生物油雾化特性的数值研究
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摘要
基于两相界面追踪方法 VOF(volume of fluid)研究生物油在离心式喷嘴内的雾化特性,考察喷射流量对流量系数、雾化锥角和液膜厚度的影响,并与生物油/甲醇混合燃料的雾化特性进行对比。结果表明:喷射流量对雾化锥角及液膜厚度有较大影响,对流量系数影响较小。喷射流量从0.03 kg/s增至0.12 kg/s,流量系数增大3.4%,雾化锥角增大30.6%,而液膜厚度减小22.3%;雾化锥角随甲醇含量的增大呈线性递增,而液膜厚度随甲醇含量的增大呈线性递减;利用数值结果拟合得到生物油液膜厚度的经验公式,拟合值和数值计算值吻合较好。
The atomization characteristics of bio-oil in centrifugal nozzle for combustion were investigated by using the Ansys Fluent two-phase flow numerical method VOF model. The effect of jet flow rate on the flow coefficient,film thickness and atomization cone angle was investigated and compared with that of the bio-oil/methanol blended fuel. The results show that the jet flow rate has a great influence on the atomization cone angle and the film thickness,and has little effect on the flow coefficient. As the jet flow rate increased from 0.03 kg/s to 0.12 kg/s,the flow coefficient increased by 3.4%,the spray angle increased by 22.1%,and the film thickness decreased by 22.3%.By adding methanol to the bio-oil,the atomizing quality was improved. The cone angle of the atomization increases linearly with the increase of the methanol content,while the film thickness decreases linearly. The empirical equation for the film thickness was derived. The predicted results were found to be in a good agreement with the experiment results,which can predict the atomization characteristics of the nozzle.
The atomization characteristics of bio-oil in centrifugal nozzle for combustion were investigated by using the Ansys Fluent two-phase flow numerical method VOF model. The effect of jet flow rate on the flow coefficient,film thickness and atomization cone angle was investigated and compared with that of the bio-oil/methanol blended fuel. The results show that the jet flow rate has a great influence on the atomization cone angle and the film thickness,and has little effect on the flow coefficient. As the jet flow rate increased from 0.03 kg/s to 0.12 kg/s,the flow coefficient increased by 3.4%,the spray angle increased by 22.1%,and the film thickness decreased by 22.3%.By adding methanol to the bio-oil,the atomizing quality was improved. The cone angle of the atomization increases linearly with the increase of the methanol content,while the film thickness decreases linearly. The empirical equation for the film thickness was derived. The predicted results were found to be in a good agreement with the experiment results,which can predict the atomization characteristics of the nozzle.
引文
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[22]Rizk N K,Lefebvre A H. Internal flow characteristics of simplex swirl atomizers[J]. Journal of Propulsion and Power,1985,1(3):193—199.
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[2]Chiaramonti D, Oasmaa A, Solantausta Y. Power generation using fast pyrolysis liquids from biomass[J].Renewable and Sustainable Energy Reviews,2007,11(6):1056—1086.
[3]Czernik S,Bridgwater A. Overview of applications of biomass fast pyrolysis oil[J]. Energy&Fuels,2004,18(2):590—598.
[4]朱锡锋,陆强.生物质快速热解制备生物油[J].科技导报,2007,25(21):69—75.[4]Zhu Xifeng,Lu Qiang. Fast pyrolysis of biomass for producing bio-oil[J]. Science&Technology Review,2007,25(21):69—75.
[5]刘联胜,杨华,衡国辉,等.气液质量流量比对气泡雾化喷嘴燃烧特性的影响[J].燃烧科学与技术,2007,13(1):10—14.[5]Liu Liansheng, Yang Hua, Heng Guohui, et al.Influences of air/liquid mass flow rate on spray combustion produced by effervescent atomizer[J].Journal of Combustion Science and Technology,2007,13(1):10—14.
[6]杨华,杜聪,周晓芳,等.空气旋流强度对气泡雾化喷雾流场及火焰的影响[J].燃烧科学与技术,2008,14(6):523—528.[6]Yang Hua,Du Cong,Zhou Xiaofang,et al. Influences of air swirl intensity on the atomization and combustion performances of effervescent atomized spray[J]. Journal of Combustion Science and Technology,2008,14(6):523—528.
[7]刘庆磊.高粘生物质焦油进料喷嘴的数值模拟及实验研究[D].济南:山东大学,2013.[7]Liu Qinglei. Numerical simulation and experimental study of feed nozzle for high viscosity biomass tar[D].Jinan:Shandong University,2013.
