Study of splash characteristics and spreading mechanism of liquid droplets impacting walls at low temperature
-
摘要: 液滴撞击低温壁面现象是导致飞机机翼结冰、电线覆冰和内燃机冷起动恶化的关键因素之一，其中液滴飞溅和铺展特性是造成上述问题的主要原因。因此，本文运用高速摄影法对正十二烷液滴撞击不同温度铝板的飞溅及铺展特性进行系统的试验研究。结果表明：随着壁面温度降低（20 ℃～−40 ℃），液滴破碎阈值明显降低，二次液滴直径与数量显著增大，附壁液膜铺展速度和最大铺展距离显著减小。本研究针对低温壁面附壁液膜快速铺展阶段的运动学特征，考虑了壁面温度对粘性力的影响，构建了新的无量纲铺展系数βT = (D/D0)/ReT0.07，建立了新的铺展模型βT = 1.76τ0.5。该模型不仅实现了对于不同入射条件下的液膜铺展过程的准确描述，还将适用范围由传统铺展模型的0.1 ≤ τ ≤ 1.0拓宽至0.1 ≤ τ ≤ 1.5，从而能够准确描述更长时间内液膜铺展规律变化。Abstract: The phenomenon of droplets impacting on the cold wall is one of the key factors leading to the deterioration of aircraft wing icing, wire icing and cold start of internal combustion engine. Droplet splashing and spreading characteristics are the main causes of the above problems. High-speed photography was used to study the splashing and spreading characteristics of n-dodecane droplets striking aluminium plates at different temperatures. The results show that as the wall temperature decreased (20 ℃ to −40 ℃) the droplet fragmentation threshold is significantly reduced, the secondary droplet diameter and number increase significantly, and the spreading speed and maximum spreading distance of the attached liquid film decrease significantly. In this study, a new dimensionless spreading coefficient (βT = (D/D0)/ReT0.07) and a new spreading model (βT = 1.76τ0.5) were constructed for the kinematic characteristics of the fast spreading phase of the liquid film attached to the low temperature wall, considering the effect of wall temperature on the viscous forces. The spreading model not only enables an accurate description of the liquid film spreading process under different insertion conditions and wall temperatures, but also widens the range of application of the model from 0.1 ≤ τ ≤ 1.0 to 0.1 ≤ τ ≤ 1.5, allowing the resulting low temperature spreading model to accurately describe changes in the spreading pattern of the liquid film over a longer period of time.
-
Key words:
- droplet impact wall /
- breaking process /
- spreading model /
- high-speed photography
-
图 2 液滴以3.5 m/s的入射速度撞击−10 ℃低温壁面飞溅到铺展过程
Figure 2. The droplet splashing onto the low-temperature wall at −10 ℃ at the incident velocity of 3.5 m/s
图 3 液滴以2.3 m/s撞击速度撞击不同温度壁面下液滴破碎现象
Figure 3. The droplet breaking phenomenon under the impact velocity of 2.3 m/s on the wall surface at different temperatures
图 4 不同温度壁面二次液滴特征
Figure 4. Secondary droplet characteristics on walls at different temperatures
图 9 液膜铺展因子随入射速度变化趋势
Figure 9. Trend of liquid film spreading factor with incident velocity
图 10 不同撞击条件下液滴的铺展过程
Figure 10. Droplet spreading processes under different impact conditions
图 12 不同
$ \alpha $ 取值下铺展因子的归一化比较Figure 12. Normalized comparison of spreading factors for different values of
$ \alpha $ 
图 13 不同
$ \alpha $ 取值下铺展因子离散系数Figure 13. The spread factor corresponds to the normalization coefficient under different
$ \alpha $ values
图 14 新铺展因子液膜在不同撞击条件下的归一化效果
Figure 14. Normalization-effect of new spreading factor liquid films under different impact conditions
图 15 液膜最大铺展直径随壁面温度的变化
Figure 15. Variation of the maximum spreading diameter of the liquid film with wall temperature
图 16 不同撞壁条件下的液膜最大铺展系数变化
Figure 16. Variation of the maximum spreading coefficient of the liquid film under different wall impact conditions
表 1 壁面参数（20 ℃）
Table 1. Parameters of the impact surfaces at 20 ℃
表面材料 材质 表面粗糙Ra/（μm） 导热系数λ（W/mK） 铝合金板 1050 ＜0.025 224 
下载: 导出CSV
-
