Simulation and Prediction of the Evaporation Process of Ethanol Droplets Impacting High Temperature Wall
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摘要: 采用CLSVOF方法,引入描述壁面润湿特性的动态接触角,建立了乙醇液滴撞击高温壁面的数值模型,对乙醇液滴撞击高温壁面后的沸腾蒸发过程展开了研究,并与实验数据进行了对比验证. 研究表明:在相同液滴温度下,壁面温度越高,亲水性越强,乙醇液滴的撞击速度越快,液滴的沸腾时间越早,蒸发完成所用时间也越短. 在此研究基础上,基于机器学习算法,建立了液滴蒸发预测模型,对乙醇液滴撞击高温壁面后蒸发剩余量随时间的变化进行了预测研究,并通过将不同机器学习算法的预测结果与模拟结果对比,选出最优预测模型.Abstract: The coupled level set and volume of fluid (CLSVOF) method was used to establish a numerical model for ethanol droplets impacting high temperature wall through introduction of the dynamic contact angle to describe the wetting characteristics of the wall surface. The boiling and evaporation process of ethanol droplets impacting high temperature wall was studied and compared with the experimental data. The results show that, at a fixed droplet temperature, the higher the wall temperature is, the stronger the hydrophilicity will be, and the faster the impacting velocity of ethanol droplet is, the earlier the droplet will boil and the shorter the evaporation time will be. Based on this, a prediction model for droplet evaporation was established with the machine learning algorithm, to study the change of the evaporation residual with time after the ethanol droplet collision with the high temperature wall. The optimal prediction model was selected through comparison of the prediction results of different machine learning algorithms with the simulation results.
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表 1 乙醇液滴完全蒸发时间与实验结果误差对比
Table 1. Comparison of errors between complete evaporation time of ethanol droplets and experimental results
Tw/K experimental tmax/s simulated tmax/s relative error δ/% 360 5.58 5.19 -6.98 365 4.81 4.75 -1.24 370 4.29 4.49 4.66 378 3.31 3.21 -3.02 表 2 模拟工况相关参数
Table 2. The relevant parameters of the simulation condition
parameter name parameter value wall temperatureTw/K 370~420 contact angle θe/(°) 30~60 impact velocity uc/(m·s-1) 0.23~0.8 initial droplet temperature Td/K 293 表 3 预测结果与模拟结果的误差对比
Table 3. Error comparison between prediction results and simulation results
algorithm name mean absolute error mean squared error R2 SVR 0.067 5 0.005 7 0.943 6 RF 0.104 0 0.018 3 0.804 9 KNN 0.019 0 0.001 0 0.992 4 MLP 0.016 5 0.000 4 0.996 2 表 4 采用SSA优化后预测结果与模拟结果误差对比
Table 4. Error comparison between prediction results of the SSA optimization and simulation results
algorithm name mean absolute error mean squared error R2 SSA-KNN 0.015 8 0.000 39 0.995 7 SSA-MLP 0.015 4 0.000 29 0.997 0 -
[1] 金艳艳, 单彦广. 水-乙醇二元混合固着液滴的蒸发特性[J]. 化工学报, 2018, 69(7): 2908-2915. https://www.cnki.com.cn/Article/CJFDTOTAL-HGSZ201807012.htmJIN Yanyan, SHAN Yanguang. Evaporation characteristics of sessile ethanol-water mixture droplets[J]. CIESC Journal, 2018, 69(7): 2908-2915. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-HGSZ201807012.htm [2] 沈胜强, 张洁珊, 梁刚涛. 液滴撞击加热壁面传热实验研究[J]. 物理学报, 2015, 64(13): 270-276. https://www.cnki.com.cn/Article/CJFDTOTAL-WLXB201513035.htmSHEN Shengqiang, ZHANG Jieshan, LIANG Gangtao. Experimental study of heat transfer from droplet impact on a heated surface[J]. Acta Physica Sinica, 2015, 64(13): 270-276. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-WLXB201513035.htm [3] GUO Chunfang, SUN Yanjun, ZHAO Danyang. Experimental study of droplet impact on superheated cylindrical surfaces[J]. Experimental Thermal and Fluid Science, 2021, 121: 110263. doi: 10.1016/j.expthermflusci.2020.110263 [4] HE M, QIU H. Internal flow patterns of an evaporating multicomponent droplet on a flat surface[J]. International Journal of Thermal Sciences, 2016, 100: 10-19. doi: 10.1016/j.ijthermalsci.2015.09.006 [5] SUSMITA D, SURESH V G. Droplet evaporation on heated hydrophobic and superhydrophobic surfaces[J]. Physical Review E, 2014, 89(4): 042402. doi: 10.1103/PhysRevE.89.042402 [6] 梁佳, 高明, 陈露, 等. 