[8]宋云超,宁智,刘耀东,等.氢气/柴油发动机NOx和微粒排放特性的数值模拟[J].内燃机学报,2011,29(6):495—503.[8]Song Yunchao, Ning Zhi, Liu Yaodong, et al.Numerical simulation of NOxand particulate emission characteristics of hydrogen/diesel engine[J]. Transactions of CSICE,2011,29(6):495—503.
[9]吴东垠,王武强,李明.柴油甲醇水三相乳化液雾化特性的数值模拟[J].吉首大学学报:自然科学版,2016,37(1):60—63.[9]Wu Dongyin,Wang Wuqiang,Li Ming. Characteristics analyses of kitchen waste leachate[J]. Journal of Jishou University:Natural Sciences Edition,2016,37(1):60—63.
[10]Dong Quan,Long Wuqiang,Ishima T,et al. Spray characteristics of V-type intersecting hole nozzles for diesel engines[J]. Fuel,2013,104:500—507.
[11]Burkert A,Paa W,Reimert M,et al. Formaldehyde LIF detection with background subtraction around single igniting GTL diesel droplets[J]. Fuel,2013,111:384—392.
[12]Kiuchi M,Fujisawa N,Tomimatsu S. Performance of a PIV system for a combusting flow and its application to a spray combustor model[J]. Journal of Visualization,2005,8(3):269—276.
[13]姜磊,葛蕴珊,何超.生物柴油喷雾特性的数值模拟[J].内燃机工程,2009,30(5):17—21.[13]Jiang Lei,Ge Yunshan,He Chao. Numerical simulation on spray characteristics of bio-diesel fuel[J]. Chinese Internal Combustion Engine Engineering,2009,30(5):17—21.
[14]刘娟,李清廉,王振国,等.基于VOF方法模拟离心式喷嘴内部流动过程[J].航空动力学报,2011,26(9):1986—1994.[14]Liu Juan,Li Qinglian,Wang Zhenguo,et al. Numerical simulation of flow field in pressure-swirl injector based on VOF interface tracking method[J]. Journal of Aerospace Power,2011,26(9):1986—1994.
[15]Elbadawy I,Gaskell P H,Lawes M,et al. Numerical investigation of the effect of ambient turbulence on pressure swirl spray characteristics[J]. International Journal of Multiphase Flow,2015,77:271—284.
[16]Hutt J, Mcdaniels D, Smith A. Internal flow environment of swirl injectors[A]. 1994 30 th AIAA/ASME/SAE/ASEE Joint Propulsion Conference[C],Indianapolis,1994.
[17]龙潭,马善为,丁浩植,等.基于Matlab的生物油雾化特性的实验研究[J].太阳能学报,2016,37(4):963—967.[17]Long Tan,Ma Shanwei,Ding Haozhi,et al. Study of spray characteristics of bio oil by using Matlab[J]. Acta Energiae Solaris Sinica,2016,37(4):963—967.
[18]Halder M R,Dash S K,Som S K. A numerical and experimental investigation on the coefficients of discharge and the spray cone angle of a solid cone swirl nozzle[J]. Experimental Thermal and Fluid Science,2004,28(4):297—305.
[19]郭涛.生物油燃烧的试验研究和数值模拟[D].合肥:中国科学技术大学,2007.[19]Guo Tao. Experimental research and numerical simulation of biological oil burning[D]. Hefei:University of Science and Technology of China,2007.
[20]Nouri-Borujerdi A,Kebriaee A. Numerical simulation of laminar and turbulent two-phase flow in pressure-swirl atomizers[J]. Aiaa Journal,2012,50(10):2091—2101.
[21]Datta A,Som S K. Numerical prediction of air corediameter,coefficient of discharge and spray cone angle of a swirl spray pressure nozzle[J]. International Journal of Heat and Fluid Flow,2000,21(4):412—419.
[22]Rizk N K,Lefebvre A H. Internal flow characteristics of simplex swirl atomizers[J]. Journal of Propulsion and Power,1985,1(3):193—199.
[23]王国辉,蔡体敏,何国强,等.一种旋流式喷嘴的实验和数值研究[J].推进技术,2003,24(1):28—32.[23]Wang Guohui,Cai Timin,He Guoqiang,et al. An experimental and numerical study swirl nozzle[J].Journal of Propulsion Technology,2003,24(1):28—32.