[1] CAO Y H, TAN W Y, WU Z L. Aircraft icing: an ongoing threat to aviation safety[J]. Aerospace Science and Technology, 2018, 75: 353–385. doi: 10.1016/j.ast.2017.12.028 [2] 苑吉河, 蒋兴良, 易辉, 等. 输电线路导线覆冰的国内外研究现状[J]. 高电压技术, 2004, 30(1): 6–9. doi: 10.3969/j.issn.1003-6520.2004.01.003YUAN J H, JIANG X L, YI H, et al. The present study on conductor icing of transmission lines[J]. High Voltage Engineering, 2004, 30(1): 6–9. doi: 10.3969/j.issn.1003-6520.2004.01.003 [3] YIN M, XU L J, DAI Y, et al. Flow characteristics of oil-guiding splash lubrication: simulation and experiment studies[J]. International Journal of Simulation Modelling, 2021, 20(2): 363–374. doi: 10.2507/ijsimm20-2-co6 [4] ARUMUGAM R, XU H M, LIU D, et al. Key factors affecting the cold start of diesel engines[J]. International Journal of Green Energy, 2015: 1–56. doi: 10.1080/15435075.2014.938748 [5] SHI Z C, LEE C F, WU H, et al. Effect of injection pressure on the impinging spray and ignition characteristics of the heavy-duty diesel engine under low-temperature conditions[J]. Applied Energy, 2020, 262: 114552. doi: 10.1016/j.apenergy.2020.114552 [6] LIU H Q, HENEIN N A, BRYZIK W. Simulation of diesel engines cold-start[C]//Proc of the SAE Technical Paper Series, 400 Commonwealth Drive. 2003. doi: 10.4271/2003-01-0080 [7] MA T Y, ZHANG F, LIU H F, et al. Modeling of droplet/wall interaction based on SPH method[J]. International Journal of Heat and Mass Transfer, 2017, 105: 296–304. doi: 10.1016/j.ijheatmasstransfer.2016.09.103 [8] CHEN B L, FENG L, WANG Y, et al. Spray and flame characteristics of wall-impinging diesel fuel spray at different wall temperatures and ambient pressures in a constant volume combustion vessel[J]. Fuel, 2019, 235: 416–425. doi: 10.1016/j.fuel.2018.07.154 [9] KEI F. Effect of impact velocity on time-dependent force and droplet pressure in high-speed liquid droplet impingement[J]. Annals of Nuclear Energy, 2022, 166: 108814. doi: 10.1016/j.anucene.2021.108814 [10] 戴宇晴, 叶学民, 李春曦. 电场作用下表面张力对液滴运动特征的影响[J]. 电力科学与工程, 2016, 32(11): 66–73. doi: 10.3969/j.issn.1672-0792.2016.11.012DAI Y Q, YE X M, LI C X. Effect of surface tension on droplet dynamics in the presence of electric field[J]. Electric Power Science and Engineering, 2016, 32(11): 66–73. doi: 10.3969/j.issn.1672-0792.2016.11.012 [11] DE GOEDE T, DE BRUIN K, SHAHIDZADEH N, et al. Droplet splashing on rough surfaces[J]. Physical Review Fluids, 2021, 6(4): 043604. doi: 10.1103/physrevfluids.6.043604 [12] CHOWDHURY I U, MAHAPATRA P S, SEN A K. Shape evolution of drops on surfaces of different wettability gradients[J]. Chemical Engineering Science, 2021, 229: 116136. doi: 10.1016/j.ces.2020.116136 [13] DAI Q W, HUANG W, WANG X L. Contact angle hysteresis effect on the thermocapillary migration of liquid droplets[J]. Journal of Colloid and Interface Science, 2018, 515: 32–38. doi: 10.1016/j.jcis.2018.01.019 [14] HAO J G, LU J, LEE L N, et al. Droplet splashing on an inclined surface[J]. Physical Review Letters, 2019, 122(5): 054501. doi: 10.1103/physrevlett.122.054501 [15] STANTON D W, RUTLAND C J. Modeling fuel film formation and wall interaction in diesel engines[C]//Proc of the SAE Technical Paper Series, 400 Commonwealth Drive. 1996: 808-824. doi: 10.4271/960628 [16] O'ROURKE P J, AMSDEN A A. A spray/wall interaction submodel for the KIVA-3 wall film model[C]//Proc of the SAE Technical Paper Series, 400 Commonwealth Drive. 2000: 281-298. doi: 10.4271/2000-01-0271 [17] HAN Z, XU Z, TRIGUI N. Spray/wall interaction models for multidimensional engine simulation[J]. International Journal of Engine Research, 2000, 1(1): 127–146. doi: 10.1243/1468087001545308 [18] KUHNKE D. Spray / Wall-interaction modelling by dimensionless data analysis [M]. Germany: Shaker Verlag GmbH, 2004. [19] ZHANG Z S, LIU X Y. Control of ice nucleation: freezing and antifreeze strategies[J]. Chemical Society Reviews, 2018, 47(18): 7116–7139. doi: 10.1039/c8cs00626a [20] JU J J, YANG Z G, YI X, et al. Experimental investigation of the impact and freezing processes of a hot water droplet on an ice surface[J]. Physics of Fluids, 2019, 31(5): 057107. doi: 10.1063/1.5094691 [21] SCHREMB M, ROISMAN I V, TROPEA C. Normal impact of supercooled water drops onto a smooth ice surface: experiments and modelling[J]. Journal of Fluid Mechanics, 2018, 835: 1087–1107. doi: 10.1017/jfm.2017.797 [22] 尚宇恒, 白博峰, 侯予, 等. 