摘要
采用离散单元法模拟新拌混凝土于搅拌机中的混合过程,研究了双筒螺带式混凝土搅拌机的混合效率。用Hertz-Mindlin with JKR接触方法建立新拌混凝土离散元模型,模拟了坍落度实验、L箱实验和流变仪实验,将模拟结果与实验结果进行对比,校准模型参数,采用混合系数定量研究了不同初始装填方式下搅拌机的混合效率。结果表明,采用上下装填方式时搅拌机混合效率较高;对任一初始装填方式,左部区域与右部区域、前部区域与后部区域间混合效率无明显差别,而上部区域混合效率比底部区域高,底部出料口处存在搅拌盲区,采用舍弃初始出料的方法可提高新拌混凝土性能。转速较高时混合效率较高,相同旋转圈数时,混合效率基本相同。
The ribbon concrete mixer with double barrels is commonly used to improve the uniformity of the fresh concrete in construction industry.In order to investigate the mixing efficiency of this kind of ribbon concrete mixer,a discrete element method was used to simulate the mixing process of fresh concrete.Firstly,a discrete element model of the fresh concrete was established by using the Hertz-Mindlin with JKR contact method.The experiment processes,i.e.slump test,L box test and rheometer testwere simulated by using this discrete element model and its parameters,and the simulation resultswerecompared with the experimental ones to verify these model parameters.Afterwards,the mixing efficienciesunder different initialloadings wereinvestigated and the mixing efficiency under top-bottom loading was highest.Under each initial loading,the mixing efficiency of the fresh concrete in mixer’s left region and front region was almost the same as that in their opposite regions respectively,while the mixing efficiency in the upper region was much higher than that in the lowerone.Besides,a mixing blind area was found near the outlet in the bottom of the mixer,and the method of discarding the initial concrete discharge was proposed to improve the uniformity of fresh concrete.In addition,the effects of rotational speed on the mixing efficiency were investigated,and it was found that the mixing efficiency with a larger rotational speed tended to be higher.However,their mixing efficiencieswerealmost the same at the same rotation number of impeller.This numerical model and results provided an effective approach to solve the concrete mixing problems in industry and some scientific references for improving the mixing efficiency of a double ribbon concrete mixer.
作者
廖泽楚
高伟
刘磊
姜胜强
谭援强
Zechu LIAO;Wei GAO;Lei LIU;Shengqiang JIANG;Yuanqiang TAN(School of Mechanical Engineering,Xiangtan University,Xiangtan,Hunan 411105,China;School of Electro-mechanical Engineering,Guangdong University of Technology,Guangzhou,Guangdong 510006,China;Shenzhen Invt Transportation System Company Limited,Shenzhen,Guangdong 518000,China;Institute of Manufacturing Engineering,Huaqiao University,Xiamen,Fujian 361021,China)
出处
《过程工程学报》
CAS
CSCD
北大核心
2019年第4期668-675,共8页
The Chinese Journal of Process Engineering
基金
国家自然科学基金项目(编号:51878184
51404209
51605409)
湖南省教育厅项目(编号:16B259)
