摘要
为了有效减少氧化沟内污泥沉积,了解其流场特性,对微孔曝气氧化沟进行模拟,模拟中引入群平衡模型(PBM),并验证了PBM模型应用在微孔曝气领域的可行性,在此基础上,建立CFD-PBM气液两相流模型,对微孔曝气氧化沟工艺的气液两相流进行Fluent模拟分析,考察了氧化沟内流速、气含率等流体力学行为.结果表明:耦合模型所得的流速值大于传统模拟结果但更接近于实际流速,其平均相对偏差分别为±8.0%,±8.5%,且收敛稳定.由于将定义一组不同直径的气泡,且考虑到气泡的聚合破碎作用,对泥水混合情况的模拟更符合微孔曝气的特点.在此基础上,建立氧化沟模型进行模拟.结果显示,PBM模型可以考虑到气泡直径微小不一的特点和气泡上升过程的聚合破碎作用,流体混合效果明显,与推流器相结合,不易出现污泥淤积的现象,泥水能够充分混合.
In order to effectively reduce the sludge deposition in the oxidation ditch and understand its flow field characteristics,the oxidation ditch with microporous aeration was simulated. The population balance model（ PBM） was introduced and its feasibility to microporous aeration was verified. Further,the CFD-PBM model was established and the gas-liquid flow of oxidation ditch with microporous aeration was studied by using Fluent. Oxidation ditch flow velocity,gas holdup and other fluid mechanics behavior were examined. The results show that the velocity obtained by the coupled model is greater than that by the traditional model,but closer to the actual value. The average relative errors for two models are ± 8% and ± 8. 5%,respectively. The convergence of solution process of the coupled model is stable. Because a group of bubbles with different diameters has been defined,and the aggregation and fragmentation of bubbles have also been considered,the simulation of slurry mixing is more consistent with the characteristics of microporous aeration. Based on that,an oxidation ditch model isbuilt and simulated. The PBM model can take into account the characteristics of tiny bubble diameter,the aggregation and fragmentation effect in bubble rising process and generates a significant fluid mixing effect. Combined with the pusher,the sludge deposition is not easy to appear,and the muddy water can be thoroughly mixed.
作者
杨亚红
刘林刚
招扬
朱天旭
YANG Yahong,LIU Lingang,ZHAO Yang,ZHU Tianxu(School of Civil Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, Chin)
出处
《排灌机械工程学报》
EI
CSCD
北大核心
2018年第7期607-612,共6页
Journal of Drainage and Irrigation Machinery Engineering
基金
甘肃省科技计划资助项目
甘肃省自然科学基金A类资助项目(1506RJZA099
1506RJZA096)
关键词
氧化沟
微孔曝气
群平衡模型
数值模拟
气含率
oxidation ditch
fine bubble aeration
population balance model
numerical simulation
gas holdup
