刘明海,李书义,郭峰,梁鹏,安钰坤.润湿梯度表面限量润滑油挤压铺展与回流特性仿真研究[J].表面技术,2025,54(1):181-190.
LIU Minghai,LI Shuyi,GUO Feng,LIANG Peng,AN Yukun.#$NP Simulation Study on Squeeze Spreading and Reflux Characteristics of Limited Lubricating Oil on Wetting Gradient Surfaces[J].Surface Technology,2025,54(1):181-190 |
| 润湿梯度表面限量润滑油挤压铺展与回流特性仿真研究 |
| #$NP Simulation Study on Squeeze Spreading and Reflux Characteristics of Limited Lubricating Oil on Wetting Gradient Surfaces |
| 投稿时间：2024-01-08 修订日期：2024-03-29 |
| DOI：10.16490/j.cnki.issn.1001-3660.2025.01.017 |
| 中文关键词: 润湿性梯度 挤压铺展 回流 限量润滑油 数值模拟 动网格 |
| 英文关键词:wetting gradient squeeze spreading reflux limited lubricating oil numerical simulation dynamic mesh |
| 基金项目:国家自然科学基金项目(52175173，52375190) |
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| Author | Institution |
| LIU Minghai | School of Mechanical & Automotive Engineering, Qingdao University of Technology, Shandong Qingdao 266520, China |
| LI Shuyi | School of Mechanical & Automotive Engineering, Qingdao University of Technology, Shandong Qingdao 266520, China |
| GUO Feng | School of Mechanical & Automotive Engineering, Qingdao University of Technology, Shandong Qingdao 266520, China |
| LIANG Peng | School of Mechanical & Automotive Engineering, Qingdao University of Technology, Shandong Qingdao 266520, China |
| AN Yukun | School of Mechanical Engineering, Shandong University of Technology, Shandong Zibo 255000, China |
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| 中文摘要: |
| 目的 机械运动副中普遍存在着限量润滑油受挤压铺展与回流现象，其直接关系接触副供油状态，而表面润湿性是影响润滑油流动的关键因素，进而对接触副润滑性能产生重要影响。基于此，十分有必要研究润湿性梯度表面润滑油流动特性，并揭示其运行机制。方法 基于VOF模型结合动网格技术，建立微量润滑油在润湿梯度表面挤压铺展与回流动态模型，运用数值模拟方法，探索亲油轨道两侧疏油区接触角、轨道宽度、润滑油黏度对油滴铺展与回流过程的影响。结果 润湿性梯度表面的润滑油在受挤压后快速铺展，而一旦挤压作用消失润滑油就会自动回流，并且在回流阶段发现润滑油内部存在较大的压力梯度与速度漩涡。通过调整疏油区接触角(从67°至130°)改变轨道两侧疏油程度，发现润滑油最大铺展系数β与最大润湿面积An分别减小23.6%和14.3%，液膜中心高度系数hn增长时间点提前57.2%，完全回流时间减小76.9%。通过增加轨道宽度，发现无量纲轨道宽度wn从0.8增至1.4时，最大β与hn增长时间点保持稳定，但最大An增大64.2%，完全回流时间减小39.4%。在润滑油物性参数方面，增大润滑油黏度(从0.032 Pa.s至0.108 Pa.s)时，最大β与最大An分别减小13.5%和12.9%，但hn增长时间点延后72.2%，完全回流时间延长58.3%。此外，低黏度区间内，虽然相邻黏度值增幅最小(0.032 Pa.s至0.046 Pa.s)，但润滑油回流速度与An减小速度降幅最大。结论 润湿性梯度表面可以抑制润滑油铺展，促进回流，其中内部压力梯度是回流的主要原因之一。随着轨道两侧疏油程度增加，抑制铺展和促进回流的效果进一步增强，回流速度增大，完全回流时间减小。增大亲油轨道宽度可提升稳定后的润湿面积，缩短完全回流时间，但轨道宽度过大导致油液分布过于分散，过小则使回流时间延长。此外，在低黏度区间，润湿性梯度表面对润滑油回流影响更显著，润滑油黏度增大导致最大铺展系数与最大无量纲润湿面积均减小，回流距离缩短，液膜中心高度系数增长点相对延后，完全回流时间延长。 |
| 英文摘要: |
| In mechanical motion pairs, the phenomenon of limited lubricating oil undergoing squeeze spreading and reflux is prevalent, directly influencing the lubrication supply state in the contact pairs. The surface wetting property emerges as a critical factor impacting the flow of lubricating oil, and consequently plays a pivotal role in the lubrication performance of the contact pairs. Therefore, it is imperative to investigate the flow characteristics of lubricating oil on surfaces with wetting gradients and unveil their operational mechanisms. Utilizing the Volume of Fluid (VOF) model in conjunction with dynamic mesh techniques, a dynamic model was established for the squeeze spreading and reflux of minute lubricating oil droplets on surfaces with wetting gradients. Numerical simulation methods were employed to explore the effects of the contact angle on the oleophilic track's outer side, track width, and lubricating oil viscosity on the processes of droplet spreading and reflux. The lubricating oil on surfaces with wetting gradients rapidly spread after being subject to pressure. Once the pressure diminished, the lubricating oil automatically underwent reflux. During the reflux phase, significant pressure gradients and velocity vortices were observed within the lubricating oil. By adjusting the contact angle of the oleophobic region (from 67° to 130°), the degree of oleophobicity on both sides of the track was altered, the maximum spreading coefficient β and the maximum wetted area An decreased by 23.6% and 14.3%, respectively. The growth time point of the height coefficient hn advanced by 57.2%, and the complete reflux time decreased by 76.9%. Increasing the track width revealed that, as the dimensionless track width wn increased from 0.8 to 1.4, the maximum β and hn growth time point remained stable, while the maximum An increased by 64.2%, and the complete reflux time decreased by 39.4%. Concerning the physical properties of the lubricating oil, the increase in lubricating oil viscosity (from 0.032 Pa.s to 0.108 Pa.s) resulted in a reduction of 13.5% in both the maximum β and the maximum An. However, the hn growth time point was delayed by 72.2%, and the complete reflux time was extended by 58.3%. Furthermore, within the low viscosity range, even though the smallest viscosity increment occurred between adjacent viscosity values (0.032 Pa.s to 0.046 Pa.s), the reflux velocity and the rate of decrease in An were the most pronounced. In conclusion, surfaces with wetting gradients can inhibit lubricating oil spreading and promote reflux, with internal pressure gradients being one of the primary reasons for reflux. As the degree of oil repellency increases on both sides of the track, the inhibitory effect on spreading and the promoting effect on reflux are further enhanced, leading to an increase in reflux velocity and a reduction in complete reflux time. Enlarging the oleophilic track width enhances the stabilized wetted area and shortens the complete reflux time. However, excessively wide tracks lead to overly dispersed oil distribution, while excessively narrow tracks prolong reflux time. Additionally, within the low viscosity range, wetting gradient surfaces exhibit a more pronounced impact on lubricating oil reflux. An increase in lubricating oil viscosity results in a decrease in both the maximum spreading coefficient and the maximum dimensionless wet area. This leads to a shorter reflux distance, a relatively delayed point of growth in the height coefficient of the liquid film center, and an extension of the complete reflux time. |
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