基于格子Boltzmann方法的液滴撞击具有不同润湿性孔板的研究[J]. 应用数学和力学, 2022, 43(1): 63-76. doi: 10.21656/1000-0887.420076LIANG Jia, GAO Ming, CHEN Lu, et al. Study on droplets impacting on orifice plates with different wettabilities based on the lattice Boltzmann method[J]. Applied Mathematics and Mechanics, 2022, 43(1): 63-76. (in Chinese) doi: 10.21656/1000-0887.420076 [7] 吴苏晨, 张程宾, 陈永平, 等. 液滴撞击热壁面的相变行为研究[J]. 工程热物理学报, 2018, 39(8): 1814-1817. https://www.cnki.com.cn/Article/CJFDTOTAL-GCRB201808028.htmWU Suchen, ZHANG Chengbin, CHEN Yongping, et al. Phase change behavior of droplet impingement on a hot surface[J]. Journal of Engineering Thermophysics, 2018, 39(8): 1814-1817. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-GCRB201808028.htm [8] 董佰扬, 单彦广, 翁志浩. 基于动态接触角的固着液滴蒸发过程模拟[J]. 动力工程学报, 2020, 40(12): 1002-1007. https://www.cnki.com.cn/Article/CJFDTOTAL-DONG202012008.htmDONG Baiyang, SHAN Yanguang, WENG Zhihao. Simulation of sessile droplet evaporation based on dynamic contact angle[J]. Journal of Chinese Society of Power Engineering, 2020, 40(12): 1002-1007. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-DONG202012008.htm [9] SEMENOV S, STAROV V M, RUBIO R G. Evaporation of pinned sessile microdroplets of water on a highly heat-conductive substrate: computer simulations[J]. The European Physical Journal Special Topics, 2013, 219(1): 143-154. http://www.onacademic.com/detail/journal_1000035959681010_9ed0.html [10] 赵可, 佘阳梓, 蒋彦龙, 等. 液氮滴撞击壁面相变行为的数值研究[J]. 物理学报, 2019, 68(24): 201-215. https://www.cnki.com.cn/Article/CJFDTOTAL-WLXB201924020.htmZHAO Ke, SHE Yangzi, JIANG Yanlong, et al. Numerical study on phase change behavior of liquid nitrogen droplets impinging on solid surface[J]. Acta Physica Sinica, 2019, 68(24): 201-215. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-WLXB201924020.htm [11] LEE W H. A pressure iteration scheme for two-phase flow modeling[J]. Hemisphere Publishing, 1980, 79(9): 407-431. http://www.researchgate.net/publication/291211634_pressure_iteration_scheme_for_two-phase_flow_modeling [12] 李家宇, 曾忠, 乔龙. 相场方法模拟液滴的动态润湿行为[J]. 应用数学和力学, 2019, 40(9): 957-967. doi: 10.21656/1000-0887.400129LI Jiayu, ZENG Zhong, QIAO Long. Numerical simulation of droplets' dynamic wetting process with the phase field method[J]. Applied Mathematics and Mechanics, 2019, 40(9): 957-967. (in Chinese) doi: 10.21656/1000-0887.400129 [13] KISTLE S F. Hydrodynamics of wetting[M]//Wettability. 1st ed. Boca Raton: CRC Press, 1993: 311-340. [14] 张洁珊. 液滴撞击加热壁面流动与传热实验研究[D]. 硕士学位论文. 大连: 大连理工大学, 2015.ZHANG Jieshan. Experimental study of flow and heat transfer during droplet impact on heated surface[D]. Master Thesis. Dalian: Dalian University of Science and Technology, 2015. (in Chinese) [15] 王希志, 单彦广, 饶玲. 超疏水表面液滴蒸发内部流体流动与传热分析[J]. 化学工程, 2017, 45(10): 27-32. https://www.cnki.com.cn/Article/CJFDTOTAL-IMIY201710010.htmWANG Xizhi, SHAN Yanguang, RAO Ling. Analysis of internal fluid and heat transfer in droplet evaporating on superhydrophobic surface[J]. Chemical Engineering, 2017, 45(10): 27-32. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-IMIY201710010.htm [16] 谢驰宇, 张建影, 王沫然. 液滴在固体平表面上均匀蒸发过程的格子Boltzmann模拟[J]. 应用数学和力学, 2014, 35(3): 247-253. doi: 10.3879/j.issn.1000-0887.2014.03.002XIE Chiyu, ZHANG Jianying, WANG Moran. Lattice Boltzmann simulation of droplet evaporation on flat solid surface[J]. Applied Mathematics and Mechanics, 2014, 35(3): 247-253. (in Chinese) doi: 10.3879/j.issn.1000-0887.2014.03.002 [17] LINARDATOS P, PAPASTEFANOPOULOS V, KOTSIANTIS S. Explainable AI: a review of machine learning interpretability methods[J]. Entropy, 2020, 23(1): 18. http://www.xueshufan.com/publication/3116286104