液滴撞击过冷壁面的结冰特性实验研究[J]. 西安交通大学学报, 2021, 55(10): 144–149. doi: 10.7652/xjtuxb202110016SHANG Y H, BAI B F, HOU Y, et al. Experimental research for freezing characteristics of droplets impacting on supercooled surface[J]. Journal of Xi’an Jiaotong University, 2021, 55(10): 144–149. doi: 10.7652/xjtuxb202110016 [23] YAWS C L, RICHMOND P C. Surface tension—organic compounds[M]//Thermophysical Properties of Chemicals and Hydrocarbons. Amsterdam: Elsevier, 2009: 686-781. doi: 10.1016/b978-081551596-8.50026-2 [24] KATRITZKY A R, CHEN K, WANG Y L, et al. Prediction of liquid viscosity for organic compounds by a quantitative structure-property relationship[J]. Journal of Physical Organic Chemistry, 2000, 13(1): 80–86. doi:10.1002/(SICI)1099-1395(200001)13:1<80::AID-POC179>3.0.CO;2-8 [25] RIBOUX G, GORDILLO J M. Experiments of drops impacting a smooth solid surface: a model of the critical impact speed for drop splashing[J]. Physical Review Letters, 2014, 113(2): 024507. doi: 10.1103/PhysRevLett.113.024507 [26] IBRAHIM E A. Spatial instability of a viscous liquid sheet[J]. Journal of Propulsion and Power, 1995, 11(1): 146–152. doi: 10.2514/3.23852 [27] PALACIOS J, HERNÁNDEZ J, GÓMEZ P, et al. Experimental study of splashing patterns and the splashing/deposition threshold in drop impacts onto dry smooth solid surfaces[J]. Experimental Thermal and Fluid Science, 2013, 44: 571–582. doi: 10.1016/j.expthermflusci.2012.08.020 [28] REIN M, DELPLANQUE J P. The role of air entrainment on the outcome of drop impact on a solid surface[J]. Acta Mechanica, 2008, 201(1): 105. doi: 10.1007/s00707-008-0076-9 [29] XU L, ZHANG W W, NAGEL S R. Drop splashing on a dry smooth surface[J]. Physical Review Letters, 2005, 94(18): 184505. doi: 10.1103/PhysRevLett.94.184505 [30] 崔宇航, 卫海桥, 王祥庭, 等. 高海拔模拟环境下柴油机燃烧粗暴可视化试验研究[J]. 天津大学学报(自然科学与工程技术版), 2022, 55(4): 383–390. doi: 10.11784/tdxbz202103051CUI Y H, WEI H Q, WANG X T, et al. Optical experiments on diesel knock under simulated high-altitude conditions[J]. Journal of Tianjin University (Science and Technology), 2022, 55(4): 383–390. doi: 10.11784/tdxbz202103051 [31] BINESH A R, MOUSAVI S M, KAMALI R. Effect of temperature-dependency of Newtonian and non-Newtonian fluid properties on the dynamics of droplet impinging on hot surfaces[J]. International Journal of Modern Physics C, 2015, 26(9): 1550106. doi: 10.1142/s0129183115501065 [32] KOBAYASHI K, KONNO K, YAGUCHI H, et al. Early stage of nanodroplet impact on solid wall[J]. Physics of Fluids, 2016, 28(3): 032002. doi: 10.1063/1.4942874 [33] TABAKOVA S, FEUILLEBOIS F, MONGRUEL A, et al. First stages of drop impact on a dry surface: asymptotic model[J]. Zeitschrift Für Angewandte Mathematik Und Physik, 2012, 63(2): 313–330. doi: 10.1007/s00033-011-0169-5 [34] LEI J L, LI J W, LIU Y. Ethanol drop impingement on ultracold surfaces under low-temperature cold-start conditions of engines[J]. Fuel, 2022, 311: 122573. doi: 10.1016/j.fuel.2021.122573 [35] 春江, 王瑾萱, 徐晨, 等. 液滴撞击超亲水表面的最大铺展直径预测模型[J]. 物理学报, 2021, 70(10): 106801. doi: 10.7498/aps.70.20201918CHUN J, WANG J X, XU C, et al. Theoretical model of maximum spreading diameter on superhydrophilic surfaces[J]. Acta Physica Sinica, 2021, 70(10): 106801. doi: 10.7498/aps.70.20201918 -
点击查看大图
计量
- 文章访问数: 177
- HTML全文浏览量: 119
- PDF下载量: 18
- 被引次数: 0
