灌水器流道结构优化数值分析

Numerical Analysis on the Optimization of the Emitter's Flow Channel Structure

采用Micro-PIV测量技术和realizable k-ε湍流方程配合多孔介质模拟壁面粗糙元的微尺度流动数值模拟方法对齿形流道的灌水器内流流场分布情况进行试验测量和模拟计算,发现在流道齿尖区域大范围存在低速回流区,仔细分析发现该三角区内有上下叠加的涡旋出现,通过湍流强度分析,流动滞止区主要表现在叠加小涡处。依此对齿形流道提出斜削齿尖和圆弧削尖2种优化流道的改造方案,并对改造后的流道数值建模及模拟计算。计算结果在流场分布、压力降变化、水力性能指标3方面的对比分析中显示,圆弧削尖的流道改造效果均优于另两种流道,流动特性得到了较大改善,在防堵和稳定出流方面更具优势。

The flow field distribution within the emitter of tooth channel is tested and calculated with simulation method by adopting Micro-PIV, realizable k-e turbulence equation and numerical simulation method, in which the porous medium is used to simulate the wall roughness elements in the micro-flow. It is found that the low speed recirculation zones mostly exist in the tooth point area, and superimposed vortex appears in the triangle area. It is also proved that the stagnant flow region mainly exists in the superimposed vortex area through the analysis on turbulence scale. Accordingly, two modification schemas are put forward, namely cutting the tooth on the slant or cutting it in arc shape. The modified flow channel is modeled with modeling simulation. According to the results and comparison on flowfield distribution, change of pressure drop and hydraulic performance, it is proved that the modified flow channel with arc shaped teeth is better than the other two ones, with which the flow characteristics is improved and has better per- formance of anti- blocka^e and stability.