于多旋转坐标系模型,计算了总长均为10.72D(D为叶轮直径)的传统筒形灯泡体和纺锥细长形灯泡体两种典型形式的后置贯流泵定常流动,获得了整体流场结果.分析了不同灯泡体对泵装置整体流动的影响,灯泡体段设计不当将引起局部脱流和漩涡区,从而影响整体水力性能.分析了两种灯泡体贯流泵装置方案的叶片表面静压分布,显示出两个方案在最优工况、大流量工况和小流量工况下的叶片压力分布相似,这表明出水灯泡体形式不影响叶片工作状态.计算表明,纺锥细长形灯泡体水力损失最小值出现在约1.12QBEP(QBEP为设计点流量)处,而圆筒形灯泡体水力损失最小值出现在约1.06QBEP处,且出水灯泡体的水力损失与流量的关系不满足传统管道内水力损失与流量成二次方比例关系的规律,而表现为与泵装置运行工况相关的特性.因此,纺锥细长形灯泡体结构泵装置形式在南水北调东线工程中有一定的应用前景.

The flow patterns and hydraulic performances of two different bulbs of pump system, i. e. normal type and slin type, were studied. Based on the RNG k -ε model, the SIMPLEC algorithm was applied to the solution of the discretization governing equation. Using multiple reference frames, the flow details of whole pumping systems whose length was of 10.72 D, where D was of the impeller diameter, were obtained. The influences of the flow of pump system on difference bulbs were analyzed. The unsuitable design of bulbs caused flow separation and vortex. The calculation resuhs illustrate that the statie pressure contours of two pumping systems which were operated at design flowrate, large f]owrate and small flowrate, were shnilar, and therefore the shape of bulb does not hnpaet on the operation status of impllers. The resuhs showed that the flowrate of minimum loss for slin taper bulb is of 112 percent of design flowrate, while that tot normal bulb is of 106 percent of design flowrate. It is not quadratic function between flowrate and hydraulic loss, and the loss is somewhat related with the operating region. 3D numervical eomputation and model lest showed that the perrformance of slin taper bulb was better than that of normal one, and consequently this type of pump system can be applied in the East Route Project of South - to - North Water Transters.