基于孔板及射流的水力空化数值模拟及实验研究

发布时间：2018-01-09 08:21

本文关键词：基于孔板及射流的水力空化数值模拟及实验研究　出处：《中北大学》2017年硕士论文　论文类型：学位论文

【摘要】：空化是很有应用价值的新型水污染治理工艺,跟别的废水处理方式作对比,其在能效方面具有一定的优势。但目前该技术尚处于基础研究阶段,规模化市场应用尚需解决一些关键问题。本文主要目的是通过CFD软件FLUENT来探索空化强化效应的机理和效果,找出作用于空化强化效应的本质规律,并以此优化空化器的结构,提高空化效率。其中空化发生器是影响水污染治理结果的关键部分。通过比较多种水力空化发生器,从而得到空化器的最优参数,设计出新型的文丘里管和孔板组合的组合空化器。本论文主要研究成果如下:(1)通过与实验结果的比较,在FLUENT中,采用标准k-?模型和空化泡动力学模型对孔板与文丘里管组合的复合空化器作出的模拟成果与实验基本吻合,说明了本论文模型选取的合理及算法的普用性。(2)当出口压力不变时,进口压力在0.4MPa以下,提高压力,空化强度随之增大,在0.4MPa时达到最佳效果;当进口压力大于0.4MPa时,升高进口压力反而会降低空化效应。(3)温度也是影响空化效应的一个重要因素,通过模拟与实验的对比,得出在20℃~40℃时,提高温度,空化强度逐渐增大,在40℃时空化效果较好;大于40℃时,随着温度上升,空化效应随之降低。(4)模拟结果表明,流体的粘性会束缚空化效应,加大流体的粘性,空化效应越弱。随着表面张力的增大,汽含率变化不大,表明表面张力对空化效应的作用很小,可以忽略。对最初气含量的模拟表明,当流体中最初气含量增加到千分位时(本文是到0.005),空化效应随之增强;继续增加最初气含量,空化效应则会随之减小。(5)不同孔板的结构对复合空化器的空化效应有着关键的作用。通过模拟计算得出22孔环状排布的孔板跟文丘里管组合的空化器空化效应较好,实验结果也表明该孔板与文丘里管组合对苯酚的降解率最高,达到21.05%,跟实验结果一致。
[Abstract]:Cavitation is a new type of water pollution treatment technology has good application value, compared with other wastewater treatment methods, has certain advantages in terms of energy. But the technology is still in the stage of basic research, the scale of market applications still need to solve some key problems. The main objective of this paper is to explore the mechanism and effect of cavitation effect through the CFD software FLUENT, to find out the effect on the nature of the cavitation effect, and to optimize the structure of cavitation, cavitation improve efficiency. The cavitation generator is a key part of the governance effects of the water pollution. Through comparing the hydrodynamic cavitation generator, in order to get the optimal parameters of cavitation, cavitation model combination design of Venturi pipe and orifice plate combination. The main results are as follows: (1) by comparing with the experimental results, in FLUENT, the standard k- model and cavitation bubble dynamic? The simulation results and the experimental composite cavitation mechanics model of pipe combination of orifice plate and Venturi made the basic agreement, the reasonable selection algorithm and model of this paper in general use. (2) when the outlet pressure is constant, the inlet pressure increases the pressure below 0.4MPa, the cavitation intensity increases, to achieve the best effect in the 0.4MPa; when the inlet pressure is greater than 0.4MPa, increasing the inlet pressure will reduce the cavitation effect. (3) the temperature is also an important factor affecting cavitation effect, through the comparison of the simulation and experiment, obtained at 20 DEG ~40 DEG, high temperature, cavitation intensity increases gradually, 40 degrees in the space-time effect good; more than 40 degrees, with the temperature rise, the cavitation effect decreases. (4) the simulation results show that the viscosity of the fluids will bind the cavitation effect, increase the viscosity of fluid, cavitation is weak. With the increase of surface tension, vapor fraction did not change And that is very small, the effect of surface tension on the cavitation effect can be neglected. Simulation of the initial gas content showed that when the initial gas content in the fluid increased to 1000 position (this is 0.005), cavitation effect is enhanced; continue to increase the initial gas content, the cavitation effect will decrease (5). Play a key role in cavitation structure of different orifice plate of composite cavitators. Results calculated by the simulation of 22 hole ring shaped arrangement of the orifice pipe combined with Venturi cavitation effect, the experimental results also show that the orifice plate and the Venturi tube combined degradation rate of phenol reached 21.05%, with the highest. The results are consistent.

【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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