新型文丘里空化器及其空化特性的数值模拟

Numerical simulation study on the cavitation flow field characteristics of novel Venturi tube

近年来水力空化技术在降解废水领域快速发展,为提高空化降解效率,本文提出一种基于窄缝型文丘里管的新型空化发生器,其主要特征是在喉部固定了分流部件,以达到增加剪切面积、提升空化汽泡产率的目的。为探究新型空化器的空化流场特性,本文基于稳态RANS方法在均匀多相流模型和Schnerr-Sauer空化模型条件下对其进行数值模拟。围绕入口压力、扩张角度和喉部几何结构的特征尺寸对空化体积的影响规律展开对比分析。定义喉部特征长度L与喉道总长L_(th)的比值γ作为控制参数。数值模拟结果显示:空化数小于0.45时,γ值对空化体积影响较为显著,空化程度随入口压力增大而增强,随扩张角度增大而减弱;当入口压力为0.6 MPa(空化数C_(v)=0.22)、扩张角度为10°、γ为0.67时,空化体积达到最大值。

In view of the rapid development of hydraulic cavitation technology in the field of wastewater degradation in recent years,in order to improve the efficiency of cavitation degradation,a novel cavitation reactor based on slit Venturi tube was proposed.Its main feature is the fixation of the shunt part to increase the shear area and improve the yield of cavitation bubbles.In order to explore the characteristics of the cavitating flow field of this type of cavitating devices,the numerical simulation was carried out under the conditions of uniform multiphase flow model and Schnerr-Sauer cavitation model based on CFD method,focusing on the influence of inlet pressure,expansion angle and the characteristic size of throat geometry on the cavitation volume.The ratio of characteristic length(L)of throat to total length(L_(th))of throat was defined as the control parameter(γ).The numerical simulation results show that the value ofγhas a significant influence on the cavitation volume.The degree of cavitation increases with the increase of inlet pressure and decreases with the increase of expansion angle.Cavitation volume reaches maximum when the inlet pressure is 0.6 MPa(the cavitation number C_(v)=0.22),the expansion angle is 10°andγis 0.67.